Straw bale construction is gaining in popularity helped in part by being featured on television programs such as Grand Designs.
12th Century Tradition
Straw bales as structural & insulation element of a building’s external walls
The traditional form, dating back to the start of the twentieth century in the United States and France, is to use the straw bales as the structural element of the building’s external walls as well as its insulation. The straw is finished by applying a lime render system to the outside of the bale, the internal finish is usually a lime or clay plaster. Because straw bale construction is relatively new to the UK there are still issues with regard to Building Control and gaining mortgages and buildings insurance, this will prevent the system becoming more mainstream for the foreseeable future.
Our processes
How All Timber Frames uses straw in construction
Insulation within a timber frame
At All Timber Frames, we construct our straw-insulated panels in a similar way to traditional timber frames. However, due to the slightly lower thermal efficiency of straw, we use timber-engineered I-joists instead of timber studs. This allows for a deeper wall construction. During the fabrication stage of the project, we sheath both the external and internal faces of the studwork and compress the straw within.
In the pictures to the right, you can see how these panels look when they arrive on-site.
Fibre render carrier board
All Timber Frames can supply and site fix a wood fibre render carrier board that is fixed to the Panelvent external sheathing boards.
Environmental benefits
Being essentially a waste product there is an abundant supply that can be sourced locally. It is a renewable product with a negative carbon footprint. Every 10kg of straw absorbs 14kg of carbon dioxide, sequestering it in the wall for the lifetime of the building.
The Straw Bale Process
Step-by-Step Guide to Straw Bale Construction
Planning & Permissions
Ensure compliance with UK Building Regulations (Part L, B, and E) and secure planning permission from your local authority. Design for weatherproofing, ventilation, and energy efficiency, choosing between load-bearing, post-and-beam, or hybrid construction methods.
Foundation Preparation
Use a raised foundation like an insulated concrete slab or limecrete with foam glass aggregate to prevent moisture issues. Install drainage and a damp-proof membrane (DPM) to protect the straw bales from the UK’s wet climate.
Structural Frame Construction
If using post-and-beam construction, build a timber frame with sustainably sourced UK wood. Pre-install door and window frames and ensure early roof installation to protect the structure from rain.
Sourcing & Stacking Straw Bales
Ensure compliance with UK Building Regulations (Part L, B, and E) and secure planning permission from your local authority. Design for weatherproofing, ventilation, and energy efficiency, choosing between load-bearing, post-and-beam, or hybrid construction methods.
Roof Installation
Construct a lightweight, well-insulated roof with deep eaves (600mm or more) to protect the straw walls from rain. Use a compression system to hold bales in place and prevent settling.
Plastering & Weatherproofing
Apply breathable lime or clay plaster, reinforced with hessian mesh, to protect against moisture and cracking. For extra durability, add timber cladding or a rainscreen in high-rainfall areas.
Utilities & Finishing Touches
Run electrical and plumbing systems in conduits to meet UK safety standards. Install triple-glazed windows, airtight doors, and eco-friendly finishes to enhance energy efficiency.
Landscaping & Sustainability
Integrate solar panels, rainwater harvesting, or heat pumps for sustainability. Use a sustainable drainage system (SuDS) and plant native vegetation to promote biodiversity and site resilience.
More about straw construction
