Retrofit UFH by grinding/milling existing concrete floor

[jtothelo]

Hi - I'm extending my kitchen/diner and want to install UFH.  Its extending by 50%, so will have half existing concrete floor and half new floor.  The floor in the new bit is yet to be done.

The cost of digging out the existing floor is a LOT - I'd like to avoid this if i can.  A couple of companies I've seen advertised lay UFH into existing concrete floors by cutting channels and laying the pipe inside.  The house was built in 2002, so the existing floor (should) be reasonably well insulated.

Example companies: https://www.outsourcedenergy.co.uk/in-cut-underfloor-heating/ and https://www.jk-gb.com/jk-in-ground-ufh.php

Has anyone had any experience of this method?

[markc]

I wouldnt be so optimistic regarding the existing floor being insulated, more likely it isn’t so putting pipes into the concrete is a waste of time and money.

Drilling a hole would give you the answer but then that would puncture a radon barrier or DPM, better to check at the interface with new floor as that area will be disturbed anyway

Edited April 25, 2022 by markc

[Nickfromwales]

2002 should have been under the BRegs radar, yes, but assume at your peril!

I’ve done exactly as you’re doing for a client who did not want to pay for excavations / removals / new concrete. 
Apart from the losses of a possibly non / not very well insulated slab, it worked quite well. That section ( about 20m2 in that instance ) just took a bit longer to heat up than the new extended area.

The advice will always be not to router them in to your floor, but in absolute real world honesty, and if you can accept a bit higher running costs, you can carry on and  do this if it saves you a chunk of cash. 
Not ideal, but sometimes life isn’t ideal, so go make the best lemonade you can out of your wonky lemon lol.