Timber sizes etc

[steq184]

Hi
Sorry if posted in wrong area, wasn't sure if to post here or in "roofing and guttering"
Anyhow I am building a storage room, the back wall and side walls are constructed of blockwork, the front will have 2 windows and French doors.
The roof will be sloping from the back to front, sizes are 4m wide x 3.20m long.
The roof is going to be constructed of metal corrugated roof panels, will have some insulation and plasterboard to the interior of roof. The panels are similar to these:
http://www.ebay.co.uk/itm/metal-corrugated-roof-panels-galvanised-roof-panels-/191884707397?
I need to know what size timber I should for joists and what distance between joists.
Thankyou for any help

 

[Deleted member 174758]

4 metres is approximately 13 feet so I'd aim for 7 x 2s or 8 x 2s at 600 mm centres (assuming 2400 x 1200 plasterboards)

 

[steq184]

The joist span would be 3.20m, would this alter the size of the timber needed at all?
Thankyou for taking the time to advise.

 

[Deleted member 174758]

5 x 2s would possibly be a bit on the light side, so I'd go for 6 x 2s. BTW all timber sizes assume kiln dried, C16 stress grading.