Leaking shiplap

[steveg94]

Ive got a shiplap shed which I use as a workshop. Unfortnately, the joins in the shiplap occasionally let small ammounts of water through. Wickes timbercare is on it at the moment but doesnt actually seal the joint. I was planning on putting a brown Dulux Weathershield onto the shed to hopefully seal the gaps. Would this work? Ideas also welcome. Thanks.

 

[JohnD]

no.

even though shiplap has an overlap of the upper board over the one beneath it, they always shrink and expand according to the weather, so the gap changes size and shape. If they warp or cup, the boards may not even stay in contact. The cladding is always leaky to some exnt.

My approach is to treat the shiplap with a water-repellent breathing stain, as used on sheds and fences, but if you have a shed, you are better off felting the frame before fitting the boards. I suppose your shed is already built so too late

I suppose you could tack it on from the inside. You have to shape the bottom so that water runs outside the shed without wetting the timber