Del-inquent Posted May 16, 2023 Share Posted May 16, 2023 Just pondering on an issue with a relatives house, trying to find any plausible solution. Property is currently being extended both sides of an existing room. The extended floor slab on one side has had too much concrete poured, its about 40mm higher than the other side. Problem is, the property had rather low ceiling height in the first place, and losing that 40mm isn't great. The room isn't that big, 2.4m x 2.8m So my questions are... What would be the most efficient/effective/remotely possible way of cutting off/grinding off/skimming off the overpour, if at all possible? Is there some sort of "super screed" that can be put down a lot thinner than usual? Link to comment Share on other sites More sharing options...
JohnMo Posted May 16, 2023 Share Posted May 16, 2023 Do you need to screed at all? Where is the insulation going, what sort of insulation and how much in the floor? Are you using radiators? Link to comment Share on other sites More sharing options...
Del-inquent Posted May 17, 2023 Author Share Posted May 17, 2023 13 hours ago, JohnMo said: Do you need to screed at all? Where is the insulation going, what sort of insulation and how much in the floor? Are you using radiators? I don't know if they need screed is the honest answer! The insulation is under the slab apparently, I believe it's Celotex PIR as there was a lot of that sat around, not sure on thickness. The oversite is... "a bit lumpy" to say the least, so would need *something* doing first. They're planning on tiling the entire ground floor so could the tops be knocked off the worst of the slab and a self levelling compound take care of the rest? Link to comment Share on other sites More sharing options...
Temp Posted May 17, 2023 Share Posted May 17, 2023 How big is the room that's too high? Might be easier to break it out and relay it the correct height? Link to comment Share on other sites More sharing options...
Del-inquent Posted May 17, 2023 Author Share Posted May 17, 2023 1 hour ago, Temp said: How big is the room that's too high? Might be easier to break it out and relay it the correct height? 2.4 x 2.8m, the breaking out option would be a lot of hard work by hand I think! Link to comment Share on other sites More sharing options...
JohnMo Posted May 17, 2023 Share Posted May 17, 2023 That is a small area, if the concrete is on insulation, it should have a plastic sheet between the insulation and concrete. So would imagine a day's work to remove, another day to backfill. Builders job to rectify at his cost, he messed up. To correct or make a rubbish floor flat, is a self leveling screed, just build up low spots to match high spots. Link to comment Share on other sites More sharing options...
Del-inquent Posted May 17, 2023 Author Share Posted May 17, 2023 2 minutes ago, JohnMo said: That is a small area, if the concrete is on insulation, it should have a plastic sheet between the insulation and concrete. So would imagine a day's work to remove, another day to backfill. Builders job to rectify at his cost, he messed up. To correct or make a rubbish floor flat, is a self leveling screed, just build up low spots to match high spots. Long story on the builder... complete and utter cowboy that frankly I wouldn't let back near the property ever again, if it were mine, and I'd be pursuing them through the courts to get money back as well. Sadly not my shout on that, I'm just being asked if I can help clear the mess up. IF we can avoid taking the floor out that would be ideal not just on a cost basis, but also "save my aging back" basis. Do you think a self levelling screed on top of the oversite would be a bad idea or a "bit of a bodge, but it'll do the job okay" idea? What's the minimum thickness and any additional bonding needed? Link to comment Share on other sites More sharing options...
Temp Posted May 17, 2023 Share Posted May 17, 2023 (edited) Self levelling screed can be as thin as 3 to 5mm up to 50mm. So 40mm should be fine. Check the spec before buying. If the room has three seperate concrete slabs you are very likely to get some cracking where the slabs meet. These cracks can propagate through tiles. So I think you will also need an isolating membrane on top of the self levelling before tiling. I think a typical 20kg bag will cover 1 sqm to between 10 and 15mm depending on brand. So I think you are likely to need betwedn 50 and 80kg per square meter. It can also start to set quite quickly so you have to be able to mix and spread it fast enough to keep up with that. It's exothermic so I think thick layers are more likely to self heat and accelerate setting. I've only used it once so others might be better to comment. Edited May 17, 2023 by Temp 1 Link to comment Share on other sites More sharing options...
Dave Jones Posted May 18, 2023 Share Posted May 18, 2023 21 hours ago, Del-inquent said: 2.4 x 2.8m, the breaking out option would be a lot of hard work by hand I think! mornings work with a hired breaker. Link to comment Share on other sites More sharing options...
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