Question for Ajax123 on anhydrite screed.

[wayne]

ajax i have been told to use a anhydrate primer and benferflex c2 on a screed what do you think

 

[Ajax123]

ajax i have been told to use a anhydrate primer and benferflex c2 on a screed what do you think

I am assuming it is an anhydrite screed ..... sorry

Firstly there is no such thing as an "anhydrite primer". There are only primers for use on anhydrite and these can be acrylic, epoxy or polyurethane. Some people have used SBR but with mixed success. Neoprene is not really suitable in my opinion. Acrylic presents the most risk and I have seen many failures on these types of primers but some are better than others. BAL and Ultra do some good ones.

My guess is that who ever you are talking to are trying to sell you a standard acrylic primer for use on anhydrite. BEWARE IMO.

If you are looking to use Benfer I would think you would be better with Befergyps as it is specifically forulated for these screeds.

Benferflex is cement based so the issue is basically one of non compatibility. Cement and anhydrite do not stick together. If you use an acrylic primer you still have this risk if there is any moisture present and especially on underfloor heating. If everything is perfect there should not be a problem. When you find the perfect building site let me know.

If you want to use a cement based adhesive I would suggest you think about a much more robust system like a water dispersed epoxy primer such as Laybond Screedmaster epoxy, tremco CS epoxy or Isoseal from Flowcrete. All of these have been specifically developed for use on anhydrite screeds. They are generally not much more pricey than acrylics and are much more effective against the migration of sulphates.

Alternatively a gypsum based addy might be of use.

 

[DHTiling]

It was posted in an anhydrite screed thread Alan before i moved it..

 

[Ajax123]

Oh OK Dave. Did I give an answer on that one or not.......think I going a bit senile today.

 

[DHTiling]

It was screedmaster epoxy thread, so i gave this one it's own..

 

[Ajax123]

Yeeeey! my very own thread.....

Now is tat a good thing or a bad one.........:lol:

 

[The Legend; Phil Hobson RIP]

Deffo a good one Alan, respect

 

[Dumbo]

alan with the benfergyp do they still recommend removing laitence off screed and priming ?

ted

 

[Thespanishtiler]

why not use Benfergyps

 

[wayne]

where can i get it from? im based in leeds.