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.

Interior stone wall

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.

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.

Undercutting the stone wall

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……..

  • Pat Lean

    In our stone cottage and against stone walls, I instructed my husband to scribe around the woodblocks which edge our carpet, and to scribe an edge facer which sits on the timber floor against the wall, to take up the shape of the wall.
    We also have a skirting trunking on the first floor which takes heating pipes and electrics, with removable top which is also scribed around the stonework. A neat but not perfect fit, but need not be absolutely precise, and looks good. Top of the trunking is removable. The trunking is fixed back to timber noggins which are screwed to the stonework. Could also stick noggins to stonework.
    I would not recommend cuttings into stone: can loosen stone, break out small and large sections, and enormously difficult to do on an amateur basis.

  • Olli Blair

    Thanks Pat
    I just have a thing about skirtings. (By which I mean I don’t like them)
    I’ve got a special wall chasing tool that cuts a 25mm channel and so far hasn’t had a detrimental effect. (The walls are around 600-700mm thick)
    Its a complete refurb and we’ve done a fair amount of stone repair anyway so I thought it worth it to do it this way.
    Would be interested to see some photos of the detail you describe

  • Ash Theasby

    Nice solution Olli

  • Pat Lean

    Olli, a late response, but can’t send pics, but if you give me your email I can send direct. In principle, it is forming a box skirting which projects 30-50mm away from wall, which takes the pipework or electrics within the box structure, and is capped with a board which itself is either square-edged against the variable stonework or scribed along it to fit. The top board projects 10mm as an articulation of the box structure and can be bull-nosed or mitre edged, and is removable for access. Another alternative to take microbore pipe is laying a flat board along the floor, scribed against the wall to take up the variable stonework with the pipe fitted on top and exposed.

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