Joist to wall restraints

[Russ H-R]

Hi all, I'm building a single story extension on my bungalow, which is quite big - nearly 60m2. It's going to have a warm flat roof, I'm at the stage where I'm thinking about the roof joists. In the designer notes, the joists will sit on top of the existing wall plates of the (soon to be removed) back wall of the house, and then sit on top of the inner skin of thermalite blocks of the new extension.
Why question is, because there's no wall plate, do I need to strap every joist to the wall, or will it be ok to space them at 1800mm ?
I'm going to put noggins in around the perimeter to tie it all together tightly. I want to make sure I don't have to change anything when the BCO comes again!
Thanks in advance!
Russ

 

[sparkypenguin]

Hi Russ,
Was the roof design done with the knowledge that the existing back wall would be removed?
Mark.

 

[Alastairreid]

do I need to strap every joist to the wall, or will it be ok to space them at 1800mm ?

1800mm is fine and at the corners with 1200mm twisty straps onto joists.

 

[Russ H-R]

Hi Russ,
Was the roof design done with the knowledge that the existing back wall would be removed?
Mark.

Yes, I've got steels going in. below the existing wall plate to support the roof.

 

[Russ H-R]

1800mm is fine and at the corners with 1200mm twisty straps onto joists.

Thanks! At the other end of the joists, they'll sit on top of the old wall plate, is it ok to screw them in with a couple of diagonal screws on each, or should I use a galvanised bracket of some sort?

 

[Deluks]

Nails, not screws. But using a proper joist hanger makes it a better job, (as does using a wallplate on the inner skin of block work)

 

[Scally-Ho]

With the weight of the roof on the joists, there won't be any unexpected movement so spike both sides of each joist with annular nails into the plate below and all should be fine.

 

[Deluks]

With the weight of the roof on the joists, there won't be any unexpected movement so spike both sides of each joist with annular nails into the plate below and all should be fine.

NOBODY expects unexpected movement!
It's chief weapon is suprise, suprise and fear!