roof for garden shed

[b21playa]

building a shed out of blocks and roof is proving to be expensive so looking at options.

Will be around 18ft x 20ft, instead of tiles or a flat roof what else can I use?

The small the pitch, the better as then I can have more headroom.

 

[redtonybbb]

Tb.XRoofer/Surveyor.
The cheapest option would be a lightweight option and this is probably what you need given the span of the roof,and being a big shed roof you can these days find metal coated profiled sheets that can be made to fit any length and they are apparantly quite reasonably priced.The sheets will keep water out as side lapped on a profile.It is not like it used to be where problems occur because of laps according to roof panel size ie garage roofs for example always had problems of water driving up under the sheets after the compound putty under laps had gone.You can now simply get the roof sheets made to fit the roof,and of course you will need the structure to handle it.Given the width you may need a couple of central pillars or wall section,which can be used to break the span.Fix the sheets on top of the profile -given you may try for going flat.(It is a shed after all)obviously even a shed has to be safe for the roof to be maintained.Exchange and mart normally has someone selling these or trythe web,all these manufacturers deliver for a min. cost.