Repairing & Levelling Concrete Floor In New Workshop

[Jake]

Three potential problems to work through for anhydrite screed. First, I don't think it is suitable as a wearing surface. Second, you need to sand it all down to remove laitance before you can stick anything to it. Third, it's usually used for thinner layers and the drying time for thicker layers seems to go up dramatically.

Maybe they have special sauce though.

 

[Delaney]

I have used Flow Screed and have been very impressed with the results. 'Sticking' the screed to the base isn't an issue at all in normal use, as it is generally poured on top of a plastic sheet over insulation. The plastic needs to be sealed around all pipes or upstands and the sheet carried up the walls, as the liquid screed will go under the insulation and float it.
I would have no hesitation in using it in your situation. Indeed, I would even install a layer of hd insulation under it as a thermal break.
When you see it being laid it is difficult to see how an installer could get it wrong.

Tom thanks for the knowledge.
I might not be able to add more height than the 30mm minimum due to entrance ways etc.. but will speak to the owner and suggest it.
I think the farmers take a view that these are pretty rough snd ready sheds but it would no doubt save me money in electric bills, at commercial rates.

 

[Delaney]

Three potential problems to work through for anhydrite screed. First, I don't think it is suitable as a wearing surface. Second, you need to sand it all down to remove laitance before you can stick anything to it. Third, it's usually used for thinner layers and the drying time for thicker layers seems to go up dramatically.

Maybe they have special sauce though.

Agreed and it is more like plaster than a liquid concrete but the installer preferred it I think due to it being less problematic when curing.

I’m going to ask him to give a breakdown of his choices and why. I’ll report back when I have them.

I’ve also got Surrey Flow Screed coming on Friday to take a look. They have a good rep and reviews by builders who do a lot of work.
I’ll be interest to see what they recommend on inspection.

 

[Jake]

I think it is easier to pour mostly, and fewer problems with shrinkage cracking. Although I've never used a gypsum screed, I have used SCC and it's called SCC not SLC for a reason - quite hard work to agitate it to get it to flow to level and the larger the area the more that would multiply. But that was trenchflow not a screed specific flowcrete so the latter might be easier to deal with for all I know.

 

[Delaney]

I think it is easier to pour mostly, and fewer problems with shrinkage cracking. Although I've never used a gypsum screed, I have used SCC and it's called SCC not SLC for a reason - quite hard work to agitate it to get it to flow to level and the larger the area the more that would multiply. But that was trenchflow not a screed specific flowcrete so the latter might be easier to deal with for all I know.

It’s certainly a mixed bag.

Just spoke to someone else who was a very nice guy, tile fitter by trade but has vertically integrated underfloor heating and screed work, which makes sense.
He does not like anhydrite screeds but as a tiler he wouldn’t.
He recommends pumped liquid cement.

I must say I’m half tempted to divide the room into 3 sections and have a go myself. Of course that will end in disaster lol