Can't afford underfloor heating.

[Ooops]

Hi Guys
I have been searching this site for an answer but can't find it. We are going to install 600x600x20mm concrete tiles to our groung floor. We cannot afford underfloor heating and was wondering how best to insulate it?
I'm going to replace the floor boards with 18mm ext ply, add some extra noggins and have the joists treated. Anything else I should consider? Thanks for any advise offered.

 

[jdp-tiling]

whats the sq/m of the area to be covered
most leading ufh companies do an insulation board.
one link here.
http://www.warmup.co.uk/uk-tile-backer.phtml

 

[Ooops]

Thanks for the quick reply jdp.

There are two rooms each about 16sqm. I hope this doesn't make me sound thick but do you think I could put this board under the Ply, in between the joists? My concern is that the height of the floor is getting ever higher. The ply is 18mm thick, the adhesive is 5mm thick and the tiles are 20mm thick = 43mm.

 

[jdp-tiling]

you can get insulation that sits between the joists..i think it will be much like loft insulation. may be worth thinking about.
then the threshold of the room wont be too raised much.

 

[Ooops]

Thanks Pal I'll have a hunt around.

 

[ColJack]

could try rockwool suspended on chicken wire to stop it falling through...

 

[Ooops]

I have lifted a couple of boards to see what's underneath and found a 3 foot void. So my next question was going to be how to I stop the insulation falling through? Thanks for your tip ColJack spot on.
By adding the insulation will I be restricting the airflow around the joists which may cause problems in the future or am I just being thick again?