I feel the need, the need for screed

[MortarThePoint]

The next big step for me is installing UFH and screed. For the ground floor (GF) we have used 375mm Thermobeam which has a 50mm concrete deck over 325mm of EPS. For the first floor (FF) we have used 150mm hollow core planks. We'll be using an ASHP to heat wet UFH.

 

We had to cut blocks to establish a good coursing on the GF as the Thermobeam height control wasn't very good and so that has pinched 10-30 mm in places. Consequently, and because we have 50mm of concrete as the next layer down, I want to use a thinner screed. I have been looking at Thermio+ which supports screed depths down to around 40mm (20mm above pipes).

 

I think I am sold on Ahydrite liquid screed over the more traditional type, though am open to persuasion.

 

The first floor HCF is much more level, but it makes sense to use the same screed throughout. I had wondered about forgoing underfloor heating on the FF, but we are interested in using the attic space so having two floors without significant heating seems a stretch. Again this would be around 40mm thick.

 

On thing I was wondering was about stud partitions. Should these be established (or at least their sole plates fitted) before applying screed or is it best done afterwards on top of screed?

[ToughButterCup]

4 minutes ago, MortarThePoint said:

...

On thing I was wondering was about stud partitions. Should these be established (or at least their sole plates fitted) before applying screed or is it best done afterwards on top of screed?

 

Our partitions were fitted beforehand. I think  ( in my case thats dangerous ) it doesn't matter. What does matter is that the screed be given more than long enough to dry out completely.

@nod will be along in a minute. He's forgotten more about screed than all of us put together  know about it.

Edited April 7, 2021 by ToughButterCup

[MortarThePoint]

4 minutes ago, ToughButterCup said:

Our partitions were fitted beforehand. I think  ( in my case thats dangerous ) it doesn't matter. What does matter is that the screed be given more than long enough to dry out completely.

 

I'm expecting to have to leave the house alone for a week to 10 days and then only do non floor based tasks for another month after that. I guess an advantage of getting the sole plates in before screed is that the stud partition could then be assembled after 10 days rather than possibly waiting the extra month.

Edited April 7, 2021 by MortarThePoint

[nod]

You can do it either way 

Personally I’d have a day getting the studs in and put a 100 mil rip of ply around each stud 

You can normally walk on most screeds after a week 

If you go for liquid screed it harden and dry much quicker than C&C 

We normally tile liquid screed after a week 

[simon45089]

I had 50mm of Ahydrite screed poured last Thursday. 120 sq metres. It was fine to walk on after 24 hours although I waited 48 as per advice of very experienced screed chap. It was a joy to see it being laid, so quick, he took longer to clean up than pour and level the screed. It is dead flat according to my level. I did all stud  partitions first, fitted kingspan upstands 50mm higher than the expected  finished screed level,  and then  attached the foam expansion upstand tapes to these as advised. Worked a treat.

Simon.

[MortarThePoint]

1 hour ago, simon45089 said:

I had 50mm of Ahydrite screed poured last Thursday. 120 sq metres. It was fine to walk on after 24 hours although I waited 48 as per advice of very experienced screed chap. It was a joy to see it being laid, so quick, he took longer to clean up than pour and level the screed. It is dead flat according to my level. I did all stud  partitions first, fitted kingspan upstands 50mm higher than the expected  finished screed level,  and then  attached the foam expansion upstand tapes to these as advised. Worked a treat.

Simon.

 

Thanks Simon. Would you mind passing on the name of the supplier (DM you prefer)? I'm really keen for it to be level as that saves a lot of messing about and is one of those signposts that they have taken pride in their work which gives you confidence the rest has been done right.

 

Is there a reason you added Kingspan upstands as well as the foam expansion upstand tapes? Are you then using insulated plasterboard above that?

[MortarThePoint]

1 hour ago, nod said:

You can do it either way 

Personally I’d have a day getting the studs in and put a 100 mil rip of ply around each stud 

You can normally walk on most screeds after a week 

If you go for liquid screed it harden and dry much quicker than C&C 

We normally tile liquid screed after a week 

 

One complication I'll have is on the ground floor we have a gas membrane, so I'll have to work out how to anchor the sole plate of the stud work walls. That will be easier after screed won't it, or should I be casting something into the screed? possibly the act of casting the sole plate itself in is the way to go.

[dpmiller]

We're certainly well pleased with our hemihydrate screed.

[simon45089]

I used Express Screed, based in Ripon. They will travel all over though I was told.

Kingspan upstand as I am overlaying  the studwork with 50mm more kingspan and that will tie in nicely.

A useful tip  is that when securing the plastic that goes under your pipes, and also comes up the wall above screed level, it is possible to simply use a few spare pipe staples and poke them through the plastic and into the kingspan upstand to stop it flapping down. Holds much better than tape- my tape anyway !

Simon.