CLT (Cross Laminated Timber) structures demand breathable, robust insulation systems to match their inherent sustainability and structural benefits. Gutex's wood fibre board range, including Multitherm, Ultratherm and Multiplex Top, provides an ideal external insulation solution for CLT buildings.
These high-density boards deliver exceptional thermal performance while supporting vapour permeability, a critical requirement for ensuring the long-term integrity and health of timber-based structures. Gutex wood fibre insulation has exceptional acoustic properties, helps to regulate humidity within the building fabric and can buffer against temperature fluctuations, creating a more stable and comfortable indoor environment.
Multitherm and Ultratherm are designed for installation as external wall insulation in thicknesses up to 160mm for Ultratherm and 200mm for Multitherm. Their density ensures effective thermal buffering and impact resistance, while their vapour open structure allows water vapour to pass through, minimising the risk of trapped moisture. Multiplex Top, a weather-resistant wood fibre insulating sheathing board, adds an additional robust outer layer for wind and rain protection during the construction phase. Available in thicknesses of 22mm and 35mm.
Together, these components create a continuous, breathable insulation envelope that works in harmony with CLT panels. This not only improves the energy efficiency of the building but also supports the natural ability of CLT to manage moisture effectively.
Ideal for low-energy and Passive House standard buildings, this system offers an environmentally responsible insulation solution made from renewable raw materials. Each product carries verified ecological credentials, contributing to a healthier indoor climate and reduced embodied carbon.
About External Insulation for CLT
This wood fibre system is tailored for CLT projects where external insulation must support breathability, moisture vapour diffusion openness and low environmental impact. Gutex Multitherm and Ultratherm are dense yet vapour-permeable boards that regulate humidity and ensure long-term fabric health. Their high thermal mass also helps stabilise internal temperatures, reducing heating and cooling demands.
All boards are made from sustainably sourced post-industrial recycled wood chips and processed with minimal energy input, supporting net-zero construction goals.
The external insulation is made windtight with a Pro Clima external breather membrane and airtight tape. Vertical battens are then fixed with Heco structural woodscrews that go through the batten, woodfibre boards and then into the CLT. The system is then finished with cladding.
Gutex Multitherm, Ultratherm and Multiplex Top offer a breathable, high-performance external insulation solution for CLT buildings. The system combines excellent thermal performance with moisture safety, maintaining the natural drying ability of CLT structures. It supports low-energy design, contributes to airtightness, and enhances indoor comfort through thermal buffering. Made from natural wood fibre, the system is sustainable, low in embodied carbon and high in sequestered carbon, and safe to install. Whether you're aiming for Passivhaus certification or simply creating a comfortable, efficient home, this solution delivers long-term performance and ecological integrity.
Key Benefits
Breathable system
to support CLT’s natural moisture-regulating properties
Exceptional thermal properties
for improved energy efficiency
Vapour permeable
prevents the build-up of condensation
Sustainable
Low-carbon materials with high durability
Quick and easy install
With mechanical fixings external insulation is quick and easy to install
Compatible
Suitable for a range of cladding finishes
Pro Clima Solitex Fronta Quattro Plain black UV resistant windtight breather membrane
Gutex Multitherm Natural wood fibre T&G external insulation board
Pro Clima Tescon Vana Multi-purpose airtight adhesive tape
Pro Clima DA Airtight Weather Resistant Vapour Control Membrane
Pro Clima Tescon Profil Airtight adhesive tape for use on corners and junctions
Gutex Multitherm and Ultratherm boards provide breathable external insulation for CLT structures, supporting high levels of thermal performance while allowing moisture to escape. Installed in singular or multiple layers, these boards offer protection from heat loss and weather exposure while preserving the structural benefits of CLT.
- Pro Clima Solitex Fronta Quattro Plain black UV resistant windtight breather membrane
- Gutex Multitherm Natural wood fibre T&G external insulation board
- Pro Clima Tescon Vana Multi-purpose airtight adhesive tape
- Pro Clima DA Airtight Weather Resistant Vapour Control Membrane
- Pro Clima Tescon Profil Airtight adhesive tape for use on corners and junctions
Pro Clima Solitex Fronta Quattro
