Tieing block extension into house.

[2020c]

The extension will be going on the back of this house.

What i want to know, when tieing the block extension into the house, should i cut out 100mm in the blockwork to create a cavity if im to return the blocks away from the house and let the cavity continue on where ill be cutting out.

I know i could use the screw in type tie strips however if i use them, will this create a cold bridge in the corner of the new room .




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[23vc]

Ask the building inspector.
I’ve never once found one who asks for the cavity to be cut out for any extension I’ve been involved with, not saying that’s right though, I know others have different views!
Never known first hand of any damp issues caused by horizontal tracking of damp along the join either...

 

[2020c]

Ask the building inspector.
I’ve never once found one who asks for the cavity to be cut out for any extension I’ve been involved with, not saying that’s right though, I know others have different views!
Never known first hand of any damp issues caused by horizontal tracking of damp along the join either...

We dont have building inspectors here. Its not so much damp im worrying about, its a cold bridge. The outside block can carry cold over into the next room and when the heat hits it, it can create moisture(kind of damp as you say)

 

[^woody^]

You need to cut a least a vertical DPC at the line of the rear of the outer skin, and this will be the thermal break. Other wise cut out a wider slot for the cavity.

If you don't use wall starters, you risk tied in walls cracking when the extension settles or moves seasonally.

 

[johnny2007]

I never understood why they insist so much on vertical dpc.
All of us have seen older properties with returned walls, windows and doors without any dpc and no such tragic apocalyptic damp.

 

[2020c]

You need to cut a least a vertical DPC at the line of the rear of the outer skin, and this will be the thermal break. Other wise cut out a wider slot for the cavity.

If you don't use wall starters, you risk tied in walls cracking when the extension settles or moves seasonally.

Would it not be better to tie key in the blocks rather than the wall tie starters?

I was even thinking a 25mm vertical cut and inset 25mm rigid board insulation to stop the col bridge. Would a vertical dpc do instead.

 

[^woody^]

Just a thin cut with a disc saw is enough to create a thermal break. Slide some DPC in, no need to point it, wedge it or squeeze some silicone in.

As for bonding, it's a risk. Someone may be able to calculate or assess the risk, but it's there all the same.

 

[2020c]

Just a thin cut with a disc saw is enough to create a thermal break. Slide some DPC in, no need to point it, wedge it or squeeze some silicone in.

As for bonding, it's a risk. Someone may be able to calculate or assess the risk, but it's there all the same.

Good to know this. I think this would be the easiest method then use the starter ties into the block work.
In saying this,I'm near sure my stihl con saw doesn't cut the whole way through though, especially with the render on the face.

 

[23vc]

I was thinking that. Iirc those saws get nearly but not fully through a brick. Maybe that’s sufficient for this purpose

 

[JohnD]

We dont have building inspectors here

Where?

 

[2020c]

Where?

The emerald isle

 

[JohnD]

We don't know the rules in the mining towns of Columbia.

 

[2020c]

I was thinking that. Iirc those saws get nearly but not fully through a brick. Maybe that’s sufficient for this purpose

I think it would still create a bridge. This is why i was thinking of cutting out the block. Its either this or ill have to slab the inside of the walls with insulated plasterboard so i dont have any issues effecting the warm flat roof

 

[2020c]

We don't know the rules in the mining towns of Columbia.

??

 

[JohnD]

Where the emeralds come from!