External shed door, how much of an expansion gap?

[perky416]

Hi guys,

Im in the process of building a small shed that i need to be water tight and insulated (i know its going to be a bit of a project).

I am constructing the frame out of 63 x 38 treated cls. Im also making the doors (double doors opening outwards away from each other) out of this.

I intend to seal the gaps of the door with AQ21 seals.

What sort of expansion gap would i require so that the doors still open when the wood swells due to rain?

The AQ21 requires a max 7.5mm gap. But when ive done external doors in the past, ive left a 5mm gap and it still swelled up that much i had to shave some off.

Thanks

 

[foxhole]

Seal is unsuitable for shed door, better to design the doors with an overlapping exterior so they can be left with a wide gap between the frame while the overlap keeps them weather tight. Large overhang on roof would also help keep the weather off.

 

[perky416]

Why is it unsuitable?