Stu_22
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Registered: 25th Mar 02
Location: Luton
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Want to build a big 7M x 7M Garage/Workshop
Would really like it to be an open space but a 7M span is looking prety big and expensive for celling joists.
If I were to use a steel hollow box section how big/thick would it have to be
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Gary
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Registered: 22nd Nov 06
Location: West Yorkshire
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Andykent helped me out the other week re some structural stuff.
3cm can do the design for you too.
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sc0ott
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Registered: 16th Feb 09
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Why dont you put in some load bearing walls?
Or just look into some sort of industrial type roofing.
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sc0ott
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Registered: 16th Feb 09
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Or go for something like;
Two double garages joint together. Built using block.
1 load bearing wall seperating each but with a door in between.
4 single external garage doors or 2 large doors.
Size - 5.5m x 11m.
That way you could run the roof from front to back which is only 5.5m.
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AndyKent
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Registered: 3rd Sep 05
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Engineered webbed joists rather than plain old timber?
Or actually more sensible would be to run a single steel the opposite way through the garage to halve the clear span.
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Dave
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Registered: 26th Feb 01
Location: Lancs
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Engineered timber joists can do a 7m span,I fitted some today that were over 9m, although they did sit on two internal block walls. I would imagine they'd be quite costly though as they'd have to be pretty wide. I did a floor recently that was approx 8m x 6m that used a gluelam/kerto down the middle like a spine with smaller joists running off it, again that needed two posts under the kerto though.
Best bet might be to install a steel down the middle as a trimmer and span both ways off that.
The engineered joists are superior to timber in just about every way, although I have no idea of cost differences.
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Dave
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Registered: 26th Feb 01
Location: Lancs
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On second thoughts, are you actually storing stuff on them or is it just to form the ceiling?
If this is the case use roof trusses if it's going to be a pitched roof, they'll span 7m easy and will be a much easier way of forming the roof.
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sc0ott
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Registered: 16th Feb 09
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If its going next to a house then a pitched roof would look and suit it better for obvious reasons, and like you say you could store things along the bottom chord.
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Gary
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Registered: 22nd Nov 06
Location: West Yorkshire
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We got told last week that our 5m ish span wouldnt take anything other than residential load. But they seemed to think we could lay new joists above and it would be ok.
I'd do what Andy said and run a steel joist across the middle
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Dave
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Registered: 26th Feb 01
Location: Lancs
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We're all sort of assuming it's a floor though when it could be just a ceiling.
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sc0ott
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Registered: 16th Feb 09
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Funnily enough one of the suppliers we use for joists and trusses has gave as a 300mm deep joist which spans 5.6m at 400mm centres. Could get 240 joists to work but that would mean the spacing would be shortened to 200-300mm which wouldnt work. This is for the second floor on a 2.5 storey house. There is no load bearing partitions on the first floor hence why theyre so deep.
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Dave
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Registered: 26th Feb 01
Location: Lancs
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The 8mx6m I did was a second floor, the columns are going to be hidden in a non load bearing partition, bearing onto a block wall on the ground floor. These were 240deep 38mm joists @600, think the kerto was 240x80mm.
What width is the 300mm deep one?
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sc0ott
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Registered: 16th Feb 09
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Two kertos were 138? I think. 1 has the stairwell connected to it and the other is on the opposite side of the stair opening.
The TJIs are just the standard size but 300 deep.
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Dave
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Registered: 26th Feb 01
Location: Lancs
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You can get the TJI's in all different widths, 38mm is usually used but I think they go upto about 90mm for longer spans. I'm pretty sure I did some second floors a few years ago where they spanned approx 6m in one go but they were definately much wider joists.
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sc0ott
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Registered: 16th Feb 09
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Where they near enough span the entire length they are 89 and 38 for the shorter length ones.
Kertos are actually 133x300 and are 120kg. Beasts.
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Gary
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Registered: 22nd Nov 06
Location: West Yorkshire
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That sounds expensive! Why not just run a steel rsj and use normal beams?
I can pass the number of the engineers we used on, they can do you a full design etc. Not cheap though, they charged us 200wuid for a quick survey!
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Dave
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Registered: 26th Feb 01
Location: Lancs
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I'd imagine the TJI/FJI joists are cheaper than timber, we use them in pretty much every housing job now so there must be a certain amount if cost saving. Also they work out what size you need as part of the package, saving on separate structural engineers/architect fees.
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sc0ott
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Registered: 16th Feb 09
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The stairwell takes up near enough the whole gable on one side so we cant run anything over than.
Drainage and pipe runs would be a problem, We would need to redesign the layouts.
We have various engineers we use on different projects so their approval is free.
[Edited on 28-09-2011 by sc0ott]
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Stu_22
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Registered: 25th Mar 02
Location: Luton
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This thread seems to be getting a bit technical.
its just to hold a pitched roof up and storage above in the loft space but car stuff can be heavy with engine stuff.
Yes was thinking of having a steel beam running through the centre joining to another steel beam on the top of the front and back walls and having one in each corner bolted to the concrete floor
Was thinking box steel as I could weld joining plates on them to keep cost down just needed to know what size I should be looking at
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AndyKent
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Registered: 3rd Sep 05
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Are you putting this building through building control, because you should be.
I suspect welding up your own beam is unlikely to be acceptable.
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Gary
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Registered: 22nd Nov 06
Location: West Yorkshire
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Defiantly would need to be coded if owts getting welded.
Why not just not put heavy stuff up there? Would make it all a he'll of a lot easier!
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Dave
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Registered: 26th Feb 01
Location: Lancs
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Roof trusses would be the perfect solution then. They'd span the 7m with ease and you form the roof and ceiling in one hit. You can also store a fair bit in the roof space, especially if you specify that when you are having them drawn up. Most of the large builders merchants supply roof trusses now, they just act as agents to the manufacturers.
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sc0ott
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Registered: 16th Feb 09
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you will need planning permission before you go for a building warrant.
where is this going to be located?
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3CorsaMeal
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Registered: 11th Apr 02
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Roof truss or cut the span in two with a steel UB.
you require building regs for a garage of that size and will need structural calcs done.
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Stu_22
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Registered: 25th Mar 02
Location: Luton
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Yeah i realise i need planning permission as it going on my front garden. So part of the planning permission forms are what it goong to be built of and just want to see if i can build it this big first
There is so much differing info out there. I though i would avoid building inspectors as one site i read said they only inspect 15+ square meters
If i get the steel wour done by a proper company will it still need inspecting
Looks like trusses are the way foward
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