Expansion joints, cracks and Pecilastic - TilersForums.com

[Paul R Cox]

I've a largish stone floor to tile that I've mentioned on here before. The largest area being about 10m x 5m. It has UFH and I'm thinking it may well need expansion joints. Although it's a new build there's no way of contacting the architect, so no discussing with him. I think I'll have to write a disclaimer on this one as there's no info on the screed etc.
My question is, can I simply tile as normal but fill joints with silicone where exp. joint is required? I think this might look less offensive running through natural stone than a Schluter strip.
Also, the tiles come in varying sizes so I'll have straight lines running one way but a staggered joint in the other direction, so how do I put an expansion joint in? Would I have to "cut through" the pattern? Or would it be sufficent to only have a joint running across the 5m (in the direction of the straight line)thus breaking up the 10m run, or do I need expansion joint in both directions?
One more thing, there are some cracks in places so I was thinking of filling with expoxy and covering with Pecilastic. Does this sound suitable and does anyone know where I can buy Pecilastic? - I live near J1 of M3 if that helps. Sorry, there's about 5 threads rolled into one here!

 

[grumpygrouter]

Never used Pecilastic and PJC is the man to talk to here. Sounds like a good case for Ditra/Durabase decoupling membrane to me and yes maybe split the floor in half with an expansion joint

 

[david campbell]

are you not supposed to have an expansion joint every 8m or so!

 

[R Montgomery]

I'd ask Aaron to see if the ufh acts as an uncoupling membrane in this case then you might not need the expansion joint.Grumpy seems right on but I don't know how the ditra would work with your ufh.

 

[faithhealer]

Wet or Electric UFH Paul

 

[brundlefly]

I find customers hate expansion joints, when they have said definitely no to a break in the floor ive put 10mm around perimeter & skirts on top, joints at doorways, full coverage with pecilastic, Which is a lot thinner than ditra and no need to fill the doves

I did some repair work to a stone floor a while ago,
I spoke to a PCI rep about cracks & pecilastic, as a work around
Chop out the crack (check the depth of the UFH) & fill with flexible silicone and cover with the matt, About 200mm strips which ive done about 12 months ago with no problems

Any chance you can start from a main doorway and put joints on all door ways
& a perimeter expansion with full coverage with the matt

Pecilastic & nano lite adhesive from PCI I think CTD will order it in

 

[Uheat]

I'd ask Aaron to see if the ufh acts as an uncoupling membrane in this case then you might not need the expansion joint.Grumpy seems right on but I don't know how the ditra would work with your ufh.

Wet or Electric UFH Paul

It sounds like a Wet system as it being a new build. I think David is right with the expansion joint but i think should be closer if using ufh.

I think Grumpy has given some sound advice

 

[batiling]

This might be a bit of a stupid question.I usually leave a small gap around the perimeter of the room and silicone round at the end of the job for any expansion no matter how big the floor.Is this right and does expansion only apply over u/f heating and on timber floors.This is what i was told

 

[wetdec]

Yes your right about the gap around the outside.

On the floor question you need to use a true uncoupling membrane, by that I mean one whos lower membrane actually fractures on the screed moving. This would mean as Grumps has said Schluter or Durabase.

Pecilastic and Dura-wp allow movement but are elastic based fleece tear membranes more suitable for wood substrate, not as suitable for your job in my opinion.


..

 

[batiling]

Thanks for that wetdec i was having terrible thoughts about customers ringing me up for doing the job wrong!I always try and use latex based addy when tiling to ply anyway(if cust will pay up for it,its dear stuff)

 

[Paul R Cox]

Sorry, yes it is wet UFH. The problem with dittra is the thickness and to cover all would be at such a cost. If i did a local, i would probably have to skim some off the screed - unless I try to lose the thickness difference with adhesive.
So can I use silicone as an expansion joint and is there a suggested joint thickness?

Cheers.
Oh yes, I will be leaving a joint around the outside beneath the skirts.

 

[lent]

what if any advantage would i gain by using pecilastic on chipboard rather than just adhesive and primer.
Is pecilastic stuck down with a dedicated adhesive.
Yes i am aware that i should not be fixing to chipboard, but tell that to the clown who wrecked the job in the first place.

 

[Perry]

Pual pm me with your number and i will let you know where you can get Pesalastic if you want it Pete