Bathroom vinyl onto Caberboard

Rekusu · 30 Apr 2011

Hi there,

I am in the latter second fix stages of a new build and have been getting some prices for laying vinyl in the bathroom. It's a timber frame house.

The build-up from the joists is; joists, 18mm flooring OSB, 30mm polystryene with spreader plates (UFH pipe run in this) and 18mm t&g water resistant Caber board as the final surface. The Caber is isloated from the walls with 10mm of foam insulation, as supplied by the UFH company. There are a few screws in the Caber to prevent vertical movement, going through the styrene into the OSB.

As far as I am concerned, the floor is flat, level and stable. The various vinyl people all want to put 6mm WBP over the Caber board, stapling it every few mm. Personally, I think this is unnecessary (and will make life complex regarding the bath side panel and the floor that it butts up to) so we are at a stand-off.

What is the opinion of forum members? I am prepared to accept that if not installed the vinyl company's way, there will be no guarantee.

Thanks

rex

lymmranger · 30 Apr 2011

You will also be wasting your money and risking failure of the floor...

....why seek advise from a professional (your supplier) and then want/expect us to reassure/approve your desire to ignore that advice???

By the way your question should have been asked in the flooring section where you will get betterg advice

Rekusu · 30 Apr 2011

I'm asking the question because I am receiving conflicting advice from the various companies.

Caber Floor techs tell me that it is OK to lay vinyl directly onto the floor. The company who poured the anhydride screed tell me that the screed mix is suitable for laying tiles and or vinyl directly onto the floor as there is no laitance to remove.

But the vinyl layers say differently. And if I mention Caber Floor and /or anhydride screed, they glaze over and do not seem to know what I am talking about. Seems their experience of screed is sand and cement, which certainly will not be 100% flat and level.

Rex

lymmranger · 3 May 2011

I`m a flooring retailer, and new systems do tend to throw us

....Without research I cannot answer your question properly, but I can say that if you were my customer I would make sure I found out!!!

Your first post does not mention screed, where does that come in?

Vinyl tiles - I presume you mean LVT (karndean/amtico)????
Fitters WILL want to lay these on 6mm ply because THIS is how they are trained to install i.e. -
- Concrete - screed first.
- Wood - Ply first
Most LVT floors are suitable for UFH and they usually installed as above..
the ply will not compromise your heating, but WILL ensure your floor stays firmly adhered!

By the way, alot of fitters get very nervous about UFH - they always seem to get the blame, later on down the line when the system plays up/ leaks / etc

Rekusu · 3 May 2011

Thanks for your reply.

I think I have it sused now. The anhydride screed is on the ground floor and is flat, so in my opinion, it is not necessary to apply another screed.

Following further research, I will be applying a Stopgap P121 dispersion primer over the screed that will have vinyl. This is the stuff recommended for anhydride screeds.

Regarding 6mm wpb onto the caber floor, I have been told that is to isolate the vinyl from the structure. I understand, but in my case, the caber floor is floating on 30mm expanded polystyrene which carries the UFH pipes and is only held down by a few screws where there were unwanted creaks.

I will speak to F. Ball regarding a suitable primer for the caber floor.

Rex

lymmranger · 3 May 2011

OK - good for you .....BUT

Why are you so against a further screed and the layer of ply?

...is it to save money? (cos it wont save much)

or are you worried about blocking out your UFH output? (it wont)

I ask merely because if you are having LVT (you didnt confirm, this) then any fitter will be reluctant to guarantee the longevity of the job without screeding it or plying it first. I do see where you are coming from but I hope you can see where I/your fitter is coming from also.

If by vinyl you mean another product such as cushion floor then you are correct just lay it

mointainwalker · 3 May 2011

The company who poured the anhydride screed tell me that the screed mix is suitable for laying tiles and or vinyl directly onto the floor

If I were you I would check this out with Bal too, to avoid possible problems later.

Anhydride screed is basically calcium sulphate which reacts with cement products like powdered tile-cement. I have a screed like this and I am certain that you must apply a "primer' or similar to isolate the two materials

Rekusu · 3 May 2011

lymmranger said:
OK - good for you .....BUT

Why are you so against a further screed and the layer of ply?

...is it to save money? (cos it wont save much)

or are you worried about blocking out your UFH output? (it wont)

I ask merely because if you are having LVT (you didnt confirm, this) then any fitter will be reluctant to guarantee the longevity of the job without screeding it or plying it first. I do see where you are coming from but I hope you can see where I/your fitter is coming from also.

If by vinyl you mean another product such as cushion floor then you are correct just lay it

Save money and heat output, no and no!

It is a fairly resilient contract quality vinyl we have selected. I'm against more screed because my anhydride screed is already smooth and flat. Why add something else on top of an already good surface? Additionally, I know that 4-5mm will not make much difference, but it just adds another problem to be solved where the timber floor and leveling screed/vinyl meet.

Same applies to the WBP. What is the point of having a smooth, flat, 18mm t&g CaberFloor and then add another layer, which will not be t&g, to it? I'm told it is to do with expansion and contraction issues. Since one cannot stop expansion/contraction, why will 6mm WBP on top make any difference?

Additionally, I have spoken with the CaberFloor manufacturer, and they suggest 6mm WBP if the UFH is electric but not totally necessary if wet (which it is.) They also suggest that the CaberFloor has a 10mm expansion gap on the outer edges (it has.) But the vinyl layers are suggesting putting the 6mm WBP hard up to the walls. Where will any expansion go then?

Do you see my confusion? Depending upon who I talk with, the goal post swing around.

Regarding the anhyride screed, I am rectifying the issue and will be applying Stopgap P121 dispersion primer, which the vinyl layer is happy with.

Rex

Petest67 · 4 May 2011

Sounds like you're going to install a sheet vinyl. If the existing floors are smooth, flat and has no gaps / holes that will telegraph through, then if the vinyl is going to be loose laid you can lay them directly over the existing floor. If you want t5he vinyl fully bonded it will have to be prepped with ply / screed.
As you've mentioned, the anhyride screed needs priming with 121 if its going to be screeded over otherwise the smoothing compound will break away.
Remember that you can not crank the underfloor heating up suddenly, you have to increase it in slow increments over a few days untill its at the final temp you want.

lymmranger · 4 May 2011

Ahhh - right sheet vinyl....

.......well then you are correct, you can just lay onto the floor as it is.

So long as you have no lumps and bumps and as Petest67 says provided you are loose laying then go for it.
As mointainwalker says the screed you already have would need priming, but only if you are over-screeding which now I know your final flooring choice, I agree you do not need to do this....

phew - we got there in the end

Rekusu · 4 May 2011

Gentlemen,

Thanks for the replies and comments.

I'm not putting a 'levelling screed' on the anhydride screed, as it is already smooth and flat. But the sheet vinyl will be fully adhered, so am coating the Stopgap P121 as recommended by both the vinyl installers and the screed company.

Regarding the CaberFloor, you are only confirming what my instinct tells me, if loose laying, then I don't need a 6mm WBP. But I still don't get why I would need WBP if fully adhering it?

I spoke with Forbo today, and they say that t&g needs the WBP layer, but since the CaberFloor only has gaps of about 0.5mm between the sheets, it shouldn't be an issue and they agree. But may be I'm missing something?

Rex

lymmranger · 5 May 2011

Because sheet vinyl SHOULD be loose laid

....if you are fixing it with adhesive then it WILL absolutely trash the sub-floor should you ever need to lift it! - it will come up with chunks of screed and chunks of the Caberfloor - hence the correct advice for ply and further screed which will sacrifice itself, instead of wrecking your true (existing) floor. In other words the advice you recieved from your installer was correct...

I must say I have found this post very frustrating....I feel that FULL information has had to be painfully dragged out of you. I asked very early on, what type of final finish you were installing, this finally came out as sheet vinyl and now you add in that you wish to stick it down!!!

Right, lets start again....

If you are having sheet vinyl, but loose laying it just do it

If you persist in adhering it (WHY??????) then you will HAVE to overply the caberboard and screed the anhydride screed asrea (priming first)

I dont suppose there is anything else we should know about this job is there?

idntblvit · 5 May 2011

its probable the joints in the boards as to why they want to ply it just tell them to use ardex feather finish that will sort the bad joints and is only half a mm thick and shouldnt pose a problem to your bath panel if the joints are fine and theres only slight movement sand the joints and lay over using takifier glue on the whole area hope this is a help

Rekusu · 5 May 2011

lymmranger,

Have no intention of leading anyone astray. When I say vinyl, that is what I know I mean, but I guess as a flooring expert, when you hear vinyl, you think Amtico tiles.

Yes, it is sheet vinyl and I can understand a WBP on the CaberBoard if using Amtico tiles. But you raise an interesting point that I had not previously considered, regarding the WBP as a disposable layer should I wish to fully adhere. That make total sense.

Having considered everything, I will loose lay the vinyl in the bathroom over the Caberfloor. However, the installer is recommending that the kitchen and utility rooms should be fully adhered to the anhydride screen having applied Stopgap P121 first to prevent the adhesive from drying too fast.
Are you recommending the leveling screed (over the P121) as a disposable layer should I need to lift the vinyl?

Rex

Rekusu · 5 May 2011

idntblvit

Yes, I think it is the joints in the Caberboard which is why they want to WBP it. But the WBP will have joints, so what is the difference?

Rex

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Bathroom vinyl onto Caberboard

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