The beauty of the way this house is constructed is that the outer skin is the airtight layer – and that anything outside it is almost cosmetic. Well, almost.
The frame – walls and roof – is covered with this layer of wax-impregnated, medium density, tongue and groove fibre-board. It isn’t MDF, the structure is considerably coarser. Each sheet is “glued” in the tongue and groove with a slow drying mastic. The wax impregnation means that it can stand the weather for months if necessary. It forms the airtight layer of the house. The walls and roof can then be covered with whatever you want – they’re battened out and you then attach brick, stone, render, whatever – in our case Thermowood rebated weatherboard.
This in turn has brought a further decision. Thermowood is, of itself, dimensionally much more stable than untreated weatherboard and the treatment also protects it from rot (see www.finnforest.co.uk/products/exteriorcladdings/Pages/ThermoWood.aspx). If we paint it then we will have to go on painting it over the years. Remembering that this is our retirement house, we could be making a rod for our own backs by doing so. If the wood is left as is, it will silver down over the next few years – which should fit in very well with the cart barn concept and the slate roof. Or it could be “painted “with a UV resisting coating so that it stays its current colour. But I suspect even this will need recoating in due course and so be as much work as painting it conventionally. And we, or a future owner, could have the whole lot off and replace it with something quite different – apart from keeping the weather off, it is not part of the structure of the house.