Substrate Raising

[kimboslash]

Hi all,

Looked at a job on Friday (new build) where the customer originally wanted a thick basalt stone tile and then decided to go for a thinner porcelain tile - so now they are asking a for an adhesive bed of 25mm over 100m2 of screed (with wet UFH).

The finished tile height needs to remain the same regardless of the thinner tile so what is the general consensus of the best way to build up the floor allowing for a much smaller bed of adhesive?

 

[Ajax123]

Lay an unbonded layer of TS15 or TS20

 

[Dan]

I'd assume more screed? can you add 20mm or so of screed or is that not enough?

 

[Ajax123]

Broken Link Removed

 

[widler]

I like the look of that alan, what would the price differance be to say self leveling itfor 100m2 at 25mm you would probably need 1bag per m2 ish, so say £2000 ish in matts then labour, im guessing here while bored while the wife watches corrie

 

[Rizzle from the Portizzle]

Hi all,

Looked at a job on Friday (new build) where the customer originally wanted a thick basalt stone tile and then decided to go for a thinner porcelain tile - so now they are asking a for an adhesive bed of 25mm over 100m2 of screed (with wet UFH).

The finished tile height needs to remain the same regardless of the thinner tile so what is the general consensus of the best way to build up the floor allowing for a much smaller bed of adhesive?

can you lay tiles into wet sand and cement

 

[Ajax123]

I like the look of that alan, what would the price differance be to say self leveling itfor 100m2 at 25mm you would probably need 1bag per m2 ish, so say £2000 ish in matts then labour, im guessing here while bored while the wife watches corrie

Where in the country are you. I can get you a price sorted? No obligation of course but I would think it would come out better than bagged levelling compound as its a ready mixed product. I also think from memory 1x25 kg bag of levelling compound usually does about 1m2 at 10mm although I'm happy to be corrected.

 

[Ajax123]

can you lay tiles into wet sand and cement

You can lay it unbonded so put a polythene slip membrane over the sand cement and then pour minimum 15mm of it on top.

 

[Dan]

Most SLC can't go deep. You have to start adding things to it to bulk it out.

 

[Ajax123]

Most SLC can't go deep. You have to start adding things to it to bulk it out.

Or lay in several layers. There are compounds that can go deep but it becomes a cost thing and thick cement based compounds can be prone to shrinkage cracking and can only be laid bonded.

 

[Ajax123]

You can lay it unbonded so put a polythene slip membrane over the sand cement and then pour minimum 15mm of it on top.

Sorry. I misread your your question....

 

[Rizzle from the Portizzle]

why has such an easy job to do. at low cost .become a high cost job

 

[Rizzle from the Portizzle]

ok here you go sub the job out to tilers who know how to fix in wet sand and cement should be no problem for them this will save you over £41 m2 in levelers decouplers adhesive labour before you lay a tile sit back watch how it should be done and make a few grand and save the same for your client

 

[Dan]

Because there's a woman involved who's changed her mind, again. Haha

why has such an easy job to do. at low cost .become a high cost job

 

[Just Rizzle]

forgott to ask what type of sub straight is it?
think every one is assuming its cement based or is it anhydrite the ufh is layed in?

 

[Ajax123]

At 100mm I'm hoping its sand cement. Not a very efficient way to use underfloor heating but still pretty common.

 

[Ajax123]

ok here you go sub the job out to tilers who know how to fix in wet sand and cement should be no problem for them this will save you over £41 m2 in levelers decouplers adhesive labour before you lay a tile sit back watch how it should be done and make a few grand and save the same for your client

But he's only got 25mm to play with. For a cement sand bedding I would expect around 40mm.

 

[Ajax123]

Ok widler I've worked out a rough price for 100 m2 of ts15 at 15mm and I reckon you'd have quite a lot of change out of £1500. So cheaper than levelling compound. That would include materials, labour and pump.

 

[Just Rizzle]

you could stick down ditra mating to decouple the floor and lay a 25mm sand and cement bed on top of mat total material cost approx.£1000 PAY YOU SELF EXTRA 500QUID your quids in plus floor usable in 2days after laying

 

[Ajax123]

you could stick down ditra mating to decouple the floor and lay a 25mm sand and cement bed on top of mat total material cost approx.£1000 PAY YOU SELF EXTRA 500QUID your quids in plus floor usable in 2days after laying

The standard for tiling calls for sand cement beds to be laid bonded to a fully prepared slab which has been mechanically abraded so there goes the £500 saving. It will cost at least that to hire a sander or shot blast machine. It then says that the cement sand bed should be bonded using a cement slurry with a polymer dispersion primer e.g. acrylic primer.... to be fair it does actually say the bed should be 20mm deep and not 40mm as I had thought. If you stick down ditra...that's an extra 6mm with the mat and the addy. That only leave you 19mm for bedding. Ditra is designed as an uncoupling membrane. It wont offer any protection from the sand cement bed curling or shrinking which at 19mm I would suggest it would do both quite liberally.

 

[Rizzle from the Portizzle]

if this is a sand and cement screed it will already have an abraded surface by its nature so you can aproach this in two ways why would i want to decouple the floor when i want it to act as one so wet slurry screed now tile knowing the tile will double the strengh laid into wet sand and cement or you could put down exspanding metal not raising the hight slurry screed then tile still bineded as one layer but with a bit more scope with dealing with the ufh

 

[Ajax123]

if this is a sand and cement screed it will already have an abraded surface by its nature so you can aproach this in two ways why would i want to decouple the floor when i want it to act as one so wet slurry screed now tile knowing the tile will double the strengh laid into wet sand and cement or you could put down exspanding metal not raising the hight slurry screed then tile still bineded as one layer but with a bit more scope with dealing with the ufh

No it won't!! I would love to see the science behind some of your claims.... How does the tile double the strength laid into a wet bed. And what is the point of the expanding metal?? Think I'm going to leave this thread now before I say something I'll regret.

 

[Just Rizzle]

WHAT IS THE SUBSTRAIGHT THE UFH IS LAID IN?
TILL WE KNOW THISTHEN NO ADVICE IS RELEVENT

 

[Rizzle from the Portizzle]

No it won't!! I would love to see the science behind some of your claims.... How does the tile double the strength laid into a wet bed. And what is the point of the expanding metal?? Think I'm going to leave this thread now before I say something I'll regret.

ok regret so regret away lucky for me here when i was at school many years ago i made sand and cement blocks then we had to test there breaking strenght by adding weight in the middle intill they broke if i did the same today made some with screed only. then some tiled. and then some tiled with exspanded metal each would prove you wrong and whats more i will do this and post pics all the way and i suggest you do the same if you are so sure.with out the know how science does not move forward only fools

 

[Rizzle from the Portizzle]

No it won't!! I would love to see the science behind some of your claims.... How does the tile double the strength laid into a wet bed. And what is the point of the expanding metal?? Think I'm going to leave this thread now before I say something I'll regret.

and if you would like to send me 25mm x50 mm x150mm bit of your sceed i will test that to and all are welcome to test the out come with me