Row outbuildings have a flat roof. Most often this is brick garage or utility units. Concrete slabs are usually used as roofing. For year-round operation of the premises, there is a need to insulate the floors. In this regard, the questions of how to cover a concrete garage roof and what is the principle of performing this operation require detailed study.
Principles of thermal insulation
The garage, or rather its roof, is insulated according to the same laws and principles that apply when insulating the walls of residential buildings:
- the thermal insulation layer must be located outside;
- waterproofing should protect concrete floor slabs and, if necessary, insulation;
- conditions must be created to prevent mechanical damage layers of hydro- and thermal insulation.
The last condition is especially relevant in cases where the roof is in use (which is quite common).
The thickness of the thermal insulation layer that needs to cover the roof is selected in each case separately. It depends on the mode in which the garage is operated, the climatic characteristics of the area and the thermal characteristics of the insulation itself.
Insulation materials
Because of the abundance thermal insulation materials The question of choosing the most suitable insulation can be confusing at first. Upon closer examination, the entire variety of thermal insulation that can be used in this case comes down to three groups:
- slabs mineral wool;
- extruded polystyrene foam (EPS);
- bulk mineral insulation.
The roof can be insulated with slabs of dense, hard mineral wool. The density of the slabs should be in the range of 170-230 kg/m3.
The advantages of mineral wool include its non-flammability, stability of physical and chemical characteristics over time. Light weight, which distinguishes the material, play special significance there won't be, because Concrete slabs have a very high load-bearing capacity.
The main disadvantage of mineral wool is its strong water absorption and, as a consequence, a sharp decrease in thermal insulation characteristics. The insulating layer must be covered with an insulating barrier. Moreover, a roof insulated with mineral wool must be protected both from precipitation and from moisture rising from the side of the room.
It is more preferable to use extruded polystyrene foam boards. They have great rigidity and are able to withstand mechanical loads, which allows you to create a garage with a serviceable roof. The density of EPS used for flat roofing must be at least 30 kg/m3. You should also give preference to low-flammable grades of material.
The folds made along the perimeter of the slabs ensure a tight connection of adjacent sheets. The garage is almost completely covered with monolithic thermal insulation.
A very big advantage is the EPS structure. The closed, sealed air-filled cells that make up the material practically do not absorb water. The water absorption coefficient is extremely low. This makes it possible to perform less severe waterproofing than that required for mineral wool.
Concrete slabs that act as floors have a very high load-bearing capacity. The roof can withstand significant loads, and restrictions on the weight of the insulation are removed. It becomes possible to use a material such as expanded clay.
Among the advantages of insulation, it is worth mentioning its low cost and ease of operation. Expanded clay is also afraid of moisture and it is necessary to take appropriate measures to prevent it from getting wet. The backfill layer is leveled, then it needs to be covered cement screed, on top of which, after hardening, a carpet of rolled waterproofing materials is applied.
If the roof has a large area, then it is advisable to lay expanded clay inside the layer reinforcing mesh, it will add rigidity to the backfill layer and prevent cracking of the cement screed.
Traditional insulation scheme
With the traditional roof insulation scheme, the main layer of waterproofing protects the insulation from the effects of atmospheric moisture.
The garage is covered with a roofing “pie” having the following layers:
- concrete floor slabs;
- vapor barrier;
- layer of insulating material;
- waterproofing;
- roofing material.
As waterproofing for a garage roof, roofing felt laid in several layers or specialized roll materials can be used. Required condition is the fastening of waterproofing materials using mastic or liquid bitumen.
Using the fused deposition method open fire unacceptable, because there is a risk of fire.
Coating
When choosing the best way to cover a garage roof made of concrete slabs, you should pay attention to the following materials:
- flexible bitumen shingles;
- rolled materials;
- sheet materials (slate, metal tiles, polymer slate).
In some cases, the garage is designed for the active use of the roof. In this case, the roof can be paved with paving slabs or paving stones.
The thermal insulation layer can be made of any suitable physical characteristics materials (mineral wool, EPS, bulk mineral insulation).
Inversion insulation scheme
In this case, the roof is protected by a waterproofing barrier, which is laid on concrete floor slabs. Then a thermal insulation layer is applied. With this scheme, the insulation will protect the waterproofing from exposure to sunlight, and most importantly, from temperature changes.
The created conditions make it possible to obtain a garage, which has a significantly increased maintenance-free service life of the entire roof structure.
The use of mineral wool or expanded clay in this case is unacceptable due to their hygroscopicity. They will get wet very quickly and lose their properties. The only possible option is to cover the roof with EPS boards. It has the required rigidity and almost zero water absorption.
Roof structure structure
The roof structure will look like this:
- concrete floor slabs;
- leveling cement screed;
- waterproofing;
- insulation;
- roofing covering.
Moisture protection and coating
Concrete slabs are leveled using a screed and covered with a layer of waterproofing. This allows for fastening by fusing insulation using an open flame. Fastening with mastic also does not lose its relevance.
The final roofing covering installed on the garage is made from the same materials and using the same technology as when carrying out work according to the traditional scheme. Roofing materials in in this case serve mostly a decorative function.
Floors different types have their own installation technology, which must be strictly followed.
The general rule is that the ceiling is aligned with the ceiling of the lower floor. Since it is this that gives spatial rigidity to the structure of the house, all its parts are rigidly connected to each other and to the walls (welding, concreting, anchors).
It is not allowed to punch holes in the floor slabs that are not provided for by the design (so as not to damage the ribs and reinforcement in the slab), shorten (cut) the floor slabs, or overload them during installation in excess of the standard load. The most common mistake is reducing the area of support of the ceiling on the wall(compared to design).
Consequences. Deflection and collapse of ceilings, cracks in walls and ceilings (for example , the permissible deflection for a round-hollow slab with a span of 6 m is 15 mm).
Elimination. If the deflection is greater than permissible, the load on the slab should be reduced or strengthened in a manner specified by a specialist.
How right. It is necessary to strictly follow the design and instructions for the technology of installation of floors. If, as a result of an error during the construction of the wall, the problem of insufficient support area has arisen, the specialist must develop a unit for this area that allows it to be increased.
Mistakes during roof construction
The attic wall is not reinforced
Consequences. The inclined rafters act on the attic wall in a horizontal direction, creating a thrust, which causes the wall to collapse.
Elimination. Convert the hanging rafter system to a layered one.
How to do it right . When constructing an attic wall, it is initially necessary to provide a layered rafter system (with a support point in the ridge area).
The vapor barrier film is not tightly installed
Consequences. There are pockets of steam penetration into the insulation, causing moisture to accumulate in the under-roof space. .jpg)
Elimination. Disassemble the structure, inspect the rafters, replace damaged elements. The insulation needs to be dried or replaced.
How right. When installing a vapor barrier, the film is placed on the walls around the perimeter of the attic. A special wide mounting tape is used to carefully seal the joints and junctions with structures. The use of nails is prohibited.
There is no ventilation layer in the roofing “pie”
Consequences. Moisture can accumulate in the insulation, causing it to lose its properties.
Elimination. Disassemble the structure, inspect the rafters, eliminate damage, and re-install the roofing “pie”.
How right. The under-roof space must be ventilated through an air gap that is left between the insulation and waterproofing film. Without a gap, only a superdiffusion membrane can be laid on the insulation.
When installing bitumen and metal roofs(seam, metal tile), under which condensation forms, the ventilation gap is also arranged directly under roofing covering. Openings are left under the roof overhang for air flow, and devices for air outflow are installed in the ridge area.
The type of coating has been changed to a heavier one
Consequences. The rafters die, as a result of which the roof becomes deformed, begins to leak and may collapse.
Elimination. Strengthening the rafter system.
How right. When changing the type of roof, it is necessary to order from a design engineer a recalculation of the rafter system for a more massive covering.
ROOFING WITHOUT ROOFING MATERIAL
on reinforced concrete floor
(MALTSEV ROOFING SYSTEM)
V.V. MALTSEV, deputy gene. Director for Science, Doctor of Chemical Sciences, Academician of the Russian Academy of Natural Sciences, Chief Ecologist of Russia for wooden housing construction
· Composite material REFLECTOPLIT, which is made on the basis of heat-insulating fibreboard (fibreboard), on which aluminum foil is glued on one side. The thermal resistance of this material is equivalent to 50 mm of polystyrene foam, but polystyrene foam is toxic, it burns well, and when burned it melts and drips, and the melt burns, etc.
WARM
WARM- This is a non-woven fiberglass fabric made of ultra-thin fiberglass, backed on one side with a metallized lavsan film, which reflects 97% of heat rays back. This material solves 3 problems at once:
· retains heat indoors, i.e. provides high thermal insulation;
· prevents the penetration of water vapor into the protected structure;
· absorbs noise - being an excellent sound insulator.
When using this material as internal thermal insulation, water vapor from the room does not penetrate into the reinforced concrete floor slab. And thanks to the heat-reflecting and parapermeable layers WARM the complete absence of water condensation is ensured. And there is no need to fence anything on top of the ceiling.
REFLECTOPLITE
REFLECTOPLITE- This is a heat-insulating wood-fiber board (fiberboard), which is impregnated with a fire-bio-protective composition, giving it biostability and flammability category G2. On one side, such a plate is covered with aluminum foil, which is glued using low-flammability coking glue TETRACOLL-KOKS. This glue glues aluminum foil very firmly, while the strength of the fiberboard itself increases several times and the board stops crumbling. It becomes an extremely technologically advanced material when used. At the same time, aluminum foil reflects at least 95% of infrared (heat) rays back into the room and is practically impermeable to water vapor. Thus, an excellent thermal insulation layer is created, which completely eliminates the formation of any condensation on the inside of the concrete floor.
Moreover, aluminum foil does not burn. When exposed to flame, the foil in a split second turns into aluminum oxide Al2O3, which melts at a temperature above 1500ºС, and such a temperature does not occur in any fire.
Use of slab material REFLECTOPLITE more technologically advanced, since it does not require specialized technological equipment used when gluing roll material WARM.
INSULATION OF REINFORCED CONCRETE FLOORS FROM THE INSIDE
From the inside, the concrete floor is treated with the composition WHOOPRIN, which penetrates the pores of concrete and closes them. Then comes a layer of glue TETRACOLL-COX, applied using a notched trowel, which completely and irrevocably closes all the pores of the concrete. Light board material is glued to it REFLECTOPLITE(bio-fire-resistant fibreboard thermal insulation with aluminum foil) or roll material WARM(bio-fire-resistant fiberglass with metallized Mylar film). The glue is very durable, practically not subject to aging, will not emit any harmful substances and does not burn. And the seams are taped with ordinary transparent tape, which is a Mylar film of the same nature as the metallized Mylar film that is used in WARMER. This design will not catch fire under any circumstances. It eliminates the penetration of water, provides effective thermal insulation along with heat reflection - finally eliminating the issue of penetration of water vapor to the upper outer part of the floor slab.
CONSTRUCTION OF THE UPPER LAYER OF THE ROOF
system « DISPERLEY"
The essence of the DISPERLEY system (“ protective layer"or "planar" concrete protection technology) consists of using the body of the reinforced concrete floor itself to create a waterproofing layer with very high mechanical strength on its surface instead of traditional roofing materials.
For this purpose, a water-dispersed solution of a low-flammability copolymer is used, the particle size of which is smaller than the pore size in concrete. Moreover, by introducing certain additives into this solution, it is possible to achieve deep penetration of such a solution into the capillaries and pores of the iron. concrete slab roofing.
By applying such a solution to the surface of concrete, the polymer particles penetrate deeply into the concrete and begin to grow together when dry. The polymerization mechanism is turned on. Now you should also apply a layer of water-dispersible copolymer so that the particles fill all the pores completely, and a polymer film forms on the surface of the concrete. The main objective - close all pores in concrete.
Such a dispersion is available - this is the “VUPRIN” composition, which is a dispersion of an aqueous, low-flammability copolymer with various additives that increase the hydrophobicity of the layer and promote the wettability of concrete capillaries, etc. After closing the pores, this composition forms a completely durable frost-resistant film on the surface of the concrete.
And then this polymer layer is covered with frost-resistant, weather-resistant, antiseptic acrylic (also water-dispersion) paint “DOKAS”, which completely prevents any penetration of moisture into the concrete body, completely blocking this process.
The result is a hydrophobic and waterproofing layer of aqueous dispersions. This does not require any roofing material. Moreover, all irregularities and bends of the roof can be processed. And where there are joints between roofing panels, they are pre-sealed. There are now a sufficient number of sealants, including domestic ones - frost-resistant and durable.
As a result, it turns out that there are two substances, but these are not roofing materials. Roofing material simply no. Not rolled, not slab, not welded, or anything else. Roofing waterproof material becomes impregnated and treated upper layer concrete.
And there is no need to roll out these terrible 10-12 cm layers of bitumen, and even with roofing felt. All this is flammable, all this is toxic. All this should remain in the 20th century.
The polymer not only makes the concrete layer waterproofing, but also strengthens it. And nothing bad will happen even if you hit it with a crowbar, because the pores of the concrete are saturated with the copolymer. The pores are closed, the scrap will not penetrate into the pores. And in the spring, you can simply touch up the impact area with water-dispersed acrylic paint.
So in winter time workers breaking off ice by hitting with a crowbar do not greatly destroy the roof, because the pores of the concrete are reliably closed with a hydrophobic polymer. Another thing is that there will be a breakaway. But in the spring you can apply the same DOKAS paint and everything will be eliminated. Moreover, the roof is fire-resistant and easy to clean. Once every 5 years I renew the DOKAS paint in one layer, and it serves again.
Moreover waterproofing coating, which is formed on the outer part of the reinforced concrete floor, by weight (the composition that has already hardened in the pores of concrete and formed on the surface) is about 250 g/m2, which is simply ridiculously small compared to any roofing covering known today, which has a mass starts from 1.5 kg/m2, i.e. it differs by an order of magnitude.
In case of damage to the coating, repair work is carried out extremely easily and with high performance. Dirt is washed off using a mop. summer time. Roof repairs in winter are crazy. And then comes one layer of DOKAS paint of the same or a different color. No cracks in the concrete will play a role, since all joints will be closed, and most importantly, the pores of the concrete will be closed. There will be no question about leaks and their elimination.
The composition is VUPRIN and the paint is DOKAS, which are industrially produced at the EkRusKhim enterprise (Ecological Russian Chemistry) (see www. *****).
Compound WHOOPRIN contains a low-flammability copolymer, which they have already learned to modify so that the films become frost-resistant. Moreover, the copolymer enters into a chemical bond with concrete due to lateral groups and a powerful bond is formed between the inorganic concrete base and the low-flammability copolymer - the so-called ionic bond.
Dye DOKAS won two international frost resistance competitions. Moreover, the paint contains non-fading pigments, is durable, has no peeling mechanism, and is flame retardant (mineral flame retardants and flame retardant plasticizers, etc. are added to it).
That's why technological process The design of the outer layer of such a roof will look like this:
1. 
We pre-seal all seams with frost-resistant Russian sealant.
2. First treatment with diluted composition VUPRIN.
3. Second treatment (after the first layer has dried) with undiluted VUPRIN.
ROOF STRUCTURE IN GENERAL
The proposed technical solution for roofing is completely environmentally friendly and does not spread flames. DOKAS paint is fire-resistant because it contains very effective mineral and organomineral flame retardants.
General technical solution "ROOF WITHOUT ROOFING MATERIAL" presented in the diagram.
No water vapor enters such a roof. There is a powerful reflection of heat back into the building. Plus noise absorption. Similar design the roof opens huge opportunities in waterproofing roof slabs, reducing the cost of this process by at least 3 times compared to known variants, dramatically reduces the load on the roof and avoids numerous damage to the roofing carpet. There will be no swelling.
But even if moisture somehow gets into the reinforced concrete ceiling, then the films that are formed by water-dispersed compositions WHOOPRIN and paints DOKAS are vapor permeable. Therefore, any steam will both enter and exit this structure. The main thing is that there will be no condensation or moisture.
All this is simple, cheap and technologically advanced. When using this design on a large scale: THE ROOFING PROBLEM IN RUSSIA WILL BE SOLVED. Complex issues of roof installation and repair will become a thing of the past.
Instead of built-up bitumen, which quickly ages and cracks; during subsequent repairs, many layers begin to weigh down the roof with the threat of destruction of the ceiling (repair layers of the rubyroid-bitumen cake, as a rule, are not taken into account by the designer, who only calculates snow load), a polymer formed from an aqueous dispersion is proposed.
Note that drugs for protective coatings, developed specifically for construction and industrially produced at the EkRusKhim enterprise - DOKAS paint, VUPRIN and VUPREKS compositions - are chemically inert, i.e. they do not react to either acids or sea water, nor on saline solutions reagents that are used to sprinkle roads in cities to melt snow. Therefore, the scope of their application can be extensive.
This technology has been used in underground structures for a long time. Thus, in Nizhny Novgorod, the ceiling of a metro station, which is located under the Oka River, was treated with VUPRIN. There was water dripping from the ceiling. Therefore, 12 years ago, the station vaults were treated with VUPRIN, and the leaking stopped. This coating still serves successfully today.
Before using this waterproofing technology, preliminary tests were carried out, which showed that dew appeared on the VUPRIN side only at a pressure of 6 atmospheres on the back side of the concrete slab. This is a very high figure for this type of technology.
Therefore, if not only roofs, but also others reinforced concrete structures processed in the proposed manner (for example, those used for bridges, for underground structures, shallow metro stations), then it is possible to ensure an increase in the durability of structures by at least 10 times.
But no one is interested in such technologies. Those who are in charge of financing issues are not interested in domestic developers and their developments. They are more attracted to expensive Western technologies. And the reasons are different.
Using the proposed solution for installing roofs on reinforced concrete floors may with Russian market throw away all hazardous materials and designs, usually offered by Western companies. They are simply prohibited there. But the money invested in their production must be returned. They come to us because of the lack of consumer awareness and the corruption of officials responsible for environmental assessment and licensing of building materials.
This problem in ours can be solved through healthy competition. The winner must be the technology that, in addition to ensuring simplicity, environmental friendliness, aesthetics, durability and non-flammability, will provide the most economically advantageous technical solution, which will be many times superior to everything that is on the market now, including “Western provocations.”
Today, a flat roof is not the most obvious solution to the roofing issue. But in Switzerland and Germany, this particular type of roof began to gain increasing popularity. It is possible that in the near future European fashion will come to us.
The following factors contribute to the increasing popularity of flat roofing:
- Ease of installation of the roofing pie. All materials are laid on a flat surface directly under your feet.
- A flat roof has better heat transfer. The roof area is evenly heated throughout the sunny day.
- Opportunity beneficial use space. You can do it on the roof summer terrace, install a small pool, etc.
But there are also disadvantages:
- A flat roof wears out faster. It will have to be repaired more often, although this is not difficult.
- On a flat roof winter period A large amount of snow accumulates. Firstly, it creates unnecessary power load. Secondly, if it is not removed, over time it will begin to melt, and there may be so much water that it will somehow find its way through the roof.
- There is an opinion that a flat roof is cheaper than a pitched roof. This is not so, and if you calculate all the costs, which include: floor slabs; slope-forming screed; insulation that experiences high compressive loads, and is therefore more expensive than pitched roof; waterproofing; installation of parapets - it becomes clear that a flat roof will cost more.
Traditional or inversion roofing
Before you make a flat roof with your own hands, you need to choose the type of roofing pie. It can be traditional or inversion.
The fundamental difference lies only in the order in which the elements are laid out flat roof.
The traditional type involves first installing a vapor barrier, then thermal insulation, and only then waterproofing. This allows you to protect the insulation, but puts it at risk waterproofing material. The inversion type involves the installation of waterproofing, followed by thermal insulation. Thus, the waterproofing material is protected from temperature changes and excessive pressure.
The installation of a flat roof in a private house most often involves the use of a traditional type, and that is what we will consider in this article.
Preparing the base
Preparation of the foundation begins immediately after construction load-bearing walls. It directly depends on whether the roof will be used or not. Can be made from:
- Reinforced concrete slabs, subject to the construction of walls made of bricks, blocks or concrete panels.
- If the roof is not in use, it is possible to install a base made of corrugated sheets on iron beams. Profiled sheets must have sufficient wave height, type N-153.
- A flat roof in a private house allows installation wooden slabs ceilings on wooden beams. They are used only on unused small-area roofs. They are laid with a gap of two millimeters, which is subsequently compensated by thermal expansion.
- Can be used wooden planks minimum thickness 40 mm and a maximum width of 180 mm. They are also laid with a small gap. Suitable for used roofs.
When using wood, do not forget to treat it with antiseptics and fire retardants to increase durability and fire resistance.
Deflection device
The next stage is the deflection device. Necessary for draining water to gutters.
- By reinforced concrete slabs pour the screed with an approximate slope of 2-5 degrees. This is approximately 2 centimeters of slope per 1 meter. It is possible that the screed will be preceded by a backfill of expanded clay. Also, a slope can be created using a special wedge-shaped insulation.
- The construction of a flat roof using corrugated sheets involves the implementation of a slope at the stage of installation of the base. That is, profiled sheets are initially laid with a slope of 2 centimeters per meter. If this was not done, it would be permissible to use wedge-shaped insulation or make a slope-forming screed made of polystyrene concrete.
- Wooden slabs are also initially laid with a slope. In its absence, wedge-shaped insulation is used.
When constructing a roof base from corrugated sheets or wooden slabs, the box walls are initially made with a slope in the desired direction to facilitate the subsequent installation of floor slabs.
Let us note that using wedge-shaped insulation will cost you more than arranging a slope using a screed, and even more expensive than installing a slope at the stage of installing floor slabs.
Vapor barrier
Vapor barrier is used only in the construction of a traditional type of flat roof. It is necessary to prevent the penetration of vapors from the room to the insulation. For vapor barrier, specialized films are used. They are laid with an overlap of 10 cm. The joints are carefully taped with adhesive tape. The film is glued no less carefully in places adjacent to various kinds protrusions (parapet, steps, etc.). It is attached to the base using construction stapler or special galvanized nails.
Bitumen-containing materials, such as roofing felt, can be used as a vapor barrier. They are attached to the base using gas burner, the joints are glued in the same way. Also, modern market building materials offers self-adhesive films, the installation of which does not require additional materials.
Please note that ballast roofing does not require mechanical fastening of the vapor barrier to the base.
In turn, ballast roofing is a roofing for the finishing coating of which weighting materials are used - paving slabs or loose washed gravel.
Thermal insulation
Do not forget that before making a flat roof for a house, you need to decide on the slope-forming layer. The type of insulation will depend on this.
The insulation is laid in several layers. To prevent the formation of cold bridges, each subsequent layer must overlap the joints of the lower one. Polyurethane glue is used to glue the layers one to one. In its absence, the use of polyurethane foam is allowed. Also, polyurethane foam All possible holes and cavities are sealed.
Before installing the thermal insulation layer, you must ensure that there is no moisture on the vapor barrier. It is better to carry out the installation itself in parts. That is, lay several squares of thermal insulation, followed immediately by waterproofing on top. This is necessary so that in case of rain the insulation does not get wet.
Waterproofing
One of the most important stages Do-it-yourself flat roof installations - waterproofing. Can be made from:
- Bituminous materials, roofing felt.
- Bitumen-polymer materials, euroroofing felt.
- PVC films.
- Liquid rubber.
Let's take a closer look at each of the materials.
Ruberoid is the simplest, cheapest, but also the most short-lived of all. Stacked on concrete base, or insulation resistant to high temperatures. Its service life is only 5-10 years. To install it you will need: a gas burner, a painting knife, a spatula, a brush and a primer for roofing felt. The work order is as follows:
- Primer treatment.
- After it has completely dried, the roofing material is rolled out and allowed to rest for 24 hours.
- They glue it with mastic. Don’t forget to carefully apply the waterproofing to the protrusions.
- The joints (minimum overlap of 7 cm) are processed with a torch.
- After the first layer, lay the second one. The sequence of actions is the same, with the exception of primer treatment. The lower the slope, the more layers, up to four.
Bitumen-polymer waterproofing will last an order of magnitude longer. The installation procedure is as follows:
- Cleaning the base from dust, dirt and moisture.
- Primer treatment.
- Installation of material using a gas burner. If the roofing felt was glued with mastic, then there is no need to do this here. The burner heats the entire width of the roll, but it is very important not to overmelt the material, otherwise it will become too brittle. Especially for this purpose, a pattern is applied to the rolls; as soon as it begins to deform, it can be rolled out further. The waterproofing is attached to the base using a wooden mop. Minimum overlap 8 mm.
- In some cases, when installing a flat roof with your own hands, installing the first layer using a burner is difficult to accomplish. Then use mechanical fastening in increments of 50 cm.
Due to the need to use highly specialized tools PVC installation membranes and liquid rubber becomes almost impossible without the involvement of specialists. Therefore, it makes no sense to consider these materials in detail. We only note that both types of waterproofing are quite durable.
Drainage system
A flat roof in a private house can have several types of drainage systems:
- Interior.
- External controlled.
- External uncontrolled.
We’ll immediately discard the last option, since it is used mainly for outbuildings.
External controlled drainage involves collecting and draining water using gutters located with outside. To drain water, special holes are made in the parapet.
The internal one is mounted directly into roofing system, even before it was collected roofing pie. Due to this, its installation is more complicated, but in this case the drain can be hidden inside the building. In this regard, the issue of water drainage must be resolved before making a flat roof.
A hip roof is a rather complex architectural roof structure, most often used on big houses with plan dimensions of at least 10×10 m. The roof has many rafter legs, which require intermediate supports. Only professional architects can plan their locations in advance; ordinary craftsmen make decisions on the spot intuitively. Due to these features of the hip roof, special requirements are put forward for attic floors.
| Floor type | Short description |
|---|---|
| The dimensions of the beams are at least 50×150 mm, the pitch is approximately 60 cm. The load-bearing parameters of the beams must withstand the maximum design loads on the roof, taking into account wind and snow forces. Advantages wooden beams– versatility of use, such an overlap can be used on both brick and wooden buildings. Disadvantages - wood is afraid of fluctuations in humidity, constantly changes linear dimensions. Another drawback is the stops of the rafter system hip roof must be located strictly opposite the beams, and this complicates the construction process. |
| They are used only on brick buildings; they can be factory-made or home-made. Factory-made slabs are hollow, which reduces the load on the walls and foundation and improves heat saving performance. Disadvantage of factory plates - high price, installation is only possible using a special construction equipment, standard linear dimensions. In exclusive projects, concrete floors are poured during construction work At the construction site, due to this technology, it is possible to use unique architectural solutions. |
In this article we will look at the process of building a hip roof on concrete floor slabs. To begin with, you should familiarize yourself with the general technical characteristics these types of roofs.
Technical parameters of hip roofs
Like any building construction, the hip roof has its own strengths and weak sides. The decision to choose the type of roof should be made only after a detailed analysis of the characteristics of the structure, the features of the project and your preferences. As already mentioned, from a technical point of view, a hip roof is much more complicated than a gable roof; only professional roofers can build such a structure based on working drawings of the house design.
What are the advantages of such a roof? The rafter system has several varieties, from the relatively simple classic hipped one to the very complex Danish hip one.
This variety of technical solutions significantly expands the scope of use of the design. In addition, hip roofs make it possible to increase the amount of overhang of rafter legs and, due to this, create canopies and protect facade walls from negative impact atmospheric precipitation.
The hip roof can be completely symmetrical, which simplifies the selection of the building site depending on the direction of the prevailing winds in the area.
Disadvantages - technical complexity, high estimated cost and small size attic space. Because of this, by the way, hip roofs rarely have attic living spaces.
Tips for building a hip roof on slabs
As mentioned above, hip roofs must withstand significant loads, and the length of the rafter legs requires the presence of additional intermediate vertical or corner supports. The lower point of these legs rests on the concrete floor, which significantly increases the requirements for the strength of the floor.
Conclusion - only high-quality and properly made floor slabs can guarantee the strength, reliability, stability and longevity of a hip roof. This should be taken care of even at the stage of building the house box. If the overlap meets all existing requirements, then the construction of the rafter system itself is much simplified.
In order to prevent problems from arising during the assembly of the rafter system, you should dwell in more detail on preparatory stage –pouring concrete flooring in the attic.
Step 1. Construction of formwork for a monolithic floor.
The concrete slab has a lot of weight; all load-bearing elements must be designed for maximum load with reserve. You must always remember that in addition to its own weight, large forces from the hip roof will act on the slab; the structure must withstand the loads without problems. And not only static ones, but also multidirectional dynamic ones.
The formwork must be strong, rigid and stable. If errors occurred during concreting the walls, then this is not critical. In the worst case, the surface of the wall is slightly deformed, then it is leveled and sealed without consequences. The same errors that occur during pouring of floor slabs can cause their complete destruction. If the structure collapses during the dismantling of the formwork, then this is not the worst option. The worst thing is when the slabs are lost load-bearing capacity after the construction of a hip roof or during the operation of the building.
The formwork is made of wooden beams, vertical supports are 100×100 mm, horizontal supports are made of boards 50×100 mm.
The distance between the boards is approximately 60 cm, the specific pitch depends on the thickness of the formwork lumber. All racks must be positioned strictly vertically in level; to prevent spreading in the lower part, they should be fixed together with various pieces of boards. The distance between the posts should be such that the total load on one element does not exceed 500 kg.
Lower part of the formwork, additional connections
Practical advice. To increase stability vertical racks It is recommended to make additional connections for them at approximately half the height. Due to this technique, it is possible to increase the stability of the structure by approximately 30%.
For formwork, you can use used boards 25 mm thick and approximately 100 mm wide. You shouldn’t nail every board, fix only the outer ones, fill the middle, but don’t nail it. This does not affect the strength of the structure, but it greatly simplifies the process of dismantling the formwork after the floor slab has hardened.
There is no need to achieve ideal density between the boards; small gaps will be covered with plastic film. It's much easier, faster and better.
Along the perimeter of the house, make an edge according to the thickness of the slab, in our case the slab is 20 cm thick. The same edges must be made for the stairs to the attic.
Step 2. Manufacturing of reinforcing belt. Lay the pieces on the formwork polyethylene film, you can buy the cheapest one, there is no difference. For reinforcement, you will need construction reinforcement of a periodic profile Ø 8 mm. In order to raise the reinforcement above the surface of the slab, use any pads. If there are passages in the slab electrical cables or ventilation holes, it is recommended to immediately provide openings in these places. This is much easier than then hammering into a solid concrete floor.
Close attention should be paid to the junction between the façade walls and the slab. There should be metal rods in the walls; they are bent and tied to the reinforcing belt.
Step 3. After the reinforcement has been laid in the first section, it can be filled with concrete. It is much easier to prepare floor slabs in parts, rather than the entire area at once. Why?
- There is no need to constantly walk on laid reinforcement. Only the area that is planned to be filled first is reinforced. Walking on a reinforcing belt is very uncomfortable and dangerous. In addition, there is a possibility of a change in its spatial position, which has a very negative effect on the strength of the concrete floor. The fact is that the reinforcement only works to its maximum when there is about five centimeters of concrete on all sides. If this layer is thinner, then the strength of the slab decreases noticeably. We have already talked about how important it is to adhere to the technology of pouring the floor slab, what heavy loads are applied to it and what sad consequences can arise due to the destruction of integrity.
- Much easier to pour concrete. If the solution is made and supplied manually, then to facilitate the work you need to have a large free area.
- It's easier to plan your work time. It is highly advisable to fill the entire slab at once; if this is not done, the strength of the structure is significantly reduced. During preparation, the size of the area can be selected taking into account labor productivity and weather conditions. The slab will be strong, perfectly compacted and even.
The concrete is leveled using a rule or a trowel; there is no need to achieve special accuracy. The difference in height at the corners of the house can reach two centimeters, this parameter is within the tolerances. The proportions of concrete are 1:2:4, for one part cement there are two parts sand and four parts gravel, water as needed.
In order to increase the adhesion strength between two separately poured concrete floor slabs, it is recommended to leave a special recess in the side part. It is very simple to do: a beam measuring approximately 50x50 mm is nailed in the middle of the dividing board. It will leave a groove in the first slab, the tenon will fill fresh concrete second slab. Using the same algorithm, you need to fill the entire area of the attic floor.
Formwork design - an additional board is nailed from the inside
Important. The formwork can only be dismantled two weeks after the last section has been poured.
If the weather is very warm and windy, then the surface of the ceiling should be moistened generously with water at least twice a day, watering it in the morning and evening. During the day, it is advisable to cover wet concrete with film. Why is this necessary? In order for concrete to gain strength, it is necessary chemical reactions cement, and they leak only in the presence of moisture. If there is little water, then the cement remains cement and crumbles after drying, the strength of the concrete slab will never correspond to the calculated values.
Prices for timber
Construction of a hip roof
After the ceiling has gained strength and the formwork has been dismantled, you can begin building the hip roof. We have already mentioned that this is very complex design, it can only be built according to the project. The working drawings contain details of each unit, indicating the materials and hardware used, and methods for fixing individual elements into a single structure. A plan for the placement of rafter legs, purlins, vertical and corner stops is separately attached. It is recommended to impregnate all wooden structures with antiseptics and fire-retardant compounds. Currently, there are drugs with complex effects on the market; one or two impregnations are enough. Special attention you need to pay attention to the ends, this is where moisture is absorbed most.
Important. Between concrete floor and the rafter system must be waterproofed.
To simplify the assembly of the rafter system, you can use galvanized metal corners and plates. These are excellent devices for quickly and securely fixing boards and beams.
But there is one note. Quite often you can see how even professional builders They try to screw self-tapping screws into every available hole. They think that there are so many holes in order to increase the strength of the joint being connected, but this is not so. Designers are not so stupid as not to understand the direct connection between the number of screws in the board and the strength of the fastening. They know that a large number of hardware causes the board to crack and, accordingly, the strength of the connection decreases sharply.
The maximum number of screws in the board does not exceed three or four, the distance between them is at least two centimeters. Why do perforated ones have so many holes? metal elements? It's simple, boards may have knots, cracks, natural defects and other problem areas into which it is not recommended to screw screws.
Prices for various types of fasteners for rafters
Rafter fasteners
We'll consider option for assembling a hip roof according to the American system with notching of all support points. During marking we will use very convenient tool carpenter - Svenson's square. As you might guess, it was also invented by an American; they have been using the square for many decades, but in our country it is still an outlandish tool.
Step 1. Mark the main rafter, the angle of inclination in our case is 30°.
All preparation work must be done on the ground; ready-made elements are lifted onto the ceiling for final assembly.
No one in America measures each rafter leg individually; one template is made and all other elements are adjusted according to it. This labor technology increases the productivity of builders at least three times. However, to work using this technology, several conditions must be met.
- The frame and ceiling exactly meet the design dimensions, actual deviations do not exceed acceptable standards.
- Measurements are taken accurately, and you need to use special devices.
- Cuts are made for all workpieces at once; they are first firmly fixed with clamps.
- Roofers are responsible and competent specialists who can work not only with their hands, but also with their heads. Every action must have a logical explanation.
Take a Swanson's square, place it at a right angle to the edge of the rafter board, and turn it until the 30° mark on the hypotenuse is aligned.
Draw a straight line on the board along the second leg. From the top point along the length of the board, set aside the length of the rafter. The length is calculated using the formula; to do this, you need to divide half the length of the house by the cosine of thirty degrees.
From the top point of the rafter leg, again draw a line at an angle of 30°.
Important. All measurements must be taken to the nearest millimeter with a margin for the width of the cut.
Do not take away the Svenson square, mark the distance from the top edge of the rafter to the stop pad, in our case it is eight centimeters. Make a point.
Turn the square over, set the angle to 90° and draw a line. You will get a small triangle, you need to cut it out, in this place the heel of the rafter leg rests on the mauerlat.
Set an angle of 90-30=60 degrees on the square, draw a line perpendicular to the drawn one
Now you should measure the length of the protrusion of the rafter leg, in our case it is about thirty centimeters. Using a square, draw the last line at the intended point at an angle of 30°. On the line, measure a vertical mark to the height of the end board, turn the square over, set it to 60° and draw a line. The two lines will be strictly perpendicular.
Note how high the side end on the cornice will be (5 cm). A perpendicular line is drawn along the 5 cm mark, having first turned the square over
Make cuts on the workpiece, check the accuracy of the rafters on the roof. Everything is fine - use the completed element as a template for cutting out the remaining rafter legs.
Step 2. Mark the corner rafter. This is the most important and complex element of a hip roof. When marking, we also strongly recommend using a Svenson square. Place it on the board and rotate until the 30° mark on the inner scale is aligned. On the outside at this time the angle will be approximately 22°. This is the actual slope, draw a line.
Swenson calculated all the data for the corner rafters and plotted the results on the internal scale. Now it’s easy to recognize slopes; you don’t have to run around with tables or calculators. The scale on the square covers all possible cases of slopes of the hip roof slopes.
Step 3. Measure the effective length of the corner rafter, attach a square at this point and at an angle of 30° on the second scale, draw a line.
Turn the square over and draw a line perpendicular to the first one. This is done in the same way as described above when marking ordinary rafter legs.
Maintain all dimensions accurately, otherwise the corner rafters will not lie in the same plane as the main ones. Keep in mind that the actual cut in this area will be increased by half the thickness of the board, it is cut in the corner.
The actual cut in this place will be increased by half the thickness of the board (25 mm)
From the top point, set aside the full length of the rafter, taking into account the overhang at the eaves.
Important. After rafter leg cut out, you need to make cuts at an angle of 45° at the ends on the side of the ridge and cornice.
Step 4. Prepare the moneymakers. We will have eight of them in total. They are marked in exactly the same way as the main rafters. The difference is in the effective length and direction of cutting the ends. The left one has a cut to the right side, and the right one has a cut to the left.
Practical advice. Remember that to cut boards at a 45° angle you need to have a long saw offset. For example, to saw a 50 mm thick board at this angle, a saw offset of at least 75 mm is required.
Prices for popular models of circular saws
Circular saws
After all elements of the rafter system are prepared, you can begin assembling the frame.
For your information. A hip rafter system on a 12x12 m house in America is completely assembled by two carpenters in two days. Now you can estimate labor productivity and find out why the earnings of domestic builders are many times different from the earnings of Americans.
The structure must be assembled from corner rafters and frames. First, the elements are baited and temporarily fixed with pieces of boards. After checking the position, the corner rafters and flanges are truly attached, a rope is pulled between them and simple rafters are installed.
The rope is not needed to correct mistakes, that's all individual elements The rafter system must fit exactly into place without various adjustments.
The rope is used to check the position of the planes of the rafter system, due to this, the installation of sheathing, filing of overhangs, etc. is accelerated. If you want to work, have the tools and know Hi-tech, then even the most complex rafter systems done without much effort.
Video - Hip roof, part 1 (ceiling)
Video - Hip roof, part 2 (installation of rafters)
Video - Hip roof, part 3 (lathing)
Video - Hip roofing, part 4 (bitumen shingles)