Morning,

We have converted a conservatory area into what I would call a normal room, with a TF extension which was built off of existing foundations as they were deemed adequate enough. We also retained the ground bearing slab, 100mm PIR and traditional screed with UFH.

With the wall now out, its apparent that what was the conservatory screed is circa 25-30mm lower than the kitchen screed across the floor - measured using laser a measuring stick.

Where the wall has come out, circa 250mm gap, the DPMs have been joined up to be continuous across the gap and so far, 50mm of PIR has been laid. Could maybe getaway with another 25mm, but cannot match to the PIR in the kitchen because of the height difference and would leave screed thin in that area.

Conservatory area screed has 25mm PIR and a 10mm foam expansion strip around its perimeter, which finishes at the height of the screed. Unfortunately the polythene slip sheet is not present all the way around. Looks like someone has previously gone round and torn it out once the screed was dry when done originally. Eg, may removing excess, I dont know........

Contractor 1 - advised optimal solution would be to screed the wall gap to the height of existing conservatory screed then use a self levelling compound to required height. However, in their view, there is currently no way to contain the self levelling compound from draining down the sides at the perimeter, as this would usually be done by membrane/ slip sheet being brought up the sides. Bonded screed was a no as new layer too thin and heated screed below would cause it to fail.

Contractor 2 - Remove the old screed and start again, but stating this may damage the UFH pipes.

Is there a way to re-do the perimeter side of things to make it liquid proof and hold in the self levelling? Or should I bite the bullet and careful remove the old screed - about 23 Sqm of it.

Thoughts / advise welcomed.

John

create a dam with expanding foam all round the perimeter?