A hip roof is one of the types of roofs that has four slopes. But at the same time, two slopes are made in the shape of a trapezoid, and the other two are triangular (instead of pediments), which are also called hips. Hence the name - hip roof. The main thing is that the end slopes occupy the entire space from the cornice to the ridge. If they do not reach the eaves, then such a roof will be called half-hip. If a hip roof is cut, then in this projection it will look like an ordinary triangular gable roof.
Hip roof- rafter system
A hip roof is not only durable protective structure for a building, it is also intended for its decoration, and is also capable of giving it a special charm and personality.
On a note! In Russia, more often are used simple options roofs - for example, gable. But in Europe, hip roofs are very widespread. However, in our country we can see such roofs in last years possible more and more often.
Advantages hip roof are primarily as follows:
- beautiful appearance;
- excellent protection of the structure from the effects of precipitation;
- high strength and ability to withstand wind and snow loads;
- the hip roof structure is very rigid due to the presence of corner ribs;
- such a roof can have far protruding overhangs, and this is additional protection buildings from precipitation.
But, as usual, even the best option always has its drawbacks. For example, a hip roof is a rather complex structure, so it’s difficult to install it. Due to the fact that more material is spent on it, it will cost more than a regular gable. It is also important to understand that the attic space underneath will be small due to the installation of additional supports. Therefore, by the way, it is impossible to create a full-fledged attic under such a roof. In general, in a number of cases these shortcomings are not critical, and the hip roof is equipped Lately Often.
The design of such a roof
As already mentioned, such a roof has complex design. And first of all, the difficulty lies in the fact that the roof has a lot of fastening points, components, which will be extremely difficult for a person without experience to install into a single system. The hip roof design includes the following elements.
- Mauerlat as the basis and support for the entire system. It is made, as a rule, from powerful timber with a cross-section of 10x10 or 15x15 cm. The Mauerlat helps to evenly distribute the weight of the entire roof along the perimeter of the building. And it is to this that the rafter legs are attached during the construction process.
- Lezhnya- a relative of the Mauerlat, which is mounted on internal partitions and has the same function as its brother. It is also made of timber, usually with a section of 10x10 cm.
- Ridge run is a support beam for the upper parts of the rafters. Vertical support posts are installed under it.
- Rafters diagonally oriented in the amount of four pieces they help to form just the hip slopes. Such rafters are fixed so that they continue the ridge, but at the same time diverge towards the corners of the house. Fixation is carried out on the ridge and Mauerlat. They must be very strong and thick, as they are subject to a lot of stress. These are very long rafters.
- Ordinary rafter legs are supported by trapezoidal slopes. As a rule, they are made from boards with a cross-section of 5x15 or 10x15 cm. They are fixed on top to the ridge, and from below to the mauerlat. The distance between adjacent legs is from 60 to 120 cm.
- There are also shortened rafters - narozhniki, - which are attached to the mauerlat and diagonal rafters. A distance of 70-80 cm is established between adjacent roof panels. They do not experience heavy loads, but are indispensable when creating a hip roof. The spigots are mounted either by cutting or by installing support bars for half-legs.
- Racks, acting as supports, are made of timber and installed on a bench. Their purpose is to support the rafters or the ridge in the middle.
- Between the elements of each pair of rafters are installed puffs, which act as horizontal jumpers. They help to pull the rafters towards each other and reduce the load on the walls. The tie in the ridge area is called a crossbar, and the one below can be used as a floor beam.
- Rafter legs or struts are installed at a certain angle to the rafters themselves and help them not to bend under their own weight.
- Vertical supports or trusses needed to support diagonally located rafters. They have the shape of an upside down letter T. The base of the truss should be perpendicular to the slanted rafters.
Important! Some of the hip roof parts can be very long, depending on the size of the roof itself. But all lumber is limited in size. In this case, you can use typesetting or glued rafters.
Also, a hip roof, like any other type of roof, must be equipped with a water drainage system. Snow guards and other additional elements can be installed.
Types of rafter systems and hip roofs
Hip roofs depending on their design features may have a different rafter system, and also belong to a certain type of roof. The table below shows the types of hip roofs.
Table. Types of hip roofs.
| Variety | Description |
|---|---|
| The overhangs of such a roof are at the same height relative to each other. The pediments have the shape of a triangle, the slopes are trapezoidal. Diagonal ribs rest on the ridge. |
| This roof has vertical gables; windows can be inserted into them to improve lighting. attic space. |
| This type of roof does not have a supporting ridge beam. Diagonal rafters converge at one point, then ordinary ordinary elements are installed. An ideal roofing option if the house has a square shape. But making a ridge unit in the center of the roof is very, very difficult. |
| This is the most complex version of such a roof. Here the rafter system is very complex, since all the slopes differ in area and angles of location. But inside under the roof you can in interesting ways use the free space, and make the house spectacular and memorable. |
Also, a hip roof may have different rafter systems as a whole.
- Hanging when the rafters rest on the ridge and the mauerlat. Here there is a large load on deflection and expansion. So you will have to install tightening. It is not recommended to use this version of the rafter system for a hip roof. But the system can be used for buildings no more than 6 m wide.
- Layered when the rafters rest on the mauerlat, ridge and stand installed in the middle on the supporting interior wall. The load on the system in this case is less. It is reliable and durable option, and even easier to install. This option is suitable for buildings up to 12 m wide or more, depending on the number of additional supporting elements.
- Combined system has both hanging and layered elements. All beams will be visible, they will not be covered by the sheathing, since the racks in this case rest on columns or pillars, and not on internal partitions.
Materials and calculations
You can create a rafter system for a hip-type roof from either wood or metal. For independent work, wood is preferable, since it is much easier to make anything from it. A good option- pine. It is light, durable and low cost.
Important! In order for the tree to serve for a long time, before work it is important to treat it with special protective compounds, which will help prevent the onset of the rotting process.
If the rafter system is made of metal, then it is important to choose a galvanized version, which will be able to resist corrosion and will last for many years, and can also withstand heavy loads.
The most difficult thing in creating a hip roof is its correct calculation. It is important to take into account not only the size of the house, but also the wind load in the region, the amount of precipitation during the year, the type of material from which the roof will be made, as well as the need for installation additional elements, performing insulation work, etc.
In any case, the calculation is made according to certain formulas. And here it is important to consider optimal slope roofs. You can select it based on the table. The slope will also help you navigate with regard to the laying of the rafters.
Table - roof inclination angle depending on roofing material
The distance between the rafters can be seen in the table below.
Calculation of rafter cross-section
The laying of the rafters and the relationship between their lengths can be calculated using the coefficients in the table below.
So, the formulas used to calculate a hip roof are as follows:
- H = D*tan a / 2, where H is the height of the ridge, D is the width of the house, and is the angle of inclination of the slope;
- L = l – D, where L is the length of the ridge, l is the length of the building, D is the width of the house;
- L c = H 2 +d 2, where L c is the length of the central rafters. Ordinary rafters are calculated in the same way;
- ∆L = k/cos a, where ∆L is the required length of the rafter extension for the overhang;
- B = 90 0 – a, where b is the slope of ordinary elements;
- LD = √(L 2 + d 2), where LD is the diagonal length of the shaft rafters;
- L1 = 2/3L and L2 = 1/3L, where L1 and L2 are the length of the spigots (the first short and the second short);
- The roof area can be calculated as ∑L * (2B + 4k).
The result of all calculations can be a detailed drawing of a hip roof indicating all the dimensions and parameters that will simply need to be transferred to the roofing material. By the way, based on these calculations, it will be possible to calculate how much you need to buy in order to make such a roof yourself.
Important! After self-creation drawing, it is strongly recommended that the diagram be checked by experienced specialists. Errors made in calculations can lead to dire consequences.
Hip roofing is one of the types hipped roof, its design includes two main trapezoidal and two end triangular slopes, forming a closed surface with a common ridge run. If the side slopes are located over the entire area from the ridge to the eaves, then the roof is called hip, and if they do not reach the eaves - half-hip.
Types of rafter structures for hip roofs
If the rafter structure rests only on the main walls of the building, it is called hanging, and if it has additional support points due to the walls inside the house, then it is called layered.
If the rafter system rests only on the external load-bearing walls of the building, it is called hanging
If the building has two main walls, then a tension beam is laid at the top of the vertical posts, which strengthens the rafters and distributes the load over the entire area of the vertical support posts.
To create a hip roof, a layered rafter system is most suitable, since it has a greater degree of strength and makes it possible to lighten the roof structure, evenly distributing its weight over the entire building frame.
The hip roof rafter system can have several structures with different installation methods, each of which requires certain features during assembly.
- Traditional rafter system. In this design, the diagonal ribs rest on the main ridge support beam, and the overhangs are at the same height. This system consists of two isosceles triangles and two trapezoids.
The rafter system of a classic hip roof consists of two triangles and two trapezoids
- Tent system. This design does not provide for the presence of a supporting ridge beam, because it is installed above buildings square shape and consists of four identical triangular-shaped slopes. All diagonal ribs converge at a common point, and short spigots are connected to them. Only professionals can make a reliable ridge unit for a hip roof.
The hip rafter system consists of four triangular slopes, converging at their upper parts to one point
- Half hip design. This system provides for the presence of vertical parts in the gable slopes, into which standard windows can be installed.
The half-hip roof has vertical sections of gables into which ordinary windows can be inserted
- Broken roof (attic). This is the most complex and labor-intensive hip roofing system, since all slopes have different shapes and areas and diverge from each other under different angles. Such a roof allows you to make the most efficient use of the area under the roof and create additional living quarters on it.
A broken or attic roof structure allows you to equip full-fledged living quarters in the under-roof space
How to calculate a rafter system for a hip roof
When calculating the design of hip roof rafters, the following factors must be taken into account.
- Degree of regional wind load. The larger it is, the smaller the roof slope angle should be and the stronger the system. The main supporting rafters must be made of thick timber.
- Amount of precipitation. The more precipitation falls annually, the steeper the roof slopes should be in order to avoid large pressure on the rafter structure.
- Material for covering the roof of a house. Depending on the type and weight of the roofing material used, the lathing system is selected. This factor is taken into account at the development stage of the house project.
- Thermal insulation of the roof. The width of the insulation, the grade and thickness of the timber are taken into account when calculating the installation pitch of the rafters.
- Roof inclination angle. The slope of the roof affects the choice of finishing material.
Each roofing material has its own permissible range of roof slope angles
The angle of inclination of the roof slope determines the position of all rafters. The installation location of the intermediate rafters is calculated as follows:
- A center line is drawn on the top beam of the side wall.
- The middle of the ridge beam is determined by thickness and the location line of the first of the center intermediate rafters is marked.
- The end of the measuring strip is connected to the location line of the previously marked center support rafter.
- At the other end of the plank, the line for the location of the internal contour of the end wall is marked.
- The point obtained at the previous stage will be the installation location for the intermediate rafter.
The relationship between the size of the rafters and the length of their laying (horizontal projection) is determined using a correction factor, the value of which is directly proportional to the angle of inclination of the slope. If you multiply the size of the laying by this coefficient, you can determine the exact length of the rafters.
Table: correction factors for determining the length of rafters
| Slope roof slope | Coefficient for intermediate rafter | Coefficient for corner rafter |
| 3:12 | 1,031 | 1,016 |
| 4:12 | 1,054 | 1,027 |
| 5:12 | 1,083 | 1,043 |
| 6:12 | 1,118 | 1,061 |
| 7:12 | 1,158 | 1,082 |
| 8:12 | 1,202 | 1,106 |
| 9:12 | 1,25 | 1,131 |
| 10:12 | 1,302 | 1,161 |
| 11:12 | 1,357 | 1,192 |
| 12:12 | 1,414 | 1,225 |
Formulas for calculating rafter structures
In the process of developing a project for any roof, you should determine the exact angle of inclination of the slope, which is necessary for all subsequent calculations.
Calculation of hip roof area
The roof area is calculated as follows:
- We determine the height of the ridge using the formula h = d / 2 · tg α (where d is the width of the building, α is the angle of inclination of the slope, h is the height of the ridge).
- We calculate the size of the side rafters using the formula c = d / 2 · cos α.
- Find the length of the diagonal rafters l = √(h 2 + d 2 /4).
- We calculate the area of the roof by adding up the areas of all structural elements (two trapezoids and two triangles):
- area of the triangular slope S 1 =1/2 · d/2 · c;
- area of the trapezoidal slope S 2 = 1/2 · (b + k) · e, where b is the length of the cornice, k is the length of the ridge girder, e is the height of the trapezoidal slope;
- S = 2 (S 1 + S 2).
To determine the area of a hip roof, it is necessary to use formulas for the area of simple geometric shapes: triangles and trapezoids
Calculation of the distance between rafters
Most rafter systems are created with a pitch between two rafters of 1000 mm. Minimum valid value pitch is 600 mm.
- We select the approximate distance between the rafters, guided by standard dimensions (for example, let’s take this parameter equal to 0.8 m).
- We measure or take from project documentation slope length. Let's say it is 12 m.
- We divide the length of the slope by the previously selected value of the rafter pitch, round the total up and add 1. We get 12 / 0.8 + 1 = 16.
- We divide the length of the slope by the number obtained in the third point. The final pitch of the rafters will be 12/16 = 0.75 m = 75 cm. The resulting value will be equal to the distance between the central axes of the rafter joists.
Preparatory work
The rafter system drawing is prerequisite when constructing this type of roof, since there are no identical schemes that are ready for immediate use without taking into account the specific type of building and the location of its construction.
The more difficult roofing system, the more accurate the calculations must be, since they will affect not only the quality of the work performed, but also their cost.
The drawing of the main components of the structure must accurately indicate the dimensions of all elements of the rafter system, the location of the junction points of the diagonal posts to the ridge beam and the places where the rafters are attached to the mauerlat.
Tools required to assemble the structure:
- construction level;
- hacksaw;
- large hammer;
- long tape measure;
- construction cord;
- stapler;
- electric drill;
- riveter;
- metal cutting shears;
- nails;
- measuring bar.
Materials for work:
When installing a hip roof on a house made of timber that shrinks, experts recommend using special floating fasteners for the rafters to compensate for the movement of the crowns.
When installing a rafter system in wooden house recommended to use sliding system fastening of rafters, which compensates for the deformation of the building during its shrinkage
Video: ensuring the rigidity of a hip roof
Features of the hip roof rafter system
All types of hip roof truss systems have identical parts that create the frame of the structure:
Video: assembling rafters
Technology for creating a hip rafter system
Since a large load is placed on the roof truss structure, all components and connections must be made in strict accordance with the technology, otherwise the roof will not be able to fully perform its functions.
Installation of main components
Installation of units comes down to the following steps:
- We prepare the rafters. We determine the angle of inclination of the rafters, the length of short supports and slanted rafters, which carry a significant load. In order to obtain all the elements of the required length, we use the method of overlapping boards. To do this, we lay two boards on top of each other with an overlap of 1 m and fasten them with nails arranged in a checkerboard pattern. This is the simplest and most durable method of splicing rafter legs.
The most durable and reliable method splicing of rafter legs is an overlapping fastening
- We fasten the Mauerlat. We install timber along the entire perimeter of the walls of the building in the upper part. We overlap the timber using a large number of attachment points with the base of the load-bearing walls. We fasten the connection nodes with metal staples.
The Mauerlat beam is attached to the upper end of the wall using anchor bolts
- We lay a layer of roofing felt between the wall and the timber to create a water barrier. In brick, aerated concrete, foam concrete and wood concrete houses, a reinforced concrete belt with pre-fixed pins for installing the timber is poured under the Mauerlat. The pin must have a diameter of at least 10 mm and protrude approximately 30 mm beyond the belt. The pitch between the pins is from 1 to 2 m.
A layer of roofing material creates a water barrier between the Mauerlat and the wall made of moisture-absorbing material
- Installing the bed - central beam between the two short sides of the mauerlat to provide additional strength under the rafters. Such a run is necessary to create a hip roof of a large area.
- We install support posts. They act as supports for the ridge girder.
Support posts are mounted on the bed and serve as supports for the ridge girder
- We install the ridge beam. When installing the ridge of a hip roof, accurate measurements should be taken, since it will support the entire roofing system. We check the accuracy of its installation with a level in height.
Carrying out work on the installation of a ridge beam requires accurate measurements, since it carries the greatest load in a hip roof system
- We nail the rafter legs. We install the central rafters, and after them the diagonal ones. During installation, we rest the lower part of the beams against the Mauerlat. This can be done in two ways: with a cutout or with support posts. In the first case, we cut a groove in the Mauerlat, insert the rafters into it and secure them with metal corners. In the second case, we simply place the rafter on the mauerlat and place a block with an oblique cut under it. We also secure them using metal corner.
Rafter legs can be attached to the mauerlat in two ways: with a notch and on a support block
- We install the unit on the ridge beam using the “half-tree” method. To do this, we cut out a notch at the end of the rafter legs, which should be equal to half the thickness of the board. Then we connect these recesses to each other and secure them with nails or dowels. The result is a strong ridge knot. For greater strength, all nodes are secured with steel corners.
To create a durable ridge assembly on a hip roof, the “half-tree” cutting method is used.
- There is a lot of pressure on the diagonal rafters, so we strengthen them with the help of racks that we mount on the ceiling or install struts at a certain angle. You can use a sprengel in the form of a T-shaped beam rotated 180°.
Sprengel is one of auxiliary elements to ensure the necessary rigidity of the rafter system, transferring part of its load to the Mauerlat
- We install ordinary rafters in the same way as the central ones, forming the edges of the trapezoidal structure. We support the bottom of the beam and fasten it to the mauerlat, and rest the top against the ridge beam.
- We install spigots, which we make from a solid board. In the place where they are attached to a long rafter, we make special notches or install support beams and provide the necessary strength with the help of metal fastenings. To simplify the work, the spigots can be installed staggered.
The flanges are attached using a notch into the rafter beam and are installed in a checkerboard pattern
All wooden parts Before assembly, the rafter system is treated with special fireproof and antiseptic agents.
Video: hip roof rafter system
Creating a hip truss structure is a long and complex process that requires attention to every specific detail. But if you carry out all stages of work correctly and accurately, then as a result you will get a beautiful, durable and reliable roof for your home.
We have already talked about the hip roof on the website. There the roof structure was described with the rafters resting on the mauerlat. After publishing the article, I received many requests to show how to make a hip roof with rafters supported on floor beams, and also to answer the question whether it is possible to make a hip roof with different slope angles.
Thus, I wanted to “kill two birds with one stone” with one example. Now we will look at the design of a hip roof with the rafters supported on the floor beams and with different slope angles.
So, let's say we have a house box of 8.4x10.8 meters.
STEP 1: Install the Mauerlat (see Fig. 1):
Picture 1
STEP 2: We install long floor beams with a cross section of 100x200 cm in increments of 0.6 meters (see Fig. 2). I won't dwell on it any further.
Figure 2
The very first to install are the beams that run strictly in the middle of the house. We will be guided by them when installing the ridge beam. Then we put the rest with a certain step. For example, we have a step of 0.6 meters, but we see that there are 0.9 meters left to the wall, and another beam could fit, but it doesn’t. We leave this span specifically for “removals”. Its width should not be less than 80-100 cm.
STEP 3: We install the stem. Their pitch is determined when calculating the rafters, about which a little later (see Fig. 3):
Figure 3
For now we are installing only the stems corresponding to the length of the ridge, which will be equal to 5 meters. Our ridge length is greater than the difference between the length and width of the house, which is 2.4 meters. What does this lead to? This leads to the fact that the corner rafter will not be located at an angle of 45° in plan (in the top view), and the angle of inclination of the slopes and hips will be different. The slopes will have a gentler slope.
It is enough to secure the stem on the Mauerlat with nails. We attach them to a long floor beam, for example, like this (Fig. 4):
Figure 4
There is no need to make any cuts in this node. Any cut will weaken the floor beam. Here we use two LK type metal rafter fasteners on the sides and one large nail (250 mm) driven through the beam into the end of the extension. We hammer in the nail very last, when the stem is already fastened to the Mauerlat.
STEP 4: Install the ridge beam (see Fig. 5):
Figure 5
All elements of this structure except the struts are made of 100x150 mm timber. Struts made of boards 50x150 mm. The angle between them and the ceiling is at least 45°. We see that under the outer posts there are beams resting directly on five floor beams. We do this to distribute the load. Also, to reduce the load on the floor beams and transfer part of it to the load-bearing partition, struts were installed.
We determine the installation height of the ridge beam and its length for our home ourselves, making a preliminary sketch on paper.
STEP 5: We manufacture and install rafters.
First of all, we make a template for the rafters. To do this, take a board of suitable length the required section, apply it as shown in Figure 6 and make markings using a small level (blue line):
Figure 6
The height of the block that we placed on the stem to mark the lower cut is equal to the depth of the upper cut. We made it 5 cm.
Using the resulting template, we make all the rafters of the slopes, resting on the ridge beam, and secure them (see Fig. 7):
Figure 7
IN similar designs, where the rafters rest not on long floor beams, but on short extensions, we always place small supports under the rafters above the mauerlat, forming, as it were, a small triangle and unloading the attachment point of the extension to the beam (see Fig. 8):
Figure 8
There is no need to bring these supports further inside the roof, much less place them at the junction of the extension with the beam. Most of the load from the roof is transmitted through them (this can be seen in the calculation program) and the floor beam may simply not withstand it.
Now a little about calculations. When choosing the section of rafters for a given roof, we calculate only one rafter - this is the slope rafter. It is the longest here and its angle of inclination is less than the angle of inclination of the hip rafters (explanation - we call a roof slope in the shape of a trapezoid a slope, a hip - a roof slope in the shape of a triangle). Calculations are made in the “Sling.3” tab. Example results in Figure 9:
Figure 9
Yes, I forgot to say. Who has already downloaded this calculation program from my website before December 1, 2013? There is no “Sling.3” tab. To download the updated version of the program, go to the article again at the link:
This article has also been slightly adjusted thanks to feedback from some readers, for which special thanks to them.
STEP 6: We add an extension and attach wind boards (see Fig. 10). We add enough stems to leave room for attaching the corner stem. For now, we simply sew the wind boards at the corners together, controlling their straightness. Check visually to see if the corners are sagging. If so, place temporary supports under them directly from the ground. After installing the corner extensions, we remove these supports.
Figure 10
STEP 7: We mark and install corner offsets.
First we need to pull the string along the top of the floor beams, as shown in Fig. 11
Figure 11
Now we take a beam of suitable length (the cross-section is the same as for all stems) and place it on top of the corner so that the lace is in the middle of it. From below on this beam we mark the cut lines with a pencil. (see Fig. 12):
Figure 12
We remove the lace and install the timber sawn along the marked lines (see Fig. 13):
Figure 13
We attach the corner extension to the Mauerlat using two roofing corners. We fasten it to the floor beam with a 135° angle and a large nail (250-300 mm). If necessary, bend the 135° corner with a hammer.
This way we install all four corner offsets.
STEP 8: We manufacture and install corner rafters.
The hip roof that I described earlier had the same angles of slope and hips. Here these angles are different and therefore the corner rafter will have its own characteristics. We also make it from two boards of the same section as the rafters. But we sew these boards together not quite usually. One will be slightly lower than the other (about 1 cm, depending on the difference in the angles of inclination of the slopes and hips).
So, first of all, we pull 3 laces on each side of the roof. Two along the corner rafters, one along the middle hip rafter (see Fig. 14):
We measure the angle between the lace and the corner stem - the bottom cut. Let's call it “α” (see Fig. 15):
Figure 15
We also mark point “B”
We calculate the angle of the upper cut β = 90°- α
In our example α = 22° and β = 68°.
Now we take a small piece of board with the cross-section of the rafters and saw one end on it at an angle β. We apply the resulting blank to the ridge, combining one edge with the lace, as shown in Fig. 16:
Figure 16
A line was drawn on the workpiece parallel to the side plane of the adjacent rafter of the slope. We will make another cut using it and get a template for the top cut of our corner rafter.
Also, when we apply the workpiece, we need to mark point “A” on the rafters of the slope (see Fig. 17):
Figure 17
Now we make the first half of the corner rafter. To do this, take a board of suitable length. If one board is missing, we sew two boards together. You can sew it temporarily by cutting an inch about a meter long onto self-tapping screws. We make the top cut according to the template. We measure the distance between points “A” and “B”. We transfer it to the rafter and make the bottom cut at an angle “α”.
We install the resulting rafter and secure it (see Fig. 18):
Figure 18
Most likely, due to its length, the first half of the corner rafter will sag. You need to place a temporary stand under it approximately in the middle. It is not shown in my drawings.
Now we make the second half of the corner rafter. To do this, measure the size between points “C” and “D” (see Fig. 19):
Figure 19
We take a board of suitable length, make the top cut at an angle β, measure the distance “S-D”, make the bottom cut at an angle α. We install the second half of the corner rafter and sew it to the first with nails (100 mm). We drive the nails at intervals of approximately 40-50 cm. The result is shown in Fig. 20:
Figure 20
The upper end of the second half of the corner rafter needs to be sawed down again. We do this with a chainsaw right on the spot (Fig. 21):
Figure 21
In the same way, we manufacture and install the three remaining corner rafters.
STEP 9: We install racks under the corner rafters. First of all, it is imperative to install a stand resting on the junction of the corner extension with the floor beam (see Fig. 22):
Figure 22
If the length of the span covered by the corner rafter (its horizontal projection) is more than 7.5 meters, we install more racks at a distance of approximately ¼ of the span from the top point of the corner rafter. If the span is more than 9 meters, add racks in the middle of the corner rafter. In our example, this span is 5.2 meters.
STEP 10: We install two central hip rafters. At the beginning of the 8th step, we already pulled the laces to measure them.
We make the rafters in this way - we measure the angle of the lower gash “γ” with a small tool, calculate the angle of the upper gash “δ”:
δ = 90° - γ
We measure the distance between points “K-L” and make a rafter along it. We file the ends at the angles we have determined. After this, the upper end needs to be filed down (sharpened) again, taking into account the angle “φ”, which we also measure using a small tool (see Fig. 23):
Figure 23
STEP 11: Add offset to the corners. We make the outermost extensions, which do not reach the mauerlat, lightweight, from a 50x200 mm board (see Fig. 24):
Figure 24
STEP 12: We install spigots. I described in detail how to make spigots in the first article about. Here the principle is absolutely the same, so I will not repeat it (see Fig. 25):
Figure 25
We attach the corner rafters to the corner rafters using a 135° metal corner, bending it if necessary.
After installing all the frames, all we have to do is hem the cornices from below and make the sheathing. We have already talked about this many times.
The hip roof is perhaps the most popular type of hip roof. It is suitable for covering large and small private houses, bathhouses, even gazebos. A recognizable geometry is given to it by the rafter system, a set of supporting elements that work as a frame.
The complexity of this design lies in large quantities components and fastening units requiring special skills and experience. This article will answer questions about what it consists of, what materials are used for construction, and how installation work is performed.
Hip roof design
The hip roof is of the hipped type, that is, it is formed of four slopes, planes having one common side. The two slopes that replace the pediments are called hip or end slopes; they have a triangular shape. And the other two, in the form of trapezoids, are designated by the term façade. The line where all four slopes converge is the ridge, the highest part of the roof. The hip type design consists of:
- The hip slopes, which have the shape of a triangle, are located in the place belonging to the pediments.
- Facade slopes are trapezoidal in shape.
- Ridge, the line that forms the upper connection rafter pairs, peaks .
- An overhang, a part of the roof protruding beyond the perimeter of the house, formed by the length of the rafters or fillies. It protects the surface of the walls from melt and rain water.
- The rafter system of the hip roof, the frame supporting and distributing the weight of the roof structure.
- Roofing material, a covering that is laid on the rafters of a hip roof to protect against precipitation.
- Gutters, systems for removing water accumulating on the roof. It consists of a gutter, a water inlet and a downspout and carries moisture from the surface of the blood to the storm drain.
- Snow retainers, elements that prevent snow masses accumulated on the roof from collapsing and injuring people passing by.
Types of rafter system
The hip roof rafter system can be of three types, depending on how the rafters are positioned:
- Hanging.
- This means that the rafters are supported by two points: in the upper part on the ridge girder, and in the lower part on the mauerlat. A hanging rafter system experiences deflection, compression and expansion loads. All these forces have a destabilizing effect on it, so additional compensating elements are needed - tightening, crossbars, headstocks. They complicate the design and installation of a hip roof, so experienced roofers advise abandoning hanging rafters, if possible.
- Naslonnogo. With this type of hip roof rafter system, the rafters are supported at three points: at the top on the ridge, in the middle on the post, and at the bottom on the mauerlat. The racks are installed on internal load-bearing walls. Additional vertical supports reduce the deflection of the rafter legs and eliminate the bursting force. Therefore, the layered system is considered more reliable and stable than the hanging system, and also easier to install. Combined. This term means that the rafter system consists of alternating layered and hanging elements. This is possible if a pillar or column is used as support for the rack rather than an internal load-bearing partition. The roof turns out
open type
, that is, all beams and racks are not hidden by the skin, but are visible.
Important! Using a hanging rafter system, you can cover a structure no more than 6 meters wide. The use of layered rafters with one additional support increases this distance to 12 m, with two – up to 18 m.
Material used The hip roof truss system consists of many components, which are reflected in the drawing; they are made from the following materials:. And a reasonable price will reduce costs. Especially metal carcass roofs can only be afforded by those who are confident in the safety margin of the foundation.
System elements
Depending on the area and features of the layout of the house, the rafter system of the hip roof takes on different types, but its basis is made up of the following elements:
Note! Some elements of the hip roof rafter system are of considerable length. A standard size timber lumber is limited to six meters. To get out of this problematic situation, roofers make glued or stacked rafters, made up of two or three parts.
Mauerlat installation
Installation of the Mauerlat is the starting point for creating a rafter system for a hip roof. Correct installation will provide solid foundation for rafters. During the construction of a house made of timber or logs, the role of the Mauerlat is performed by the upper crowns. In buildings made of bricks and gas silicate blocks, it is secured as follows:
- On the upper section of the walls, formwork is installed and a concrete belt reinforced with reinforcement is poured into which metal studs are embedded.
- The Mauerlat timber is treated with a deep penetration antiseptic and holes are made in it for the studs. Moreover, the location of the holes is calculated in such a way that they do not coincide with the places where the rafter legs are attached, but are located between them.
- After the concrete belt hardens, which occurs within 2-3 days, waterproofing is installed on it. These functions are usually performed by roofing felt folded into two layers.
- The Mauerlat is laid on the waterproofing and secured with metal pins.
Please note that a large number of holes reduce the strength of the Mauerlat, provoke the appearance of cracks and defects, reducing its supporting functions. Remember, cuts under the rafters are never made in the mauerlat; its integrity must not be violated!
Assembly steps
The result of the calculation, made manually or by program, is recorded by creating a drawing that reflects the dimensions and mutual arrangement elements of the rafter system, and then begin to assemble it according to the following plan:
Competent calculations, detailed drawings and high-quality installation are the key to long service and reliability of the roof truss system.
Video instruction
Hip roofs give the building an elegant and complete appearance; its slopes withstand gusts of wind and snow load. An attic space can be placed under this type of roof large volume. We will talk about the features of the rafter group of hip roofs, about the methods of calculation and installation of rafters, as well as about the roofing pie, ventilation and insulation of the structure. Let us dwell on the description of the properties of roofing materials and tell you how to make a hip roof for a gazebo with your own hands.
Design features of hip roofs
Hip roofs give the building a certain chic, but the peculiarity of their design is that they perfectly withstand multidirectional wind influences. This is due to the rigid rafter system and the presence of triangular and trapezoidal slopes. Increasing the height of the ridge and the slope of the slopes makes it possible to place a habitable room under the hip roof.
The hip roof consists of two triangular and two trapezoidal slopes, which rest on a ridge girder
The following distinctive features can be considered as design features of hip roofs:
The unique rafter system determines the strength characteristics of hip roofs and their resistance to weather conditions.
Preparing a roof project
When preparing a hip roof project, it is necessary to determine the height of the ridge, since the angle of inclination and length of the slopes will depend on this parameter. For a habitable attic space, the ceiling height must be at least 2.3 meters in accordance with fire safety standards.
The angle of inclination of the slopes is associated with the choice of ridge height, since this parameter determines the volume of the comfortable living area
To prepare the project, after choosing the height of the ridge, it is necessary to take measurements that will help calculate the length of the rafters, the area of the slopes and the volume of the habitable room. To design a roof you will need the following parameters:
The developer determines whether the attic space will be cold or habitable, because the method of fastening the ridge girder, the presence or absence of pitched windows, the design and number of rafter elements. After preparing the project, you can begin to calculate the hip roof and elements of the rafter system.
According to the author of this article, to design a hip roof, especially one complicated by bay windows, gables and hipped fragments, it is better to use the services of a design engineer. During construction mansard roof country house The author was greatly helped by a set of drawings with the calculated length of the rafter beams, the method of their connection, the angles of the cuts and the number of fasteners. The list of insulation and roofing materials indicating the area and installation order made it possible to order them in advance. Procuring project-based components minimizes material waste and saves time. The calculated dimensions of the rafter system and a clearly defined assembly sequence eliminated defects, unnecessary calculations and additional adjustments. Installation work was carried out by a team of four people with little construction experience, which managed even the difficult section of joining the slope with the roof of the bay window, however, with the help of consultation from the author of the project.
When designing independently, you need to start by calculating the basic parameters of the roof and the dimensions of the rafter group, creating your own drawings and layout layouts.
Hip roof calculation
When calculating the parameters of a hip roof, the house owner sets the height of the ridge for practical reasons. For a cold attic, it can be less than two meters, and when building an attic roof, you need to remember that according to SNiP, the height of the ceilings of a living space must be at least 2.3 m.
At preliminary calculations First, the height of the ridge is determined, and then the length of the central purlin, the size of the main and diagonal rafters
Length of the central purlin at equal angles the slope of the slopes is chosen such that the ends of the run are located at the same distance from the side and end walls. In the course of further calculations, the dimensions of the rafters, extensions and auxiliary elements are determined. It is necessary to choose the type of rafter system, because if for hip roofs with an uninhabited attic layered rafters are more typical, then for roofs with an attic both layered and hanging types of rafter connections can be used.
Calculation of slope angle and rafter length
The roof's resistance to wind influences and its ability to withstand snow loads depend on the angle of inclination of the slopes. The slope of the slopes is the most important parameter for calculating the length of the main and diagonal rafters, as well as rafters. We will take the following parameters as the basis for the calculations:
- ridge height H k = 3 m;
- building length L ds = 10 m;
- building width L dts = 6 m. We denote half of this size as L pts: L pts = 3 m;
- ridge length L k = 4 m;
- distance from the house wall to the ridge girder T = 3 m.
Calculations are carried out in several stages.
Table: values of trigonometric functions for the slope angles of the attic roof slopes
| a, deg. | tg a | sin a |
| 20 | 0,36 | 0,34 |
| 25 | 0,47 | 0,42 |
| 30 | 0,58 | 0,5 |
| 35 | 0,7 | 0,57 |
| 40 | 0,84 | 0,64 |
| 45 | 1 | 0,71 |
| 50 | 1,19 | 0,77 |
| 55 | 1,43 | 0,82 |
| 60 | 1,73 | 0,87 |
Calculation of the area of hip roof slopes
The area of the slopes must be known to calculate the quantity building materials and drawing up a cutting diagram. The hip roof has two triangular and two trapezoidal slopes; to calculate their area we will use standard formulas from the school geometry course.
To calculate the area, it is necessary to increase the height of each slope by the size of the eaves overhang and keep in mind that their lengths will also increase.
Calculation of the volume of the attic space
Calculating the volume of habitable under-roof space will be needed when calculating the heating and air conditioning systems of the attic. Since under the hip roof there is a multifaceted living space with varying height and shape, to calculate the volume it needs to be divided into simpler shapes. Usually we consider the section of the attic formed by some rafter, divide it into rectangles, triangles and trapezoids, calculate their areas using the above formulas and multiply by the length of the attic. The volumes of each part obtained in this way are added up and the total volume of the attic is obtained.
To calculate volume attic room it is divided into elementary figures, the volume of which is calculated separately and added to each other
If, when dividing the attic, more complex elements are separated, then their volume is calculated using the formula V = S H, where S is the cross-sectional area, H is the length of the element.
Video: calculation of the hip roof rafter system
Roof layout layout
The model is a reduced copy of the roof, from which you can determine optimal height ridge and the angle of inclination of the slopes in relation to the size of the building. The diagram of the rafter system of a hip roof, made in the form of a drawing indicating the dimensions and location of the elements of the rafter group, is called a layout layout. Such diagrams indicate the location, length and height of the ridge girder, as well as the size and number of main, diagonal and outer rafters.
The diagram of the rafter system indicates the dimensions of the elements, their installation location, installation method and angles of inclination of the rafter legs.
The drawing indicates the method of fastening the parts, the angles and dimensions of the insert, the pitch of the rafters and the arrangement of the eaves overhang. Using the diagram, you can calculate the amount of materials, cut and place individual parts at the installation site.
It is necessary to take into account that the calculated data requires practical verification, therefore, before making templates for cutting parts, it is necessary to carry out a trial joining of the main and diagonal rafters.
Hip roof rafter system
The hip roof is formed by four slopes, and its rafter system contains elements of a gable and hip roof. Basically, layered rafters are used, which rest on a ridge girder fixed to racks. The hip roof consists of the following elements:
- a mauerlat is mounted along the perimeter of the walls; if there is an internal main wall, a bench is attached to it;
- tie rods or floor beams are installed on the Mauerlat;
- on vertical racks the ridge girder is attached;
- the main rafters rest on the mauerlat and ridge girder, forming trapezoidal slopes;
- diagonal rafters form triangular slopes;
- sprigs are shortened rafters that form a load-bearing frame between the diagonal and row rafters;
- struts and trusses are used as additional supporting elements;
- fillies are used to lengthen rafters and beams;
- the counter-lattice creates a ventilation gap;
- sheathing is used to secure the roof covering.
The hip roof consists of standard elements and specific rafter units that provide the necessary structural strength
In addition, the rafter legs are reinforced with crossbars and additional racks. Often these elements form the walls and ceiling of the attic space.
Mauerlat and its dimensions
The Mauerlat is the connecting link between the building frame and the rafters and is a solid beam attached to the wall with threaded rods. To eliminate the bursting effect of the rafters on the walls, the Mauerlat bars must be attached to a continuous reinforced belt. The studs in increments of 80 to 100 cm are embedded in a monolithic belt.
The Mauerlat runs along the upper perimeter of the building and is attached to the reinforced concrete belt with studs
The Mauerlat evenly distributes the load from the roof to the walls of the building; its length is equal to the perimeter of the house. For its manufacture, pine lumber with a cross-section of 150X150, 150X200 or 200X200 mm is used. At the corners of the house, the beams are connected to each other using threaded rods.
Installation of ridge girder
The ridge girder serves as a support for the main and diagonal rafters and is installed on vertical posts that rest on floor beams or beams. To add rigidity to the rectangular structure, it is recommended to install diagonal struts between the posts and the purlin. To install the central girder, timber 100X100 mm or 50X150 mm is used.
Installation of the central girder is carried out using vertical posts supported on the floor or on the floor beams
Most often, layered rafters are used, but for habitable attic spaces you can also design hanging type rafters to free the living space from the clutter of auxiliary structures.
The option with hanging rafters frees up the living space as much as possible from bulky structures
In this case, the main and diagonal rafters are attached to the central girder, which are reinforced with crossbars and racks that form the walls and ceiling of the attic.
The procedure for carrying out installation work
Before installing the hip roof rafter system, workplaces must be equipped with ladders, scaffolding and ladders, since ease of use significantly speeds up installation. Then they begin to assemble the roof elements in the sequence described below.
- To monolithic reinforced belt lay out the waterproofing material and place pre-drilled Mauerlat beams on it, securing them with threaded rods, washers and bolts.
The Mauerlat beams are laid on a layer of roofing felt waterproofing and secured with studs through pre-drilled holes
- Floor beams or tie beams are attached to the Mauerlat in increments of 60 to 120 cm, and vertical posts for the central girder are installed on them.
- A ridge girder is attached to the vertical posts, then the entire structure is reinforced with diagonal struts. Relative to the outer legs, the purlin should have extensions of 15 cm for attaching diagonal rafters.
The arrangement of the roof begins with the installation of the central purlin and the main rafters
- Between the floor beams and the ridge girder, rafter legs are placed in pairs, the tie-in is marked and the rafters are cut. The outer main trusses are installed, cords are pulled between them and the remaining rafter legs are placed along them.
- If the rafters are long, they are reinforced with crossbars, struts and racks. After this, the diagonal rafters are marked.
To install diagonal rafters, it is necessary to carefully mark, cut and cut for joining with the ridge and mauerlat
- The marked diagonal rafters are cut and installed; if necessary, they are reinforced with trusses and struts.
- The eaves are marked and installed, the ends of the rafters on the eaves overhang are cut vertically, and the front boards are attached to them.
- A waterproofing membrane with an overlap of 10 cm is attached to the rafters and sills, and a counter-lattice and sheathing are installed.
Based personal experience, the author of this article would like to recommend equipping a place at the construction site for marking, cutting and templating elements of the rafter system. It is convenient when precise goniometer tools are in one place, suitable for marking and sawing. Equipped workplace saves time when preparing parts, which are then lifted and mounted without additional adjustment. Below it is easier to prepare an assembly kit of fasteners for each stage of work.
Video: hip roof rafter system
The roofing pie of a hip roof consists of the following elements:
- rafter legs;
- vapor barrier membrane;
- insulation located between the rafters;
- waterproofing membrane;
- sheathing and counter-lattice;
- roofing material.
The roofing pie of a hip roof is used to create a certain sequence of protective layers, on which the finishing coating is laid on top
For a cold attic, the roofing pie consists of rafters, a waterproofing membrane, counter-lattens, sheathing and roofing material. Thermal insulation layer and vapor barrier film do not apply here.
Ventilation of the under-roof space of an insulated hip roof occurs through a ventilated gap between the insulation and the waterproofing membrane. A ventilation gap is formed when installing the membrane on rafters with a sag of 1.5–2 cm, so air penetrates the insulation through the perforated finishing of the cornice and exits through the holes of the ridge aerators.
The roof is ventilated through eaves soffits and ridge aerators.
A vapor barrier film protects the insulation from evaporation from residential premises, and a waterproofing membrane protects the insulation layer from moisture from condensation. Condensation accumulating on the waterproofing is removed through a ventilation gap 5 cm high, which ensures air circulation and keeps the rafter system intact. At the same time, the layer of heat-insulating material does not lose its properties from excess moisture.
The cold attic is ventilated through perforated eaves trim openings and dormers, as well as ridge aerators. The temperature difference between the outside environment and the attic is minimized, so icing of the roof does not occur.
The advantage of a cold attic is that there is no difference in temperature between the roofing and the attic, which prevents icing of the roof.
With this hip roof ventilation scheme, it is necessary to remember to carefully insulate the ceiling and the upper part of the walls between the living space and the cold attic.
Video: hip roof dormer windows - cold attic
Insulation of a hip roof
Roof insulation is carried out after installation of the roof from the inside of the attic or from the outside during installation roofing pie. This sequence of work protects the insulation from unexpected precipitation. Thermal insulation material placed between the rafters in a layer of 20–25 cm.
Insulation from the inside occurs by stuffing insulation between the rafters and fixing it with a cord or fishing line
The following materials can be used to insulate a hip roof:
- expanded polystyrene with a size of 600X1200 mm and a thickness of 20 to 100 mm;
- fiber boards and mats mineral wool size 600X3000 mm and thickness from 50 to 200 mm;
- foam insulation, which includes ecowool and expanded polystyrene.
The elasticity of the mats and slabs allows them to be stuffed between the rafters in several layers with shifting the joints to get rid of cold bridges, and foam insulation is applied by spraying using special equipment.
For different types of roofing, certain types of additional elements are produced. The hip roof uses ridge strips with aerators, caps for hip joints and tees for diagonal rafters. They cover ridge and pitch joints, as well as eaves overhangs.
At the final stage of installation of a hip roof, numerous additional elements are used
Of the remaining additional elements on hip roofs, ladders, ladders, snow retainers, seals and drips can be used.
Ridge extensions
Ridge extensions have different configurations and sizes, for example, straight strip 150X150X2000 mm or semicircular R110X2000 mm. Ridge strips can have aerators different types. Let's consider the features of installation and joining of ridge extensions.
Installation of straight ridges on a hip roof is carried out with an overlap of at least 5 cm and begins on the side opposite to the prevailing winds. The planks are attached in increments of 15 to 30 cm, and plugs are mounted on the outer planks. The design of some ridge strips includes polymer aerators that provide ventilation of the under-roof space.
The joining of horizontal skates occurs with an overlap of at least 5 cm
The spinal strips are attached, starting from the cap, from the bottom up, and at the junction of the hip ridges and the ridge they are joined to the tee Y-straps. If necessary, the joints are additionally sealed.
The design of the round ridge includes stiffening ribs that serve as locks for joining individual planks. Such ribs prevent water from penetrating into the ridge space. The round ridge is attached to top bar sheathing through an aero-element, which ensures air circulation through the ventilation gap.
The round ridge is installed through a seal using special plugs
When installing any type of ridge strips, it is important to ensure that the vents are not blocked and that air circulation is maintained between the cornice and the ridge.
Wind bars and drip edges
Drips are installed on the eaves of a hip roof to drain condensate, and to protect the under-roof space from wind and rain, wind or eaves strips are mounted on the sheathing.
The drip tray on the eaves (item 7) is used to drain condensate, and the wind strip (item 5) protects the under-roof space from wind and rain
This type of extensions is installed with an overlap of at least 5 cm, the standard length of the planks is 2 m.
Video: installation of metal tiles and additional elements
Types of roofing for hip roofs and their installation
For hip roofs are used different types roofing materials, which are offered in large quantities by manufacturers. When choosing, you need to evaluate color scheme, ease of installation, weight and durability of the roofing. The cost and effective area of the material are of considerable importance. Let's consider the most popular types roofing covering:
- ceramic and cement-sand tiles;
- metal tiles and roofing corrugated sheets;
- slate and ondulin;
- soft tiles.
According to the author of the article, attention should be paid to the noise-absorbing properties of the roofing material. From this point of view, metal profiles are inferior to ondulin and soft tiles with their excellent sound insulation. In addition, condensation forms on the metal surface due to temperature changes, so measures must be taken to remove it. Soft tiles are easy to install, but they require a continuous sheathing of 12 mm thick plywood and lining material, which makes their use somewhat more expensive. For these reasons, as well as due to its light weight and ease of installation, the author of the article chose ondulin to cover a residential country house. During the operation of the roof it became clear that during heavy rain A slight noise is heard in the attic, and after insulating the attic, the extraneous sounds practically disappeared.
The roof covering is installed on the sheathing. Before roofing works you need to install drips, wind boards and drainage system brackets. Fastening sheet materials made with self-tapping screws with a washer and a rubber gasket in a checkerboard pattern. Laying the sheet covering of the hip roof begins from the center of the slope to the edges.
Installation of the roofing sheet begins with the first solid element, then the sheets are attached symmetrically to the left and right
Installation is carried out using a cord stretched along the eaves. Soft tiles are laid from bottom to top with an overlap recommended by the manufacturer.
Metal profile
Metal profiles include roofing corrugated sheets and metal tile coverings. The total width of the metal tile sheet is 1180 mm, the effective width is 1080 mm, the length can vary from 765 to 8000 mm, the lathing pitch is 350 mm. The roofing corrugated sheeting has an installation width of 1000 mm and a length of up to 6 m. The service life of these coverings reaches 50 years, while the material is lightweight and easy to install.
Corrugated sheeting is easy to install and lasts up to 50 years
Slate
Slate is heavy and fragile, so modern construction its lightweight (sheet weight 6 kg) analogue is used - ondulin.
Slate is heavy and fragile, but is still popular
The length of the ondulin sheet is 2 m, width - 0.95 m, effective area- 1.6 m 2. Ondulin is mounted on the sheathing in increments of 45 cm, with a longitudinal overlap of 20 cm, and the lateral overlap is one wave. Additional advantages: service life up to 50 years, good noise absorption, ease of installation.
The service life of ondulin reaches 50 years, while the roof is noise-absorbing and easy to install
Length soft tiles is 1 m, the average width is 333 mm, the overlap depends on the type and shape, and the thickness is 6 mm. This is a lightweight sound-absorbing material that is easy to install, lasts up to 35 years, is inexpensive, but requires a continuous sheathing and a lining layer.
Soft tiles give the roof modern look and is simply mounted on a continuous sheathing
Do-it-yourself hip roof for a gazebo
A gazebo with a hip roof creates a unified architectural space on the building site. For construction, it is necessary to build a frame like a Mauerlat and then perform the following steps.
All wooden parts of the gazebo must be treated with antiseptic and fire retardant compounds and given the appropriate color shade.
We talked about the design and calculations of hip roofs, the rafter system and the step-by-step procedure for installing its elements. We touched on ventilation, insulation and the structure of the roofing pie. Self-installation a hip roof will allow you to save money and be completely convinced of the quality of the work performed. We hope that the materials in this article will help you in building a roof for a cozy home.