Greenlane

Doing an extension and have laid a concrete slab which is due to have insulation and wet underfloor heading and then screed installed. I want to build the stud walls before the UFH is put in, but worry about cold bridging damp up the studs. Could do with advice on how to fit the sole plates either 1) screwing it into the concrete (could wrap it in visqueen) 2) laying a row of concrete blocks on dpm just below final screed level and then screwing the sole plate into them. Any practical advice would be welcome about the way to go...

Over the last few months have built a large single storey extension block with cavity and insulation on a currently empty property. We have recently had the flat roof done covering the entire area. The cavities got wet due to bad weather, so I've recently covered them and the external block work with sheeting as I'm still awaiting the arrival of the coping stones to close the walls around the parapet. There is plenty of airflow inside due to the Windows not yet being fitted. Particularly in this cold, damp, wet weather Some of the interior block walls are getting damp/wet and the roof joists and Visible roof steels are the same, most of the moisture evident where the joists sit on the external walls. I can't see it being the weather getting through the block work or down the cavities as they are now covered with plastic sheeting.. Is it likely to be condensation? Should I cover all the window openings as best I can to try and get the inside dry? Any advice would be helpful.....