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duotwr
23-05-2012, 12:54 PM
Hi

I'm posting having been directed here by Matt, after asking some questions on DIYnot. He suggested I'd get good advice on here.

Situation is I've got a concrete kitchen floor with thermoplastic tiles set on black (bitumen?) adhesive. Spoke to building control who confirmed that the bitumen is the only form of dpm. We want to lay vinyl sheet in the kitchen.

Time, money, and space for increasing the floor level are tight unfortunately - but I need something which will work. I've seen a number of suggestions on different forums.

An initial look suggests the tiles are bonded well, but would lift if I wanted too (asbestos risk notwithstanding). Assuming I remove the tiles, but leave the bitumen, how about one of these options:

1. Arditex NA 2 part latex levelling compound with no primer, OR
2. SBR followed by Everbuild 708 with latex additive
3. F-ball 131 primer followed by Stopgap 200

Is it likely I'd also need a dpm on top of these, with another layer of SLC again, or would the bitumen layer suffice?

And if the tiles turn out to be well bonded would any of the above options work over them?

Thanks in advance

Keith

Neilydun
23-05-2012, 03:02 PM
I`m sure there are plenty of opinions, but for me

Uplift the tiles
Latex screed NA
2x coats dpm
Latex screed
New tiles

Anything else, could end up being false economy

tarkett85
23-05-2012, 03:27 PM
If the bitumen is damaged above answer wont work, so asphalt over concrete, latex screed, either NA or latexplan trade etc.... but you should always prime the subfloor first, I believe you need to give the bitumen a slurry coat first.

duotwr
23-05-2012, 03:39 PM
Thanks for replies.

Tarkett85 - what is the risk if the bitumen is damaged - that it just comes away from the concrete? If it came off in places as I was removing tiles, and I removed it back to where it adhered, would this reduce the risk?

Keith

Neilydun
23-05-2012, 04:09 PM
If the bitumen is damaged above answer wont work, so asphalt over concrete, latex screed, either NA or latexplan trade etc.... but you should always prime the subfloor first, I believe you need to give the bitumen a slurry coat first.

So, if there is a concrete floor, with ata adhesive troweled on to stick down tiles, why would my answer not work ?

Just curious as thats a solution thats always worked for me

dazlight
23-05-2012, 05:17 PM
I do the same as Neil alot. Worked for me so far. Would only not do it if very high moisture reading.

I also have done f.ball as cheaper.
Green bag
2 coats F75
Primer
Green bag again.

Neilydun
23-05-2012, 05:32 PM
I`m not saying i`m right or wrong, but I have never put asphalt over anything.

Never had a job fail through moisture, except one, which was found to be a pipe, which was weaping below floor level.

dazlight
23-05-2012, 05:44 PM
When woodblocks have come up I've had jobs Ashpalted as brings the height up too.

duotwr
23-05-2012, 05:54 PM
Guys - thanks for the responses.

As a diy-er costing it up there's not a lot between using Ardex and F Ball - although things will be quicker with Ardex so I may well go with that.

One last question, that I probably know the answer to already - I take it the bitumen won't be a sufficient dpm in itself and I could get away with just the latex screed?

Keith

merit
23-05-2012, 06:02 PM
Have you looked into using an isolator sheet as a moisture barrier?

duotwr
23-05-2012, 06:07 PM
That did occur to me. Again, not cheap, but presumably I could stick down a single layer of acrylic screed and then loose lay the isolator sheet? The only one I found details on was the F Ball one - although I assume the other manufacturers do their own?

Keith

Neilydun
23-05-2012, 06:45 PM
Ardex make one, and it`s a little cheaper

merit
23-05-2012, 07:36 PM
Yeah, the last one I used was made by mapei, I'm sure it's cheaper than f.ball

tarkett85
23-05-2012, 07:53 PM
Ardex and mapei make cheaper than balls although they are more of a temporary solution, also as I said if bitumen gets damaged when removing tiles then asphalting will be cheaper than digging up and replacing the concrete base.

duotwr
23-05-2012, 08:10 PM
OK - thanks for the replies. I'm minded to go with the Arditex and liquid dpm option - I've got a Carpet & Flooring depot near me so I'll give them a call and see what they've got in stock.

Thanks for the advice - I'll let you know how I get on.

Keith

Charlie
19-06-2012, 12:38 PM
Hi,

I'm wondering if anyone can help me please because I have a similar query as the above? I've just bought a 70's house which has thermoplastic (Marley) tiles laid to the kitchen and utility. I'm looking to have Karndean tiles laid on top of these tiles (not going to take them up or deal with the bitumen) and would like some advice on how to prep the old tiles. Should the old Marley tiles be cleaned first? Any broken bits stuck down properly? What primer should be used on top of these tiles? Then which latex screed is best? What adhesive should then be used to stick the karndean down with?

Thanks,

Charlotte.

dazlight
19-06-2012, 01:36 PM
Hi Charlotte, I wouldn't screed over them as the adhesive used under the Marley tiles will be a very week bond and over time walking on the floor they can come loose which will then crack the screed and then the Karndean will be up.
Chances are there might not be a damp proof membrane under the tiles as well.
Is your house on the top of a hill or above ground level as that can help with not much raising damp coming through the floor.
But if you want to gamble then in answer to your question-
Use a floor primer neat then screed with A bag and bottle smoothing compound like mapei trade plan, ardex NA, laybond screedmaster ulimate or f.ball stopgap green bag.
Which ever one you use get the matching primer.
if using Karndean best to buy their own adhesive.

tarkett85
19-06-2012, 01:51 PM
Or mapei's, they make karndeans ps Addy which is inferior to mapei's own.

tarkett85
27-06-2012, 09:36 AM
If the bitumen is damaged above answer wont work, so asphalt over concrete, latex screed, either NA or latexplan trade etc.... but you should always prime the subfloor first, I believe you need to give the bitumen a slurry coat first.

Yep needs slurry coat,

tarkett85
27-06-2012, 09:38 AM
BBest practice is to replace concrete with a new slab and Dpm, then surface membrane screed and good to go.