Do I need to put in a new DPM?

[wildelady007]

I have a 1978 built house. In the hallway downstairs we pulled up the carpet to find marley tiles/thermoplastic tiles.

Nervous about the asbestos our preferred plan to deal with them is to cover them in ceramic floor tiles and never see them again! The carpet treads have shattered the edges of the tiles a little. We are reluctant to pull out the skirting boards in case we disturb more tile, but would do this if we really had to.
I called BAL and a local tile store and have got the following advice:

Apply BAL fibre base self levelling compound
Graze tiles and apply acrylic primer
Use BAL rapidset flexible adhesive to secure the tiles
then micromax2 grout and sealant on the edges close by skirting boards due to movement.

My questions are:
1. Do I need to put in a new damp proof membrane? I have read around on forums that once you break up these tiles a little, that you have broken the DPM and would need to install another?
If so, should we just paint on a DPM paint prior to applying the self levelling compound?

2. Can a self levelling compound be used without removing skirting boards or do they need to come off?


I am an absolute DIY novice so apologies if I have asked any silly questions!

 

[wildelady007]

Just wanted to add that there are no signs of damp in the house.

 

[tony1851]

Is there actually asbestos in them? It doesn't seem right tilling over them. Just get a mask (if you're that worried) and pull them up. No need to be uptight about that!
For a house of that age, there will probably be a dpm under the concrete.

 

[wildelady007]

I wouldn't be able to tell, without sending a sample off for testing, if there was asbestos in the tiles.

Is it bad to tile over them? Is there a reason I shouldn't tile over them?

Thats good that there should be a dpm under the concrete for a house this age. Would you suggest then, that I do not need to apply a dpm?


Thanks for any advice!

 

[tony1851]

I wouldn't be able to tell, without sending a sample off for testing, if there was asbestos in the tiles.

Is it bad to tile over them? Is there a reason I shouldn't tile over them?

Thats good that there should be a dpm under the concrete for a house this age. Would you suggest then, that I do not need to apply a dpm?


Thanks for any advice!

1. Testing will be £££
2. Generally better to start from scratch when re-tiling;
3. You can never be 100% sure, but floors of that age would be expected to have a dpm. Why not drill/chisel a small hole in a corner to check?

 

[wildelady007]

what does a dpm look like? if we were to drill down and check.

 

[tony1851]

It's usually a thick sheet of polythene - probably black - directly under the concrete (the concrete is usually around 4" thick).

 

[wildelady007]

aha ok thanks, maybe we will do that.
I'm kind of thinking that the liquid dpm stuff is only £12 so maybe we should just put it on anyway, it won't do any harm i'm thinking.

 

[crazydaze]

If you don't lift the tiles, there is every likelihood that they will become unstable resulting in the cracking and falling apart of the tiles that you fit over the top. I would'nt be too concerned with uplifting the old tiles, screed and fit your new floor. If there is no DPM as part of the build, then it was a dodgy building job. DPM were building reg's introduced in 1962/63.

 

[lymmranger]

If you don't lift the tiles, there is every likelihood that they will become unstable resulting in the cracking and falling apart of the tiles that you fit over the top. I would'nt be too concerned with uplifting the old tiles, screed and fit your new floor. If there is no DPM as part of the build, then it was a dodgy building job. DPM were building reg's introduced in 1962/63.

I always was taught that the tiles were part of the DPM......

on this type of floor the ground was levelled with sand, then concrete, then bitumen with the tiles being put onto the wet bitumen(used as glue)
....visqueen hadn't really come into use yet (in the 60`s and 70`s)

ignore the asbestos issue it is an infinitesimal risk and unlikely in any case

 

[crazydaze]

If you don't lift the tiles, there is every likelihood that they will become unstable resulting in the cracking and falling apart of the tiles that you fit over the top. I would'nt be too concerned with uplifting the old tiles, screed and fit your new floor. If there is no DPM as part of the build, then it was a dodgy building job. DPM were building reg's introduced in 1962/63.

I always was taught that the tiles were part of the DPM......

on this type of floor the ground was levelled with sand, then concrete, then bitumen with the tiles being put onto the wet bitumen(used as glue)
....visqueen hadn't really come into use yet (in the 60`s and 70`s)

ignore the asbestos issue it is an infinitesimal risk and unlikely in any case

I can't recall having an issue with primer and screed over such a floor, however a moisture test and/or liquid DPM primer and screed for a belt and braces approach could be taken.

I think in reality, the op would probably be fine to uplift, screed and fit but yes, there are ways to thoroughly test the floor to get a definitive answer.

 

[lymmranger]

If you don't lift the tiles, there is every likelihood that they will become unstable resulting in the cracking and falling apart of the tiles that you fit over the top. I would'nt be too concerned with uplifting the old tiles, screed and fit your new floor. If there is no DPM as part of the build, then it was a dodgy building job. DPM were building reg's introduced in 1962/63.

I always was taught that the tiles were part of the DPM......

on this type of floor the ground was levelled with sand, then concrete, then bitumen with the tiles being put onto the wet bitumen(used as glue)
....visqueen hadn't really come into use yet (in the 60`s and 70`s)

ignore the asbestos issue it is an infinitesimal risk and unlikely in any case

I can't recall having an issue with primer and screed over such a floor, however a moisture test and/or liquid DPM primer and screed for a belt and braces approach could be taken.

I think in reality, the op would probably be fine to uplift, screed and fit but yes, there are ways to thoroughly test the floor to get a definitive answer.

Agreed! - we used to screed over them with no problems

 

[wildelady007]

hmmmm I wonder if its better to use the self levelling compound and then instead of ceramic tiles, just put on a roll of vinyl, then its less pressure on them, and if they do start to come apart its easier to get at than with ceramic on it.

 

[wildelady007]

do i need to remove skirting boards prior to using the self levelling compound?

Thanks so much for the help!

 

[crazydaze]

You CANNOT screed over the tiles. they need uplifting first.

You would not need to remove skirtings to screed the floor.