I’d be really grateful if anyone can wrap their head around this: I want to put in underfloor heating in two adjacent rooms and install ceiling insulation in the smaller one which is a side extension. I’m trying to work out how to achieve the fewest changes in floor levels while minimising the amount of structural alterations. I’m attaching a sketch which hopefully might help with the following explanation.

The rooms are at the bottom of a short flight of stairs. The door to the rooms is about 1.5 metres from the bottom tread of the stairs. This door (door 1) is 197cm high. The room (room 1) it leads to has a ceiling height of 254cm. The current floor is roughly level from the bottom tread of the stairs outside the room to the far end of the room except for the last 33cm where there is a small step up by 9cm to a set of patio doors (door 2). The threshold of these doors is another 9cm above this step. The ground level on the outside of the patio doors is 12cm below the threshold.

Room 2 is to the left (as you enter room 1). This door (door 3) is 195cm high. The ceiling height in this room is 224cm. This is the room where I want to put in ceiling insulation.

I would REALLY love to get rid of the small step just before the patio doors in room 1 (I think it basically boxes in service pipes).

These are the options I can see at the moment:

* Floor insulation is going to raise the floor level anyway so it could be raised to be level with the step in front of door 3 but then this means you either step up 9cm on entering via door 1 or continue at that floor level to the bottom of the tread but then the last step would be half the depth of the other steps. Also door 1 height would be reduced by 9cm meanwhile door 3 would shrink to 186cm.

* As above but raise the height of doors 1 and 2. I’m not sure about door 1 but door 2 would be problematic because it is in a main external wall and may involve party wall issues. Also the ceiling height when insulation has also been added to the ceiling would probably make it too low. (Definitely do not want to take the external flat roof off to install insulation).

* dig out the floors in both rooms 1 and 2 to install the insulation and retain the current floor height. The current flooring in both rooms is tiling on solid floors which would take some serious breaking up. This still leaves the pesky step in front of door 3.

If you’ve managed to get to the end of this, thanks for your persistence, and I’d welcome any opinions or ideas as to the best solution!