Daryl Posted August 15, 2014 Share Posted August 15, 2014 (edited) Just boarding out some of the roof in the garage, and after doing a little research, was wondering if any builders could offer their opinion on what they think the best course of action will be. My main issue are the trusses (iv just seen they should not be called joists) and that there is a join of these that is only held by some plates on the side. Just wondering if what i have/intend to do is safe generally, and if i need to put a couple of straps over these plates to beef up the trusses so i can put some stuff on them. Here is what iv done, and the lay out of the garage roof. Edited August 15, 2014 by Daryl Quote Link to comment Share on other sites More sharing options...
Flex Posted August 15, 2014 Share Posted August 15, 2014 Looks identical to mine, I've part boarded it out and have a fair bit stashed up there and hasn't fallen down yet Quote Link to comment Share on other sites More sharing options...
Ebized Posted August 15, 2014 Share Posted August 15, 2014 ATTAK Z will be along soon But I personally would not trust lying my15 stone on that chipboard given the joist butt-jointing of those trusses (deserves a Will ) Quote Link to comment Share on other sites More sharing options...
Flex Posted August 15, 2014 Share Posted August 15, 2014 ATTAK Z will be along soon But I personally would not trust lying my15 stone on that chipboard given the joist butt-jointing of those trusses (deserves a Will ) You're never 15stone Colin Quote Link to comment Share on other sites More sharing options...
Martinjj Posted August 15, 2014 Share Posted August 15, 2014 Just boarding out some of the roof in the garage, and after doing a little research, was wondering if any builders could offer their opinion on what they think the best course of action will be. My main issue are the trusses (iv just seen they should not be called joists) and that there is a join of these that is only held by some plates on the side. Just wondering if what i have/intend to do is safe generally, and if i need to put a couple of straps over these plates to beef up the trusses so i can put some stuff on them. Here is what iv done, and the lay out of the garage roof. Where those horizontal plates are joining the trusses together it would be very sensible to have the board above it 50/50, ie half the board on one truss and half on the other, joints on top of joints create a weak spot Quote Link to comment Share on other sites More sharing options...
Ebized Posted August 15, 2014 Share Posted August 15, 2014 ATTAK Z will be along soon But I personally would not trust lying my15 stone on that chipboard given the joist butt-jointing of those trusses (deserves a Will ) You're never 15stone Colin Guess Daryl, it depends how many gold bars you are stacking up there, or you could always let the Zed get wet and use a few acrow props Sorry, hit the weekend pop early Quote Link to comment Share on other sites More sharing options...
Daryl Posted August 15, 2014 Author Share Posted August 15, 2014 Dont worry Colin, my neighbour popped round at 1.20 with 2 beers in his hand! Just finishing off a bottle of fizz with the wife before some cocktails. Quote Link to comment Share on other sites More sharing options...
ioneabee Posted August 15, 2014 Share Posted August 15, 2014 I'll comment later for you - i'm having my dinner Quote Link to comment Share on other sites More sharing options...
ioneabee Posted August 15, 2014 Share Posted August 15, 2014 Fink Trusses (commonly known as gang nailed trusses - thats the metal spiked plates joining the 2 bits of timber together) are designed on the whole to carry light storage and your ceiling load ie plasterboard. As Martin ^^ said it is best to spread the weyrock chipboard across the joint (although the gang nails are very strong) You'll be fine to store stuff up there, so long as it is "light" storage ie not your weight lift kit in one spot. Also its best to try and spread the loading out and to keep the heavier stuff nearer the node points - the struts and wall plate points (better closer to the wall plate) Whatever you do - DON'T remove any of the struts and or bracing hope that helps Quote Link to comment Share on other sites More sharing options...
Commander Posted August 15, 2014 Share Posted August 15, 2014 My garage is identical to that and I've got all sorts of crap spread out up there. Seems solid enough with 100kg of me strolling around on the boards too. Quote Link to comment Share on other sites More sharing options...
ioneabee Posted August 15, 2014 Share Posted August 15, 2014 true - but thats not what they're designed for you can keep loading it up and find out what the shear and bending stresses are for real - good luck with that though Quote Link to comment Share on other sites More sharing options...
350zedd Posted August 15, 2014 Share Posted August 15, 2014 ^^^ as ioneabee says....those nail plates are damn strong and do an excellent job of holding 2 lengths of timber together. imo you should be fine as long as you spread the load out. Check with a straight edge under the bottom truss between the joint for any misalignment if you suspect overloading. Quote Link to comment Share on other sites More sharing options...
ATTAK Z Posted August 15, 2014 Share Posted August 15, 2014 Here I am ... nearly ready to comment ! Just come back from having a nice Indian in Bawtry Quote Link to comment Share on other sites More sharing options...
ATTAK Z Posted August 15, 2014 Share Posted August 15, 2014 Right ... Gang nail trusses are designed to take compressive and tensile loads in the members. The strength of the joints (gang nail plates) is determined by trial and error rather than calculation, thus it's a bit of a black art. Bending stresses in individual members are induced by UDLs (uniformly distributed loads) which can be dead or live. The UDL in the top chord of the truss is composed of the dead weight of the roof tiles, battens etc. and the live load of snow and wind. The bottom chord of the truss is designed to take the dead load of ceiling finishes, mechanical/electrical services etc. and the live load of access for maintenance and repair. The raking members of the truss are simply in compression or tension with no induced bending stresses. What you are proposing will induce increased bending stress in the bottom chord of the truss whilst increasing the overall loading on the system and increase the tensile and compressive loads in all the members. This could be a bad thing as sooner or later you will overload the system. However, factors of safety are built in, 1.4 for dead loads and 1.6 for live loads IIRC, so providing you don't increase the load too much you should be OK HTH 2 Quote Link to comment Share on other sites More sharing options...
ioneabee Posted August 15, 2014 Share Posted August 15, 2014 yep - what I said, but I put it in English for you 2 Quote Link to comment Share on other sites More sharing options...
ATTAK Z Posted August 15, 2014 Share Posted August 15, 2014 PS the bracing that ioneabee mentions holds the masonry up rather than the roof Quote Link to comment Share on other sites More sharing options...
Daryl Posted August 16, 2014 Author Share Posted August 16, 2014 Thanks for the help and info guys. Il move that last strip of boards so it is evenly over the 2 trusses. What im thinking of doing is putting additional bracing over the nail plates and screwing them to the trusses for exfra strength. Would this be adviceable of would it weaker the trusses? Quote Link to comment Share on other sites More sharing options...
ioneabee Posted August 16, 2014 Share Posted August 16, 2014 If you want to screw extra timber over (probably not necessary) but plywood would be your best option. The longitudinal bracing (the horizontal ones) and the diagonal bracing stop the roof from racking ie domino effect - there are (should be) metal straps built into the wall and fixed over the last 3 trusses - these are the ones that stop the gable masonry falling over - all form part of the whole 1 Quote Link to comment Share on other sites More sharing options...
350zedd Posted August 16, 2014 Share Posted August 16, 2014 If I decided to fit extra bracing I would fix it using 2 x 10mm nut & bolts either side, rather than screws. I've had screws shear off. That would be my own personal preference of course! Quote Link to comment Share on other sites More sharing options...
ATTAK Z Posted August 16, 2014 Share Posted August 16, 2014 Don't try to increase the strength of the joints in the bottom chord by adding flitch plates (as you suggested you might do in post 17) Quote Link to comment Share on other sites More sharing options...
Zhorno Posted August 16, 2014 Share Posted August 16, 2014 (edited) U could put a lot of weight on that and it won't go no where , I do loft conversions for a living , trusses are very strong 👠That tonne and a half steal was sat on the ceiling , no problems 👠Edited August 16, 2014 by Zhorno Quote Link to comment Share on other sites More sharing options...
Daryl Posted August 17, 2014 Author Share Posted August 17, 2014 Blimey,thats some steel there! Though the question was more to do with the straps that are holding the two trusses together. Il have a look again tomorrow, but il move the last row of ply so it is evenly over both trusses, and just leave it as that. Im going to be boarding the inside of the ceiling also and putting some lights in there. The roof area will be storing my car mags and some other bits like wheels etc and although il occasionally be crawling around up there, im hoping it will hold. Quote Link to comment Share on other sites More sharing options...
ioneabee Posted August 17, 2014 Share Posted August 17, 2014 you won't have any problems with that Daryl Zhorno - the reason that holds (at the moment) is that the weight is unifomerly spread along all the roof and you're quite close to the support point ie the wall plate. Timber will bend a lot before breaks - so what you will be getting there is deflection, but for a short time - my suggestion to you though is DO NOT do that again - put the steel in first and then cut the struts out - alternatively get some acro struts under the ceiling below 1 Quote Link to comment Share on other sites More sharing options...
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