DIY Doctor UK DIY Forums

My first post & not familiar with timber nor building DIY.

Have base & timber upstands ready for new timber shed. Looking at a rectangular flat roof with a slight angle. What material is advised for roof boards please?

I read somewhere that 11 mm OSB could possibly be used. Or does it sound too thin? Roof will be approx 2.5 m by 5 m.

What to go over (felt or some bitumen roof sheets)? Thanks.

Hi berkovius,
Standard size for sheets of ply/osb is 1.2x2.4m so you will have to find a way of extending the boards to fit 2.5m.
If you use OSB you will have to select the correct grade e.g. exterior grade. 11mm is probably too thin, so use 18mm but you will need joists to support the board edges.
25 year felt will probably be the best covering.
Regards S

Thanks Stoneyboy, my kids are fed up of me not getting the shed built, has been an eyesore for ages now. Got the confidence to start it properly now.

I'll go for the 18 mm OSB then, sounds like a safe bet. And 'exterior grade'. Cheers for also recommending the 25 year felt.

To avoid wasting money on expensive timber panels for the outside walls, what kind of panels (& width) would be suitable for a shed / store, doesn't need to look fabuous.

Hi berkovius,
Use the cheapest sheet material you can buy - probably 9mm osb. You may need extra bracing and the weathered face must be painted with some form of paint/varnish.
Look out for multibuy offers which can help with savings.
Regards S

Hello, 18 mm that OSB turned out to be perfect. Thank you for your advice.

Now I've bought (apparently good strong) roof felt. Watched some videos and thought I can simply glue where they overlap. So bought only 1 x 5L tin adhesive.

On the Wicks roof felt instructions they also mention some underlay - is this really necessary? Videos online didn't show any underlays for shed roofs.

Finally, if glue is needed throughout like some say... I don't mind buying some more tins. Does anyone know how much is needed? Btw I'm also using 13 mm roof felt nails.

Hi berkovius,
5 litres should be plenty for the laps, use the clout nails all along the overlaps at about 75mm maximum spacing.
Regards S