Roof insulation with foam

Table of contents:

Roof insulation with foam
Roof insulation with foam

Methods for insulating an attic and flat roof with a foam-based coating, the advantages and disadvantages of creating a protective layer on the roof from this product, the choice of consumables. But not everything is so good with the foam cover:

  • It becomes a refuge for mice, which quickly destroy it.
  • It takes a lot of time to insulate a house that has been in operation for a long time due to the presence of the crate. In this case, you have to cut the blanks in place.
  • In the absence of good ventilation, mold appears on the surface.
  • The foam roof does not comply with modern fire regulations. The material melts under the influence of high temperature, and begins to burn in case of fire.
  • At high temperatures, which occurs in summer, the roof heats up strongly and the heat insulator emits fumes that are harmful to humans.
  • The sun's rays are harmful to the product and quickly destroy it. Therefore, it is necessary to have a protective layer over the insulating one.

Materials and tools for roof insulation

Polyfoam for roof insulation
Polyfoam for roof insulation

It is necessary to cover the roof only with high-quality foam plastic.

In the store, you can perform simple operations that will help you get an idea of the condition of the insulation:

  1. Examine the structure of the panels. The presence of fragments of the same size, which are evenly spaced in the slab, indicates a high-quality product. Granules should be small, large particles cause voids and water saturation of the insulator.
  2. Styrofoam is always white. A change in shade indicates the use of low-quality components for its production.
  3. Check product storage conditions. They are usually sold in lots of 10, wrapped in a plastic wrap. Discard the product in torn packaging. Sometimes it is sold individually, with characteristics applied to the surface at the factory.
  4. Carefully study the label, which should contain information about the manufacturer, dimensions of plates, characteristics of the product, etc.
  5. The blocks are manufactured with great precision. The deviation in size, especially in thickness, should alert you.
  6. The foam sheets don't smell at all.
  7. Make sure the sheets are flexible and not stiff. After pressing with your finger, the surface is slightly deformed, and then the shape will return. Products become solid due to a violation of technology. Such samples do not do their job well.
  8. Find the broken plate and inspect the damaged area. Broken granules should be visible on the fault. If the fragments remain intact, you have a fake in your hands.
  9. Weigh the mass of 1 cu. meter of goods. It must weigh at least 15 kg.

The following information can help with the choice:

  • It is possible to accurately determine the thickness of the sheets based on the requirements of SNiPs, but it must be at least 100 mm. The size is influenced by the climatic zone, the material of the roof and its structure. For areas with mild winters, the approximate thickness of the coating is 150 mm, for harsh conditions - 200 mm.
  • High-quality insulation is made by such companies: Knauf, Penoplex, Stav Polyster, T-life.
  • You can determine the scope of the product by labeling. For the roof of the attic, PSB-S-15 foam with a density of 15 kg / m is best suited3… More rigid products PSB-S-25, PSB-S-35 can also be used, but they are more expensive. These modifications differ from other models in self-extinguishing properties, which are inherent in materials for internal use.

There are two types of compounds to glue foam to a flat roof: universal and special.

They all must meet the same requirements:

  1. The products are intended for use outside (for flat construction) or inside (for attic roofs).
  2. Perform internal work with compounds with a minimum degree of toxicity. Thus, in a room closed on all sides, a person will not feel discomfort. The degree of toxicity is always entered by the manufacturer in the certificate of conformity.
  3. The substance retains its basic characteristics at any ambient temperature, throughout the entire service life of the insulation.
  4. The adhesive does not harm the insulator. It does not contain gasoline, kerosene, solvents and other components that can dissolve foam.
  5. Adhesive mixtures are hygroscopic and must therefore be stored under suitable conditions.
  6. Give preference to products that do not freeze instantly. This will make it possible to move the slabs along the surface to correct their position during installation.
  7. The goods must not have expired. For this reason, discard the glue that the store offers for promotions. Usually it can no longer be used.
  8. Ask the seller for a quality certificate.
  9. Use a reputable manufacturer. If the company is unknown, look for reviews on the Internet.
  10. Purchase funds with a margin. The reference information on the label indicates the average consumption, but on a non-flat surface, the number of used packages of the substance will be greater.
  11. The most convenient is glue in the form of foam, which is sold in cylinders ready to use. The disadvantage is the high price.

In the process of assembling blocks, small samples or panels of irregular shape are always needed. To facilitate the task, craftsmen use simple devices:

  • All kinds of sharpened knives - kitchen, wallpaper, stationery. The work is accelerated if the blade is held over the fire.
  • The electric jigsaw has worked well for thick workpieces. The downside of using the tool is poor cut quality.
  • The heated nichrome wire will quickly cut a curved section with straight ends.

Insulation of the roof from the inside with foam

Thermal insulation of the roof from the inside with foam plastic
Thermal insulation of the roof from the inside with foam plastic

When insulating the roof from the inside with foam plastic, the panels are laid between the rafters. The high density of the sheets allows them to be fixed in the frame with improvised means, which does not increase the load on the structure.

The structure can be thermally insulated if the following conditions are maintained:

  1. The drainage system is installed taking into account the slope of the structure.
  2. The height of the attic roof allows you to close the stack from the inside.
  3. After installation, a guaranteed ventilation gap remains between the waterproofing and the roof cladding.

The installation of the protective shell is as follows:

  • Apply antiseptic to all beams and battens. The job is made easier if the outer roof cladding has not yet been installed.
  • Cover the rafters from the street side with a waterproofing film and fix in any way to the beams. The membrane is necessary so that water does not get into the room from the outside, and moist air from the insulating "cake" can freely go outside. Do not stretch the cloth, leave a slight slack. Lay the cuts with an overlap of 15-20 cm on adjacent pieces and on the walls. Connect the joints with reinforced adhesive tape.
  • If an operated house is being finalized, lay the film from the inside of the attic, while controlling the gap of 50-60 mm between it and the roofing material.
  • When covering the roof with soft bituminous tiles, it is allowed not to lay the waterproofing tape, because the cladding itself is waterproof. Only corners and cornices are covered. In the case of insulation of a soft roof with foam, the membrane is placed directly under the cladding. If the top is made of metal, the protective covering should include soundproofing elements to drown out the noise from the rain.
  • Fasten the lathing to the rafters and install the outer cladding. Make sure that there is a ventilation gap of 50-60 mm under it to the film, which is necessary to remove moisture. Through it, the moisture remaining in the roofing "cake" is eroded. To organize the air flow, special holes are made in the eaves and in the upper part of the roof. You can also ventilate the space forcibly using special devices.
  • Measure the distance between the rafters, add 0.5 cm and cut the blocks out of the blanks. Increasing the size will allow the panels to self-adhere between the beams, making assembly easier.
  • Place the panels in such a position that there is a 10-15 mm gap between them and the outer foil. It is necessary so that the insulation does not close the pores of the diaphragm.
  • To ensure the required thickness of the coating, the panels can be laid in two rows, while the lower one should overlap the joints of the upper one.
  • The fastening method depends on the roof structure. You can fix the products in this position with thin slats or special corners that are sold in the store. Manufacturers also allow gluing and mechanical fixing using wide-headed dowels, anchors, etc. The options can be combined.
  • Seal the gaps between the panels, as well as near the rafters with scraps. It is allowed to eliminate defects with polyurethane foam.
  • Cover the beams from the attic side with waterproofing foil and secure with a construction stapler to the slats. The canvas should sag slightly. The membrane will prevent the rafters from getting wet from the humid air rising from the lower rooms. Lay the fabrics with an overlap on top of each other and on the walls. Glue the joints with reinforced adhesive tape. Optionally, you can upholster the rafters with boards.
  • For vapor barrier, it is advisable to use a special three-layer membrane reinforced with a polymer frame. Modifications with a foil coating have also proven themselves well.

Protecting the roof from the outside with foam

Thermal insulation of the roof outside with foam
Thermal insulation of the roof outside with foam

This is the most common option for attaching material to concrete slabs. Usually, in this way, a flat roof is insulated with foam outside. It is used both on a new roof and on a restored one.

The order of operations is as follows:

  1. Remove dirt and build-up from the floor.
  2. Inspect the slabs for cracks, fill them with cement-sand mortar. Knock down the protruding parts.
  3. Fill the surface with a cement-sand screed 15-20 mm thick, ensuring the roof slope within 5 degrees.
  4. Check the flatness of the roof with a straight edge. After applying the tool to the surface, there should be no gaps under it.
  5. Treat the screed with a deep penetration primer. Polyfoam does not absorb moisture, therefore, in the case of gluing, the waterproofing film from the side of the room can not be installed.
  6. If desired, it is allowed to cover the screed with bitumen mastic.
  7. Spread the entire sheets with a layer of glue 10 mm thick, make sure that there are no untreated areas. Do not lubricate the ends.
  8. Sweep over the surface with a notched trowel.
  9. Place the panel on the floor and press down lightly.
  10. Repeat the operation for all plates. Press them firmly together during installation.
  11. Place products so that there is no one seam line. Fill the resulting gaps tightly with scraps of material. Use custom panels last.
  12. When laying in two rows, position the top layer so that it overlaps the joints of the bottom one. Glue the panels together with special means that are designed for foam.
  13. Cover the insulation with geotextile - an ultra-dense fabric made of a special material that protects the product from ultraviolet radiation. It also distributes the load to the base when walking. The material is almost impermeable to water.
  14. Cover the area with 16-32 mm gravel with a layer of no more than 5 cm. Another option is to lay a concrete screed 5-6 cm thick, but this method will require additional costs for cement. Solid protection allows you to cover the insulation with additional waterproofing. The most popular option is roofing felt. It significantly increases the service life of the entire layer.

How to insulate the roof with foam - watch the video:

Whichever option of insulation the master chooses, the device of the protective "pie" will always consist of foam and waterproofing. Meeting the requirements of the installation technology will ensure the comfort of living and reduce heating costs.

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