Gypsum based tile adhesive.

[Dumbo]

thanks dave did do a search but was looking for the one i read before on here and couldnt find it.

ted

 

[Ajax123]

Hi Ted

Dave is absolutely right it is best to sand any screed prior to coverings with floor coverings. The primer from creative impressions is used to reduce the suction into the screed to prevent premature drying and thus weakness of the adhesive and its bond to the screed. Thing to bear in mind with this addy is that it acts very much like a rapid set with a relatively short open life on the floor. It declares a pot life of about 40minutes so don't mix more than you can use in that time and when it is on the floor it will begin to skin in about 10 minutes so don't spread out more than you can tile in that time. This is the info I got from the last time I saw it used (about 2 weeks ago) I know that their technical manager was going to play with the formulation to see if this can be extended. I am not yet sure if he has been able to do so or not. Might be worth a call to their office to speak to the techs to confirm one way or the other.

In terms of underfloor heating - this MUST be comissioned and run prior to tiling. This is non negotiable in my opinion and indeed in my experience. The procedure is generically switch on and run for 3 days at 20degrees C then increase by max 5 degrees per day up to maximum temperature (no higher than 55degrees) leave at max for 3 days then drop down by 5 degrees per day to 20 then switch off for 3 days prior to priming and tiling. The sanding and vaccuuming to remove any dust and debris can be done any time before during or after but bear in mind that if there is surface contamination the action of heating the screed can bake this onto the surface making it more difficult to remove. It is a bit of a trade off cos if you sand it before heating it could get dirty again and if you wait till after it could be more difficult. I will leave that conundrum for you to decide upon.

The technically correct moisture test is to use the hair hygrometer. If using the GBTA you need it to be down below 85% RH. My guess is that you don't have one of these. It would certainly be unusual. You could buy yourself one but to be honest I would do a simple polythene bag test first to see if it is worth it. Place a peice of DPM polythene on the top of the screed in an area where you think it will have dried least (High foot traffic area in main walkway, enclosed cupboard, manifold cupboard where water was spilt during plumbing - those sort of places are ideal) place a couple of bricks on it to hold it in place then lift it after about 48 hours and see if there is moisture under the polythene. It will be self evident if there is lots of moisture as there will be condensation on the underside of the polythene or the screed will go darker. If you see this report back to the forums for further instruction as it were. If there is no moisture I would suggest that you could commence tiling on the basis that the GBTA is much more moisture tolerant during installation anyway. It is pointless doing a moisture test untill after the heating has been switched off at the end of the commissioning cycle.

 

[DHTiling]

See, i knew Alan would love to type a long reply..:lol:..

 

[faithhealer]

See, i knew Alan would love to type a long reply..:lol:..

better have lots of coffee on standby for his talk on monday then lol

 

[Dumbo]

thanks alan excellent advice there cant fault you wish i could make the talk this coming monday. Will report back when ive done the job let you all know how i got on.

many thanks again

ted