Underfloor Heating Question???

[Rise Park John]

Evening All,

Quick question about electric underfloor heating.

Most mats recommend insulation boards but is there a lower profile option? I'm fitting a heating mat as part of a new kitchen but the insulation boards, plus the heating mat, plus the adhesive, plus the new tiles is pushing the floor level up a bit high. Is it possible to use a reflective foil to produce the same effect as insulation boards?

Cheers,

John.

 

[cr0ft]

I'd call the manufacturer to ask them on this one. I very much doubt it though as the insulation boards will be far better insulating, hence the depth required.

It is, unfortunately, one of the reasons why retro-fitting underfloor heating can be an expensive job.

 

[Rise Park John]

I thought that might be the case and can raise the base units by a few mm. I'm leaving the original tiling under the kitchen units so the levels won't be miles out but I'm trying to avoid a step at the kitchen door.

Thanks for the advice.

 

[StephenF]

If you were using a wet UFH system you could use a system called RETRO18 which is a grooved fermacell board. The board is 18mm and if you insulate with SuperfoilUF (equivalent to a 40mm Celotex) the total additional height is 24mm. Output well over 75wm2

 

[Rise Park John]

Thank you Stephen,

I've been able to source a pretty good solution to this problem. I'm using some Delta tile backer insulation boards that are 1200 x 600 x 6mm added to the heating mat which is 4 - 5 mm you get an additional 10mm (ish.) You do have to bed the backer boards on tile adhesive but I spent several fun hours leveling the concrete slab which has bought me a few more mm.
Previous comments about the difficulties of retrofitting underfloor heating are absolutely correct in that you have to estimate kitchen unit heights based on what the ffl will be, so fingers crossed that my calculations were reasonably accurate.

Cheers,

John.

 

[StephenF]

No problem - glad you sorted it.
It may be useful to know there are low profile options if a wet UFH system is preferred.

 

[Rise Park John]

I thought that it might be worth adding an update to this thread now that the job is finished. I used 6mm thermal boards bedded on Mapei flexible tile adhesive, (highly recommended,) and then rolled out the sticky heating mat. Don't be put off by the roll, it can be cut numerous times and straightened out to fit. One issue is the mat is typically 500mm X 1M / 2M / 5M etc. so it takes a bit of working out to get a good fit. Bear in mind that you can not shorten the mat / element, but you can create a loop / loops to take up a bit of slack / turn corners etc. My tiler embedded the heating element in a flexible self level, this added virtually no depth. Tiles went on top with a very nice finish. Couple of weeks to wait before I can switch on but the tested resistance values look good. Total depth of all the layers is around under 25mm which resulted in the kitchen ffl being under 2mm higher then the adjoining hall floor, easily lost with a threshold strip.With under floor being pretty much my only option I'm really pleased, (as long as it heats up!!!)

Cheers,

John

 

[Dan]

Surprised you aren't on our tilers forum

 

[Rise Park John]

Surprised you aren't on our tilers forum

I'd love to take the credit for the tiling!!!

 

[Dan]

Fair play lovely job that.