im tiling a concrete floor with 600*300 porcelain tiles. I noticed yesterday that the addy was taking ages to set. 36 hours later i find that a few of the tiles next to the patio door are moving. I pulled one up and find that the addy is as soft as it was when i first spread it. Do you think this is just down to the weather? Its currently snowing in Harrow! Where im currently working. Cheers Sean