Boundary wall

[dapperman]

I have a boundary wall that I will be building up against and was wondering if damp could get up this wall and effect my cavity wall, a diagram below shows the possible action:

Thanks

 

[blup]

Yes that would be a classic example of the dpc being bridged.

Blup

 

[dapperman]

Yes that would be a classic example of the dpc being bridged.

Blup

Where would the damp go? can it then cross the cavity?

Thanks

 

[noseall]

Where would the damp go? can it then cross the cavity?

Thanks

That depends on the quality of your build. If it's anything like how they used to build in the '70s or '80s...

Snot

• noseall
• 19 Mar 2021

 

[Charlie George]

Put a DPC membrane against the existing wall, you can stick it with bitumen paint, you may get away with just using bitumen, you should also put a flashing at the top of the existing wall to prevent water running down wall.

 

[blup]

Where would the damp go? can it then cross the cavity?

Thanks

Walls need to breathe so building against a source of damp increases the likelihood of bridging if the risks are already present (poor construction, failed ties etc).

Blup

 

[Charlie George]

You could also build this section of wall in engineering brick

 

[^woody^]

You'll need a tray

 

[Dereekoo]

You'll need a tray

To put his tea and sandwiches on?

 

[dapperman]

You could also build this section of wall in engineering brick

Bang on what I was thinking Charlie. The wall is actually made of breeze block built in 1999-2000. On there is also two courses of them butterfly decorative blocks, finished with concrete capping at the top. I would suppose that it would be better to take the butterfly blocks and put normal bricks or leave it at the height it is after I take them off, got to be careful though as it is a party wall.

Thanks

 

[dapperman]

Walls need to breathe so building against a source of damp increases the likelihood of bridging if the risks are already present (poor construction, failed ties etc).

Blup

so putting a dpm membrane up between the wall will stop damp rising and contaminating my outer leaf

 

[^woody^]

To put his tea and sandwiches on?

I doubt he's posh enough for that.

 

[dapperman]

I doubt he's posh enough for that.

I’ll have you know I have many trays in my house.

 

[John D v2.0]

got to be careful though as it is a party wall

If it's a party wall why not serve notice and build it up, rather than ending up with a weird situation?

 

[dapperman]

If it's a party wall why not serve notice and build it up, rather than ending up with a weird situation?

serve notice to neighbour?