Wall plate into top course of brick?

[scott08]

I'm building an l shaped loft dormer, with lowered loft floor ( 25cm) as a requirement for planning. The house steps down a little at the back, so because of this, If I attach the wall plate to the face of the brick, it will extend over the top of the brick, and any fixings will be in the top 1 or 2 courses of brick. Attached is a section (bricks not perfectly to scale). This is just on the external side - on the party wall I can resin fix a plate to the brick face no problem.

My first thought was to remove the top 3 course of internal brick, bed and strap a 100x50 wall plate on, and sit the new joists on top of this. I can also then use this as the base for the dormer wall. Does this make sense or is there a better way of doing it?

 

[scott08]

Alternatively I could just remove 2 courses of brick, and notch a quarter of the ends of the joists and sit on a wall plate, which would mean less bricks removed. Any thoughts?

 

[^woody^]

If you notch joists, you reduce their load capacity.

Face fixings may require a certain amount of masonry above the fixings, greater than what you have.

Joists don't need a plate.

Where are the rafters?

 

[scott08]

If you notch joists, you reduce their load capacity.

Face fixings may require a certain amount of masonry above the fixings, greater than what you have.

Joists don't need a plate.

Where are the rafters?

Yeah the joists don't need a plate, but i'll be building a dormer wall on top of it too.

Currently there are 100x50 rafters sitting on the wall, and 100x50 for the loft floor. Both of these will be removed, with the floor lowered 15cm, and 200x50 floor joists, then a flat roof dormer will be built up, in place of the pitched roof.

 

[^woody^]

The sole plate for the dormer goes on top of the joists. Full depth noggins in between the joists.

Line the bearing with a DPM to protect from damp if the wall is solid.

 

[scott08]

The sole plate for the dormer goes on top of the joists. Full depth noggins in between the joists.

Line the bearing with a DPM to protect from damp if the wall is solid.

Thanks @^woody^ - would I sit the floor joists directly onto the inner skin of brick then, and noggin between at this end?

So remove 2 courses of internal brick, DPC on top of brick (mortar underneath or no?), then joists and noggins directly on top, sole plate on top of joists, build wall off of this?

 

[^woody^]

Yes. But the DPC would be horizontal and vertical up the wall to provide a barrier to the timber. No mortar required.

 

[scott08]

Yes. But the DPC would be horizontal and vertical up the wall to provide a barrier to the timber. No mortar required.

Amazing, thanks!

Is it fine to put packers between the brick and joists, to get them level? The brickwork is far from perfect.

 

[^woody^]

Use slate

 

[scott08]

Just looking at the levels now more of the roof is off, and it looks like the height of joist I need is around 55mm higher than the top of the brick. It may be far simpler to just bed a sole plate on top of this, build the dormer wall off of it and hang the joists from it too. I'm not too sure however if this is the done thing, and if there's even a hanger that will be appropriate for it?

 

[scott08]

Better image:

 

[scott08]

I still can't find a joist hanger that would work with this setup so emailed Simpson, but no response yet. What I could do is use a 4x3 sole plate instead of a 4x2, which should allow for more face fixings on the hanger. Per hanger I could get 6 in on the front face, 12 on top, and 8 on the back, which I assume is more than enough fixings?

 

[^woody^]

Safety Fast Lite Hanger - Solid Joists - SFLH

The SFLH is an innovative single piece hanger designed to support timber joists from masonry walls,

www.strongtie.co.uk

 

[scott08]

Safety Fast Lite Hanger - Solid Joists - SFLH

The SFLH is an innovative single piece hanger designed to support timber joists from masonry walls,

www.strongtie.co.uk

I saw these but it says for masonry walls, and i'll have the timber sole plate on top (pink in my diagram). Can they be hooked on to timber too? If so, they're perfect

 

[^woody^]

The key thing is that they are designed for walls with no further loading on top of them to hold them down. Whilst it does state masonry walls, I can't see why they would not be useful for your situation. You could get the Simpson tech team to confirm.