DPC question - garage conversion

[JonHeath]

Hi all,

I’ve started doing my garage conversion. The garage is 2 skins thick but there’s no cavity (solid wall).

I’m wanting to brick up the bottom of the original garage door opening. It’ll be matching bricks on the outer skin and block work on the inner skin. I’ve installed 2 lintels side by side to take this brick/block work which has been signed off by building control. They’ll be no cavity. The insulation will be on the inside.

They’ll be 2 rows of engineering bricks on the outer skin before the normal bricks start. As I’m doing blockwork on the inside, the heights will be different unless I cut the blocks down. My question is should the DPC go across both skins but go up vertically to the block height and then across the top of it? Sorry probably a basic question!

Thanks, Jon.

 

[noseall]

Hi all,

I’ve started doing my garage conversion. The garage is 2 skins thick but there’s no cavity (solid wall).

I’m wanting to brick up the bottom of the original garage door opening. It’ll be matching bricks on the outer skin and block work on the inner skin. I’ve installed 2 lintels side by side to take this brick/block work which has been signed off by building control. They’ll be no cavity. The insulation will be on the inside.

They’ll be 2 rows of engineering bricks on the outer skin before the normal bricks start. As I’m doing blockwork on the inside, the heights will be different unless I cut the blocks down. My question is should the DPC go across both skins but go up vertically to the block height and then across the top of it? Sorry probably a basic question!

Thanks, Jon.

If it's a solid (twin skin) 225mm wall, then the chances are the inner and outer masonry will be in contact in any case. Covering both skins with the DPM will be fine.

 

[JonHeath]

Thanks for that. Is the DPC ok to go up the middle vertically between brick and block to reach the block height, or would you normally trim the block so they’re the same height?

Also presumably I should still use ties every so often even though the skins will be touching? How often should I use them? Thanks.

 

[Charlie George]

You will need the 2 skins level to put tie wires in,but you can lap the dpc up and onto the blockwork, ties should go every 2 course of block.

 

[^woody^]

Normally the DPC would be level across the two leafs, so if you have two course of engineers to DPC on the external, there would be two on the inside - or whatever it takes to get up to the same height.

Your floor DPM would then lap on top of this course on the inner leaf.

A vertical DPM should be on the inner face, not in the middle of the wall.

You will need think about how the wall DPM seals with the floor DPM, to prevent any moisture that may run down the wall from going over the top of the the floor DPM.

 

[JonHeath]

Normally the DPC would be level across the two leafs, so if you have two course of engineers to DPC on the external, there would be two on the inside - or whatever it takes to get up to the same height.

Your floor DPM would then lap on top of this course on the inner leaf.

A vertical DPM should be on the inner face, not in the middle of the wall.

You will need think about how the wall DPM seals with the floor DPM, to prevent any moisture that may run down the wall from going over the top of the the floor DPM.

Sorry I just meant I'd raise the level of the DPC vertically between the inner and outer skins. A bit like this picture (for illustration only).

I can cut the concrete block down though to be the same height. I was just trying to avoid having to cut the blocks. I have the 7.3N blocks for below DPC level and the lighter 3.6N blocks for above.

You're right about having to think about how the DPM from the floor seals into the wall. I'll be doing a floating floor.