I have 100 m2 stick down engineered wood to install over cemex liquid screed which has underfloor heating. I have had problems with gripper not taking to this type of subfloor using rapid set/ gripfill. It is making me think my dpm/latex will not take to the subfloor? Does any1 have any prep advise?
Yeah it seems like that, and I can already see a few small patches that look like they have broke away? The builder seems to think there may be a primer for it but doesnt seem to interested in looking any further. I spoke to one fitter who suggested feather finnish over it??
well you cant use a feather finish or any screed over a soft surface. You do indeed need a primer to harden it but you need to be carfull as some primers will stop the epoxy DPM from sticking! How old is it? It may be best to speak to which ever company's dpm you plan to use and see what they advice.
Its a new screed, about 2 months old I was going to use Bona R580 dpm so I think I will contact them as you suggest
F.Ball and Ardex say no but Tremco and Bona have products that are suitable. I used the Bona on 300 m2 of engineered stick down and it seemed a really good product
As a genural rule the answer is no but there are a few manufactories that say you can. If they say you can then its o.k but make sure you use all there products so if there is a problem they cant blame something else.
There are a few products available that can be used to renovate and strengthen weak and crumbling screeds - not used any myself so can't comment on how well they work. Ardex do a few. http://www.ardex.co.uk/ardex_psrs.asp
Thanks Trimmer, I have seen this product before, only problem is ardex dont have a dpm that can go over ufh. I will have to see if tremco do a similar product to save me coming unstuck (excuse the pun) using different manufacturers. Also do u know if the hardener can be used over ufh? it doesnt seem to say on the tec sheet
Apparently the cemex screed is calcium sulphate based, so I cannot use a dpm and an accrylic primer will ensure the adhesive will bond
Only thing I can suggest is calling the tech departments at ardex, balls, tremco, etc. Get the info direct. Let us know how you get on.
If i'm right this is an anhydrite screed. This type of screed does not dry uniformly in that it can dry in one part and 100cm away can still be wet. There is no manufacturer way of testing if there is moisture other than a bomb test which is not carried out in the UK as there is no machinery to do so. You need to abrade the floor with carb stones to remove the calcium deposit that is left on the surface of the screed as it dries. Very dusty so a hoover attached to a rubbing down machine will help. Once you have done this apply the primer (I used F Ball P121). This will slow the moisture release and will give you a good finish for bonding to. I can't gaurantee this will work for wood but so far it works for Tiles, Carpet, Vinyl & Marmoleum. Hopefully it will work for you.
yeah it is anhydrite, I didnt realise, should of spoke to cemex earlier, the tech guy was very helpfull he basically said the same, ruff the surface, apply accrylic primer and it would be ok. The screeds been down 2 months now and I dont need to fit the floor for at least another month. Surely it will be dry by then?
It should be fine by then. The only problems might arise in the comissioning of the heating. Has it been done yet and if its not being done till after the floorcoverings are down make sure they do it slowly. 2 degrees a day. Not cranked up like they normally do or you could get puddles.
the wood has all been fitted this week, the oiled finish is dark and very matt and seems to show every bit of dust, I am thinking of putting a hardwax oil on but some of the people on site are saying to use bonakeemi traffic. Any 1 know of this product?
