Shed Roof Timber Size

[MenBehavingBadly]

HI all - been a while since I posted

Can anyone help re. shed roof construction ?

I'm planning a DIY shed 2.4m x 3m pent roof with polycarbonate sheets as covering and am thinking 2x4 roof rafters across the 2.4m span - 40cm spacing - does this make sense or this overkill ?

I only ask because shed kits use much smaller roof timbers and they keep to hold up fine - I've even been up on the roof of our old shed (apex roof) and that has tiny thin timber everywhere

Also I'm planning to put 4x solar panels up there so maybe 100kg spread over the roof

Just sounding opinions really - the google has people suggesting massive deep timbers so I'm suspecting they are more thinking building regs etc rather than just a shed

Thanks in advance

 

[foxhole]

Fine with 2x4 , but why poly roof if you are putting solar panels on top.

 

[MenBehavingBadly]

A good question

I was planning to build some kind of frame above the roof to increase the angle of the panels.

Maybe erdm would be better. This would be better as the slope can be less I think.

That part of the project is a bit fuzzy tbh

Not keen on mounting them directly on the roof as I don't want to put holes in whatever the roof gets made of

Any suggestions would be great

 

[foxhole]

Epdm is ideal , maybe frame over roof, braced to sides for solar panels.

 

[MenBehavingBadly]

Yeah thats what I'm thinking - but the frame would have to span 2.5 m to get from side to side on the shed - not sure what to make it of ? Too long to use solar rails by themselves - and any wood would need to be reasonably deep

Many some lightweight I beam or T beam if thats even a thing