Help with Roof

[rosinante]

Hi, i am soon to replace the roof on my garage with the double skin insulated steel panels, They weigh about 11kg per m and will be about 6m long , the clear span is about 5.8m,Q what size trusses/beams should I fit? either engineered timber [ no condensation or metal, all help welcome, the sheets will run front to back and the trusses/ beams left to right, also what spacing should i use? TIA

Chris

 

[gavuk]

When i built my garage ,with concrete roof tiles ,i went to the local builders merchant ,they did the calcs ,and came back with a price .£300 for 4M span and 11 or 13..trusses.????..delivered ,i was expecting a lot more ...think it was "bradfords " i went to as the have their own saw mill.....you could ask any of them for the same service, and quote at the same time...good luck

 

[decepticon]

bit of a daft question really, if you cant give roof pitch or width of building cant see how people can answer you, suggest you approach some one who knows what they are doing and can give professional guidance-failing that nail some 4x2 to some 6x2 with some 2x2 going crossways, backways, longways and upways and im sure it will be fine
cheers

 

[Hitch]

What pitch, probably steel zpurlins, spaced at 1500 or so.

 

[cumbriasteve]

My garage is near enough the exact same size and also has the metal profile sheets on, I used 9" x 3" at 24" spacing, there was 2 of us up there laying the sheets..total of about 32 stone.
Been up 2 years now with no problems..I have photos on here showing the build.

 

[rosinante]

Roof Help

Hi
Thanks for replies, the building is essentially 6 m square with a nominal pitch of 10deg,nominal clear span of 5.8 m,with this as a "lightweight" composite roofing system would engineered wooden trusses be suitable,if so what size?
can anyone help with the calculations for this kind of beam,z purlins are a consideration but I think would cause condensation runs in an unheated building.Perhaps I asked the question in a"daft manner before",helpful answers welcome

Thanks
Chris

 

[cumbriasteve]

bit of a daft question really, if you cant give roof pitch or width of building cant see how people can answer you, suggest you approach some one who knows what they are doing and can give professional guidance-failing that nail some 4x2 to some 6x2 with some 2x2 going crossways, backways, longways and upways and im sure it will be fine
cheers

Why is it a daft question?.. if there was insufficient information then it would be much nicer to simply state that.

 

[decepticon]

if it was me i would use galv zed purlins, approx 200mm deep 1.6mm thick. ends to be built into brickwork (or you could fix approx 700mm long steel angles to inside face of wall at right angle to roof, then bolt purlins to these, this would prevent any wind uplift)these fixed at approx 1500mm ctr's.
if you have an insulated roof then purlins wont condensate
you will need a central run of rigid struts between purlins to prevent them twisting and bowing.
fix roof sheets with self drilling tek screws
hope this makes sense
i would imagine timber roof trusses would be alot more expensive and be alot deeper sections which reduce head height
cheers
neil

 

[mike os]

a guess.... 225mm zed purlins at max 1.5m centers, 2 ties equally spaced.... but it is just that an educated guess

thing is if its wrong 6-12" of snow & its new roof time.

ask teh place you are getting teh sheets from to advise

 

[decepticon]

Why is it a daft question?.. if there was insufficient information then it would be much nicer to simply state that.

sorry, probably could have been worded a bit better-it's been a long day

 

[cumbriasteve]

I think the last 2 replies by decepticon and mike os have provided you with the correct method to fix the sheets, the comment about wind lift is a very valid one, I know that because I came home once many years ago and my garage roof was 2 gardens down ...all in one bit!!! Its amazing the weight that can be lifted by a gale.

The condensation is an interesting point, my roof is double insulated, the door is a well sealed insulated door and the building is draught proof..... I now have some black mould on one area of the ceiling and two areas of the wall, warm air will always find the coldest part, be it the roof, wall or items..it will then condensate, my stock of metal scrolls is often wet to the touch

My plan is to core drill several areas and cover with fly screen upvc ventilators, hopefully to get some air movement.

 

[rosinante]

Roof

Hi Thanks for all replies, I wiil take on board the fixings and ties advice, maybe post some pics when in progress and completed , the space is currently used as a general home workshop but will gradually become a "proper" wood workshop, i will still have welding/turning facilities but will no longer be messing around with vehicles, the inpection pit will now house my compressor and dust extraction system,
Cheers

Chris

 

[mike os]

for tie down I would use 1600mm long 30 x 5mm bent & twisted straps, fixed 2x with screws per block, for at least 3 full courses below bottom of z.

also 3 straps, ditto, at each end, max 2m apart, evenly spaced, ie 1m off ends & middle

again educated guess as unseen etc...