Wall plate size?

[GaryinAshby]

Hi, I am building a single story side & rear extension on my house. This will have a flat roof. What size should the wall plates be? I was going to use 4" x 2", but I have been told by a friend (who is a builder) that I should be using 4" x 3". Any comments?

Thanks

 

[softlad1971]

4 x 3 is the norm as it is the same size as a brick and motar bed.

 

[^woody^]

If you have a flat roof, then there is no need for a wall plate.

I don't know what your builder friend was thinking

 

[GaryinAshby]

Thanks. Cavities are closed with 9mm Master-board (B.I request), so I can just drop the joists (9" x 2") straight ontop of the closed cavities?

Thanks for all the advice, brilliant web site.

 

[^woody^]

Thats odd advice from the BCO, as the wall insulation should be continuous with the roof insulation.

The joists can then run across the wall to fix the fascia to

Or the wall built up to the underside of the roof deck