Sand cement Floor Screeds

[Ajax123]

Re: Floor Screeds

British standards should reflect best practice but this is best practice in the opinion of the comittee writing them. D they stack up in a court of law, sadly they probably would because a judge would not be an expert and wild take a view that he standard shold reflect best practice.

Where products exist which are outside of national standards there are other systems in ace which allow manufacturers to warrant that they are fit for purpose. Additionally manufacturers can self test. We do this sometimes at Gyvlon where we develop new systems which have no standards available to cover them. A good example of this is the thermoplane system which is a new underfloor heating sytem or the soundbar system which was developed as a screed to go in a timber frame building. these are proprietary systems tested to destruction by third parties to demonstrate compliance with the requirements of the applications.

 

[Diamond Pool Finishers]

Re: Floor Screeds

yes i would agree that they might stand up in a court of law if the judge was a lay person ,but i understand that the judge would seek an expert advice ,ie a building surveyor ,or specialist expert ,someone like yourself
ALAN , THERE YOU GO A NEW SIDE LINE FOR YOU LOL!
i thought the BBA would test most systems and be a good source of compliance that a material /system is fit for purpose .
i hate these peeps who don't have any real accreditation for a product/system ,but just come to market anyway, usually leaving a wave of failures in there wake .

 

[Fliselege]

Re: Floor Screeds

This is the gear I was on about. Looked at the additives, no viagra.

 

[Ajax123]

Re: Floor Screeds

Bit like some of the ones over here. Ardex done and so do Mapei.

 

[c1432666]

Re: Floor Screeds

Bit like some of the ones over here. Ardex done and so do Mapei.

Sorry to resurrect such an old thread, but it seems this is the appropriate topic and has been replied to by those with the knowledge I seek.

I have a 8m x 2.6m room (~20m2 internal space), with a standard 100mm sand/cement screed (no additives other than poly fibers and retarder to work with it for the initial lay) going on top of UFH pipe, on a floating floor of XPS insulation.

I intend to do the recommended full 1mm/day dry out period ~100days, and do a couple of full heating cycles in the last week prior to tiling, as I have 15mm thick granite tiles going on top and do not want any thing propogating through.

During the drying out period, I will be doing lots of work completing the room, boarding out, 1st and 2nd fix electrics and lots of walking on the surface. So when it comes to tiling the floor surface will need a deep clean before laying down any adhesive. I have some bondit branded, cement based flexible adhesive (product name: CTA Flexible).

My question is do I need to do any other preparation to the surface prior to laying tiles, is an SBR required? Anything I have missed?

Thanks in advance,
Kev

 

[Ajax123]

As it Is likely to be dirty particularly with dust a light sanding to loosen any racked in dust followed by a good vacuum clean is appropriate. Do not wet clean it.

Then prime it using a standard acrylic primer. Bond it will undoubtedly have one available.

As you are using granite which is a natural stone it is also appropriate to use an uncoupling membrane such as Ditra or Durabase. This is a recommendation of the stone federation.

Your screed dimension is just about at the point where it should have a movement joint it based on the depth and overall size you will probably get away without one but to remove any long term risk of movement cracking uncoupling becomes more important. Looking at the size this should not add a significant cost to the job but will save you the grief of cracked tiles later on.

 

[Mark S]

John,
As per most of the advice already given, unless the screed is a polymer-modified screed that has hydraulic binders in, then stick to a minimum of 28 days before even considering laying tiles on it.
There are numerous de-coupling mats available, but take advice from each manufacturer.
The BS recommendations do state 1mm per day ave. drying, this varies on each site condition.
hope this helps.
Mark S, Technical and Specification Manager, Gyvlon Ltd

 

[bugs183]

Ajax is your man for screed advise as said above!
If you're going to uncouple the floor i'd certainly use Ditra matting, we've been using for nearly 20 years and i'm as confident in it now as ever, i've used Dural on a few jobs as it was supplied, but i've got very little confidence in it, the Ditra feels and performs as a far superior product.