Extending sleeper wall to support SHS Windpost and existing suspended timber floor

[Optimal_Muffin]

Hi,

I’m in the midst of taking down an internal wall between my kitchen and dining room. The span is 3 meters and connects an external wall to an internal wall of my house. The structural engineer drawings indicate I will need the RSJ sitting on top of a square hollow section windpost at the external wall (the RSJ is also inserted into the external cavity by 100mm to sit on top of a new padstone which we’ll call Padstone A), and at the other end on the internal wall, it’s on top of a cripple stud (3 studs fixed together).
 

The SHS windpost is bolted to the inner leaf (with 6 welded on lugs), and is sitting on top of another new padstone (Padstone B) underneath the sub floor. Where Padstone B is planned to go, currently there is a sleeper wall supporting the dining room floor.

 

Couple of problems I’m seeing:

1. What’s the best method to support the two joists which are closest to the external wall (next to the SHS and Padstone B)?

• These joists will have to be cut since the SHS and Padstone B will be in the way.
  • The structural engineer suggested masonry to timber joist hangars, but these seem to need a couple of layers of breeze on top.
• Padstone B is taller than the gap between the subfloor base and the underside of the joist, so the joist can’t sit on top of the padstone.
• Can the outer most joist be screwed into the brickwork since it is against the wall?

 

2. How best to create foundations to move the sleeper wall? My thinking is concrete footing, 1 layer of brick, DPC, Padstone B.

• Our plan is to remove the existing sleeper wall and move it slightly (the removed wall didn’t sit directly over it and we need the RSJ to line up with the removed wall so that it’s flush with another wall in the room).
• Are the layers I’ve indicated OK for a stable base for the SHS?
•  How thick should the concrete footing be if we put down a new one?
• Currently there is a layer of bitumen over the top of everything I think for damp mitigation? We plan to remove that to find the concrete underneath, build on top, then we can re-seal with more bitumen.

Appreciate any help, and I can add some sketches / pictures if something isn’t clear.

 

Cheers.