Underfloor electric heating for piered timber floors

Wow - that was a bit of a waffly title

So the next project is a house on piers, and the extension will just continue this flooring line. The remains of the existing house are beautiful 100 year old timber floors - but the extension will be a standard tongue and groove chipboard flooring underneath an engineered timber floor ... and I'm researching heating options for winter.

We will have a gas fireplace for aesthetic reasons - but can't keep it on 24/7 like my good old trusty wood fire - cannot stand aircon for heating as too muggy and claggy for my liking - will have a double solar array with battery , so no shortage of electricity ... so ... I'd like to install underfloor heating in the new section.

No idea of cost (so might yet get canned) but the best option appears to be the 2.5mm foil matting installed between the chipboard and the floating engineered timber. Yes, the extension subfloor will be lower to compensate for the 18mm thick floating floor, so easy to go the extra 3mm.

Anyone done this before? How did it turn out? Did you feel you needed extra underfloor insulation? Was the cost worth it?

https://www.thermogroup.com.au/wp-content/uploads/2018/09/Thermofoil-140W-Datasheet.pdf

 

IMHO heating of a timber floor would be unnecessary as it is already an insulator and does not transfer the cold in the same fashion as tiles on concrete. Heating the floor may also make the timber too dry and brittle (lower moisture content).

Definitely would be using R-Max styrofoam insulation under the floor regardless of heating on top.

The alternative would be ceiling-mounted infrared panels.

 

I'm not totally up to speed with underfloor heating (never used in QLD).. but pretty sure it wouldn't be used in a suspended timber floor.. the heat would be lost in the subfloor as apposed to heating a concrete slab (thermal mass).

 

Did a couple of hours of research and looks like "yes we can" ...

Looks like the mesh electric system could work - for $2,500-3,000 installed for the 65sqm living/dining/kitchen. Would need to be pre-and-post-wired by the electrician, a 6mm fibre cement "underlay" laid over the chipboard, under the mesh, and then the mesh on top. We probably wouldn't lay the mesh until we put the flooring down, and it appears to be a self do job, except for installing the thermostat. Would have to work out layout so that get the right size roll (cannot cut) as no need to do under kitchen benchtops or in study cupboard. Comes in at a 4mm height, plus fibre cement underlay, total 10mm under timber flooring.

Cost:
45 sqm roll $1250 - Wood Floor Heating | Coldbuster Underfloor Heating
50 sqm roll $1359
65 sqm 6mm fibre cement @20/m $600 - James Hardie Ceramic Tile Underlay 1800 x 1200 x 6mm FC Flooring 2.16sqm
Thermostat $112 - Thermostats | Coldbuster Underfloor Heating
Electrician $500-ish
Padding on top of mesh (checking out what is required)

Install: https://www.coldbuster.com.au/learning-centre/timber-heating/

A bit of insomnia reading over a wee dram

 

Ceiling panels - Heat On Systems | Heating Solutions For Contemporary Living

Or these- Herschel Select Ceiling heater panels

 

Gas is connected to the property - so the potential is a gas fireplace ... BUT ... the electricity from the solar is free so might as well use it.

Can't see the point of ceiling based heat panels as heat rises

 

That’s not too bad considering it’s powered by free solar power..
I’d probably install thermal bats with a foil backing in the subfloor (between the joists) to minimise heat loss in the subfloor.