Roof

The roof is a key part of the 'envelope' of the building. In conventional houses you can expect to lose about 25% of your heat through it. So great care has been taken her to ensure that the roof is very well insulated and also airtight.

In this picture you an see that the roof trusses have been deepened so that there is space for more insulation. This has been achieved by using light weight steel spacers as opposed to using larger timbers. This saves on cost and more importantly on weight.

Here you can see the hemp insulation coming up to the roof structure and again the deeper rafters.

This shows the internal OSB board in place before the insulation is added to the roof structure.

The hemp was then laid on top of the OSB board. It was very important to ensure that the spaces in the rafters were also filled with the insulation layer (see below).

Once totally filled the final layer of insulation was added. This is a wood fibre board that interlocks to improve airtightness and hence insulation values. This is a Pavatherm board normally referred to as an Isolair board.

The structure will now be finished off with a zinc roof. There is an air gap between the Isolair board and the final roof finish to allow for ventilation. The roof structure is designed to 'breathe' and so as the warmer moisture laden air is vented so it needs to be removed before it condenses on the underside of the tiles, hence this vented space. The Isolair board is attached to the roof via fixing that go through the battens and into the rafters.