As I have already said, as well as high levels of thermal insulation, we are making the house as airtight as possible: so absolutely no drafts.
This has been a major undertaking – very slow and painstaking to make it satisfactory. We are making the inside of the insulation our principal air-tight layer – to create an entire envelope around the house.
We have taken advice from an air-tightness specialist – and in fact we may have left this rather too late in the day. His view was that we should build up many layers of air-tightness, as air has such an uncanny way of finding and creeping along any possible gaps and tracking from one area to another. Also, many layers probably provide a more robust solution for the longer term. He would have started, for example, with sealing the brickwork on the inside – we did this up to a point in places though not for this reason, and not comprehensively. He also recommended taping both sides of the insulation joints – but it is hard to know whether this is overkill and where to stop. We are never going to achieve perfect air-tightness in an old house.
He thought there were lots of good points in what we have done, including:
- staggered joints in the inner and outer layers of insulation on the external walls,
- good taping at the edges of each board
- space between the floor and ceiling well taped around all the joists
- air-tight membrane in window reveals, taped to window frames and walls.
|Under the eaves in the attic is being left as cold space, hence the floor behind the studwork,
and eventually the studwork, will be insulated.
|This is the area at the front of bedroom 1 that is under this cold space in the attic, so it too is insulated.|
|The wall insulation is then continued up to meet the ceiling insulation and everything well taped.|
|The continuity of air-tightness from above coming through the floor
from the attic above.
|The whole area, including all over the joists, is encased in DB+ membrane and taped.|
|Residual gaps were filled with expanded foam. Here the tops of the walls in the first floor ensuite
(where they are against the external wall) have foam squirted in.