New member here...question on adhesive for matting.

[Bob2]

Hi everyone,

I have been following this forum for about 14 years now and have always found answers to my questions...so thanks for all the previous info you have all provided me. Excellent forum!

I cannot however find an answer to this next question...
...I will be doing an 18sqm floor in glazed porcelain tiles, 10mm thick, 600x300mm in a brick bond pattern. Grout will be grey. The client, (a friends dad), has extended his conservatory and the new floor is a concrete screed which has been brought level with the existing ceramic tiles, and there is the obvious join between the two substrates. The tiles are solid with no movement. I did ask him to lift them and get the builder to self level the whole floor, but he was adamant he wanted them left alone and I tile over them, so I have to deal with what i've got.

I am going to put a Durabase Ci matting over the whole floor, but the data sheet says to make sure I use an S2 adhesive. Now my tiling is good, but my speed is not and all I can find is rapid setting S2 adhesives. I usually use Mapei. Can anyone tell me a good standard setting S2 adhesive to use with this matting please? I will be very grateful for your replies.

 

[Tile Shop]

You should also install a movement joint between the new and old floors. They will expand and contract independently.

Always thought that S2 adhesives impedes the function of cavity mattings like Durabase or Ditra. Looked at the instructions and it actually says C2 adhesive. Most people will use rapid or slow set C2 or C2S1. Lots of good brands about, Tilemaster, Ultra, Mapei.... the list is endless. Shop around locally, see what's available then come back to us and we can give you some further opinions.

 

[Bob2]

You should also install a movement joint between the new and old floors. They will expand and contract independently.

Always thought that S2 adhesives impedes the function of cavity mattings like Durabase or Ditra. Looked at the instructions and it actually says C2 adhesive. Most people will use rapid or slow set C2 or C2S1. Lots of good brands about, Tilemaster, Ultra, Mapei.... the list is endless. Shop around locally, see what's available then come back to us and we can give you some further opinions.

Hi Paul, thanks for reply. I was going to use Mapei Keraflex as it's one I'm familiar with, however, didn't think it was suitable for the matting? As regards the movement joint...the customer would rather not have one as he says it will look out of place and 'industrial' in his conservatory floor.

 

[Middlesex Tiles]

An admix to a standard set S1 will give S2 flexibility - but I had heard the same as @Paul C.

 

[Bob2]

An admix to a standard set S1 will give S2 flexibility - but I had heard the same as @Paul C.

Thanks Middlesex, I will have to look into this again then.

 

[hmtiling]

Rocatex do a standard set s2. You can't use s2 on top of durabase. The expansion joint doesn't have to be mechanical. It can just be a grout joint with colour matched silicone in it. You'll never know it was there

 

[Bob2]

Rocatex do a standard set s2. You can't use s2 on top of durabase. The expansion joint doesn't have to be mechanical. It can just be a grout joint with colour matched silicone in it. You'll never know it was there

Thanks mate...I hadn't thought of the silicone idea...I wasnt aware of it. I've obviously read the durabase data wrong then if an S2 can't be used. Will read it again tonight.

 

[hmtiling]

Thanks mate...I hadn't thought of the silicone idea...I wasnt aware of it. I've obviously read the durabase data wrong then if an S2 can't be used. Will read it again tonight.

It'll be c2 as Paul said mate

 

[Bob2]

It'll be c2 as Paul said mate

Yeah..thanks mate....Mapei Keraflex should be fine then. If the customer wants a brick bond pattern over the floor...how will I put a movement joint of silicone in over where the substrates meet? Or is that just not feasible with that pattern?

 

[hmtiling]

Yeah..thanks mate....Mapei Keraflex should be fine then. If the customer wants a brick bond pattern over the floor...how will I put a movement joint of silicone in over where the substrates meet? Or is that just not feasible with that pattern?

it's either cut them through or have them the other way on the transition

 

[Bob2]

it's either cut them through or have them the other way on the transition

Ok...thanks. I'll speak to customer. What if he doesn't want a movement joint or to turn the tiles? I mean what is the reality of tiles cracking without one over the 6m span? I have never had to deal with movement joints before.

 

[Dumbo]

I not about length in this instance it's to do with bridging to different substrates and the prospect of the two substrates moving independently of one another .

 

[Time's Ran Out]

All the forum can supply is professional advice to the best of our knowledge and intent.
Crack mats and membrane allow for a small amount of lateral movement but any vertical movement would crack the tile. You could make sure there is enough tiles left in case of future issues.

 

[Bob2]

I not about length in this instance it's to do with bridging to different substrates and the prospect of the two substrates moving independently of one another .

Thanks Jcr...I think I understand it. I'm pretty sure he won't want a movement joint in his design so I'll have to make sure he knows there could be trouble down the line.

 

[Old Mod]

Hi and welcome to the forum Richie.

 

[Albert]

Welcome to the forum .

 

[Flintstone]

As above really no need for an S2 ant nor recommended either. Prime the existing tiles with a gritty primer, fit your dural but done bridge the joint. It's not really about if he does or doesn't want an expansion joint it's about it needs one, and your tiling it and ultimately your the one he's gonna call and your the one who's gonna have to try and fix the mess if it cracks on that joint. Not worth the hassle. Tell him it's a must imo

 

[Bob2]

As above really no need for an S2 ant nor recommended either. Prime the existing tiles with a gritty primer, fit your dural but done bridge the joint. It's not really about if he does or doesn't want an expansion joint it's about it needs one, and your tiling it and ultimately your the one he's gonna call and your the one who's gonna have to try and fix the mess if it cracks on that joint. Not worth the hassle. Tell him it's a must imo

Hi...what do you mean when you say don't bridge the joint with the dural? The tiles and screed meet in a straight line on a length of 3m. I was going to lay a length of dural straight over it so the joint sat in the middle of the matting for the full length. Are you saying that would be wrong?

 

[Flintstone]

Mat each side seperately with a joint in the dural where the joint is in the two surfaces

 

[Bob2]

Mat each side seperately with a joint in the dural where the joint is in the two surfaces

Ok...so do I butt the dural edges up together on the joint and then tape the joint with the sealing tape?