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By MikeG.
#461378
Tom,

I agree with you re adding to the original post...........and I did that this morning with the suspended timber floor variation. As for adding a link in my signature......good idea, but it might take some working out! I'll have a look.

Mike
By yogibe4r
#462357
Mike,

Thanks for putting this together.
Below is a design for my workshop roof I plan to build this spring. I would appreciate if you could check my sizings, especially the rafter size ( 6x2). Where the joists stop in the middle I plan to leave the ceiling open. The slightly irregularly rafter spacing in the centre is to ensure they sit above studs.
Regards, JK
Image[/img]
User avatar
By MikeG.
#462368
yogibe4r wrote:Image[/img]


Right, let's have a look.......

Seems like you need to re-post your picture, JK. Firstly, you haven't enough postings to get through our spam filter (which I can overcome), and secondly you appear to have 2 [/img] instructions at the end of the image address.

Mike
By yogibe4r
#462383
2nd try's a charm...

Image
User avatar
By MikeG.
#462391
OK, that's better.

Before I check the timber sizes, let's look at the principles. Are you hoping to rely on the joists to prevent the walls from spreading? There is a huge amount of good sense in having a hybrid roof like this, because it does enable access into the loft areas from inside the building, and with easy access for longer pieces of stuff than if you try and use a loft hatch. It is exactly what I am planning to do in my new workshop.

If you aren't relying on the joists to prevent spread, then your ridgebeam needs to be structural, and will be huge. If you are relying on the joists then we have to deal with the trusses which don't have ties.

Mike
By yogibe4r
#462392
Mike,
My intention was to rely on the joists to stop the walls spreading. What would be the maximum gap between 'un-joisted' rafters? The wife has already earmarked the 'loft space' for storage.

Regards, JK

edit: The wife has now informed me she is to be referred to as SWIMBO from now on!
User avatar
By MikeG.
#462406
JK,

in which case, we will simply double up the last of the rafters that have a tie, and use a structural ridge beam to span between them. The rafters without a tie will be "held up in the air" by the structural ridge beam, and thus prevented from spreading the walls.

What sort of roofing are you proposing (tiles, felt, sheet-roofing etc)? Are you required to get Building Regulations approval for this shed?

Mike
By yogibe4r
#462431
Mike,
The roof will be 12mm OSB covered with felt shingles. Not sure about building regs, as neighbour built a simliar structure and told me he didn't need them. However will be popping down the planning office to make sure. Overall height is 3.85m.
Regards, JK
User avatar
By MikeG.
#462529
I'll sort your timber sizes out when I know whether that this doesn't need BR approval.

Mike
By yogibe4r
#462536
After a brief conversation with the duty planning officer, they have explained that only the electrics may be of concern to them. This I will plan closer to build time.

Regards, JK
By yogibe4r
#466051
Not sure if this thread is still being looked at due to recent events, but can anybody else have a look at my roof design to see if it's ok?

Sorry to be a noob without a clue!?!
User avatar
By 9fingers
#467146
yogibe4r wrote:Not sure if this thread is still being looked at due to recent events, but can anybody else have a look at my roof design to see if it's ok?

Sorry to be a noob without a clue!?!


I can only offer a tiny fraction of Mike's expertise but post some details and we can have a look.
Bob
By yogibe4r
#468122
Thanks 9fingers.

Image

Proposed timbers are 6x2 for rafters and joists, 8x2 for ridge beam.
Roofing will be 12mm OSB and felf shingles. All rafters sit above wall studs, hence slightly odd spacing in the centre. The ridge beam isn't to be structural so my concern is whether the amount of space between 'un-joisted' rafters would cause the walls to spread.

Thanks in anticipation, JK
User avatar
By 9fingers
#468156
Such a shame we don't have Mike here for an experienced opinion.

I share your concern on wall bulges. Very attractive to have what must be about a 3m access to the roof but unless you are going to store very long lengths up there, I'd be tempted to close is up to say 2m and make sure the wall plates on top of your studs lay with the widest dimension horizontal to stiffen the walls as much as possible.

Also I wonder if your joists are over spanned at 6x2. If it were my shop, all sorts of stuff would end up there imposing quite a load. I think I'm right in saying if that were a habitable floor you would be looking at least 9x2 to meet regs. So I'd consider 8x2 stress graded timber. Should not add a huge amount to the cost.
Are you going to put a deck up there? It would tie the joists together nicely.

The OSB will tie the rafters and stop them racking.

Thes are just my gut feel - I'm not a professional in this field.

hth

Bob
By yogibe4r
#468191
Image

Updated with 8x2 joists, extra joists, deck of 22mm chipboard, and doubled up last pairs of rafter.

Thanks for your advice 9fingers

Cheers, JK