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INSULATION
to install than others – so those which take less time obviously mean fewer man hours and therefore less outlay on labour. The more thermally efficient the building, the less needs to be spent on renewables to achieve the required energy efficiency targets. The motto is ‘fabric first’ – that is, look to making your building thermally sound as a priority rather than finding ways to warm a constantly cooling, poorly insulated internal environment – which, as well as being a nuisance, is a waste of time and money.
Vapour control layers & breather membranes
The most usual places where thermal bridging can be found are at angles, where one element joins another – the eaves, for example. Basic science dictates that if you use something solid and inflexible to insulate a roof with all its many various shapes, there’s a greater chance of gaps, which then need to be infilled with compressible tape or expansion foam. Using a flexible, stretchable, forgiving product, on the other hand, means that the gaps can be eliminated. Its edges can be overlapped and taped together to ensure an airtight seal and a continuous insulation layer.
A breather membrane is designed to control moisture, and like vapour control layers, some also act as insulation
Vapour control layers, used on the warm side of any insulation material – behind the internal finish in roofs, walls and ceilings – can massively reduce the risk of interstitial condensation and provide air tightness. Some also act as an insulation, which means the thickness of the main insulation can be reduced to achieve the same U-value. A breather membrane is designed to control moisture, and like vapour control layers, some also act as insulation. Reflective and watertight, yet vapour permeable, breather membranes are used on the cold side of roofs and walls. Because water vapour molecules are smaller than those in water droplets they let moisture out, but not water in, and add air tightness and boost ‘thermal resistance,’ by keeping heat in.
Thomas Wiedmer is UK technical director at Actis Insulation
WWW.ARCHITECTSDATAFILE.CO.UK
ADF MARCH 2022
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