140x45 doubled up Bearers, nailing pattern

kenw1, Feb 15, 3:50pm
2 140x45 side by side, how far apart do they need to be nailed?

250mm or 9 x the thickness is what I have used before and doing it in a zig zag top and bottom of bearer pattern, on one side only, someone is telling me this is not enough and they need to have more nails and the pattern needs to be on both sides, using 90mm nails.

Cannot find it in 3604.

Any comments, thanks

skin1235, Feb 15, 4:02pm
does 3604 actually have such info?
I've often done as you have ( similar pattern )
have also sandwiched a tin plate between them, paslode 4's ( 90mm ), way stronger but does cost a bit more, single strip of flashing material 140mm wide
the principal of leverage is where the strength lays, a row along each edge 25mm in 150 apart is surprisingly strong
but as query'd, does 3604 actually address such?

kenw1, Feb 15, 4:07pm
These have also been glued together, reckon it would take a good go to give them any problem, but just trying to be extra sure.

skin1235, Feb 15, 4:16pm
in a dwelling you'd have to be sure they're acceptable,( ie 3604) sheds etc are a lot more forgiving

skin1235, Feb 15, 4:16pm
not a fan of gluing, have never found a decent glue that will still have grip in 10 yrs time

kenw1, Feb 15, 4:59pm
This is an Olde bungalow, 70 years or so. The floor is like a sprung dance floor, anyone remember those.

While we are in there repiling, we are straightening out the bearers.

When the house was extended, they put the extension bearers in all at odd spacing from the front of the house so, SFA lines up.

Anyway might just turn them over and stick a few more nails in for a quiet life :-).

The existing bearers are being left in anyway so these are really just extra's.

Such fun.

kenw1, Feb 15, 5:01pm
If you want a glue to really depend on, use Cascamite, its there forever and a day.

mm12345, Feb 15, 7:54pm
We used 12mm cup head galv bolts at 450 centres, 110 long, 50mm square washers on nuts. That was designed by engineer, for double 140x45 joists.

johotech, Feb 15, 8:22pm
Seems like this thread has little to do with the building code.

kenw1, Feb 15, 8:38pm
If we had followed the design that was initially signed off as meeting the building code by the TA, the house would have disappeared under ground.

It was only our insistence of soil tests that stopped this.

So dont preach the Building Code to me.

I have been unable to find a reference to this is 3604, which why I asked.

budgel, Feb 15, 11:09pm
I only have a 1999 code to hand, but back then, for nail laminated bearers, table 6.8 specified 1 nail top and bottom 50mm from each end and offset lapped at 200mm centres. That applied to hand driven 100x3.5 or gun driven 90x3.15 nails.
The offset means a zig-zag pattern, so start your first nail near the lower edge 100mm from the end nails and the first one near the upper edge 200mm from the end nails, then 200mm centres.

I dont think it has changed in recent years.

kenw1, Feb 15, 11:31pm
Thanks, I have a 1999 here, my new one is in town on a job.

Just had another read at it.

6.12.3 refers you to 2.4.4.7, good init

bi says spacings of nails shall not exceed 6 times the thickness of the thinnest framing member

bii says nails shall penetrate 3/4 of the last member

and biii says for 140mm there shall be two rows of nails.

Will photocopy this page and put it onsite for safety.

Thanks for all the construction comments.

krames, Feb 16, 1:39am
if in doubt overkill it,then its done,you can carry on with the next part of the job without having a big post-mortem over it.

survivalkiwi, Jun 21, 12:46am
The answer I give to my boys when they ask me a question like that is "just riddle it with nails like its Bonnie and Clyde"