Fixing Joists

[Toppers]

We have a kitchen extension where the brickie has built the outer floor joists into the brickwork, the other ends of the joists will be fixed to the existing building, which fixing method is best:

 

1. Cut pockets into masonry and sit on DPC
2. Fix joist hangers directly to the face of the existing blockwork
3. Fix joist hangers directly to the face of the existing blockwork but cut in with grinder to allow lateral restaint
4. Fix a timber wall plate and sit joists on this

[PeterW]

4.... and use resin bolts or anchors to fix the plate. Then use timber joist hangers

[Toppers]

2 hours ago, PeterW said:

4.... and use resin bolts or anchors to fix the plate. Then use timber joist hangers

 

Thanks I've been using 150mm anchor fixings for other timbers which are a great product, probably do the same for this.

[Toppers]

Sorry another question - the brickie has built some of the joist hangers into the walls which is fine but there is a run of approx 4m where the bi-fold doors are where he obviously couldn't, would I need to fit a timber wall plate along that section or just sit the hangers on top of the blockwork?

[Temp]

Not sure I follow. Are these floor joists below a bifold door? or ceiling joists above a bifold door? I'm guessing its the former?

 

As I recall there should be a minimum number of brick/block courses above a joist hanger so no you can't just rest them on top of the blocks.

Edited June 10, 2019 by Temp

[Toppers]

1 minute ago, Temp said:

Not sure I follow. Are these floor joists below a bifold door? or ceiling joists above a bifold door? I'm guessing its the former?

 

As I recall there should be a minimum number of brick/block courses above a joist hanger so no you can't just rest them on top of the blocks.

 

Sorry joists below a bi-fold, I'm guessing I'll have to put a timber wall plate there then.

[Temp]

If you don't like the ideal of a timber wall plate, could you build a dwarf wall inside and put dpc on top to protect the joist ends?

[Toppers]

3 hours ago, Temp said:

If you don't like the ideal of a timber wall plate, could you build a dwarf wall inside and put dpc on top to protect the joist ends?

 

I think I'll stick with the timber wall plate as it would mean bringing the brickie back to build the dwarf wall where I can do the wall plate myself with anker fixings.

[Temp]

Ok. If it's going to be fixed to the wall below DPC I would put DPC or DPM between it and the wall.

[PeterW]

2 hours ago, Toppers said:

 

I think I'll stick with the timber wall plate as it would mean bringing the brickie back to build the dwarf wall where I can do the wall plate myself with anker fixings.

 This doesn’t sound safe - you’re saying you want to wall plate a 4m length and it’s effectively the top (potentially of 2) course of blocks ..?? The top course will move and try and rotate as there is nothing on the the top of them to stop them moving. 

 

How deep are your floor joists..??

 

I would  just knock a block out, build up if you need with a timber wallplate and then sit the joists on top - make sure there is a decent DPM along the ends and into the cavity. 

[Toppers]

12 hours ago, PeterW said:

 This doesn’t sound safe - you’re saying you want to wall plate a 4m length and it’s effectively the top (potentially of 2) course of blocks ..?? The top course will move and try and rotate as there is nothing on the the top of them to stop them moving. 

 

How deep are your floor joists..??

 

I would  just knock a block out, build up if you need with a timber wallplate and then sit the joists on top - make sure there is a decent DPM along the ends and into the cavity. 

 

Floor joists are 150 x 50mm.

[PeterW]

 

4 hours ago, Toppers said:

 

Floor joists are 150 x 50mm.

 

What is the span ..?  Less than 3m..?

[Toppers]

9 minutes ago, PeterW said:

 

 

What is the span ..?  Less than 3m..?

 

3.2m

[PeterW]

Unless you’re at less than 400mm centres then that is absolute borderline to meeting regs. Who’s designed / signed off ..?

[Toppers]

11 minutes ago, PeterW said:

Unless you’re at less than 400mm centres then that is absolute borderline to meeting regs. Who’s designed / signed off ..?

 

I was going to go 400mm centres as they are not in yet.

[PeterW]

This will need to be a very lightly loaded floor as it’s borderline for 150 joists.  

[Toppers]

Another alternative would be to span the joists the other way (approx 5.6m) and put a sleeper wall in the centre, do you think that would be a better option?

[PeterW]

I would always go the shortest way possible but I would just up the size on those joists by one to 170x45 to make it stiffer