All the floors downstairs have had 80mm Kingspan installed and the joints taped up. Then, as you can see in the pictures, there has been Visqueen put over the top - this is the stuff they use for DPM - it is there because the flow screed that we are using reacts with the Foil backed foam insulation (Kingspan) - so to stop it you use this plastic membrane. Then the Electric Underfloor Heating cables have been put in (red in pics) where required, with floor sensors.
This has taken a bit longer than we thought - we were hoping to have poured the screed by now. Laying the cables right has been the problem, they are of fixed length and cannot be shortened. So if you consider that the cable for the heating in the lounge is about 150 metres long, you need to cover the floor with evenly spaced loops over 20 sq m, it is a bit of a bugger to get this spot on. The fixing strip for the cables has loops to clip the cables to - these have been securly taped to the membrane.
So why use electric UFH when the most popular by far is the hot water pipes UFH you ask. This is the idea - where we live the electric suppliers Scottish Power have an economy tariff (option 14) which gives 14 hours off peak electricity each day. This gives you electricity at about 1/3 of the normal price between 9pm and 8am then again from 1pm and 4pm in the afternoon. So you put a nice 60mm flow screed (much denser then normal screed) on top of the EUFH - and basically 'charge-up' the floor using the off-peak electricity. It then switches off before you go on-peak and the floors act as a 'thermal mass' holding the heat nicely. The MVHR system also helps - it recycles the heat around the house. So we should have a nice warm house for cheap! well thats the theory, we'll tell you if it works when we move in!
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