Roof truss bracing and strapping

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Hi all, in the house we bought the surveyor pointed out that there was no bracing or strapping in the attic and that this should be done.

I've done a load of research on how to do this myself and it doesn't seem difficult. my roof is 8.5m long by around 6m wide and the trusses are \/\/ (with the outer web members being short of course)

I believe I simply need

Lateral restraints running the length of the building (2 along the bottom chord and 2 along top chord)

a couple of diagonal braces at each end of the building spanning 3 trusses @ 45 deg angles (attached to bottom chord)

a couple of X braces (sway/wind brace I think) attached to longest web members (spanning 3 trusses)

a couple of wind braces at each end of the building attached to top chord in /\/\ patten (spanning 3 trusses)

some 1.6m long gable straps on each end on each lateral restraint

My questions are
1. does this sound sufficient
2. what size and grade wood should I use (45x70 kiln dried C16) ?

thanks for any thoughts - it has been a long road to get here as there isn't much information around!
 
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How old is the house?

If more than 12 months, why has the roof not blown off previously?

Is there actually a problem with the roof?

But if you want to do it, then what you propose is OK. Use 100x25mm timber and screw don't nail - two fixings per truss
 
You won't need c16, off the top of my head we use something like 22x97mm, you wont need it kiln dried either,tanalised.
I don't know how you can stand a roof, let alone tile one without bracing.
 
I find it more and more bewildering when I hear of a surveyor stating something needs to be done. What training have the had for this, what calculations have they used, which regs are they quoting, or is this to justify there existence?
If the local doesn't merit it hold down straps are not required, they are fitted to the roof/walls to prevent wind suction from lifting the roof off the building, is that what's required for your building ?? wind bracing is fitted where it's deemed necessary that the roof will rack out of wind, and has to be set out from the windward side, is that whats required for your building??? speak to an SE before you go any further, find out for sure if all or any is indeed necessary...pinenot
 
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I believe I simply need

Lateral restraints running the length of the building (2 along the bottom chord and 2 along top chord)

a couple of diagonal braces at each end of the building spanning 3 trusses @ 45 deg angles (attached to bottom chord)

a couple of X braces (sway/wind brace I think) attached to longest web members (spanning 3 trusses)

a couple of wind braces at each end of the building attached to top chord in /\/\ patten (spanning 3 trusses)

some 1.6m long gable straps on each end on each lateral restraint

My questions are
1. does this sound sufficient

Probably, unless you live in a hurricane area.

The tiling battens can offer reasonable lateral bracing to the trusses themselves. As long as you've got the metal straps tying the gable walls to the first 3 trusses at each end, you should be fine.

(The diagonal straps are often included just to stabalize the trusses while they are being errected).
 
It is usually diagonal bracing from the top corner down to the (far) wall plate. The bracing timber must reach the wall plate if raised tie trusses.

Longitudinal bracing on every node and one fitted to each of the very outer nodes (where the rafter chord meets the joist chord) if it is raised tie trusses.

Chevron bracing if over 8m or if it is raised tie trusses.

Restraint straps every 2m must pass over 3 rafters/joist and have solid bridging.

Always fix the diagonal bracing first. All are a pain to fix whilst the roof is open, i can only imagine what it will be like once tiled in!
 
Probably, unless you live in a hurricane area.

The tiling battens can offer reasonable lateral bracing to the trusses themselves. As long as you've got the metal straps tying the gable walls to the first 3 trusses at each end, you should be fine.

(The diagonal straps are often included just to stabalize the trusses while they are being errected).
I was going to ask, why is bracing necessary on a trussed roof, but not on a cut roof. Both could potentially rack in the same way, and if battens are sufficient to prevent racking on a cut roof, then they should do the same on a trussed roof.

I guess that's what you are saying Tony?
 
Do your neighbours have similar roofs? If so - ask if you can take a peak.
 
I was going to ask, why is bracing necessary on a trussed roof, but not on a cut roof. Both could potentially rack in the same way, and if battens are sufficient to prevent racking on a cut roof, then they should do the same on a trussed roof.

I guess that's what you are saying Tony?

Exactly; I always assumed the diagonal straps were just to keep them upright while positioning them?

It must be easy for a surveyor saying do this and do that, without having to actually prove that 'this and that' are structurally necessary!
 
The truss manufacturer produces a drawing that usually specifies the bracing required. I thought chevron bracing was standard on all trussed roofs :s
 
I thought chevron bracing was standard on all trussed roofs :s
No.
Standard on raised tie and duo pitch roofs greater than 8m and mono pitch greater than 5m. Chevron bracing being the zig zag fellas that are fixed to the vertical or leaning members of the internal chords.
 
I was going to ask, why is bracing necessary on a trussed roof, but not on a cut roof. Both could potentially rack in the same way, and if battens are sufficient to prevent racking on a cut roof, then they should do the same on a trussed roof.

I guess that's what you are saying Tony?

Exactly; I always assumed the diagonal straps were just to keep them upright while positioning them?
Jeepers what business did you say you two were in? :eek:
 
Jeepers what business did you say you two were in? :eek:
I'm an accountant, and Tony's an insurance salesman :p

Seriously though, I've seen the British Standard, and know that trussed roofs have to be braced while cut roofs don't, but don't know why. It's amazing how often I ask my fellow "accountants" similar questions and the answer is "just because"...
 

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