Hi All, bear with me as theres a bit to read: We are having almost our entire house renovated and remodelled, and we are 85% there, however we have run into an issue that 1) I'm not sure how to approach the builder about and 2) not sure how to solve. Basically, we have an old extension on the back that was knocked through to make a large kitchen/diner. This was always planned to have underfloor heating, however, because we didn't want to disturb the existing concrete slab underneath, our builder said he would lay a low profile underfloor system on top of the existing slab after some levelling between extension and old house, and we could floor on top. We also had large bi-fold doors fitted at the end of this space intending for the floor to be flush with the door threshold and a new patio at a later stage. The doors went in long before the floor was finished, and I double checked with the builder that we would have space for him to lay the underfloor heating and our finished floor on top (this was planned to be vinyl, similar to amtico or karndean. Usually vinyl tiles are 5-6mm thick. The vinyl tile is about 3mm thick) The underfloor heating is now in, a wet system thats run in 18mm foil faced polystyrene boards, and we are left with approx 15-18mm of space between the top of this and the door threshold. The builder is not fitting the floor for us, we are using a separate installer, so he has left the underfloor system bare, ready for whatever goes on top. EDIT: The amount of space between the top of the boards and the line on the door frame where floor should finish is 10mm. However, our vinyl installer says he won't fit vinyl or guarantee an installation unless he can lay the vinyl on top of 18mm of ply - this is for structural reasons, so that the floor feels solid underfoot, as well as to glue the vinyl to. The plumber says the insulation boards are fine, just put 12mm OSB boards on top, but installer says no. So the installer needs 24-25mm minimum, and we only have 18mm. Alternatively, these foil faced boards are suitable for laying engineered wood flooring directly on to them, however we are now stuck with choosing engineered wood but only wood that is 18mm thick, not the thicker standard 21mm, narrowing our choices quite a bit. The installer isn't keen on that either, although this might be for guarantee reasons, not installation guidelines. So our options are either, go with an 18mm engineered wood floor which potentially might be a little bouncy over the underfloor, or the two big ones which I would prefer to avoid: remove the brand new bifolds and refit about 15mm higher - which would mean re-plastering inside and re-rendering outside, OR lifting all the underfloor heating and digging down into the subfloor by 15mm, which I can't quite see happening. EDIT: The amount of space between the top of the boards and the line on the door frame is 10mm, ruling out pretty much every floor covering. There is no space to allow for standard sub floor preparation in the form of 18mm ply or screed, and then a finished floor on top. We need an additional 20mm of space to allow for most floor coverings. The builder had a planned 5 week trip which we knew about and he has now gone away, leaving the house just after 2nd fix stage had started, his electrician and plumber have been back and forth but we can't do much until the floor is down in the back room. Strictly speaking, he has left us enough space for flooring, but not really. He knew from beginning that we were planning vinyl floors, so speccing polystyrene insulation is his mistake surely? Any thoughts? I don't want to get into an argument with the builder just need a solution. New Question: Has anyone successfully removed and refitted aluminium bi-fold doors without affect the integrity of the frames and/or voiding the guarantee? Of course I will get the bi-fold installer to come back and fit them.