Wall insulation timber frame walls are an increasingly popular choice in new-build houses, extensions and barn conversions. Their advantages for thermal and sound insulation as well as providing a strong nailing surface are obvious.
Retrofitting insulation into traditional timber-framed buildings can be challenging without significantly impacting their hygrothermal performance or historic fabric. While several options exist for retrofitting insulation into these spaces, one method that proves most invasive involves cutting rigid insulation boards to fit within each timber stud space.
Vapour Control Layer (VCL)
Vapour control layers (VCLs) are an essential part of building with timber frames, as their use helps minimise interstitial condensation that could otherwise lead to mould, rot and structural damage as well as dampness that compromises insulation efficiency. When implemented properly, VCLs reduce risk for this condition that causes mould growth, structural damage and can even result in loss of insulation efficiency.
Traditional timber frame VCLs were polythene sheets; now we recommend an intelligent membrane such as Ampatex Variano or Proclima’s Intello membrane which have low permeation ratings to allow moisture to pass either way at equal rates. Furthermore, these membranes will ensure any summer moisture drives towards your wall can pass back out again slowly before reaching insulation and potentially corroding its structure.
It is critical that when choosing to install a proprietary VCL product on site, that you review their third party accreditations before forwarding this information to your warranty surveyor. Incorporating standard products could result in condensation problems later and invalidate your LABC Warranty policy.
TLX Silver
Many insulation solutions come in rigid sheets that must be cut on site to fit the profile of timber studs, creating air gaps that compromise thermal, fire safety and acoustic performance. Mineral Wool rolls or slabs can be friction fitted between studs in order to eliminate air gaps while still allowing natural expansion and contraction of timber for a highly effective wall structure.
TLX Silver multi-foil insulation from BBA saves time during new build construction, barn conversions and loft conversions by providing an airtight vapour barrier and restricting air movement between its multiple foil layers. It reduces condensation risk by creating an airtight vapour barrier; and can be placed under or across rafters to improve thermal performance without increasing timber stud depth.
TLX range comes in various thicknesses to meet your building’s desired U value; insulation values are listed on each product page for easy selection. Need help picking out an optimal U value? Just reach out our technical team.
PIR Board
PIR insulation boards, more commonly referred to as ‘boards”, can be fitted between the studs at standard centres with friction fitting, making installation quick and efficient for both new build and renovation projects. With dimensions that reach up to 2.4m in length and 1.2m wide, PIR boards make quick work of covering large areas where services need to be located quickly and cost-efficiently.
Insulation products like foam offer substantial thermal efficiency advantages that allow much thinner construction while providing equivalent U-value performance at half of their thickness. This makes foam an attractive alternative to mineral insulation products which often require twice the thickness for similar performance.
PIR insulation boards are highly resilient products, lasting much longer than their competition in terms of shape and strength retention. Furthermore, they’re moisture resistant and close-cell; meaning that water does not absorb into them and promote the growth of mold or microorganisms. With an Euroclass fire classification rating of F, they can easily meet various building codes related to smoke production and flammability.
Air Barrier
When insulating timber frame walls it is crucial to protect them from moisture. Condensation can cause wood rot and compromise performance – to avoid this install a vapour control layer such as Tyvek as an air barrier.
Airtight insulation is also important. Rigid foam sheets may be difficult to cut precisely around timber studs and lead to air gaps which decrease thermal performance of walls significantly. To improve thermal performance and avoid air gaps altogether, we advise installing Glass Mineral Wool rolls or slabs into timber frame walls.
These friction fitting panels are designed to snugly seal between studs, preventing gaps from forming between them and prevent heat loss or sound transmission. When used together with TLX Silver panels they create an airtight system critical for timber frame walls which will reduce moisture build-up and condensation while increasing performance while decreasing energy bills.