New concrete slab DPM/DPC question

[miser]

Hi
I'm planning to dig up an old floor in our 100 year old house.

It's quarry tiles laid onto a thin mortar mix and then soil underneath
This has led to some damp, and uneven floors - and of course it's cold

So... i'm planning to dig out about 12", chuck a layer of hardcore in, level with sand, then dpm, polystyrene and a concrete slab. the three 'main' parts being approx 4" thick.

The advice i've read already on these forums mentions tying the DPM into the existing DPC - how would i do this?

thanks in advance

 

[mointainwalker]

What typr of DPC do you have ?

 

[miser]

when i say DPC i'm assuming the guides mean the blues in the wall - i.e. do i need to tie the PDM into the blues on the internal wall - they are about 5" above floor level.
Thanks

 

[mointainwalker]

First off, you are really in the wrong forum. I know it says floors, but it really means floor-finishes like tiles, parquet etc - Building would have been right.

I'm not a builder, so hope one comes on after me.

I don't see how you can "tie-in" your DPM to the existing DPC without destroying the latter and it being a hideous job. Having said that, I don't see why you would need to.

If you ensure that your DPM is brought up higher than the existing DPC, this will ensure that no water can cross into your house.

If you wanted belt and braces, you could remove mortar from a course of bricks ABOVE the existing DPC, insert your DPM into that and re-point.

 

[miser]

thanks for the help, although i'm still unsure

I have one of the guides in front of me and i quote:
"All floors should include a suitable damp proof membrane which should seal with the damp proof course" - the diagram then shows the DPM lapped into the brickwork just under the PDC - not easy and like you say a real pain. I can understand the reasoning but it's a big enough job to start with. I might post a new topic asking if the whole job is even worth the effort!!


many thanks for the advice

 

[mointainwalker]

I'm sure your book does say that, but I would be pretty certain that this book is telling you what to do WHEN IT"S A NEW BUILD.

Then , of course, it's no trouble at all to fold the DPM onto the DPC.

Anyway, your choice.

 

[noseall]

The advice i've read already on these forums mentions tying the DPM into the existing DPC - how would i do this?

It is not practical to retrospectively apply this to an existing build so don't bother. That is if you do have a physical dpc in any case.

.......as MW has already pointed out.