Advice required on new subfloor install pls

[Ady88]

Hi!

I have been reading through lots of posts on this forum and I think I have most of the information I need so I'm looking for clarification or confirmation on details pls

I have removed the old subfloor in my property which was poorly installed on joust hangers embedded into the masonry.

I am installing a new wood subfloor at a new height and wanted advice on details before I speak to Building Control.

I intend to install the new floor joists onto timber wall plates which will be bolted to the wall. Now one side the wall is a party cavity wall with brick and the other side is a brick partition wall, single brick thick.

1- Am I correct in understanding that the wall plate is to be bolted to the brick with M12 resin bolts or rawplugs?
2- Are the intervals for the bolts specified by building control?
3- where the wall plate is bolted to the partition brick wall, there is a concrete door lintel and I want it to run across the lintel ,would it be OK if a bolt was to go through the lintel or must this be avoided ?
4- Final question, must I ensure the bolts go through the brick and not the mortar and check this by removing the plaster?

Any advice is much appreciated!!

Ady

 

[noseall]

1- Am I correct in understanding that the wall plate is to be bolted to the brick with M12 resin bolts or rawplugs?

Use sleeve anchors or similar - basically bolts, yes.

2- Are the intervals for the bolts specified by building control?

No, just approved by BC. A typical specification would be "M12 bolts at 600mm c/c staggered....etc".

3- where the wall plate is bolted to the partition brick wall, there is a concrete door lintel and I want it to run across the lintel ,would it be OK if a bolt was to go through the lintel or must this be avoided ?

Expanding bolts will not be good for a concrete lintel. Besides, you would likely strike the reinforcing bar whilst heading for the centre of the lintel. Odd place for a lintel? Why is there no masonry above the lintel? Why is the lintel at floor level?

4- Final question, must I ensure the bolts go through the brick and not the mortar and check this by removing the plaster?

Ideally, yes. You want to be aiming for the centre of the brick. However, if the mortar is strong and full then it will be equally as good. Edges of bricks/blocks is what you want to avoid.

 

[^woody^]

Hangers are a much better way of reducing sound transmission through party walls

 

[Ady88]

Thans for getting back to me, I will attach some photos when I go back on site today to show you what I mean. I'm looking to install the new subfloor to give a downstairs ceiling height of 2.1.. That's why the wall plate would line up with the lintel above the door.

What happens if there is only one course of brick above the brick which the bolt is driven into ? Does that matter?

I'm not worried about sound transmission woody, more concerned about having the floor level and secure that's why I want to use wall plates. The old hangers were slid into a gap where mortar was excavated but were loose and just slid out with the joist!

 

[Ady88]

Hey noseall and woody,

I have attached two sets of photos.
First set are the single leaf brick partition wall and it has a wooden lintel not concrete as I thought. So I can either attach a wall plate to the bricks just above the lintel or I can sit then onto the bricks and directly above the lintel.

The other set is where I want to attach the wall plate to the party wall.. Showing the height reduction from the original ceiling joists and the joist hanger of previous sub floor.

What do you think?