Joining floor Joists

Yak_Chat · Mar 15, 2008 9:52 am

Í need to join onto some existing floor joists to extend them another 1100mm to make a small landing.

Currently there are 3 stairs pointing west, that go down to the lower level.

I want to go out 1100mm to make a landing (1100 x 1900) turn the stairs to the right (north) which will go down from the edge of the landing.

So basically it is extending the upper level floor in the same direction as the existing joists.

I have a brick wall to sit the joists on beside the existing joists and it's all pretty accessible.

Question is, what's the proper way of joining the new joists to the existing joists.

How much overlap is required etc.
Size of timbers required to span the 1100mm.
What size bearer is required for the 1900mm front edge?

Do i use coach screws, or 2 x bolts right through?

How much overlap is required to get stability.
I'll be building in underneath the landing for storage and also a section for a small TV, steroe etc, so some cross bracing and framing can be done to strenghten it if needed.

Tips please.

Steve

Dukekamaya · Mar 15, 2008 7:02 pm

Its easier if the new joists sit on or attach to a wall ledger in the same size - do the new joists sit on the bricks? If so you can just join them with a nail plate if you like, otherwise 450mm is plenty to overlap and join, just bugle screw them.
90x45 will single span 1100mm no worries.
I can size the bearer for you, what type of timber do you wish to use ( hardwood or softwood) and is size important or not ( as in height restrictions)

Yak_Chat · Mar 15, 2008 9:55 pm

Thanks Duke,

Existing joists are hardwood, hence thinking of screwing versus nailing.

Bugle screw - new name to me - but after looking it up - yep know what they are. Will have to pre-drill to get them into the hardwood, but that'll be fine.

The joists are sitting on top of a 20mm x 70mm strip of hardwood which rests on top of the brick foundations/sub wall which has the galv moisture barrier plate.

re the bearer, I can either support it midpoint, (around the 1030mm due to a bearer and foundation located on the 2nd level at that point) easy to do and will not change the plans in anyway, or I can go the full span.

Prefer to use recycled timber, so suggested sizes of oregon, (I have a bit of that around the place) or suggested soft woods such as pine etc.

No height or size restrictions.
It's a landing with a few shelves etc under it, so if the opening is cut back a bit by the bearer, no issues.

Cheers
Steve

Dukekamaya · Mar 16, 2008 2:46 pm

Yak_Chat

Prefer to use recycled timber, so suggested sizes of oregon, (I have a bit of that around the place) or suggested soft woods such as pine etc.

Oregon is a softwood (and is a type of pine) :wink:

If you had a bit of 200x50 oregon it would be fine. What sizes do you have?

Yak_Chat · Mar 17, 2008 9:20 pm

Most of it is wall framing and not of that size, so recommend a some structural pine and I'll do it with that.

The exisiting hardwood joists are 90x45, so pine joists and a bearer to suit will do.
Steve

Dukekamaya · Mar 17, 2008 9:35 pm

Joists to be 90x45 MGP10 pine (F5 will also span)
Softwood bearers are always listed as 2 pieces 'laminated' together in tables - the idea is that the two different grain structures make the overall strength much greater than a single piece. The reality is very few people bother to use/make them and simply use a larger single piece of timber.
The span program rates 2/90x35 MGP10 pine at 78% loading. If you were to get a piece of 190x45 pine it would be more than fine. Otherwise you could buy a length of laminated 90x70 GL8 pine, or, glue and nail 2 bits together yourself.

Yak_Chat · Mar 17, 2008 11:23 pm

Thanks Luke,
The only other bit of oregon I have that could suit is 290 x 70, so a tad big for the landing bearer.
Will keep it for another project.
Cheers
Steve

Dukekamaya · Mar 18, 2008 5:39 pm

It would certainly do the job

Yak_Chat · Mar 18, 2008 8:34 pm

Quote:

It would certainly do the job

Ya reckon ? :wink:

I think I might have to upgrade the corner posts first to hold the mother of a beam up :shock:

Thanks for the help Luke, I'm currently working out my cut list to buy at the the local timber merchants tomorrow for my easter projects buy up

Steve

Dukekamaya · Mar 18, 2008 10:50 pm

NO worries Steve. Are you going to sit the joists on top of the bearer or butt them in with joist hangers? (either way is fine)

Yak_Chat · Mar 18, 2008 10:56 pm

Planning on joist hangers to make it cleaner from the front of the landing and also for putting cupboards underneath.
Steve