Sawdust roof insulation technology - the pros and cons

Experienced builders know that for thermal insulation of roof structures of the cold type, they often use filling insulators. They fall asleep in the space between the lags when arranging the attic floor. This measure will not seem superfluous if you know that more than 20% of heat loss occurs through the fault of an unheated roof. The fact that thermal insulation is necessary for any heated room, agrees with the majority of builders. But the question of the choice of thermal insulation material does not cause such unanimity: some masters use modern technological materials, while others prefer the traditional insulation of the roof with sawdust. In this article we will explain how you can use wood waste to optimize the temperature at home.

Insulation Characteristics

Sawdust is a waste product of the woodworking industry, which can be purchased for almost nothing at any sawmill. They are of organic origin, and therefore are absolutely safe for human health, and also do not cause allergies. Sawdust mixed with clay, traditionally used as insulation in Russia. Since all residential buildings were built of wood, which is still rich in Russian land, during the construction process there was a lot of waste suitable for thermal insulation of garret floors. Sawdust has the following advantages compared with other thermal insulation materials:

1. Low price. Perhaps the democratic cost of this material is the main reason for the popularity of insulation sawdust. Sawmills and sawmills dispose of these waste products, so they are often handed over to anyone who wants it on condition of self-pickup. Therefore, the cost of the material is obtained equal to the cost of delivery of sawdust to the construction site.
2. Guaranteed security. Wood chips are absolutely safe for the health of people living in the house. It does not cause toxic poisoning, skin irritation on contact, allergies, which cannot be said with certainty about modern heaters.
3. Low thermal conductivity. Wood chips, unlike wood, due to the porous structure have a low coefficient of thermal conductivity, that is, retains heat well. A mixture of sawdust with clay or lime increases the thermo-insulating effect even more.
4. Organic origin. Wood chips have all the same qualities as wood. It lets in steam and air, which is fundamentally important for the insulation of houses from a bar and a log with a mansard roof.
5. Easy installation. Working with sawdust is very easy, you just need to mix them with clay or lime, and then fall asleep in the space between the overlapping lags. The technology of laying insulation does not include the use of special equipment, complex tools.

Note! The disadvantages of thermal insulation of the roof with sawdust are the high flammability of this material and the low resistance to biological factors. They are a favorable environment for the spread of mold and fungal microorganisms, rodents, insects. In addition, moisture is extremely negative for sawdust, increasing the thermal conductivity of insulation several times. To get the maximum effect from the thermal insulation of the roof with sawdust, they should be pre-treated with a fire retardant to prevent the spread of fire, as well as antiseptic preparations.

Preparation of the mixture

In the process of warming the roof with sawdust, the prepared material is poured into the space between the lags of the attic floor with a layer of 15-30 cm. The guarantee of high-quality thermal insulation is a dense, non-flowing coating that settles throughout the entire life cycle. To improve the performance characteristics of sawdust, various substances are added to them, producing wet or dry thermal insulating mixtures. More often, all professional builders use the following “recipes”:

• Moist sawdust (85% of the volume of the mixture) is mixed with lime-fuzz (10%), and then add gypsum (5%). The resulting mixture is thoroughly mixed to obtain a homogeneous viscous mass, and then quickly laid, as it hardens extremely quickly. To have time to decompose the mixture before drying, you need to prepare it in small portions.
• In regions with a cold climate, filling insulators should be laid with a layer of 30 cm or more. Therefore, for thermal insulation of the roof, sawdust is mixed with slag in a 1: 1 or 2: 3 ratio to obtain a mixture with low thermal conductivity.
• The traditional mixture of sawdust with clay, which was used on the territory of Russia several centuries ago, is considered to be very effective. For the preparation of this insulation container filled with clay is filled with water for disintegration. Then, in a mixer or barrel 2/3 of the bucket with sawdust is combined with a bucket of clay, mixing thoroughly.

Important! According to the insulating qualities of a 15-cm layer of sawdust, it is equivalent to a 10-cm layer of mineral wool. But the cost of wood chip insulation is 6-7 times less than the use of mineral and polymeric thermo-insulating materials. Experienced craftsmen recommend to fill in 20-30 cm of sawdust, which will take 2-3 weeks to dry and shrink.

Mounting technology

The effectiveness of thermal insulation of the roof with an insulating mixture based on sawdust and clay or lime depends on the correct installation and also on the quality of the preparatory work. It is imperative to process wood chips with preparations, fire-blocking compounds, antiseptic, add substances that frighten rodents and insects. Warming of sawdust cold roof perform in the following sequence:

1. The wiring passing through the attic floors is isolated, retracted into metal pipes. Chimney pipes, ductwork and other communications are trimmed with fire-resistant material or covered with rubble.
2. With the help of wooden boards, formwork is installed on the subfloor. For this operation, you can use substandard wood or slab.
3. To protect the sawdust from moisture, a waterproofing material (high-diffusion membrane or glassine) is spread on the surface of the subfloor, fixed with metal staples using a construction stapler.
4. Thermal insulating mixture of sawdust and clay or lime is mixed in small portions, and then immediately spread evenly onto a waterproofing material with a layer of 25-30 cm. If a dry mixture is used, it is additionally tamped.
5. Insulating layer gently level, and then leave for 2-3 weeks to dry.
6. After drying, the insulating mixture of sawdust with clay is again covered with waterproofing material, which is fixed with a stapler on the floor logs.
7. The last stage of the attic floor insulation is the floor covering.

Experienced craftsmen claim that thermal insulation efficiency depends on the quality of the drying of thermal insulating sawdust. If possible, you need to dry it for 2-5 weeks. If you do not have this amount of time, it is better to use non-wetted mixtures.

Video instruction