Electric Underfloor Screed & Tile Expansion Joints?

[Ajax123]

Ajax,

The TCNA handbook is copyrighted, and I think I probably can't post details on here from the disc that I have (of the current handbook). Yes, they always take the "CYA" approach and say, regardless of their recommendations, to follow whatever the manufacturer has to say in their literature. If I have a product to install that has less-stringent installation standards than the genaric guidelines in the TCNA handbook, I follow the more-stringent standards of the TCNA.

For exterior installations, for installations in direct sunlight, and for heated installations, the TCNA handbook recommends soft joints as close as 8' to 12' on center.

The Schluter "1:1.5" ratio is a good one, I think, and isn't unique to that company. I see evidence of that principle on a lot of new jobs going in around here, for concrete and brickwork especially.

Yes, the TCNA has info about substrate design. I could count all the details in the current handbook, but my guess is that there are ~100 separate details covering every conceivable generic installation and type of tile setting product.

normal maximum bay size for cementitious is 6mx6m and the aspect ratio we work on generally is 2:1 rather than 1.5:1 but the same principal applies. This changes with heated screeds but the relevent standards don't seem to take account of this. There are significant differences when using Calcium Sulphate when the aspect ratio changes to maximum linear bay length of 40m with an aspect ratio of between 5 and 8 to 1 unheated or 300m2 for heated screeds.
Do you come across Calcium Sulphate much in the US. I know we as manufacturers have just launched in Canada and parts of the States but I don't come across much info outside of Europe generally. It is interesting to note that the TCNA handbook has specific details outlined. I don't think that the UKTA has that - I do have a copy of their document tiling to calcium sulphate screeds which is quite comprehensive although now a bit out of date on some aspects. (it was done in 2001).
Biggest issue I have in the UK is disseminating information to those who need it. Usually they make contact with people like myself when it is too late instead of seeking technical guidance before building. There are so many "experts" in the industry giving out information and some of this is very poor advice. Still I will keep trying hence my involvement with the forums.

 

[Ajax123]

Dingers - I am curious to know why you selected a French based system instead of a UK based one - or is the project in France?

 

[Rob Z]

Hi Ajax, the Current TCNA handbook is only $12...a real bargain as far as I am concerned. Even at that, some guys still complain...


TCNA - TCA Publications

I'll be back to talk to you some more...but in general gypsum screeds here in the US have a bad reputation...I know of a lot of failures here in my area (I'm sure most if not all are because of installation errors). In other markets of the US I am told that the material is used quite often.

 

[dingers]

Hi,
Yes the house is in France and it as the Electricians choice.

I have just come back from the build, nothing happening today forgot its Bastille Day. The material on perimeters of each area is marked with the name "EFIRIVE", which I haven't Googled yet.

dingers

 

[Ajax123]

Hi,
Yes the house is in France and it as the Electricians choice.

I have just come back from the build, nothing happening today forgot its Bastille Day. The material on perimeters of each area is marked with the name "EFIRIVE", which I haven't Googled yet.

dingers

That explains the French system then. It was not Lafarge Beton so I am guessing it was a Hemi Hydrate screed. That would be usual with the type of mixer use although interestingly the UK equivalents all use anhydrite.

The practical difference from your point of view is negligible.

I am not entirely surprised that the electrician used this type of screed. Possibly of interest to Rob Z something like 75 to 80% of the French screed market is Calcium Sulphate and around 80 to 85% of this is tiled. The French too have had their share of issues with these types of screeds in the past but for the last 4 or 5 years Lafarge at least have receomnded the use of Calcium Sulphate tile adhesives rather than the more traditional cement based and there have been very few reported problems since. The product is still growing in both France and the UK so not everything can be wrong.
I mirror France's view and recomend the use of Calcium sulphate Tile Addy. It should be much more readily available there than it is here and probably cheaper as well. Its use removes any risk whatever of ettringite reaction. It also exhibits similar expansion and contraction characteristics to the screed thus reducing any risk of delamination due to substrate movement. The ones I know of can be laid when the screed is still at 85% RH (Although I don't generally recomend it). Make sure the heating is commissioned and run prior to tiling as well.
The equivalent "blue stuff" in the UK is called Gefficel, and comes in 5, 8 and 10mm thicknesses, although there are a variety of others in pink, yellow, black, grey, white and probably other colours I have not yet seen.

 

[dingers]

Hi

Yes, our French friend Claud who generally translates for us has said the electrician has a initial run up protocol which needs to adherred to prior to laying the tiles. Plus reference has been made to a primer application that is necessary. I am wondering if this is any way similair the tile addhesive addy you refer to.

dingers

 

[Ajax123]

Hi

Yes, our French friend Claud who generally translates for us has said the electrician has a initial run up protocol which needs to adherred to prior to laying the tiles. Plus reference has been made to a primer application that is necessary. I am wondering if this is any way similair the tile addhesive addy you refer to.

dingers

The primer and the adhesive (addy) are separate items and need to be incorporated into any tile installation on any screed. The difference with Calcium Sulphate screeds is the functions that the primer serves. If you select a standard cement based tile adhesive which are admittedly by far the most common available then the primer needs to serve 2 functions.
firstly it needs to "seal" the pore structure at the surface of the screed in order to reduce the level of suction from the adhesive into the screed so that the adhesive does not dry before it has time to set. Secondly the primer needs to form a physical barrier between the adhesive and the screed in order to prevent any chemical interaction between the sulphates in the screed and the cement in the adhesive. This is the bit which catches most tilers out because a standard acrylic primer is not likely to act as a satisaftory barrier unless numerous coats are used. Two is not enough IMO. A much more robust system in this instance would be to use a water dispersible epoxy primer as this serves both functions very effectively.
On the other hand if you select a tile adhesive based on calcium sulphate then there is no risk of chemical incompatibility and you only need the primer to reduce suction which the acrylic primers will do very well.
The attached document might be of some use. It is a translation of the one handed out in France by La Chappe Liquide who supply most of the calcium sulphate screeds over there.
The major difference is the moisture test method which over here is by means of the HAir Hygrometer but in Europe will be by Carbide Bomb test.

 

[Rob Z]

Ajax, We see a lot of LaFarge products here, chiefly portland cement and drywall products (mud, board, etc). I thought LaFarge was HQ'ered in Quebec, but maybe it is a French company?

Dingers, If you have the time and interest, please take photos of any part of the process of the work that is going on in your house. All of us would enjoy seeing the work in progress.

 

[dingers]

Hi Ajax123 & Rob Z

Thanks for another lot of good information.

I have tried uplading pictures on 2 occasions but without any luck. I only seem to get as far as naming a library folder then when I select pictures laptop just hangs. Dont know if its my end or other end but will certainly try again. Perhaps forum admin have an answer.

dingers

 

[Ajax123]

Ajax, We see a lot of LaFarge products here, chiefly portland cement and drywall products (mud, board, etc). I thought LaFarge was HQ'ered in Quebec, but maybe it is a French company?

Rob - Lafarge group founded in 1833 in France as a Gypsum Mining company. Group HQ currently in Paris. Since the they have grown a little and currently sit in the market largest supplier of construction materials in the world although not the largest in all market sectors. The North American and Canadian operation is indeed headed from Quebec. Gyvlon screeds have been around in Canada for a few years now but have only just been launched into the States - Not sure where but I assume the northern states to start with. They are as far as I know the Worlds largest manufacturer of these materials. I am certain you will come across them more over the next few years. Sales in the UK market are currently ahead of where they were this time last year even in a depressed market so they must be doing something right.

 

[dingers]

Hi Ajax123 & Rob Z,

Success, managed to upload pics of project......hope there of interest.

dingers

 

[Ajax123]

Hi Ajax123 & Rob Z,

Success, managed to upload pics of project......hope there of interest.

dingers

Don't know how to say this but ..... where?

 

[dingers]

Hi Ajax123,

The pics are in an Album called "Underfloor heating and screed" attached to dingers. they were also shown on front page of forum. I presume I have uploaded correctly? Am I the only person that can see them.
:mad2:
Let me know if you can't find them I will have another go. I have many pics but have got this habit of boring people with them.

Just learnt how to officially thank someone.
Bye the way the thanks is for your many other useful posts not just the last one.

dingers

 

[Rob Z]

Dingers, will take a look...thanks...

 

[dingers]

Thanks Dave,

I presume thats what I should have done?

dingers