Straw

natural building material, with a low carbon footprint, made from the dry stalks of wheat or other cereal crops that have already been harvested and threshed

Straw is an agricultural by-product from the cultivation of cereals or similar crops such as wheat, barley, oats, rice, rye, millet, flax, and hemp.
Starting from 1800, with mechanization of agriculture, straw began to be baled, collected and compressed using polypropylene or plant-based twine into various standard formats. Thanks to the modularity of the bales, they can be used in building similarly to bricks. As a by-product of the grain supply chain, straw is widely available and low-cost, which—combined with its physical properties—makes it a very attractive material for use in construction

Features:

Strength, thermal and energetic efficiency
Health and safety
Earthquake resistance
Cost-effectiveness and speed of construction
Sustainability

Applications:

Straw coats
Straw roofing
In-situ vertical straw walls
Prefabricated vertical straw wall panels

Breathability

3-5

Ability of a material to be passed through by water vapor
The lower the value, the better it prevents condensation and mold by allowing internal humidity to escape.
Thermal Conductivity (λ)

0,044-0,080 W/mK

Indicates the material’s ability to conduct heat.
To protect against the cold: the lower its value, the greater the insulating capacity
Specific Heat Capacity (Cp)

1,900 J/Kg·K

The amount of heat required to raise the temperature of the material by one degree
To protect against the heat: the higher its value, the slower it accumulates heat
Density (ρ)

120-180 Kg/m3

How is the mass of a material distributed in the space it occupies
To defend against heat: the higher its value, the greater the ability to protect against heat

Resistance, thermal and energy efficiency

Dried straw does not rot, does not attract pests, and offers three times the insulation of traditional masonry ensuring excellent thermal efficiency. Therefore, building a straw house means achieving a high-performance house, with a superior thermal insulation that allows for reduced energy consumption

Health and safety

Straw (unlike hay) is mainly made of lignin, a substance that does not cause allergies. Thanks to its density, pressed straw contains very little oxygen, which makes it difficult to ignite: the straw walls, once plastered, offer a fire resistance of approximately 90 minutes equivalent to that of conventional buildings. They are also highly breathable, helping prevent mold and condensation. Combined to natural plasters they help regulate indoor humidity, absorbing excess humidity and releasing it when it's necessary. At last, straw and natural plasters together helps the buildings be more capable of absorbing odors and sounds.

Earthquake resistance

Straw houses with a wooden load-bearing structure show excellent seismic performance. The lightweight nature of the structure, due to the use of straw, reduce seismic forces, making.

Cost-effectiveness and construction speed

The costs of building a straw bale house can be 10-25% lower than traditional construction. Furthermore, the construction technology of straw houses is rapid, allowing to reduce construction times without compromising the quality of the final result.

Sustainability

Since straw is an agricultural by-product, its use does not generate additional CO2 emissions, making it an ecological and sustainable choice.

In construction, straw is used in the following applications:

Straw coats

Is it possible to install straw bale insulation externally to improve energy efficiency, typically with bales placed transversely; However, this solution is not widely adopted due to the required thickness (36 cm) and the complexity of anchoring the structure to existing buildings.

Straw roofs

Straw can also be used for roofing, either as the outer covering or as insulation. For insulation straw bales or loose straw can be inserted between the roof rafters.

Vertical Straw Walls

They can be: “laid on-site”, that is built using straw bale laid on-site, which perform both the sealing function and that of thermal insulation. The load-bearing structure is usually timber.This solution is particularly appreciated by those who want to try their hand at self-construction; “prefabricated panels” available in different levels of pre-assembly. This option allows for faster construction, reduce costs and keep the construction site cleaner and more organized.

Mechanical and electrical systems can be installed by cutting grooves directly into the straw walls after bale placement. For wall heating systems, the thick insulation reduces heat loss, while earthen plaster acts as a thermal buffer. This allows the wall itself to function as a radiant panel, ensuring high thermal comfort and even heat distribution throughout the space.

Explore other materials

Straw

Features:

Applications:

Resistance, thermal and energy efficiency

Health and safety

Earthquake resistance

Cost-effectiveness and construction speed

Sustainability

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