Hilti bolt spacing

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.

Reply to
rog
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First question - have you asked your building inspector (BCO)?

Second question - any reason for 6x2 rather than 6x3's? Just curious...

Reply to
Tim Watts

Thanks for your reply, I'm doing this in SW Ireland where building inspectors are not as in uk, if at all !

6x3s would seem good, would I still need to double up at bath etc positions?
Reply to
rog

Ah... By SW, I assume you mean Eire?

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?

Cheers

Tim

Reply to
Tim Watts

If it were me ..

# use double hangers where double joists.

# use square twist nails to nail joists to hangers

# use Hilti resin bolts 150mm in from each end at at 450mm spacing ... i.e. between each joist.

If it is an old building consider using resin anchors must better grip especially in blocks ... in effect you resin it threaded studs.

Reply to
Rick Hughes

None of the above advisors answered your question on the hilti bolts. I'd be interested in the answer to this particular qustion.

Good luck.

Arthur

Reply to
Davao - Arthur55

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.

Reply to
Tim Watts

Thanks for the info Roger

Reply to
rog

Did you figure out your sizes and spans in the end?

Reply to
Tim Watts

That was me ....

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.

(Screwfix sell it .. easy enough to get hold of)

Reply to
Rick Hughes

Hi I've decided on doubling up into 100x150 hangers 50x150 joists bolted together. 18 inch spacing of joists, span 14ft 1in. Cheers Roger

Reply to
rog

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