Dpc question

markus2025 · 2026-01-16T21:24:13+0000

Hi guys so i have a question to ask i am doing a refurb of this old house im been fitting a dpc on the inner skin 1 brick up from the floor level im looking to tape dpm to the bit of dpc that sticks out the wall would this make a decent job or not ?

ree · 2026-01-16T22:04:10+0000

OP,
Is the floor solid or suspended?
Why not post a pic? Are there any damp signs at low level on the wall(s)?

markus2025 · 2026-01-16T22:07:18+0000

A pic of what im doing dpc 1 brick up looking to seal dpm to the bit of dpc sticking out

markus2025 · 2026-01-16T22:08:07+0000

Image

ree · 2026-01-16T22:25:46+0000

OP,
Thanks for the pics but they are difficult to understand with the dark shadows & the tilted pics - perhaps you can correct the pics & bring some light in?

Deluks · 2026-01-16T22:55:28+0000

markus2025 said:
Hi guys so i have a question to ask i am doing a refurb of this old house im been fitting a dpc on the inner skin 1 brick up from the floor level im looking to tape dpm to the bit of dpc that sticks out the wall would this make a decent job or not ?

Short answer, yes.
You could also cut a wide strip of dpm and Leave it hanging out, until such time you put the main dpm in and tape them together.

Other option is to black jack the wall just below the dpc and stick the dpm against it.

markus2025 · 2026-01-16T23:22:06+0000

Yeah ita annoying on here that images go on the side view for some reason

markus2025 · 2026-01-16T23:23:19+0000

You can see on the this image i have fitted the DPC 1 brick up from ground level i plan to install dpm sheet taped to the little bit that sticks out from the wall then blind it with sand then finish floor level will be 2 bricks above the dpm

markus2025 · 2026-01-16T23:24:50+0000

I only have about 1 inch to tape to if i had time again i should of fitted a wider dpc maybe 18inch and then i would of had a good bit to tape to

markus2025 · 2026-01-16T23:26:15+0000

Just bought some visqueen zedex mastic looking to use this to make a seal aswell

markus2025 · 2026-01-16T23:26:54+0000

Deluks said:
Short answer, yes.
You could also cut a wide strip of dpm and Leave it hanging out, until such time you put the main dpm in and tape them together.

Other option is to black jack the wall just below the dpc and stick the dpm against it.

Not sure if you can use black jack with dpm plastic ?

Deluks · 2026-01-17T00:42:15+0000

Your chosen mastic will work ok, What's going over the sand?

Bring the membrane up the wall to meet the FFL, preferably slightly above it.
Plaster/plasterboard/skirting will hide it anyway.

noseall · 2026-01-17T07:25:50+0000

markus2025 said:
You can see on the this image i have fitted the DPC 1 brick up from ground level i plan to install dpm sheet taped to the little bit that sticks out from the wall then blind it with sand then finish floor level will be 2 bricks above the dpm

Your DPC should go at FFL not one brick above. It leaves one brick course vulnerable to damp. Polythene lapped onto it will be damaged by skirting etc.

DPC can be below FFL but not above.

markus2025 · 2026-01-17T08:56:00+0000

noseall said:
Your DPC should go at FFL not one brick above. It leaves one brick course vulnerable to damp. Polythene lapped onto it will be damaged by skirting etc.

DPC can be below FFL but not above.

The damp proof course is not at final floor level its one brick above the sub base level but the final floor level once the sand has been put in and damp proof membrane laid and infilled it will be 3 bricks above the damp proof course

markus2025 · 2026-01-17T09:02:31+0000

Deluks said:
Your chosen mastic will work ok, What's going over the sand?

Bring the membrane up the wall to meet the FFL, preferably slightly above it.
Plaster/plasterboard/skirting will hide it anyway.

So the plan is get the sub layer to a rough level blind it out with sand

Lay a sheet of dpm over the sand to meet the parts of the wall where the dpc stick out tape and mastic along the edges

then as a double up lay another full sheet of dpm and this time instead of it been cut as a square sheet and taped at the ends to the dpc the ends will be folded up the wall up the 3 courses to the final floor level more sand will then be laided onto to prevent any damage from the infill
Then concrete will be laid ontop of the infill to the final floor level which is 3 bricks above the dpc level then any excess dpm going up the wall be trimmed off at final floor level

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Dpc question

markus2025

ree

markus2025

Attachments

markus2025

Attachments

ree

Deluks

markus2025

Attachments

markus2025

markus2025

markus2025

markus2025

Deluks

noseall

markus2025

markus2025

DIYnot Local

Similar threads