Hi, I have had some building work done extensions and all the floors are uneven. Like 1 part is 50mm higher than the other. Total area is 120 sqm. Had a ufh guy come out and said he can liquid screed it all but I will have to sand the floor myself to take the top layer of laitance off with a 60 grit sander….The screed he uses is anhydrite. He also said once it’s sanded the karndean I will be having can stick straight onto it. It doesn’t need a self levelling screed ontop? he did say it will need priming with a penetrating primer and to use uzin pe360 plus. Then the karndean can stick straight onto that. Any advice on his info guys? Or does that seem all good? another note on some parts where the floor is joists there will be a 22mm plyboard that will be screeded over do I need to treat that ply board before screed goes over.
After it’s grinded and allowed to dry below 75%Rh usual prep would be required inc primer and then a smoothing compound etc if they are going for it as soon as then a liquid dpm or case hardener can be applied, then primer then compound etc, what’s his thoughts over the 22m ply ?
Don't listen to the screeder about it won't need anything on top other than a primer l, I've seen a few of these fail and there's ones still ongoing 5yrs after it was laid with random planks becoming unstuck that was just primered, it's a gamble in my opinion and its a big area. I'd be giving his screed a grind aswell as he's using anhydrite so leave it a week after he's done his bit and give it a going over. As Adam says, what did he say about his screed going over the 22mm ply??
Thanks for the reply guys. he didn’t say what will be going over the ply. I think it’s like a plastic dpm sheet he is going over all the floor with. Is that ok? when you say smoothing compound what’s that? Self level screed? so a week after it’s down I need to sand the top layer off. Then put that penetrating primer down then use a smoothing compound? So like a 3-5mm self level screed? I was trying to avoid having another screed put over he said he should get it to sr1 so won’t need another self levelling screed? also no rush for the karndean to go down he did say will take 2 months to dry anyway
If you wanna go straight onto that anhydrate you will have to use ridgid clic. Stick down won’t work. You will need to get a LvT fitter/company to prepare it. On the plus side you can force dry that screed with your ufh
Arrrr really. Even if he gets it to sr1 that he said he would? what’s best screed to get for this floor? He mentioned this stuff? Ultra Tile Fix ProLevel Two Flexible Two Part Self Levelling Compound 20kg
Unless I ask them to use a different type of screed other than anhydrate screed something I can put the lvt straight onto?
If the screed is exceptional and your not fussy about the finish you may be able to sand the top and use a gypsum based micro finish over it all We use to use Shonox AST. Not the easiest to get hold of tho
