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

 

[Dan]

I love the passion we have for our jobs in life. But it's really all nothing in the grand scheme of things.

This is the sun. Our sun, as we know it. You can't even see it in this image that is an artists impression of what just our one galaxy is possibly like. We don't know what it actually looks like because we've got nothing that can see in. The sun is in one spiral 'arm' of many. And tech we fired out in the 60's wouldn't have eve reached the edge of that one spiral arm.

Let's not fall out over a floor today.

 

[Ajax123]

Youre right Dan.

Forget the testing Ray I know the compressive and flexural strength of our screeds so don't need you to test them for me. We already do that on a daily basis. You have you're opinions and I mine. We are both entitled to them and if they differ well it perhaps adds to the rich tapestry that is life.

 

[Rizzle from the Portizzle]

I love the passion we have for our jobs in life. But it's really all nothing in the grand scheme of things.

View attachment 73311

This is the sun. Our sun, as we know it. You can't even see it in this image that is an artists impression of what just our one galaxy is possibly like. We don't know what it actually looks like because we've got nothing that can see in. The sun is in one spiral 'arm' of many. And tech we fired out in the 60's wouldn't have eve reached the edge of that one spiral arm.

Let's not fall out over a floor today.

well there some think here i am working on here will blow the tile world away .and at the end of the day only the truth and nothing but the truth can be proved .i will never fall out with any body who drives me to the truth they can only stand as my heroes by making me think

 

[Rizzle from the Portizzle]

Youre right Dan.

Forget the testing Ray I know the compressive and flexural strength of our screeds so don't need you to test them for me. We already do that on a daily basis. You have you're opinions and I mine. We are both entitled to them and if they differ well it perhaps adds to the rich tapestry that is life.

ok i will do my test with a 10mm tile and a 4,8mm and test from the tile and the screed .do the same and test the added strenght the tiles give your screed .why would you not want to know the answer it should give you a great selling point .every day is a leaning day for me make it the same for you

 

[Rizzle from the Portizzle]

have been very busy today tilling giving glass a run for its money won hands down should finish tomorrow if left alone .and post some pics .but then i will move on to the test of screed and the tile strenght added if any one out there is going to be on site while an anhydrite screed is being laid could you send me a sample 25mm d 50mm w 150mm L it does not mater if they a bigger i can cut them down but it would not be ufair of me not to include these i would like four peices if poss or one lump i can cut down i will have them picked up or pay for postage or if you bring them in i will give you the best thin tile cutter in the world for free and train you on using it .we can all learen from this .thanks for your help in helping tiling move forward

 

[Ajax123]

But Ray the tile does not add to the strength of the screed. It merely add an element that might act compositely with the screed but each element remains unchanged. Sort of like the whole is more than the sum of the parts.

When testing flexural strength of screeds which is the important bit really we use prisms of 40mm x 40mm x 150mm which is the european standard test method, so testing a 25mm piece would not really tell us anything very useful. Compressive strength is less important as its generally over engineered, but as a rule we work to a minimum Ca-C25-F4 on standard mixes and on specials up to CA-C35-F7. The samples should be cast rather than cut from a lump as it is generally impossible to guarantee that the cutting process does not fracture the screed and the size can never be as accurate. the standard that we work to is BS-EN 13454 and BS-EN-13813 and are certified to ISO9001 and CE accredited. TS -15 and TS -20 have been independently tested for in situ crushing strength by Aston Services and meet the requirements for Category A when laid bonded or unbonded and the strengths are CA-C30-F5 and Ca-C35-F6 respectively. Our TimBRE product is independently tested by TestConsult Ltd for use on a timber substrate and our diamond screed (polished system) is independently tested by Warwick University. Our standard products are tested on a daily basis during manufacture using a quality assured testing regime. They are tested for setting time, strengths and a number of other factors which are not relevant to tiles and we carry out probably several hundred tests every week. We use statistical process control methods and have the only fully temperature and humidity controlled laboratory in the UK. We have carried out all sorts of other testing in house and externally over the years in order to ensure that the products we make not only meet the standards that are set for them but also that they exceed the fitness for purpose requirements that the industry sets in terms of deliverability, usability and robustness By all means carry out your tests but really you cant tell us anything that we don't probably already know and unless it is carried out in a manner that is standard, repeatable and can be compared to normative testing then it is pretty meaningless. You can buy a bag of Sureflow screed which is a Gypsol screed from CCF if you like and make your own samples. I can say with absolute confidence though that a sand cement screed hand laid and hand compacted is rarely if ever going to have as higher flexural or compressive strength as a self compacting anhydrite screed, tile or no tile.