joist hangers

[gnasher17]

Hi

I am putting a new 1st floor in (4.3m span) and will be fixing 225 mm x 50 mm wall plates to the block wall with rawl bolts. I will then hang the joists (225 mm x 50 mm) from these with timber to timber joist hangers.

My question is, do the joists have to be perfectly in line with the wall plates or can they hang below slightly. Also what nails are recommended for fixing these and do you have to nail to the top of the wall plate as well as the face of it.

Any help will be a big help !!

 

[chirpychippy]

Firstly, thats a hell of a span for 9x2, is this the length of the room, can you not span the width if this is shorter. The thing that concerns me is the bounce you will get for spanning 4.3mtrs it will be impossible to stop the joits flexing even with two sets of noggins if there isn't and intermediary support, i.e a wall.

You really want the bottom of the joists to be in line with the bottom of the plate, if you were to put the joists in lower than you would create an issue with flooring on the 1st floor wherebye, say you were to drop the joists by 50mm under the plate then you would have a 50mm shortfall from the top of the joists to the top of the plates and this would create a problem for flooring the joists. Why do you want to drop the joists below the plate?

If you are going to use 9x2 to span this distance then I would mark out the plate at the centres you want your joists at, say 300c/c and fix the hangers to the plates wrapping the hanger legs over and behind the plate, nail every other hole with square twists nails before fixing the plate to the wall. Then slot your joists in accordingly

 

[noseall]

9"x 2"s are spot on for a 4.3m span. in fact at 400mm c/c they are slightly oversize.

 

[gnasher17]

Thanks for that.. they will be at 400 c/c by the way.