Damp proofing sand and cement floor

Hi, You can apply a sealer to the floor, that will slow the moisture down. Was it a wet mix sand and cement your builder used..? If so, it can take 4-6 month to dry. A ready mix concrete slab will also take in dampness unless polished. You could take the present floor out and lay slabs on concrete and treat the slabs as well.

Its the steel shed not having insulation or ventilation thats the problem not the floor. We regularly have high humidity in this country so it will always happen. There is no difference in the chemical behaviour of sand/cement and concrete. They have exactly the same materials acting in exactly the same way, setting time and strength are the only real difference. Put in ventilation to draw the moisture out, top and bottom or insulate. There are a variety of tech options available too. You should seal the floor with a dustproofer 28 days or more after it was laid or it won't last that long and the dust will be irritating.