Hi I'm putting a new floor level in an old concrete block building. I am intending to hilti bolt a 3 x 6 wooden beam on opposing walls then using joist hangers on them joisting across ( 14ft 1in span, 18inch spacing ) with 6x2 joists. Any suggestions on dimensions and spacing of the hilti bolts, also am going to double up joists where bath & water cylinder etc will be; is it normal to have double width hangers for this or just bolt together timbers? I'm stuck with max 6in depth of joists as stuck for internal room height.
With no disrespect intended, your reply worries me slightly as you seem to be doing some serious structural stuff without the support of a good set of plans. No rudeness intended - uk.d-i-y is here to help. But that help might translate into "get a professional to advise"...
Anyway - 1st question: You presumably are/have to involve the building control dept or whatever you call it? Will what you do be assessed by a building inspector, prefereably before you start and at the end? Over here (England) if it gets passed by the BCO you can usually be fairly sure it isn't going to break.
2nd question: Just to be clear: 14' 1" (4.3m) clear span - and spacing of 18" (450mm). My dormer conversion is 3.4m span and I have 8x2" joists at an average of 450mm. That's why I mentioned 6x3's.
I'm not the person to say if this is good or not, but hopefully, someone else can. Have you looked into Superbeam software (the author is on here frequently) - that can help a lot with loading and bending calculations.
Regarding the bath and tank - I would expect a correctly designed floor to cope, but you could always space those joists closer without going for a full doubling up.
Have you got any other issues to consider, like resisting the spread of fire between the floors?
One did - he said 200mm in from the and every 450mm (or joist spacing). I think he also said "use resin bolts" which is what I would do too, especially for something like this.
in case it wasn't clear the end bolts 200mm in ... not too close to end to avoid splitting, and then one between each joist span.
Resin studs will put a lot less strain on 'unknown' quality old blockwork. You could find expanding sleeeve anchors shatter the blocks ... or spall off big chunks. Resin will give a very strong fixing and no risk of damage to the blocks.
I recently put in 64 16mm diam anchors this way into a reinforced raft, resin fix is a very good solution.
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