New concrete floor or not?

[Zebra]

The builders came today and have removed the concrete floor in the bathroom and dug a big hole. Consequently, I've decided not to have a bathroom after all, but to have it filled with water, like an old fashioned watering-hole which we used to have back home.

 

[Penners]

Sounds a good plan, Zebra. Just be a bit careful if the hippos, rhinos, giraffes et al want to come and share it with you. Things could get a bit crowded.

And I'm not even going to mention the lions... :shock:

 

[Zebra]

A new question now. I've had the floor dug out, and will be having a dpm installed and new insulated concrete slab. There is an old bitumen dpc, which may or may not be totally effective. There is penetrating damp, as it is only a single skin (four and half inch) wall, and on the other side is the neighbour's flowerbed, breaching the dpc. I've painted the wall with liquid dpm (relax, it's the 1940s part of the house, not the 17th century part) but have noticed when it rains that where a couple of roots had grown through at dpc level, a tiny bit of moisture gathers there.
I can turn my dpm up really high, but I can't lap it with the dpc. Will this tiny bit of moisture wick its way up between the bitumened walls and the dpm?
I suppose I should have filled the root-holes before bitumening the wall. Perhaps I might run a grinder along that join, fill it in with some cement mortar mix, and re-bitumen.
Thanks everyone, I think I've answered my own question. Any other suggestions?

 

[steveb]

I'd do everything I could to get the flower bed dropped below the level of the DPC , even as far as doing the work myself, so putting in a tiny wooden retainer or building them a little retaining wall just to get a few inches separation. I guess it's a political problem, not a technical one, but if the soil is above the DPC on the far side then you effectively don't have a DPC - sounds like you are considering effectively tanking the walls to hide the problem, not solve the problem. Then I would guess that your tanking would fail in about the same timescale as the waterproof cement tanking that the "damp specialists" would use would also fail - back to square one but with a more damaged wall.

-Steve

 

[Penners]

In your situation, I think I would carry the dpm in the floor up the wall to a level just above the dpc. I would then give the wall behind the dpm a generous few coats of something like Synthaprufe. I would also apply this to the back of the dpm. When both coatings of Synthaprufe have dried to the point of tackiness, I would press the dpm to the wall to "glue" it on, trying to get it as tightly sealed as possible to a point just above the dpc.

I think that's about as close to complete damp-proofing continuity as you'll get.

 

[Zebra]

Thanks Mr P, that's what I'll do.
I've been using this stuff, http://www.wickes.co.uk/Wickes-Bitumen-Based-Damp-Proof-Membrame-Liquid-5L/p/241217, do you think it's the same thing (rubberised bitumen), or is synthaprufe better?
Thanks Steve but I haven't the energy for another gully/retaining wall scenario like at the rear of the house, with all the permission required and ongoing maintenance, and I'm more than happy to use moden methods in this situation!

 

[Penners]

I've seen the Wickes stuff, Zebra, but I've never tried it myself. Assuming that it has the same adhesive qualities as Synthaprufe I should imagine that it will be OK. I should use two or even three coats (or whatever it says on the tin!).

By the way, I do agree with Steve - anything you can do to get your neighbour's soil out of contact with your wall above the dpc is going to be very beneficial.

 

[Zebra]

Tis done. Have new concrete floor. They chose a lovely colour for it, a kind of mid-grey. I'd post pictures, but fear it would draw attention away from the pictures of Joce's new render.

 

[Penners]

Wow! Once you zebras make a decision, you don't hang about, do you?

 

[philpjuk100]

Was that you?.

 

[Zebra]

No but this was!