hi there.
im putting in a screed friday in a bathroom an dutility off of the bathroom . there will be about 75mm of concreteontop of a plastic layer.
how soon can i tile on top if it. it might need a layer of SLC to lvel it up perfectly.



thanks alan

?? Are you doing a sand/cement screed or concrete ?

concrete. i dont think there would be enough strength to sand and cement only

What is the ambient temp of the room?

imo min 2 weeks before you tile, remember concrete gains its strength by curing and not drying

sorry meant curing. concrete never stops curing fully .
the temp is probable 12- 15 maybe. il check .
im not cold in there but the home owner is freezing in the house( even beside the stove)

I would be allowing for either a liquid dpm or an uncoupling membrane. The concrete this time of year will take flipping ages...... Minimum of 2months if not longer before you tile. For the sake of the cost in a room the size of a bathroom i would not be tking risks and would uncouple......

how soon after pooring the screed could i uncouple then tile

If it's concrete, it's 7 weeks, but depends on the thickness of the concrete and following temperature. In cold temps (below 5 deg C) you may have to extend the waiting time for up to 12 months. Always drill a pilot hole to determine dryness and use a moisture meter probe. It would be tiling suicide to tile on a green background as new concrete will shrink over time (especially when central heating is introduced into the room). This will result in the substrate shrinking and de-laminating from the the fixed ties, breaking the bond and resulting in complete tiling failure. It's reality.

if i put a uncoupling membrane on would it allow me to tile sooner.

Yes. Take a look at the schluter website .... Ditra matting ..... That will tell you everything

Hi Guys, sorry to jump in your thread but my coservatory is going to be screeded on tuesday to a depth of 4inches, my plan was to leave it for one month, then prime twice, install 10mm insulation board on flexible adhesive, lay UFH wire, Latex then tile....... Does this sound like the best way to go to you pro's? someone suggested thati should lay ditra matting, the the thing is that i thought that insulation board would do a similar job to the ditra ie:acting as a slight deflecter. Or should i install both?

I will be tiling it with Travertine.

Thank you very much in advance

Ajax's your man for screed advise here.
Ditra mat doesn't effect the underfloor heating, so use it.
What your saying is the right way to lay your floor.

Originally Posted by bugs183

Ajax's your man for screed advise here.
Ditra mat doesn't effect the underfloor heating, so use it.
What your saying is the right way to lay your floor.

Wow that was quick, thanks Bugs.

Are you saying to use it as well as the insulation board or instead of the insulation board? If using it with the insulation board where would it's place be on the floor

Thanks mate

I have no life but this forum Motorman!!
Yea sorry didn't make much sense that. Lay your screed, allow to dry. Fix the insulation board with a good quality flexible adhesive (i use a 10mm trowel to get there to be bed nicely). I'd leave that overnight to dry. Test the ufh and use an electronic alarm during the installation to check it doesn't get damaged.Lay out the underfloor heating. Take photos so you have an idea where the cables run.
Now i do the next part a bit differently than the others here, its a bit messy but i hate faffing with tape and glue guns and swearing at the wires that refuse to lay flat. I trowel rapid set adhesive with a 6mm notched trowel onto the insulation boards, roll the ufh into this and then lay fibreglass mesh over the top (this is used for reinforcing render and comes on a 50m roll and is 500mm wide), then i press this into the adhesive and trowel in down. Its a bit messy and sometimes awkward, but i never have any hassle with the cables afterwards!!!
Leave to dry or level straight on top.
Leave overnight, get your 5-6mm trowel and again with flexible adhesive trowel this onto the dry levelling compound ad roll the ditra onto this. Get piece of wood 3x2 is a good size and use it to press the ditra into the adhesive. Leave overnight.
Start tiling!

Great stuff, thanks mate. Just out of interest if sfter laying all this down the sand/cement shrinks a bit and cracks would the insulationboard absorb this or deflect this the same way the Ditra matting would?

All this stuff is very interesting, a bit addictive almost!

Thanks again

Good question, there and one i can't answer 100% confidently.
It must have some give due to its make up, but no normal drying cracks should effect the underfloor heating, things would have to be pretty bad for that to happen.
The ditra can part within itself, yet remain the same shape, this is why it is such a good product.
Well if you spend all day tiling pretty much 7 days a week it does make good reading, and the guys here really know their stuff (i don't get involved in any football talk, not a fan at all!).

Thanks for that, i would have thought it would act as a defection barrier simply because it's got a foamy type material in the middle of it, but then again that could just be my lack of knowledge speaking!! Probably like most other things i have read on here, there is a bit more to it than that.