Timber frame construction is moving into the mainstream. Long established as the standard method for newbuilds in Scotland, it is now being adopted by some of the UK’s largest housebuilders and accounts for roughly 15% of new homes built in England.
As its use grows, specifiers need to understand how timber frame differs from traditional masonry construction. Choosing insulation that complements its strengths and mitigates its limitations will be critical to achieving the required thermal, acoustic and fire safety performance.
A key reason for timber frame gaining ground is speed. As a modern method of construction, it uses factory-assembled panels to provide the building’s load-bearing structure instead of a traditional blockwork inner leaf. Insulation can be fitted before the panels arrive on site, while closed-panel systems can also include windows and doors. This allows a weathertight shell to be erected in days.
Timber frame can also have much lower embodied carbon than masonry alternatives, with the timber storing carbon throughout the building’s life. Its increasing adoption is helping to reduce costs, which are now comparable with masonry cavity walls. Together, faster
construction, lower embodied carbon and greater cost competitiveness explain why timber frame is becoming a more attractive option for housebuilders.
FAST AND FLEXIBLE
Speed is a key advantage of timber frame construction, so the insulation specification should also support fast and straightforward installation. Blown-in insulation is used for closed-panel timber frames for this reason, as it fills the voids and provides a continuous layer of insulation very quickly. Built-in solutions, such as glass mineral wool rolls, are a common choice for open-panel systems. They can be friction-fitted between the studs without additional tape or fixings and are flexible enough to accommodate varying stud centres.
Structural settlement is more pronounced with timber, so flexible insulation will move with the building without creating unintended gaps. This flexibility also helps the insulation completely fill the void between the studs, minimising air gaps and maximising thermal performance.
THERMAL AND FIRE SAFETY PERFORMANCE
There are different considerations when specifying insulation for timber frame buildings. The lower mass of the walls means the building can heat up and cool down more quickly.
Fire safety is a crucial consideration in timber frame construction. One way to mitigate fire risk is to specify non-combustible insulation throughout the building, which also provides reassurance to third parties and occupants. Glass mineral wool products, such as FrameTherm Roll 32, are non-combustible, achieving the best possible Euroclass A1 reaction to fire classification.
NONE OF WHAT YOU HEAR
The lower mass of timber frame buildings means adequate acoustic insulation is even more important. While conventional wisdom might suggest using rock mineral wool for this purpose, glass mineral wool, such as OmniFit Thermal and Sound Slab, can achieve the best possible Sound Absorption Class A while being easier to handle and lower in embodied carbon.
The fibrous structure of glass mineral wool traps sound waves and converts their energy into heat through friction, absorbing almost all airborne sound. Insulating a timber frame with glass mineral wool allows specifiers to address thermal, fire safety and acoustic performance with a single material.
FUTURE HOMES
With Approved Document L 2026 published and the transition period less than a year away, what will timber frame insulation specifications look like under the Future Homes Standard? The good news is that specification recipes already exist to support compliance with ADL 2026. For timber frame homes, a 140mm stud cavity using either built-in or blown-in glass mineral wool insulation, combined with 500mm of glass mineral wool loft insulation, will meet the Target Fabric Energy Efficiency (TFEE) rate for most house types.
By combining the speed and lower embodied carbon of timber frame with flexible, non-combustible insulation, you can create a straightforward specification that supports thermal, acoustic and fire safety performance. Timber frame may be growing quickly, but meeting the Future Homes Standard does not need to slow it down.