Early on in our project design we decided to put the insulation on the outside of the building, wrapping the house in a blanket of woodfibre. This allows us to have breathable construction where any moisture (in the form of water vapour) can pass through the construction and escape while heat is retained within the building. As the existing house, which was built in the 1870’s, has no DPC and no way of injecting one into the 600-700mm stone walls this seemed like the most sensible route.
Another big plus for us was that it meant we could expose the existing stone walls of the original house on the inside. Not only does this clearly express the outline of the old house against the new extension but it will also look great, and retain heat as it has high thermal mass.
Of course it’s not without its challenges.
One of the main ones on this inside is the junction between wall and floor.
I’m not a fan of skirting boards, which traditionally cover that potentially untidy join. But even if I was, skirting boards require a plumb surface to fix to unless you want to get into a sort of stepped scribed skirting board. The idea appals me.
We consider a poured floor finish (polished concrete for example) which would be lovely but has several disadvantages – cost (it’s expensive); thickness (we would need at least 50mm and every millimeter counts in the centre of the house where we have a lowered ceiling to get the dormer room in); the underfloor heating pipework would have to be cast into the concrete; its another wet trade; and we were keen to minimise our use of concrete for environmental impact reasons.
So we’ve gone for an engineered timber floor. A rather lovely oak one at that, supplied by Russwood over in Newtonmore, who have also supplied our larch cladding.
So how do we get a tidy detail where the wood meets the stone?
The answer comes from google and ebay.
Google suggest undercutting the stone, forming a notch in the stone into which the timber will sit.
Ebay provides us with an industrial wall chaser to make the cut.
And so we begin……..