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Insulation Details for Timber Frame Buildings

Timber frame insulation details walls are amongst the most forgiving when it comes to introducing insulation. They have a natural cavity between the timber studs and therefore can accept a wide variety of systems that would be difficult to use in masonry.

The best way to insulate a timber frame is with a system that is not only designed to keep moisture out but also to help the wall dries to a low level of humidity. Prefabricated panels that can be affixed to the frame and sealed with OSB sheathing are a popular option. These are insulated with either rigid foam – most often PIR – or mineral wool (sometimes known as Rockwool).

Timber Frame Insulation Details: Ensuring Proper Installation

Both of these insulation materials are very good and the best options for achieving low U-Values in a wall. They both dries very quickly on site which is critical for hygrothermal performance. However, they both have the disadvantage of relying on the vapour barrier and cavities within the construction to perform as expected or to stay dry. This means that if the building is not well surveyed and the right details used, water penetration, condensation and evaporation may raise the wall moisture content to levels where degradation will re-start.

Mineral wool rolls or slabs are friction-fitted between the studs and have the advantage of being non-combustible. These can be combined with non-combustible insulation partially filling the cavity to enhance thermal, fire safety and acoustic performance. Alternatively, a rigid XPS foam (extruded polystyrene) system can be used that is not rated as combustible and helps achieve lower U-Values.