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feature
roofing, cladding, insulation & structural systems
how natural insulation could be the answer for upgrading a loft
Neil Turner, UK Technical Manager at Ecological Building Systems, has extensive hands-on experience working with natural insulation materials. Here he advises on upgrading the thermal performance of a loft...
When it comes to improving the thermal performance of a home, upgrading the loft insulation is often seen as a relatively low cost but highly effective way to save energy. Loft insulation can be simple and straightforward to install and the benefits can be significant in terms of improved comfort, as well as significantly reducing heating bills. According to the Energy Saving Trust,
up to 26% of heat can be lost through the roof.
Although this percentage varies between
different buildings, it is a useful guide and demonstrates how a significant amount of heat energy can easily escape from a home.
When upgrading loft insulation,
improving thermal performance and airtightness is a key consideration. Moisture generated from activities like
cooking and bathing needs to be carefully managed to support long-term building performance.
Humidity in the loft Warmer air carries more moisture. As the warm air rises through the house, it takes humidity with it, which means moisture vapour from the living space will eventually end up diffusing through the top floor ceiling into the loft, which could cause a problem. Ensuring continuity of the airtight layer
at ceiling level is therefore essential, both to reduce heat loss and to manage the risk of condensation within the loft space. Based on our experience across a wide range of retrofit and new-build projects, we often recommend Wellhöfer airtight attic hatches where reliable airtightness and thermal performance at ceiling
level are required. In addition, we also recommend an airtight vapour control layer at ceiling level. Where the existing ceiling plasterboard cannot be removed then a moisture vapour diffusion variable membrane, such as Pro Clima Dasatop, can be installed from above the ceiling prior to insulating. Due to the moisture vapour diffusion variable properties of this membrane it means moisture is trapped at the top of the ceiling joists. This product performs the dual functions of providing airtightness at ceiling level and also managing moisture.
Cold ventilated lofts The most common type of loft in the UK is the cold ventilated loft, where insulation is installed at ceiling level and the loft space itself remains outside the thermal
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