A larch deck facing the Pyrenees

Larch: a timber made for the mountains

For this outdoor deck, I suggested larchLarch: a mountain softwood, naturally resistant to moisture and insects thanks to its resin. It needs no chemical treatment and greys beautifully over time. Known as mélèze on a French quote.: pronounced grain, genuine natural durability, and a timber that itself comes from the mountains. For a deck exposed to snow, frost and high-altitude sun, it is a choice that makes sense.

What makes a deck last

A timber deck that ages well is not down to luck. It comes down to technical details you no longer see once the job is finished.

First, the structure: the joist frameJoist frame: the framework of parallel timbers the deck boards are fixed to. Its spacing determines how rigid the deck is: too wide, and the boards flex. Known as solivage on a French quote. is laid with rigorous spacing between the joists, calculated in particular to match the thickness of the boards. That is what guarantees the whole deck stays stable over time.

Then the fixing: each bevelled board is fixed with A4 stainless steel screws, always pre-drilled to the right diameter. Without that pre-drilling, the natural movement of the wood, which swells with water and shrinks in the sun, ends up snapping the screws.

Finally, the gap between the boards: I set it according to the season and the moisture levelMoisture level: the humidity of the air and of the wood. Timber laid damp will shrink as it dries, timber laid dry will swell at the first rain: the gap between the boards has to anticipate that movement. Known as hygrométrie in French. at the time of laying. The wood can then expand and shrink through the seasons without ever distorting the deck.

The questions I'm often asked

Can you build a deck on soft ground or do you need a concrete slab? How much height should you allow for the joist frame and ventilation? What is the difference in price and lifespan between treated pine and larch? Why natural wood rather than composite?

I have honest answers to all of that. Don't sit there wondering: call me, and together we will look at what suits your ground and your budget.