The osb facade can be left for the winter. Is it possible to close the OSB sheathed frame of the house with a windproof film for the winter? Single-layer sheathing from boards for shingles

Good day!
We build frame house, it is sheathed with OSB plates, there is a roof - corrugated board, in the winter it will go in this form. During the summer, after several rains, the OSB stratified in some places. Is it possible to cover the walls with a windproof film under the future ventilation facade 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.

Cover an unprotected facade windproof film it is possible, however, this will not completely solve the problem of preserving OSB. The fact is that the windproof membrane is designed to withstand the effects of individual drops, which are the result of condensation on roofing... Good slanting rain, downpour, sleet is beyond her power, the windproof membrane will “cry” from the inside. Undoubtedly, wind protection will reduce the wetting of the OSB, but it will not completely eliminate it.

A windproof membrane is a good thing when it is covered with an outer trim

OSB-3 boards, which, most likely, will sheathe the frame of your house, can be called moisture resistant only with a stretch. And then about their resistance to moisture can be said only in relation to chipboard, fiberboard, OSB-1 and OSB-2, which quickly collapse under the influence of water. OSB-3 is not intended to be used as a sheathing wall material without further finishing, unlike, for example, cement particle boards(DSP). By the way, in Canada and the USA, where did they come from? frame technologies, for the decoration of decent houses that must stand for a long time, use waterproof plywood, particle boards- the lot of the poorest.

Manufacturers give such characteristics as the degree of swelling of an oriented strand board when in water for a day. 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 an upright position and are only exposed to the slanting rain on one side. However, let us assume that there are showers, sleet, wet for a week or two. The low air temperature and the absence of the sun do not allow the walls to dry out.

OSB sheets that are not protected from precipitation will get wet and swell properly. 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, which are rigidly fixed to the frame, will warp. And it's not a fact that when they dry they will take their original shape, permanent deformations are very likely. In addition, the attachment points will weaken, delamination of the ends may occur (it has already begun for you), the strength of the gluing will decrease. It is unlikely that critical damage will not be inflicted on particle panels in one season, but their service life will be reduced, the overall stability of the frame will decrease, this is a fact.

OSB is not a completely waterproof material, it will inevitably collapse with prolonged exposure to moisture

In our opinion, the following options are possible for temporary protection of an unfinished facade from precipitation:

Pull on windproof membrane Izospan A (18 rubles / m2) on a vertical crate, use a bar 4-5 cm thick. The film is rather weak, it is not a fact that it will successfully survive the winter, it will not be torn by the winds.
Use Izospan AM (24 rubles / m2) or Izospan AS (35 rubles / m2). A three-layer windscreen is stronger, less water vapor permeable, but three times more waterproof, which means it will get wet less. Under the finishing (blockhouse), it could be stretched without lathing, right along the slabs. But in your case, a ventilated gap and crate are needed. It is necessary to ensure a free flow of air, the gap should be below and above, under the roof. Option number 2 is preferable.
Stretch along the crate, observing ventilation of any steam waterproofing material cheaper: roofing paper, construction reinforced vapor barrier, dense plastic wrap for greenhouses (enough for one season). When cladding the facade, the waterproofing will have to be removed.

While there is no finishing, plastic wrap can be used as temporary protection, with or without reinforcement.

The right decision would still be to tighten up with finances and finish by the fall. exterior decoration, sheathed the facade with a blockhouse along the vertical crate. As a result, it will come out cheaper, because they themselves can serve as wind protection OSB boards if they are neatly fitted. You don't have to spend money on film.

The right decision Puff pastry frame wall... If the OSB boards are fitted 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.

Soft roof in last years gained popularity among developers. But not everyone knows in advance that the base on which bituminous tiles are usually laid is very different from the crate on which slate, ondulin or metal tiles are mounted. Let's try to figure out how the crate should be arranged under soft roof and how its installation differs from the installation of a conventional lathing.

A kind of foundation for the roof is the Mauerlat, on which the entire rafter system rests. Flexible shingles do not tolerate irregularities, unnecessary bends, height differences and protruding nails in the base on which they will be laid, therefore it is necessary to take very seriously geometric parameters roof structures from the start. All bars of the Mauerlat should lie strictly horizontally for any configuration of the structure. 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 in the same horizontal plane with them.

Rafters - the frame of the future roof

If the Mauerlat is laid and secured correctly, then the installation of rafters prepared according to one template, even for curly roofs, will be easy. As a matter of fact, this is the similarity with the frame for others roofing materials ends. For rigid roofing sheets, the sheathing can be made from non edged boards in one layer with an interval of 150–400 mm between the boards. Under shingles it is necessary to prepare a solid, even and smooth base in two layers:

The lathing itself is made of a calibrated (one thickness) edged board with a width of 100 mm, which can be mounted at intervals from 100 to 400 mm.

Solid base, on which soft tiles are glued, made of plywood or OSB-3 (OSB, OSB-3)

Plywood and / or OSB-3 board must be moisture resistant! All wooden roof structures: mauerlat, rafters, ridge run, racks, struts, boards and timber for lathing, should have a moisture content 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 the plywood or OSB board - 10 mm. At a step of 1000 mm, the thickness of the board should be already 25 mm, and plywood or OSB board should be taken with a thickness of 20 mm. The distance may be different, respectively, and the thickness of the boards and plywood sheets, or OSB-3 boards should also be taken differently. Here you need to understand that the board serves as a crate to support the board or plywood. If the distance between the boards is too large, the sheet material can bend over time, 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 named minimum. Therefore, with the availability of funds, you can purchase plywood or a plate with a thickness greater than required by calculations. In this case, the pitch of the board can be increased slightly. If the thickness is less than required, it will be better to make the sheathing of the boards solid. What is the reason for this? The point is in the mechanical characteristics of the materials:

The board can retain its rigidity for tens of years 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.
Plywood and OSB-3 board can sag over the years under the influence of temperature extremes and changeable humidity if it rests on points or support lines with a distance of even 500 mm between them.
With all its rigidity, the board can eventually "lead", warp, the edges of individual boards can go out of the general plane of the surface. And shingles don't like that. It breaks, squeezes, wipes, which will cause the need to repair the roof.
Obviously, the use of only boards or only plywood or OSB boards will lead to the fact that very soon bituminous shingles will begin to tear at the seams of the board or sag along with the boards or plywood. And this may mean that the installation of the roof will have to be done again.
Only the combination of the stiffness of the board and flat surface OSB boards or plywood will give reliability to the base for soft tiles, and there will be no need to repair the roof for a long time.

To find the best option, you need to find out the cost of all materials, and calculate the consumption for different options step. For example, the cost of the OSB-3 slab with a thickness of 20 mm is almost twice as high as the cost of this slab with a thickness of 10 mm. Training roof structures roofs for installation must take into account the fact that wood is a combustible material and subject to decay. Therefore, it is recommended to carry out appropriate treatment with fire retardant impregnations and antiseptics, and in places where rafter legs in contact with the wall, it is better to lay a waterproofing material. For example - roofing material. A layer of waterproofing must be placed under the Mauerlat.

Sheathing device

The sheathing for a soft roof must meet the following requirements:

Solid, even, smooth surface of the base without deflections, gouges, chips, cracks and protruding chips or nails.
The 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.

Only if these conditions are met, shingles will serve for a long time and reliably. Another important condition is the possibility of ventilation of the roof space.... If the attic is uninhabited, then under the cornice there should be a gap for air access under the roof, and under the ridge there should be "windows" for air to escape to the outside. When arranging an attic inner lining walls and ceilings will need to be done so that air can circulate freely in the space between the roofing "pie" and the cladding of the room from bottom to top. This space, by the way, will serve as additional sound and thermal insulation of the attic. Alternatively, with the initial planning of an attic with additional insulation, the best option there will be a waterproofing device under the roof. To do this, you need to pull the waterproofing membrane along the rafters, fix it with a counter-lattice made of timber with a section of 50 x 30 or 50 x 50 mm and already mount two base layers for a soft roof along the counter-lattice. The gap between the membrane and the boarding will serve ventilation duct for air circulation. In this case, remember to leave the air vents in the upper part of the roof so that the air coming from under the eaves and rising up under the roof has the opportunity to escape. Installation of a two-layer base for flexible shingles leads to an increase in the cost of the roof in terms of 1 m², but at the same time allows you to save on insulation. The finishing touch of the base device under soft shingles editing should be eaves or a dropper.

They will serve as protection against water ingress on wooden structures. rafter system... If at the same time it is planned to install gutters, then they must be installed before the drip.

Oriented strand board (OSB), when used inside a dry room, does not need any additional protection from moisture. V worst conditions it turns out the outer cladding of the house from this slab. Over time, it darkens not only from rains, but also from solar ultraviolet radiation. Of course, you can close the slabs with siding or a blockhouse, but this is associated with high costs... How to process an OSB (OSB) board from moisture is not an easy question. We will try to answer it.

Do you need additional processing?

The moisture resistance of oriented strand boards is characterized by the amount of swelling in thickness during the day. According to this parameter, according to the American PS 2 standard, the European EN-300 and the Russian GOST 10632-89, the plates are divided into 4 types (see table).

Recall that for outer cladding buildings, only OSB-3 and OSB-4 slabs are allowed.

If the constructed structure still somehow gets off, then during the construction of the OSB slabs lie on the construction site in packs. Even after one rain, several of the top sheets swell almost one and a half times. They will remain so even after drying. The rest of the sheets swell at the ends. By the way, in order to avoid this, the ends of North American products are painted with a 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, varnished. Experience shows that after 2-3 years their appearance loses its original freshness, they darken, in some places individual chips bulge out, the joints protrude sloppily.

Therefore, additional hydrophobic treatment will not be superfluous, especially if it is a facade of a residential building without any cladding. Consider how to treat the OSB board from moisture.

1. Transparent impregnations

Most cheap option treatments - colorless water-repellent impregnation. There are no special solutions for OSB. You can use any wood product, except for those prepared on water based... Examples of such formulations:

Elcon wood preservative, silicone-based. Designed for long-term protection wooden structures from weathering, decay, mold. Scope: for indoor and outdoor use. Forms a water-repellent film, non-toxic, allows the tree to "breathe".
Innovative domestic hydrophobizing composition NEOGARD-Derevo-40 based on organosilicon oligomers. Designed to impart water-repellent properties to products made of wood and materials based on it: plywood, chipboard, fiberboard. Water absorption for chipboard is reduced by 15 - 25 times. Obviously, it works for OSB too. Does not change the natural color of the material, the protective properties remain 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 base. Some of the popular brands:

Tikkurila UNIKA SUPER (Finland). This brand is leading in terms of resistance to environmental influences, immunity to ultraviolet radiation and temperature changes.
Marshall protex (Turkey). Creates a plastic surface film.
Marshall Protex Yat Vernik. Possesses increased wear and moisture resistance.
PARADE (Russia). Keeps fresh for a long time.
Belinka Yacht (Russia). Has dirt and water repellent properties, emphasizes the texture of wood materials.
Wood antiseptic varnish "Drevolak" on acrylic base with the addition of wax (Russia). Along with antiseptic and antibacterial action, it successfully protects wood from moisture.

Since OSB is a product of wood processing, then paints and varnishes(LMB) the same can be used for them:

Oil paints. Due to the presence of polymer resins in the OSB, varnish-based paints do not always fit well on the surface to be painted. For better adhesion to the substrate, it is recommended to make two priming with an intermediate putty before painting. Despite this, oil-based paints and varnishes under the influence of ultraviolet radiation, temperature extremes and atmospheric precipitation are prone to fading, cracking, and even peeling. We can recommend a paint based on natural and modified oil PINOTEX WOOD OIL SPRAY, which has good resistance to external factors.
Alkyd paints are better suited to chipboards, since they contain alkyd resin as a product of the chemical interaction of natural oils with acids. Their adhesion is higher in comparison with oil paints, they dry faster and more successfully resist atmospheric influences.
Acrylic compositions, being inexpensive and durable in operation, are distinguished by an optimal ratio of qualities and are most in demand for painting wood. In addition, they are available in a large assortment of colors.

Caution: Pre-treat a small area in an inconspicuous place to make sure that the water-based acrylic slurry does not swell the material.

In conclusion, we can say that the question: how to treat OSB (OSB) board from moisture, is difficult to answer unequivocally. Firstly: it depends on whether you want to emphasize the texture of the board with a transparent solution or, conversely, apply a covering (opaque) coating. Secondly: - on the financial capabilities and aesthetic ideas of the developer.

02.12.2012, 21:08

Dear forum users need advice. For the winter, there is a roof under OSB 9mm. The house is made of gas silicate, there is a rafter covered with a Eurovent membrane, covered with a counter-lattice, a crate with a pitch of 30 cm. At the top of the OSB 9mm. Partially a valley carpet is laid, the roof is accordingly not insulated and the house is not heated. The roofers, having received half of the money for the entire turnkey roof, refused to carry out further work, citing bad weather.
Help to accept the right decision.
1 Cover the roof with cellophane with nailed slats (there are fears that moisture from OSB under unventilated cellophane will destroy OSB)
2 Cover the roof with some inexpensive membrane that allows air to pass through and retains water.
3 Attract a new team and cover with flexible tiles until they finish snow and frost (it is embarrassing that the OSB base is wet and under the sealed tiles it will trample and deform, then collapse)
4 Leave everything as it is. But none of the acquaintances have experience with an uncovered OSB.
Old roofers say to wait for spring and not cover anything, the new team - they really need work, they say that it is possible to lay down on a wet one and up to -5 frost with a hairdryer.
I would like to hear the objective opinion of a disinterested specialist, thanks in advance

Good day!
We are building a frame house, it is sheathed with OSB plates, there is a roof - corrugated board, in the winter it will go in this form. During the summer, after several rains, the OSB stratified in some places. Is it possible to cover the walls with a windproof film under the future ventilation facade 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 facade with a windproof film, but this will not completely solve the problem of preserving OSB. The fact is that the windproof membrane is designed to withstand the effects of individual drops, which are the result of condensation on the roof covering. Good slanting rain, downpour, sleet is beyond her power, the windproof membrane will “cry” from the inside. Undoubtedly, wind protection will reduce the wetting of the OSB, but it will not completely eliminate it.

A windproof membrane is a good thing when it is covered with an outer trim

OSB-3 boards, which, most likely, will sheathe the frame of your house, can be called moisture resistant only with a stretch. And then about their resistance to moisture can be said only in relation to chipboard, fiberboard, OSB-1 and OSB-2, which quickly collapse under the influence of water. OSB-3 is not intended for use as a cladding wall material without subsequent finishing, in contrast, for example, to cement-bonded particle boards (DSP). By the way, in Canada and the USA, where frame technologies came to us, waterproof plywood is used to decorate decent houses that must stand for a long time, particle boards are the lot of the poorest.

OSB is not a completely waterproof material, it will inevitably collapse with prolonged exposure to moisture

In our opinion, the following options are possible for temporary protection of an unfinished facade from precipitation:

Stretch the Izospan A windproof membrane (18 rubles / m2) along the vertical crate, use a block 4-5 cm thick. The film is rather weak, it is not a fact that it will successfully survive the winter, it will not be torn by the winds.
Use Izospan AM (24 rubles / m2) or Izospan AS (35 rubles / m2). A three-layer windscreen is stronger, less water vapor permeable, but three times more waterproof, which means it will get wet less. Under the finishing (blockhouse), it could be stretched without lathing, right along the slabs. But in your case, a ventilated gap and crate are needed. It is necessary to ensure a free flow of air, the gap should be below and above, under the roof. Option number 2 is preferable.
Stretch along the crate, observing ventilation, any vapor-waterproofing material is cheaper: roofing paper, reinforced construction vapor barrier, dense plastic film for greenhouses (enough for one season). When cladding the facade, the waterproofing will have to be removed.

While there is no finishing, plastic wrap can be used as temporary protection, with or without reinforcement.

The correct decision would still be to tighten up with finances and finish the exterior finish by the fall, sheathing the facade with a blockhouse along the vertical crate. As a result, it will come out cheaper, because the OSB boards themselves can serve as wind protection, if they are neatly fitted. You don't have to spend money on film.

Correct solution of the "puff pastry" of the frame wall. If the OSB boards are fitted 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.