Advantages and disadvantages of straw as a heater for ceilings, advice on choosing raw materials, techniques for creating heat-insulating coatings, making pressed blocks from plant stems. Insulating ceilings with straw is an unconventional way to insulate ceilings, which is popular due to its environmental friendliness and low cost of raw materials. In order for a plant-based coating to reliably retain heat in a room, you need to know the secrets of creating a protective shell. Useful information can be obtained from this article.
Features of thermal insulation of thatched ceilings
Dry plant stems are commonly used in the construction of one-story houses in rural areas. They acquired thermal insulating properties due to their porous structure. Compacted hay has a lower thermal conductivity, but often the ceiling is covered according to a simplified scheme - a mixture of straw and clay.
For this purpose, the waste of grain crops is used - wheat, barley, rye, oats. The stalks of winter rye have the best properties. They are taller, denser, cleaned earlier.
Often straw blocks with sides 480x480x350 mm, 900x470x350 mm, 500 … 1200x500x500 mm are used for insulation. To obtain non-standard bales, they are cut with a chainsaw. Density of products - 80-100 kg / m3… The weight of medium-sized samples is about 16 kg, large ones - up to 30 kg.
The bales are produced using a baler (baler). The device is connected to a tractor or other agricultural machine. The principle of operation of the product is very simple: the stems are gripped by the spring tines and transported into the pressing chamber. After compression, the knitting machine is triggered. The design of the device allows the manufacture of blocks of various sizes. Finished bales are thrown into the field or fed into the back of a vehicle.
Often in the fields, straw is pressed into huge rolls, but they are of little use for warming - they are too heavy and massive. They can be rolled out and re-pressed in another machine, but at the same time the raw material wrinkles and loses some of its qualities.
Bale machines pay for themselves when there is a lot of work involved. To make blocks for the ceilings of one house, you can build the simplest homemade device. It is a wooden box with a hydraulic jack. Hay is loaded into the working chamber manually and pressed by mechanisms. The finished product is tied with ordinary twine.
For warming a surface of 70 m2 will need grain waste from 2-4 hectares. One ton of raw material can produce 77 medium-sized bales.
When laying, it is necessary to adhere to the fire safety rules: do not smoke near the place of work, prepare a fire extinguisher, and remove spilled hay in time.
Advantages and disadvantages of straw ceiling insulation
The choice of straw for insulation is justified due to the positive qualities of the insulating "pie", among which are the following:
- The stems "breathe", like all porous substances. They absorb excess moisture from the room and release it if the room is too dry. The shell will prevent condensation from forming on the ceiling.
- The coating has good vapor permeability characteristics.
- Moisture cannot accumulate in the hay.
- The material has biopositive properties.
- From the point of view of fire safety, straw in bales burns worse than wood because of a large percentage of silica, and compressed to a density of 200-300 kg / m3 does not ignite at all.
- The compacted stems are resistant to biological damage. They only start to rot at 20 percent humidity.
- High density samples will not start mice.
- The pressed raw materials have excellent thermal insulation characteristics - 0, 12 W / m2* K, which is several times lower than that of a tree. With an insulation thickness of 0.5 m, the resistance to heat transfer is 3 times better than the permissible value.
- The presence of silica in the straw guarantees long-term operation of the ceiling.
- Failed blocks are easy to replace. They are disposed of by incineration.
- The bales do not weigh much and are easy to lift into the attic.
When insulating the ceiling with straw, it is necessary to remember some problematic points:
- Unconsolidated mass ignites quickly, in contrast to block products.
- The quality of the coating depends on subjective factors. For example, the storage conditions of the raw materials harvested from the field, the density of the bales, the method of drying the material.
- Rodents start in insufficiently compressed blocks.
Straw ceiling insulation technology
The thermal insulation of the floors takes place in several stages. First, the raw materials are prepared - they are pressed into blocks or a solution based on it is kneaded, and only then they are placed in a regular place. It is also important to be able to check the quality of the workpiece.
Choosing a straw for the ceiling
The raw materials that are planned to be laid on the ceiling must have special properties:
- Only dry, grain-free stems are suitable for thermal insulation. Drying is allowed in special chambers. The heat-treated material compares favorably with field straw - it does not contain fungi and insects.
- Insulation requires only strong stems. To test the strength, bend a few pieces. Old and caked ones will break immediately, they cannot be used.
- Also discard shredded material.
Be sure to check the condition of the bales. Heat-insulating, fire-resistant and other characteristics depend on the quality of block manufacturing. Before going to the attic, carefully inspect the products and take suitable samples:
- It is allowed to lay only dry insulation. Controlling moisture is easy - pull out a bundle of straw and examine it. The stems should be dry, without any signs of delight.
- The block keeps its shape well and does not break. It can be lifted with one hand while maintaining integrity.
- If bales of the same size have different weights, check their moisture content.
- Products should be tied with a nylon cord that fits snugly to the surface. You can put a maximum of two fingers under it.
- The metal tie wire is not suitable, it will rust and break over time.
Preparatory work
Ceiling insulation begins with preparatory procedures. Perform the following operations:
- Check the condition of the floor, gable, rafters. Replace damaged elements.
- Cover the cracks with a construction mesh and cover with putty. Make sure the surface is dry.
- Clean areas with mold and mildew and treat with antiseptics. Impregnate wooden structures with a fire retardant.
- Insulate and waterproof the roof. If the roof is covered with vapor barrier material, the attic should be equipped with a ventilation system. The simplest design is air vents in the ceiling. The dimensions of the openings are within 0, 001% of the total roof area. If the roof is made of tiles or slate, ventilation is not necessary, because these elements are mounted with gaps.
- Check that there are no elements that could damage the film. Remove protruding parts from the attic floor.
Instruction for installing straw on the ceiling
You can insulate the ceiling with straw in different ways - using pressed stems or solutions based on them.
A protective shell made of blocks is considered the most effective method of thermal insulation, because after compaction, the characteristics of a plant-based material improve many times over. Samples of the same size are laid on the surface and pressed tightly against each other. Place the products so that the joints do not form one line. Cut the bales if necessary. After installation, cover the straw with waterproofing to protect against possible roof leaks. Install walking decks in existing attics.
An alternative to block insulation is considered to be stacking the stems in bulk together with clay. The work is performed in the following sequence:
- Cover the attic floor with vapor barrier foil with an overlap of 15-20 cm on the walls and adjacent pieces. Seal the joints with reinforced tape.
- Prepare a mixture of clay and straw in a 2: 3 ratio.
- Pour the ingredients into a large container, add water and stir. Dilute the mixture with water until the consistency of thick sour cream.
- Apply the solution to the base in a layer of 5 cm.
- Wait for it to dry and inspect the surface. If cracks are found, seal them with the same mortar.
- Lay hay on top in a layer of 10-15 cm. The thickness of the insulation depends on the winter temperature.
- To scare off mice, sprinkle the stems with slaked lime with added carbide. Thoroughly compact the mass.
- On the ceiling insulated with straw, clay is applied in another layer 2 cm thick to protect against fire.
- For walking in the attic, construct a wooden deck that is nailed to the joists.
The ceiling can also be insulated with light adobe - straw soaked in liquid clay. The mixture is prepared as follows:
- Pour clay into a large container or pit, fill it with water to soak and leave for a day.
- Stir the mixture until the consistency of liquid sour cream.
- Pour raw materials into it at the rate of 8 kg of stems per 1 kg of soil and drown in the solution. Wait for the straw to soak and place in a drip tray. The clay-covered stems are not afraid of fire, do not rot and retain heat well.
- Fill the entire area with a mixture of 10-15 cm and compact it.
- After drying, cover the floor with a waterproofing film.
- Install the wood flooring.
You can insulate the ceiling with heavy adobe. This option allows not only to insulate the living space, but also to create a solid floor in the exploited attic without wooden flooring. In this case, the floor structure must be very strong in order to withstand a lot of weight.
For the preparation of insulation, only certain types of clay are used, which are classified as "fatty" rocks. They absorb water well, have plasticity and stickiness. "Dry" contains a large percentage of sand and disintegrates over time. The soil extracted from the seabed is saturated with algae and does not adhere well.
To prepare adobe, mix soil and straw in a 3: 1 ratio. The work is carried out as follows:
- Pour clay into a concrete mixer, filling half of the barrel. Pour in water and mix thoroughly.
- Add straw to the barrel and turn on the device again.
- After obtaining a homogeneous mass, check its density. Put the mixture in a bucket and stick in the stick. It should be kept upright.
- In this form, the solution can be applied to the surface with a layer of 10-15 cm.
- Once dry, you will have a hard surface that you can walk on.
How to insulate the ceiling with straw - watch the video:
The use of straw as insulation for the ceiling reduces heating costs and saves usable floor space. All procedures can be performed independently, but in order to achieve the desired effect, you must pay attention to the quality of the material used. Deviation from thermal insulation technology will lead to constant heat leakage through the floor.
