Any builders roofers want to advise me on the state of this garage roof?

Soldato
Joined
7 Dec 2002
Posts
4,009
Location
UK
Basically i'm clearing a garage out to work on my Capri, and the clearing is nearly done, however i'm a bit wary about the state of the roof so if any of you guys know a bit about this subject i'd like some advice please as to wether this needs urgent attention or could probably be left a while.

As you can see the trusses themselves are a bit warped in the centre of the garage-

20121209_130933.jpg


This gives the roof a curved appearance from the outside-

20130126_162644.jpg


And along the side it's splayed out a little as you can see below-

20130126_162550.jpg


20130126_162610.jpg


In that last pic you can see that the roof was splayed out somewhat when the guttering was last painted which the GF says must have been over 10 years ago, however you can see since then if has moved possibly another inch.

Obviously i'm going to get a pro in to look at it, but this can't be done until next week and i'd like some advice quickly. I guess the house insurance will cover having a new roof built as i'd expect it'll be a few thousand pounds for the whole thing replacing?
 
I wouldn't say it's an immediate risk, but I'd get saving for the inevitable replacement.

Fine if you're using it to work on a car, not fine if you intend on making it liveable.
 
As above its not urgent, but I would certainly take care of it this summer, strip roof, retain tiles, replace trusses, make sure these are properly fixed to wall plate and wall plate properly strapped to wall to prevent further splaying of wall! Replace membrane while you're there and refit tiles replacing any broken tiles!
 
You need some lateral restraints and a new bottom chord and strengthening no need to take it all down lol

Get a structural engineer to look at it circa £200 / £300 who should do some calcs and sketches and get some quotes from builders or do it yourself
 
You need some lateral restraints and a new bottom chord and strengthening no need to take it all down lol

Get a structural engineer to look at it circa £200 / £300 who should do some calcs and sketches and get some quotes from builders or do it yourself

I agree with this, the vertical load from the roof is pushing on the walls. there has probably been weight added or suspended from the rafters causing this.

Additional timbers bolted across the roof to the foot of the rafters at intervals using spiked timber connectors.
http://www.infixdirect.co.uk/Spiked-Timber-Connectors-50mm-Diameterx2mm-Hole

and possibly some horizontal tension cross bracing, galvanised thread bar and turnbuckles or timbers nailed diagonally across several rafters although this may not be necessary.
 
Last edited:
Get another another good dollop of snow on that roof, isn't going help things.

I myself would go for a complete new roof, as you don't know whether it's been properly fixed to wallplate, it's very badly constructed in my opinion.

Looking at the photo's it's already spread a bit, & you will struggle to pulled those rafters back in to line, it's too far gone to be saved.

You can reuse the tiles,ridges,so that will save some expense.
 
Last edited:
I guess the house insurance will cover having a new roof built as i'd expect it'll be a few thousand pounds for the whole thing replacing?
Why do you think insurance is going to cover having a new roof built?
If it sagging now then it wasn't designed correctly or it was built with cheap green wood.

I'll just point out the wooden beam at the front full of knot holes has the structural strength of a wet twig. Now look at the beams in your house roof - hardly any knotholes and probably twice the depth.
It's also one of the crappier designs possible, he's left a big empty space for some reason but the bottom rail isn't capable of supporting any additional weight. If it was a normal cantilever design you probably wouldn't have an issue. Even that top tie is twice the depth of the beams when actually it's in tension* and could easily be much smaller. I wouldn't put felt on that.

*edit, put wrong term, doh
 
Last edited:
The ridge and rafters don't look very substantial at all and there is a lot of weight in Rosemary tiles. We usually tend to over engineer the roof to be on the safe side.

I'd get a decent roofer to have a look and see if he can strengthen it up, rather than pulling it down. The tiles are pretty expensive and time consuming to use, so better to try and save it imo.
 
I agree with this, the vertical load from the roof is pushing on the walls. there has probably been weight added or suspended from the rafters causing this.

Additional timbers bolted across the roof to the foot of the rafters at intervals using spiked timber connectors.
http://www.infixdirect.co.uk/Spiked-Timber-Connectors-50mm-Diameterx2mm-Hole

and possibly some horizontal tension cross bracing, galvanised thread bar and turnbuckles or timbers nailed diagonally across several rafters although this may not be necessary.

This is the best answer, the roof is poorly designed if, you fasten some timbers accross the bottom of every alternate rafter it will stop it getting any worse and probably last another 20 years or more. As it is the roof is tending to push the walls out and if you leave it as it is you might end up having to rebuild the whole garage.

Something like the first pic on here.

http://www.building-regs.org.uk/part_a.html
 
You can try and repair the already sagging roof with the hope it won't sag more next year with more snow or you can fix it properly, it obviously has not been calculated properly for snow loading etc. Maybe the insurance would cover it, but they may put it down to act of god, there usual get out clause, but worth a call at least!
 
If it sagging now then it wasn't designed correctly or it was built with cheap green wood.

I'll just point out the wooden beam at the front full of knot holes has the structural strength of a wet twig. Now look at the beams in your house roof - hardly any knotholes and probably twice the depth.
It's also one of the crappier designs possible, he's left a big empty space for some reason but the bottom rail isn't capable of supporting any additional weight. If it was a normal cantilever design you probably wouldn't have an issue. Even that top tie is twice the depth of the beams when actually it's in compression and could easily be much smaller. I wouldn't put felt on that.

So you want your garage trusses built out of knot free kiln dried timber? It's a truss not a cantilever if you can't get that right I'd doubt the rest of your toshy statement.

OMG knots pull it all down and start again

http://www.etstrusses.co.uk/wp-content/uploads/2012/05/finks5.jpg
http://www.acrooftrusses.co.uk/images/roof.JPG
http://anonw.files.wordpress.com/2009/10/dscn1568.jpg
http://www.theselfbuildblog.com/blog/wp-content/gallery/bothwell-01/00194-roof-trusses.jpg

In fact I'm struggling to find a softwood truss without knots


It's taken tens of years to get there, the roof covering apart from one or two broken tiles looks fine, the felt looks fine and there's no obvious damp. The structure could so with some strengthening and restraining but there is absolutely no need to pull what is an characterful garage for the sake of it, some people don't have the luxury of replacing every worn item with new, ever heard of make do and mend?
 
So you want your garage trusses built out of knot free kiln dried timber?
Yes please, problem?
Green timber just warps under load as it dries out, kiln dried is a few extra pennies and much stiffer. Timber with edge knots would get used for framing, not for compressive loads, this is just lazy construction.
It's a truss not a cantilever if you can't get that right I'd doubt the rest of your toshy statement.
Who are you anyway?
I didn't say it was a cantilever, I said "If it was a normal cantilever design you probably wouldn't have an issue", I'm pretty sure that was an easy to read post :confused:
Ha Ha, if you can't tell the difference between wet 2" knots that go right to the edge, as compared to a few twig knots on your links then I hope you are not a builder :D

The structure could so with some strengthening and restraining
I'd agree, I never suggested pulling it down. Although I would if it were mine, somebody might think I'd built it.
 
Last edited:
Yes please, problem?.

No not really but you can afford timber that is considerably more expensive and not what is used in 99.99999999999% of garage trusses as the timber will effectively end up absorbing / drying out to it's surrounding environment, the BS says 18% moisture for external timbers in a non heated environment and 12% for internals, your expensive kiln dried timber will just absorb the surrounding moisture and could expand popping glues joints and opening up gaps to allow water in, not a great idea.

Yes please, problem?
Green timber just warps under load as it dries out, kiln dried is a few extra pennies and much stiffer.

What makes you assume the original is green timber?

I didn't say it was a cantilever,

If it was a normal cantilever design you probably wouldn't have an issue

No your right it's not a cantilever now, but you said if it were a cantilever, show me a cantilever truss that's supported at either end, what's a cantilever got to do with a truss? do you know what a cantilever is?


Who are you anyway?

Maccapacca :confused:

Ha Ha, if you can't tell the difference between wet 2" knots that go right to the edge, as compared to a few twig knots on your links then I hope you are not a builder

You don't know the difference between live knots and dead knots, yes knots weaken timber are you saying that is the cause of the sagging?
 
Is there any topic you aren't racist in, kwerk? Or is that just an unfortunate trait amongst some poorly educated Americans?

Kwerk is American? I always thought for some reason he was Brummie.

A study was conducted in 2008 where people were asked to grade the intelligence of a person based on their accent and the Brummie accent was ranked as the least intelligent accent. It even scored lower than being silent, an example of the stereotype attached to the Brummie accent.[7]

:D

Sorry for derailing thread. Onwards.
 
Back
Top Bottom