cavity wall bridge

[bluebaron]

Morning All,

What is the preferred method of joining walls at the corner of a house. I will be attaching an internal timber frame with external blockwork (rendered).

Do I:

A/ remove a 50mm run of external existing cavity wall to blend with new cavity.
or
B/ just cut a run with an angle grinder right through and slip in a DPC?
or
c/ do nothing and leave the bridge


Ive attached a quick sketch below to illustrate.

Thanks.

 

[^woody^]

B

 

[bluebaron]

Thanks Woody any advance on B?

 

[^woody^]

Cut out a slot in line with the back edge of the new external wall. Wedge a strip of DPC in, no need to point it up, just a bit of silicone or tube adhesive to hold it in place. That's the minimum, and will be fine.

A better job though (D) would be to cut a slot as above, but then block bond the new internal wall to the existing, and that will allow you to remove the nib as per (A), and you can also run your insulation through.

 

[bluebaron]

Thanks Woody but how do I block bond the internal wall to a timber frame?

 

[^woody^]

Thanks Woody but how do I block bond the internal wall to a timber frame?

LOL, sorry I did not process that bit.

Go with plan B.

How are you dealing with the vertical joint in the plaster where the frame meets the house? You probably need to plaster board across the joint somehow

 

[bluebaron]

Ok I'll go with B was concerned that spliting the wall in two might destabilise it but it been there for 100 years already.

Im putting insulated plasterboard right across the join so should be ok on that front.

 

[bluebaron]

I'm at this stage in my building now but with a slight change in that my wall is not cavity but solid.

The timber frame butts onto it with a vertical DPM. if I tie the block work skin on with a wall starter kit then how do I stop damp travelling across the solid wall? Also need to prevent a cold bridge.

I can't cut the entire wall through to break the bridge as that will effect the Structual strength.

Thanks

 

[^woody^]

If the wall is solid, then you are in exactly the same position that you have always been in regarding potential damp getting to the inside, and so you don't need to take any extra precautions other than protecting the timber frame.

Aren't you working to detailed plans, btw?

 

[bluebaron]

Thanks woody,

Unfortunately I don't have any plans just working things out as I go along. That's the main reason I went timber frame, hopeing that I wouldn't have much to work out. Didn't quite work out that way!

 

[^woody^]

Ok. It's just a vertical DPC then between the frame and the wall.

Don't forget that you need to vent/drain the cavity. This will be by leaving a perpend joint in the brickwork open every four or maximum five bricks at DPC level and above openings.

 

[bluebaron]

Thanks woody I'll mention it to the brickie. We are blocking the front up and batten then cement weatherboarding.