MikeGrahamT21 Posted November 1, 2017 Share Posted November 1, 2017 Hi, Quick question. If you were putting up vertical structural timber (C24 grade), which interfaced with steel (lintel) and concrete, would you: Have the timber in direct contact with the steel and concrete Leave a 10mm gap on either end and point up with sand/cement to allow to movement/expansion etc? Regards Mike Link to comment Share on other sites More sharing options...
Ian Posted November 1, 2017 Share Posted November 1, 2017 @MikeGrahamT21 I'd leave a gap to allow the two differing materials to move separately and if you need a filler it should be something flexible rather than sand/cement Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted November 1, 2017 Author Share Posted November 1, 2017 OK, what filler would you suggest? Thought sand/cement in 4:1 would have offered enough movement capabilities. The ends of the timber need to be in contact somehow to transfer the load. Cheers Link to comment Share on other sites More sharing options...
Ian Posted November 1, 2017 Share Posted November 1, 2017 2 minutes ago, MikeGrahamT21 said: OK, what filler would you suggest? Thought sand/cement in 4:1 would have offered enough movement capabilities. The ends of the timber need to be in contact somehow to transfer the load. Cheers Are the timbers supporting the steel lintel? Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted November 1, 2017 Author Share Posted November 1, 2017 Yeah Link to comment Share on other sites More sharing options...
Ian Posted November 1, 2017 Share Posted November 1, 2017 @MikeGrahamT21 So is it this kind of relationship between the frame and lintel where you have an outer leaf of brickwork: Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted November 1, 2017 Author Share Posted November 1, 2017 Yeah, but steel on the inside rather than timber for the actual lintel Link to comment Share on other sites More sharing options...
Ian Posted November 1, 2017 Share Posted November 1, 2017 4 minutes ago, MikeGrahamT21 said: Yeah, but steel on the inside rather than timber for the actual lintel What does it say in your structural engineers specification? Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted November 1, 2017 Author Share Posted November 1, 2017 Let me fill in the gaps... This is for an extension which is already built, cavity wall construction using masonry blocks (2.9N), wanting to give an extra 50mm load bearing for the lintel to sit on either side, and also line the reveals at the same time, so going to use 6x2 timber, C24. Link to comment Share on other sites More sharing options...
Ian Posted November 1, 2017 Share Posted November 1, 2017 (edited) ahh I see. It's not a detail I've seen before and I don't have the necessary expertise to say whether it would give you the extra bearing support that you need. From what you are saying the lintel would partly supported off masonry and partly off your new 6x2 timbers. I'd have thought there would be problem with the two materials moving differently and you could potentially end up with one or the other taking the full weight of the lintel rather than dividing the load between them. Is there any way you could fix a steel bracket to the masonry reveal to give you the extra 2" bearing support? Edited November 1, 2017 by Ian Link to comment Share on other sites More sharing options...
Mr Punter Posted November 1, 2017 Share Posted November 1, 2017 You could use timber to support the steel but I doubt you could justify combining timber and masonry, as even if the timber shrinks by 1mm, the masonry will be carrying all the load. Link to comment Share on other sites More sharing options...
Ian Posted November 1, 2017 Share Posted November 1, 2017 35 minutes ago, MikeGrahamT21 said: This is for an extension which is already built, cavity wall construction using masonry blocks (2.9N), wanting to give an extra 50mm load bearing for the lintel to sit on either side Are your lintels supported off a padstone built into the wall or straight off the 2.9n blocks? Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted November 1, 2017 Author Share Posted November 1, 2017 Straight off of the blocks (well sat on sand/cement), its only a tiny single story extension to be fair. Yeah not thought about shrinkage of the wood, very good point! Extension has been up for 2years without any issues, but I do worry about snow, which we haven't really had. Link to comment Share on other sites More sharing options...
Ian Posted November 1, 2017 Share Posted November 1, 2017 10 minutes ago, MikeGrahamT21 said: Straight off of the blocks (well sat on sand/cement), its only a tiny single story extension to be fair. Yeah not thought about shrinkage of the wood, very good point! Extension has been up for 2years without any issues, but I do worry about snow, which we haven't really had. If it's only single storey then the load on your lintel is tiny. What bearing width do you have for the lintel at the moment? Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted November 1, 2017 Author Share Posted November 1, 2017 200mm each side, so more than the 150mm suggested. It was more of a what if something isn't right (since i built it myself), I don't think theres anything wrong, but my wife is seriously ill at the moment, and I cant be doing with any hassle if you get my meaning. Link to comment Share on other sites More sharing options...
Ian Posted November 1, 2017 Share Posted November 1, 2017 2 minutes ago, MikeGrahamT21 said: 200mm each side, so more than the 150mm suggested. It was more of a what if something isn't right (since i built it myself), I don't think theres anything wrong, but my wife is seriously ill at the moment, and I cant be doing with any hassle if you get my meaning. I don't think you've got anything to worry about as nothing is going to collapse even if you get a meter of snow. The risk with lightly loaded roofs is usually to do with wind uplift - the timber wallplate for the roof should be strapped down using this type of restraint strap: Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted November 1, 2017 Author Share Posted November 1, 2017 Yeah i've done all the straps and bracing as per requirements, BCO have signed this stage off already. Link to comment Share on other sites More sharing options...
Ian Posted November 1, 2017 Share Posted November 1, 2017 @MikeGrahamT21 It sounds like you've done everything properly and there's nothing to worry about. Certainly if you've already got 200mm bearing on each side there's absolutely nothing to be gained by trying to increase it. Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted November 1, 2017 Author Share Posted November 1, 2017 Cool, many thanks for your input on this one. Regards Mike Link to comment Share on other sites More sharing options...
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