Latchy Damp rising through concrete slab is not an uncommon problem. I can think of 3 possible reasons. As this is a newbuild it may be that the concrete has not fully dried internally and a small amount of moisture remains inside. When someone moves in and the heating goes and the place warms up on that moisture can get drawn to the surface. Another possible solution is that the waterproof membrane that should be installed prior to the slab being poured has been damaged in some way allowing water to seep up through the concrete. If this is the case you may have to waterproof the surface to prevent this keep happening. Lastly and possibly the worst scenario is that the people who designed and poured the slab didnt have any idea what they where doing and have not installed any waterproofing and used a poor concrete mix. Cant really think of any health and safety issues associated with the drying out of the slab though. regards

If it's clean fresh water and not freezing, it probably helps the concrete. Concrete cured underwater is generally better than air-cured. Significant concrete pours usually have a curing membrane, which is waterproof skin designed to trap the water in the concrete and stop the surface drying - in general terms the surface drying out during curing is much more damaging than the surface being over-wet. The traditional approach is to cover the concrete surface in hessian and hose it down twice a day to keep the surface wet. Concrete curing is a chemical reaction that uses water - its' not a drying out process. (There are controlled permeability formwork systems that use drying of the surface to mobilise a microscopic fines transport mechanism to give a more dense concrete surface - they are kind of a special case, in all other cases it's drying the surface that's bad, not wetting it). If you have too much water in the mix you get a more microscopically porous matrix, which will be weaker. However, pouring water on the surface won't do that (or water spreading across the surface from a discrete leak). However, I would worry not that the concrete might have been damaged by the leak, but that the leak indicates that the concrete or workmanship was deficient in some way (not compacted, wrong mix, no membrane) which allowed the water in. That is, the concrete may be duff and that's what has let the water in, not the water has got in and made the concrete duff.

I have just spoken to the site agent and he informs me that the floor is actually floating, beams and block with a screed over the block now does that change things, how can water be coming through the floor?

It can't. If it is a floor with a void beneath then it's not coming through the floor (unless the void is fully flooded).

Hi latchy Just to confirm it will absolutely not be leaking up , as the void beneath the bison beam to the void bottom could be up to 2" 6" no chance. However the cavity wall around the floor usually get filled with filled with concrete , this should be up to no more that 9" from the floor level. If the cavity has been loaded with concrete or the brickies have not been tidy with snots falling in side the cavity then this I could see as a "bridge" which may connect water/ damp from the outside ground to the top of the screed or directly beneath the screed and soaking the insulation thus being the final bridge from outside to in ? I would personally be looking around the cavity area at DPC level , Not conclusive and I am sorry I can not confirm or other wise but if leakage is discounted from above ie plumbing works ? but this would surely leave a big trail to follow so maybe not , let me know how things go. Regards