Botched internal concrete floor in extension

[EvilGrin]

Hi all, am having difficulties with the concrete floor laid in my new extension. There have been numerous issues with it, firstly the concrete poured into the extension hardened before it could be levelled off properly.

Our builder promised that it wasn't an issue and attempted to fix it after the house was fully built with self levelling compound, but it just made the floor even more bumpy, uneven and unlevel. He's accepted it is unacceptable and hired a local groundworks professional to dig up his bad screed and level off and fix the floors.

He's finished the floor now, and although it is better, it still isn't within NHBC tolerance (4mm over 1m) in many areas with hollows and lumps and bumps. Also he's used a sand and cement mix, it has been about 5-6 days since it was laid and when you rub your foot over the floor, it rubs off sand. For example, our fridge was a dragged across the floor by the workers leaving marks along the floor, I rubbed over the marks with my foot and they sanded away.

All we want is a floor that is fit for purpose for us to lay solid oak/engineered oak/laminate on and not come into any problems in the future.

We've been moved out of the house for 2 months while he's been trying to fix this and we're desperate to move back in. We've given so many chances to our builder to get this right, and now I'm concerned that we have another bad floor laid. Who should I turn to to check over the work, as I really have no idea what is acceptable beyond tolerance guidelines, and have no idea if it's a failed floor? Any advice very much appreciated, thanks guys!

 

[EvilGrin]

Yes, not planning to lay the floor any time soon which is another frustration as you're right I don't want to fork out a few grand for nice new floor and have it bow and warp. I'm pretty confused about everything myself, and probably not using the correct terminology, but he laid the concrete slab to very near the existing floor level, this was botched, unlevel and uneven, and he attempted a thin levelling compound (it was latex I think, can you call this screed, or is a screed something different?) on top of this to rectify it which was around 10mm at its thickets I believe.

Anyway latex levelling compound/screed/whatever has been dug up now and he's used a thick sand and cement mix, I'll try and dig out some pictures.

At the worst I think it was was probably around 35mm out total from highest to lowest point across 5 rooms. This was across Dining Room (existing) and new Sitting room (which are open plan), then through door threshold from sitting room to playroom which then leads to Utility room and Study. I believe it's now around 15-20mm out across the new surfaces, and up to 20-25mm out with the existing dining room.

 

[EvilGrin]

You can't use sand and cement under 40mm (50mm if UFH)

http://www.concretecentre.com/technical_information/building_solutions/floor_screed.aspx

So if they've used a self leveling modified screed that performs perfectly adequately under 40mm and replaced it with a un reinforced sand and cement screed less than 40mm then it's only a matter of time before it breaks up and turns to dust.

Ok, that's exactly what I didn't want to hear, yes the thickness of it is most certainly under 40mm and it is also un-reinforced. Thanks for confirming my suspicions though. I think I'm going to hire a quantity surveyor to report on the floor, and charge the cost of it to my builder.

The spec of the concrete slab from our building spec is 150mm fill, radon membrane, 130m kingspan tf 70, 125mm concrete, finish and mesh. This was up to a max of 25mm lower than our existing finished floor level, but it is so bumpy and uneven some areas may be as little as 1-5mm lower. Is there any sand and cement screed mix that would be suitable for this finish, or would it just be latex/anhydrite screed that's necessary?