suspended timber floors
If the floor is accessible from below, 200mm of wood or plant fibre insulation can be friction fitted between joists. An air seal layer should be created at floorboard level either with membrane or by sealing between the boards with a proprietary system Performance target : 0.16 - 0.25 W/m2.K.
Where the floor is over a cellar, this insulation layer is underdrawn with magnesium silicate (or equivalent) boards screw fixed to underside of joists. Performance target : 0.16 - 0.25 W/m2.K.
If the floor cannot be accessed from below due to limited space, it is necessary to lift the floorboards to install the woodfibre insulation & air tightness membrane Performance target : 0.16 - 0.25 W/m2.K.
We have been developing an innovative underfloor insulation solution using Technopor, a foamed glass pumice. This can be poured under the floor, having carefully lifted a few floorboards. We are monitoring performance of this method, but results so far suggest that this solution reduces internal humidity in previously damp properties.
In situations where joists are already rotten, or being removed to remodel the layout of the building, Technopor can be used as a solid fill, tamped down and covered with a Cemwood layer, then covered with woodfibre underfloor heating panels
Further information is available in the Retrofit Pattern Book