Extension to shed roof

by Oliver

Hi John, Firstly, Great site! I am building a shed extension for my summer house to keep all the dirty garden equipment. My extension is a 1.2m wide by 2m deep with a sloping roof. I'm trying to mirror the existing roof so it blends.

Question is, what materials should I use for the roof? The summer house came with long tongue and groove lightweight planks but I'm having problems finding similar material at a reasonable price. I don't want to over-spec the material but it should be flat so I can staple-gun the tarmac tiles to it.

Any suggestions?


Hi Oliver,

Glad you like the site.

Solid wood is getting more and more expensive so you might want to consider using plywood or OSB (Oriented Strand Board).

Make sure that you buy a grade that is suitable for external use. With plywood it is normally called classified as WBP (Water and Boil Proof) in the US it will have the letter X in its classification (suitable for external use). Either way, explain to your supplier what you intend to use it for and he will see you right.

OSB does look a bit like that very cheap chipboard material, but it is a structural product and is made using waterproof glue and so will not delaminate in a small bit of water. Though it should not really be exposed to the elements. Quite often you will find that OSB is about half the price of plywood, so there is quite a saving there.

For uses such as shed roofs, you can quite comfortably use the 1/2" (12mm) material an have your rafters at 16" (400mm) spacing.

I hope this helps, let me know how you get on with your project.


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