Soft roofing in last years has gained popularity among developers. But not everyone knows in advance that the base on which they usually lay bitumen shingles, is very different from the sheathing on which slate, ondulin or metal tiles are mounted. Let's try to figure out how the sheathing should be arranged under soft roof and how its installation differs from the installation of conventional sheathing.
The mauerlat serves as a kind of foundation for the roof, on which the entire rafter system. Flexible tiles do not tolerate unevenness, unnecessary bends, height differences and protruding nails in the base on which it will be laid, so it is necessary to take very seriously geometric parameters roof structures from the very beginning. All mauerlat bars must lie strictly horizontally for any structure configuration. And the lines connecting the ends of the mauerlats at the ends of the buildings should make an angle of 90° with them. If a device is also provided at the ends pitched roof, then the end Mauerlat should lie perpendicular to the longitudinal ones in the same horizontal plane with them.
Rafters - the frame of the future roof
If the Mauerlat is laid and secured correctly, then installation of rafters prepared according to one template, even for figured roofs, will be simple. As a matter of fact, this is where the similarity with frames for other roofing materials ends. Under rigid roofing sheets, the sheathing can be made from edged boards in one layer with an interval between boards of 150–400 mm. Under flexible tiles it is necessary to prepare a continuous, even and smooth base in two layers:- The actual sheathing is made of calibrated (one thickness) edged boards with a width of 100 mm, which can be mounted at intervals from 100 to 400 mm.
- A solid base on which soft tiles, made of plywood or OSB boards-3 (osb, OSB-3)
Plywood and/or OSB-3 board must be moisture resistant! All wooden roof structures: mauerlat, rafters, ridge girder, racks, struts, boards and timber for sheathing must have a humidity of no more than 20%.When calculating the distance between the rafter legs, it is necessary to take into account the thickness of the board, plywood sheets or OSB boards. If the pitch is 500 mm, then the thickness of the board can be 20 mm, and plywood or OSB boards can be 10 mm. With a step of 1000 mm, the thickness of the board should be 25 mm, and plywood or OSB board should be 20 mm thick. The distance may be different, and accordingly, the thickness of the boards and sheets of plywood, or OSB-3 boards should also be different. Here you need to understand that the board serves as a sheathing to support the slab or plywood. If the distance between the boards is too large, the sheet material may bend over time and sag between the supports, which will lead to deformation of the soft roof. The figures for the width of the board and the thickness of the materials used are minimal. Therefore, if you have the funds, you can purchase plywood or a board of a thickness greater than that required by calculations. In this case, the pitch of the board can be slightly increased. If the thickness is less than required, it would be better to make the sheathing of boards continuous. What is the reason for this? The thing is mechanical characteristics materials:
- The board can maintain its rigidity for decades when the right conditions operation and will lie flat even with a rafter pitch of 1200 mm or more. Of course, the board must have a thickness corresponding to this step.
- Over the years, plywood and OSB-3 boards can sag under the influence of temperature changes and variable humidity if they rest on points or support lines with a distance of even 500 mm between them.
- For all its rigidity, a board can “lead” over time, warp, the edges of individual boards can come out of common plane surfaces. But flexible tiles don’t like this. It will break, be pressed, or rub through, which will necessitate roof repairs.
- Obviously, using only boards or only plywood or OSB boards will lead to the fact that very soon the bitumen shingles will begin to tear at the seams of the boards or sag along with the boards or plywood. This may mean that the roof installation will have to be done again.
- Only the combination of the rigidity of the board and the flat surface of OSB boards or plywood will give reliability to the base for soft tiles, and there will be no need for roof repairs for a long time.
To find the best option, you need to find out the cost of all materials and calculate the consumption when different options step. For example, the cost of an OSB-3 board with a thickness of 20 mm is almost twice as high as the cost of this board with a thickness of 10 mm. Preparation truss structures roofs for installation must take into account the fact that wood is a flammable material and susceptible to rotting. Therefore, it is recommended to carry out appropriate treatment with fire retardant impregnations and antiseptics, and in places where the rafter legs come into contact with the wall, it is better to lay waterproofing material. For example - roofing felt. A layer of waterproofing must be placed under the Mauerlat. 
Sheathing device
The sheathing for a soft roof must meet the following requirements:- A continuous, flat, smooth surface of the base without deflections, potholes, chips, cracks and protruding chips or nails.
- Technical gaps between OSB boards or plywood sheets, necessary to compensate for their possible expansion, should not exceed 6 mm.
- During installation, the edges of sheets and slabs must be cleaned so that they are not sharp, even if they lie close to each other.
They will serve as protection against water entering the wooden structures of the rafter system. If you plan to install gutters, then they need to be installed before the drip line. Oriented strand board (OSB), when used inside a dry room, does not need any additional protection from moisture. IN worst conditions It turns out that the outer cladding of the house is made of this slab. Over time, it darkens not only from rain, but also from solar ultraviolet radiation. Of course, you can cover the slabs with siding or blockhouse, but this is associated with at great expense. How to treat OSB boards against moisture is a difficult question. Let's try to answer it.
Is additional processing needed?
The moisture resistance of oriented strand boards is characterized by the amount of thickness swelling during the day. According to this parameter, according to the American standard PS 2, European EN-300 and Russian GOST 10632-89, slabs are divided into 4 types (see table).
Let us recall that for external cladding In buildings, only OSB-3 and OSB-4 boards are allowed.
If the constructed structure is to be finished somehow, then during construction the OSB boards lie on the construction site in bundles. Even after one rain, the top few sheets swell almost one and a half times. They will remain like this after drying. The remaining sheets swell at the ends. By the way, to avoid this, the ends of North American products are painted with blood-red impregnation.
Among some builders there is an opinion that OSB boards do not need additional processing, since they are already impregnated with resins, waxed, and varnished. Experience shows that after 2-3 years they appearance loses its original freshness, they darken, in some places individual chips bulge, joints protrude sloppily.
Therefore, additional hydrophobic treatment will not be superfluous, especially if it is the facade of a residential building without any cladding. Let's consider how to treat OSB boards from moisture.
1. Transparent impregnations
Most cheap option treatments – water-repellent colorless impregnations. There are no special solutions for OSB. You can use any wood products, with the exception of those prepared on water based. Examples of such compositions:
- Antiseptic impregnation for wood Elcon on silicone based. Designed for long-lasting protection wooden structures from weathering, rotting, mold. Scope of application: for interior and exterior work. Forms a water-repellent film, non-toxic, allows the wood to “breathe”.
- Innovative domestic hydrophobizing composition NEOGARD-Tree-40 based on organosilicon oligomers. Designed to impart water-repellent properties to products made of wood and wood-based materials: plywood, chipboard, fiberboard. Water absorption for chipboard is reduced by 15 - 25 times. Obviously, it is also suitable for OSB. Does not change the natural color of the material, protective properties are stored for at least 5 years.
The most suitable for protecting wood (and OSB) from moisture is the so-called yacht varnish on a urethane-alkyd or alkyd-urethane basis. Some of the popular brands:
- Tikkurila UNIKA SUPER (Finland). This brand is a leader in resistance to environmental influences, immunity to ultraviolet radiation and temperature changes.
- Marshall protex (Türkiye). Creates a plastic surface film.
- Marshall Protex Yat Vernik. It has increased wear and moisture resistance.
- PARADE (Russia). Keeps fresh for a long time.
- Belinka Yacht (Russia). It has dirt- and water-repellent properties, emphasizing the texture of wood materials.
- Antiseptic varnish for wood “Drevolak” on acrylic base with added wax (Russia). Along with antiseptic and antibacterial effects, it successfully protects wood from moisture.
Since OSB is a wood processing product, then paints and varnishes(LMB) the same ones can be used for them:
- Oil paints. Due to the presence of polymer resins in OSB, drying oil-based paints do not always adhere well to the surface being painted. For better adhesion to the base, it is recommended to perform double priming with intermediate putty before painting. Despite this, oil-based coatings under the influence of ultraviolet radiation, temperature changes and precipitation are prone to fading, cracking, and even peeling. We can recommend paint based on natural and modified oil PINOTEX WOOD OIL SPRAY, which has good resistance to external factors.
- Alkyd paints are better suited to particle boards because they contain alkyd resin, a product of the chemical reaction of natural oils with acids. Their adhesion is higher compared to oil-based paints, they dry faster and resist atmospheric influences more successfully.
- Acrylic compositions, being inexpensive and durable to use, have an optimal balance of qualities and are most in demand for painting wood. In addition, they are available in a wide range of colors.
Attention: pre-treat a small surface in an inconspicuous place to ensure that the material does not swell when exposed to the aqueous acrylic suspension.
In conclusion, we can say that the question: how to treat OSB boards against moisture is difficult to answer unequivocally. Firstly: it depends on whether you want to emphasize the texture of the slab with a transparent solution or, conversely, apply a covering (opaque) coating. Secondly: – on the financial capabilities and aesthetic ideas of the developer.
Expert advice
Prev Next
To Oil paint does not dry out during storage and so that a film does not form on it, place a circle of thick paper on the surface of the paint and “fill it thin layer drying oils
"The polyethylene film covering the balcony or greenhouse is protected from being torn off by the wind by a string stretched on both sides at intervals of 10-15 cm."
"To work with concrete mixture it was easier, clay is usually added to it, but clay reduces the strength of the mixture. Add a spoon to it washing powder based on a bucket of water. "
"To prevent the screw, the head of which is hidden behind the obstacle, from rotating along with the tightened nut, you need to throw several turns of thread or thin wire over it and lightly tighten the ends. Due to friction, the screw is held well in place. The ends of the thread can be cut off after tightening."
"You can cut out a birdhouse entrance without a brace. It is enough to split front side boards in the center and cut out half-holes of the required size with a chisel or hatchet, and then connect the halves again. "
Wooden screw plugs crumble and fall out of the wall. Take your time to cut out the new plug. Fill the hole in the wall tightly with nylon from an old stocking. Using a nail of a suitable diameter heated red hot, melt a hole for the screw. The fused nylon will turn into a strong cork.
" Carpenter's level it is not difficult to turn it into a theodolite, equipping it with an aiming device from a slot and a front sight. "
"In order for two strips of linoleum to lie end to end, it is convenient to use a self-adhesive decorative film, placing it under the base of the noleum."
"So that the nail goes into in the right direction and did not bend when driven into a deep hole or groove, you should place it inside the tube, securing it with crumpled paper or plasticine. "
Before drilling a hole in concrete wall, secure a piece of paper just below. Dust and concrete fragments will not fly around the room.
"To cut a pipe exactly at a right angle, we recommend doing this. Take an even strip of paper and screw it onto the pipe along the sawing line. The plane passing through the edge of the paper will be strictly perpendicular to the axis of the pipe."
"Roll over logs or wooden beams A simple device will help - a piece of motorcycle or bicycle chain, supplemented with a hook on one side and secured to a crowbar on the other side. "
"In order for one person to be able to work with a two-handed saw, we recommend using a simple technique: move the saw handle from the top to the bottom position."
You can cut a piece of slate of the required size with a saw, but it is better and easier to punch holes along the line of the intended cut with a nail at a frequency of 2-3 cm, and then break off the slate on the support.
" The best way glue the tile to the wall: take bitumen, melt it and drop just four drops on the corners of the tile. Stuck on dead. "
When making shaped window casings, it is most convenient to cut shaped holes with a hacksaw with a sharpened blade.
"Making stained glass is a long and difficult task. You can make a quick imitation of stained glass. To do this, take thin slats or rods of vines, glue them to a sheet of glass, and then paint the glass and cover it with varnish."
"If you don't have a dowel at hand, you can make one from a piece of plastic tube. The body of a ballpoint pen can also be suitable for this. Having sawed off a piece of the required length, make a longitudinal cut, about halfway, and the dowel is ready."
"It is known how difficult it is to hang a door when working alone. But just shorten the bottom pin by 2-3 mm and the work will become much easier."
"A very durable, non-shrinking and fairly waterproof putty is made from bustylate mixed with any powder - chalk, gypsum, cement!, sawdust, etc."
"If you need to screw a screw into the end of a particle board, drill a hole slightly smaller than the diameter of the screw, fill the hole with Moment glue (not epoxy!), screw the screw in a day later. The board does not delaminate. However, the resulting connection can only be placed under load through day. "
"Attach portraits, photographs, paintings to wooden frames It is more convenient to work with glass not with nails, but with the help of pushpins bent at right angles. The buttons are gently pressed with a screwdriver. Compared to nails, the risk of splitting thin frames is reduced to a minimum. "
"It is not so easy to screw a screw into hard wood. If you poke a hole for the screw with an awl, and rub the screw itself generously with soap, then after such an operation the work will go like clockwork."
To save time, the edge of the wallpaper can be trimmed with a sharp knife without unrolling the roll. To do this, you must first align the end of the roll and with a simple pencil outline the edge border on the outside. Working with a knife, the roll must be gradually turned in the direction of rolling.
For carrying at home large sheets plywood, glass or thin iron, it is convenient to use a wire holder with three hooks at the bottom and a handle at the top.
IF you need to saw a round stick into the distance, this work is most conveniently done using a template. It is made of a metal tube with a groove in the middle. The diameter is chosen so that the template slides freely along the stick.
It will be better and easier to work with a hacksaw if in the middle part you increase the height of the teeth by 1/3.
If on the front of the machine bow saw attach a load weighing about a kilogram, then the work will become easier. The load must be made removable so that the saw can be used to perform other work.
"A wax-like coating can be obtained by painting the surface with diluted PVA glue. To obtain desired color, you need to dilute the glue with water tinted with watercolors. "
"Making a cover for an ax blade is as easy as shelling pears. Take a piece of rubber tube, cut it lengthwise and put it on the blade. It is protected from slipping off by a ring cut from an old car camera."
" Avoid using clamps when gluing wooden frames A laundry cord will help. You should put four short loops on the corners of the frame and two long ones to tighten the frames diagonally. The angles are adjusted using sticks that twist the middle loops. "
"How to silence a creaking floorboard? Between the floorboards you need to drill a hole at an angle of 45° with a diameter of 6-8 mm, drive a wooden pin into it, lubricated with wood glue, cut off the protruding end with a chisel and putty on the floor surface."
"To make it easier to sand a floor covered with varnish or paint, iron it with an iron through a damp cloth - and the work will become easier."
"Slight rotting on wood can be eliminated as follows: the affected wood is removed from the healthy layer, and then soaked in a 10% formaldehyde solution. After drying, the area is puttied and painted over."
" Door hinges they will not creak if they are lubricated in time - this is a long-known rule. But you can do without lubrication. To do this, you need to make a washer from a polyethylene cork and put it on the hinge pin. "
"A door latch that has failed due to a broken spring can be repaired as follows: the role of the spring can be successfully performed by a piece of rubber tube with a diameter of 15 mm or a piece of elastic rubber installed between the bolt and the latch body."
We offer a simple device for fixing the window frame in open position: a wooden or plastic plate in which a number of holes are drilled for the latch. The plate is attached to window box with a screw.
"Cut to sheet material big hole can be done in a simple way: clamp a nail in a vice (it will serve as an axis) and a piece of a drill (this will serve as a cutter). The circle is cut by rotating the sheet around its axis. "
There are many varieties of soft roofing. This includes numerous rolled fused materials, soft tiles and roofing felt. These materials may have different operational and visual characteristics, but they also have common feature– all of them are made on the basis of bitumen, which ensures the softness and flexibility of the final product.
For all its flexibility, a soft roof can retain the shape once given to it and withstand various loads - but in order for these properties to manifest themselves, it is necessary to install high-quality and reliable sheathing under the roof. How to make lathing for a soft roof will be discussed in this article.
Types of lathing for soft roofing
There are two fundamentally different types– solid sheathing and lattice. In a lattice sheathing, all elements are located at some distance from each other. As a rule, the pitch of installing boards in such a sheathing varies from 20 to 50 cm. This design is not suitable for soft roofing materials - the gaps between the boards are too large, so the roof will sag in them.
A completely different matter is a solid sheathing, in which, as the name suggests, there are no gaps between the elements or are reduced to a minimum. Maximum step sheathing for flexible tiles in in this case is 1 cm.
Two types of continuous sheathing can be installed under a soft roof:
- Single layer. In this design, the sheathing elements are installed directly on the rafter legs and are located parallel ridge run. For installation of single-layer sheathing, boards are suitable: moisture resistant plywood or OSB. This design is used quite rarely and only if the roof is covered with roofing felt.
- Double layer. This type The lathing consists of two layers, which can be made from the same material or from different ones. First, a rafter system is installed under a soft roof, then the first layer is arranged as a lattice, with a fairly big step installation of elements. A second layer is mounted above it, in which gaps are not allowed. The main advantage of a two-layer sheathing is the presence ventilation duct and free space sufficient for installation thermal insulation materials, which makes this design very convenient for arranging a soft roof.
The installation technology of each type of lathing is worth considering in more detail.
Single-layer sheathing made of boards for flexible tiles
As mentioned above, a single-layer sheathing for flexible tiles is attached directly to the rafters and is only suitable for laying roofing felt. In addition, when using such a design, it will not be possible to install insulation, so from the point of view of energy efficiency, single-layer sheathing is not very good.
The frame for a soft roof can be made of tongue-and-groove boards or planks. Choose unedged boards extremely undesirable - any roughness and unevenness of this material will certainly lead to deformation of the soft roof, which, in turn, will lead to a decrease in their decorative and operational characteristics.
When choosing boards, you need to take into account the following requirements:
- The material must be smooth and smooth surface without any irregularities;
- The width of the boards can vary between 100-140 mm, and the thickness - 20-37 mm;
- The moisture content of the boards should not exceed 20% (excess moisture in the wood leads to its premature deformation and damage to the roofing);
- Before making the sheathing, everything wooden elements it is necessary to impregnate with antiseptics that will protect the wood from rot, mold and pests.
Structurally, the single-layer sheathing under consideration consists of boards that are packed to the rafters close to each other. The boards must be placed parallel to the ridge. To prevent them from warping over time, they need to be laid with the concave side up, so that moisture that has made its way through the thickness of the roofing will flow out along the boards through the cornice.
It is necessary to begin the process of installing the sheathing from the eaves overhang, gradually moving towards the ridge. The length of the boards must be selected so that they fit exactly on the rafter legs. It is advisable to fasten them as close to the edge as possible, driving nails into the wood up to the head.
The optimal gap between vertical adjacent boards is 3 mm. The presence of such a gap, on the one hand, will provide reliable support for the soft roof, and on the other hand, it will allow the boards to freely change their sizes with changes in temperature and humidity. If you fix them more tightly, then the constant expansion and contraction of the boards will sooner or later lead to their curvature.
Single-layer lathing made of panel materials - pitch, frame thickness
To arrange the sheathing, you can use not only boards, but also panel materials - plywood or OSB. They have everything necessary qualities, which are required by quality supporting structure. In addition to good performance characteristics, plywood for flexible tiles is easy to install and has an initially flat surface, ideal for further installation of soft roofing.
The panel materials used in single-layer lathing are also subject to a number of requirements:
- High moisture resistance. A soft roof must be reliably protected from moisture, so it is necessary to select moisture-resistant materials for the sheathing. If we talk about specific brands, we can highlight OSP-3 and FSF.
- Suitable thickness . Panel materials can have a thickness from 9 to 27 mm (the choice of a specific value depends on the pitch of the rafters).
- Antiseptic treatment. In order for the lathing made of panel materials to be sufficiently durable and reliable, it must be treated with an antiseptic before installation.
Laying panel materials on rafters is done differently than with boards. The sheets are mounted parallel to the ridge, but their joints should not coincide. Typically, a staggered arrangement is used for such material.
Adjacent sheets should be 2 mm apart from each other. When installing the roof in winter, the pitch should be increased to 3 mm so that the sheathing can freely expand in summer time. To fix the panels, self-tapping screws or nails are used, which are used as follows: on the rafters the fastening step is 30 cm, at the end sections they are located 15 cm from each other, and at the edges - 10 cm.
Double continuous plank sheathing
A two-layer sheathing consists of two layers, one of which is made in a lattice form, and the second, located at the top, is made in a solid form. This lathing design is more reliable and efficient than a single-layer one, so it is used in the vast majority of cases. Of course, due to the greater number of layers, the thickness of the soft roof increases.
In the embodiment under consideration, each layer of the sheathing consists of boards that must meet the following requirements:
- The lattice layer boards must have a thickness of over 25 mm and a thickness of 100 to 140 mm (instead of boards, beams with a section of 50x50 or 30x70 mm can be used);
- To make a continuous layer of sheathing, boards 20-25 mm thick and 50-70 mm wide are required;
- Before installation, wooden elements must be treated with antiseptic agents.
Installation of a two-layer sheathing is quite simple. First of all, boards of the first layer are fastened parallel to the ridge across the rafters. They need to be secured at such a distance that the second layer does not sag after installation. Optimal step installation of boards of the first row - 20-30 cm.
When the first row is installed, you can begin installing the second. The sheathing elements must be installed from top to bottom. A small gap of 3 mm should be left between the boards for normal thermal expansion.
Combined two-layer roof sheathing
Best suited for laying flexible tiles combined option sheathing, in which the first layer consists of sparse boards fixed perpendicular to the rafters, and the second layer is made of panel materials. This type of construction is standard and is most often used when arranging an unheated attic.
To create an insulated attic with waterproofing and insulation, you will need a different scheme, somewhat more complex. First, you need to fill the counter-lattice along the rafters, and then all the other elements will be attached on top of it. Let's figure out why the counter-lattice is needed in general. The counter battens allow you to create a ventilation gap between the main batten and the waterproofing material.
The materials used must meet the following requirements:
- For the counter-lattice, even bars with a cross-section of 25x30 or 50x50 mm are suitable;
- The first layer is made of boards 25 mm thick and 100 to 140 mm wide;
- Plywood or OSB for soft tiles should have a thickness of 9 to 12 mm;
- All wooden elements must be impregnated with an antiseptic.
Installation of the combined sheathing is carried out according to the following algorithm:
- When installing a warm roof with insulation and waterproofing, you need to install a counter-lattice, which is attached above the rafters. In addition to creating a gap for ventilation roofing pie, counter-lattice bars provide fastening waterproofing film. To create such a structure, you first need to install thermal insulation and waterproofing, and only then begin installing the sheathing.
- Next comes the turn of the boards of the first row, which are attached to the counter-lattice (if there is one) or directly to the rafter legs. The standard step for attaching the bottom layer of the sheathing is 20-30 cm.
- IN last resort is installed the last row battens. Sheets of the selected material are laid in a checkerboard pattern with a small gap (2-3 mm). OSB or plywood for soft tiles is attached to each rafter leg with a pitch of about 30 cm. The edges of the elements should also rest on the supports, and at these points the fastening step should be reduced to 15 cm.
Checking the quality of the sheathing
If the sheathing for bitumen shingles was installed correctly, it will have a number of properties:
- No deflection under human weight - sagging elements of the sheathing will significantly complicate the installation of the roofing and its repair;
- No gaps above permissible limits(if there are large cracks in the sheathing, they need to be sealed with roofing sheet);
- No irregularities, protruding nails or knots that could compromise the integrity of the soft roofing material;
- No sharp edges around the entire perimeter of the finished sheathing;
- Well-conducted preliminary preparation wood, which includes drying boards and sheets, as well as impregnating them with antiseptics.
The roof sheathing for a soft roof is considered complete only if it meets all the described requirements.
Conclusion
Several types of lathing are suitable for a soft roof, so before making lathing for a soft roof, you need to choose a suitable design. If all the nuances have been taken into account, then all that remains is to correctly carry out installation work, And finished design will provide reliable support for soft roofing.
Good afternoon
We are building frame house, it is sheathed OSB boards, there is a roof - corrugated sheeting, in winter it will go in this form. During the summer, after several rains, the OSB delaminated in some places. Is it possible to cover the walls with windproof film for the future ventilated façade for the winter and will it not lose its properties by spring? And what material is better to take: Izospan A, AD? The facade will be a blockhouse.
It is possible to cover an unprotected façade with windproof film, but this will not fully solve the problem of preserving OSB. The fact is that the windproof membrane is designed to withstand the impact of individual droplets, which are the result of condensation falling on roofing. Good slanting rain, downpour, wet snow is beyond its power, the windproof membrane will “cry” with inside. Undoubtedly, wind protection will reduce the wetting of the OSB, but will not completely eliminate it.
A windproof membrane is a good thing when it is covered with exterior finishing
OSB-3 boards, which will most likely cover the frame of your house, can only be called moisture resistant with a stretch. And then we can talk about their resistance to moisture only in relation to chipboard, fiberboard, OSB-1 and OSB-2, which quickly deteriorate under the influence of water. OSB-3 is not intended for use as fencing wall material without subsequent finishing, unlike, for example, cement-bonded particle boards (CSB). By the way, in Canada and the USA, where they came to us from frame technologies, for finishing decent houses that should last a long time, they use waterproof plywood, particle boards- the lot of the poorest.
Manufacturers provide such characteristics as the degree of swelling of an oriented strand panel when placed in water for 24 hours. For OSB-3 it is 15%. This is not so little, contrary to the claims of sellers and manufacturers. Of course, on the walls the particle boards are in a vertical position and are only exposed to slanting rain on one side. However, let’s assume that there are showers, sleet, and humidity for a week or two. Low air temperatures and the absence of sun do not allow the walls to dry.
OSB sheets that are not protected from precipitation will get wet and swell. At the same time, they will increase not only in thickness, but also in length and width, albeit not so significantly. As a result, the particle boards, rigidly fixed to the frame, will warp. And it is not a fact that when they dry they will return to their original shape; residual deformations are very likely. In addition, the fastening points will weaken, delamination of the ends may occur (it has already begun for you), and the strength of the gluing will decrease. It is unlikely that particle boards will not suffer critical damage in one season, but their service life will be shortened and the overall stability of the frame will decrease, that’s a fact.
OSB is not a completely waterproof material; it will inevitably deteriorate if exposed to moisture for a long time.
In our opinion, the following options are possible for temporary protection of an unfinished facade from precipitation:
- Stretch the windproof membrane Izospan A (18 RUR/m2) according vertical sheathing, use a block 4-5 cm thick. The film is quite weak, it is not a fact that it will successfully survive the winter and will not be torn by the winds.
- Use Izospan AM (24 rubles/m2) or Izospan AS (35 rubles/m2). Three-layer wind protection is stronger, less permeable to water vapor, but three times more water-resistant, which means it will get wet less. Under the finishing (blockhouse) it could be stretched without lathing, directly over the slabs. But in your case, a ventilated gap and sheathing are needed. It is necessary to ensure free flow of air, the gap should be at the bottom and at the top, under the roof. Option #2 is preferable.
- Stretch any cheaper vapor-waterproofing material over the sheathing, maintaining ventilation: roofing felt, reinforced construction vapor barrier, dense plastic film for greenhouses (enough for one season). When covering the facade, the waterproofing will have to be removed.
While there is no finishing, polyethylene film, with or without reinforcement, can be used as temporary protection
The right decision would still be to tighten up with finances and finish by the fall exterior finishing, covering the facade with a blockhouse along a vertical sheathing. In the end, it will be cheaper, because the OSB boards themselves can serve as wind protection if they are carefully fitted. You won't have to spend money on film.
Correct solution"puff pastry" frame wall. If the OSB boards fit well and the insulation is completely closed, they will also serve as wind insulation. There is no need to spend money on an additional membrane.