Construction tutorial - The house itself

Roof

The roof is what will make or break the treehouse over the long term. Clearly, wood will survive a lot longer if it is protected from running water or even occasional wetting. The roof is more than just a lid for your treehouse!

As I mentioned above, a pitched roof looks better and is easier to waterproof than a flat roof (diagram of flat roof), but it takes longer to make. To waterproof a sloped roof you can attach felt over a thin plywood base and cover it with shingles or boards. It is very important to keep water from spilling off the roof and onto the walls, because it will soak through and make everything inside damp and cold. This is especially true if you have a carpet which will hide damp and prevent the floor drying, leading to rot. A good idea is to design in a large overhang at the end of the roof, and by making the roof longer than the walls so it shelters them from rain (see drawing).

A flat roof will need to have felt (tarred sheet material) securely fastened and sealed with a blowtorch. Any tiny hole can cause a leak, and this will be worse if puddles collect on the roof. You can paint the felt with thick sealing paint or you could make the roof very slightly sloped. This would let water run off the roof, but you could still stand on it.

Flat roof with recommended slope to avoid pools of water	Sloped roof with wide overhangs to keep drips off walls