Looking to raise floors and ad under floor heating

[boyyo]

Hello All,

I've posted on a couple of DIY forums with less feedback than I'd hoped for so am looking to see if this is a better place to ask...

We have an early 1900's semi, with sound well ventilated suspended floors but without any underfloor insulation. Unfortunately, we're needing to look at having the three rooms insulated and equal floor levels due to a developing medical condition for my better half.

I'm looking at the possibility to install Under floor heating throughout the ground floor at the same time as insulating. One roomneeds to be raised by approx 140mm to meet the others.

Having spent some time searching on best methods etc and coming across conflicting info from Engineering flooring and UFH suppliers, I'm looking at the following set up and would love to hear if it's OK or am I barking up the wrong tree!?

I have images to show what I'm looking to do but can't see how to show them...?

Attached are two images showing that I have to work in two ways...one adding a floating 25 sq/m slab across an existing suspended ground floor to make up the 140mm to reach two other rooms where I need to go between joists to keep the floor as low as I can.

The other two rooms are 20 sq/m each.

I've played around with the Plywoood thicknesses just to balance the end levels, and maintained 70mm on the Celotex.

All comments welcome!

what will your "slab" be made of?

Thanks for the response.

The slab will be placed down on an existing suspended floor with good floorboards, well ventilated and bone dry, its 25m/sq.

From top of existing floor boards I was going to lay...

70mm Celotex...all taped up to another and to walls etc
18mm Chipboard T&G ...glued
25mm UFH routed FPS insulation
UFH spreader plates inset into FPS insulation
12mm Ply
2mm Engineered board / UFH underlay
18mm Engineered oak boards...top surface

I had similar issues on laying under floor heating on my 1930s house a few years ago except that rather than putting insulation under the floor boards, I decided to put the under floor heating boards on top of the floor boards to reduce the amount of work. I bought a Polyplumb 20m2 kit under floor heating kit for 800 pounds and just follow the instructions. I only did the ground floor. By doing so, it raises the floor height by 18mm meaning all the doors have to be reduced accordingly. I can post some pics.

Some pics on the under floor heating I installed in my hall showing the ufh pump and mixer connected to the existing central heating pipes. And how each ufh circuit connected to the existing radiator pipes in the hall.not sure how to attach pics to this post

Thanks for the responses,

Does anyone know if you can add images to posts?

You can send pics if using a PC to see mumsnet but alas my PC has died but if you pm me with your email, I can send you pics of the ufh.