Gable roof for a double brick shed

[meso]

Hi everyone

I am looking to get some advise on my designs for my gable roof and to know if it will be strong enough or not. The shed is 6m x 4.5m with 28 courses on the outside wall and 29 courses on the inside with a cavity of 10mm (see attached pics). I had a brickie mate of mine help put that up between the xmas and new year break and the I had another mate help do the slab last year in May.

I was originally going to build the roof with no ceiling and having the centre supports higher than the roof for a bit extra clearance but now I have decided to go with ceiling. This way I can build storage space in the cavity of the roof (like an attic to store camping gear, xmas lights and stuff).

My plan is to build trusses on the ground first with a gap for the ridge beam then put it all together on the top plate. The trussess will be built out of 120mm x 35mm H2 treated pine for the rafters and the joist and 90mm x 35mm for the internal supports and will be joined together by nailplates (see attached designs). I want to try and maximise the cavity space in the roof but not compromise on strenth.

So first question which one of the three designs (900mm, 700mm or 500mm from the rafter & joist join) would be strong enough?

The next question is how many trusses do I need? Over 6m I can put in 11 trusses which will have spacings of 600mm or I could put in 13 which will have spacings of 500mm between each truss?

Cheers

Mitch

[catsteve]

Hi Meso
I had a 6.5 X 4.5m shed built. ( had someone do it for me)

I think you will have to use Laminated (LVL) for your cross beams. I am no engineer but 4.5 meters is quite a span and you will need the extra support if you are going to plan to use the space as storage.

I didnt go for the ceiling option. Having ceiling has advantages- easier/cheaper to build. and attic storage space.

I would highly recommend putting an extra couple of courses onto your build. you will never regret the extra height. (lifting vehicles, boats, building BIG things).

My builder used 500mm spacings between rafters. see pics

[paul-b]

just a quick question about your trusses ...what is the roof type is it concrete tile or iron/slate and what pitch

also is your span 4500 and your run 6000 and are you planing on using two "half" trusses

now theres a few way's you can do this you can pitch the roof using a bridge beam and as the span is only 4500 there isnt a big problem doing so or you can make some some attic trusses that give you a clear span for the roof cavity

now for your truss spacing's if you have a tile roof its 600 and under if its iron you can go 1200 max and use a I.C.J for help carry the weight off whats in the roof

also 120mm is a bit off overkill for the bottom cord so it should carry the weight but in saying that its never a good idea to load up the trusses in a shed with a lot of weight as i have seen them snap from doing so

as a day job build roof trusses and have done for 20 years and have done spans ranging form 25 metres and nearly 5 metres high with a 90mm p15 bottom cord to full hardwood trusses using railway sleepers for timber so anything is possible

the easy way is to get a trussplant to engineer some for you using there design programs

cheers paul

[coffenup]

make sure to put some insulation in before you put the roofing on will save time and stop you doing it later
regards michael

[meso]

Thanks for the posts

Sorry haven't had a chance lately to get on the web.

Catsteve, your shed looks great. I would have built it a couple more courses higher but my garage to get into the back yard is only just over 2m high, so anything higher than that wont get to shed any way. I have also decided to go with 600mm spaces between truss.

Paul, I am planning on putting a colour bond roof on, so the weight shouldnt be an issue. The span is 4500 and then run is 6000 and the roof will have a pitch of 30 deg. Yeah 120mm is overkill for the bottom cords, but I am not an engineer either so I thought it would be better to overkill it. I tried to email a few places to get an idea of the truss design and had no luck, so I ended up just ordering the timber and giving it a go.

Last weekend i started to assemble the trusses, I decided to go 2 different truss designs (fink and attic design). I ran out of knuckle plates so will have to complete the last 2 this weekend. Once thats done I have to get a few mates to help put them up.

I've attached a couple of pics.

Cheers

Mitch