Dave Blake wrote:

I'm considering using wet underfloor heating in our newly installed
conservatory. It will be an extension of the existing gas central
heating system (radiators in rest of house) driven by an on-demand gas
boiler (no water tank).

The conservatory is 4m x 3m, glass/dwarf walls on 2 sides, was
designed to be a warm living room (e-glass, high spec, insulated etc.)
and to building regs. It will have a suspended wooden floor (joists
and boards NOT concrete slab) because the garden level is much lower
than the house and we want the floor at house level. However this not
constructed yet so heating can be included into the design.

How viable is underfloor heating in this situation?


Its definitely on, but not (as) cheap or easy (as in a screed).

Since you are starting fromn scratch. its better than most tho.

Problems will be.

(i) You need GOOD insulation downwards. If you rae using a concrte
subfllor I would be inclined to actually build up a solid floor using
hardcore sub base, then usual metnods of smoothing, followed by DPM,
insulation (50-75mm polystyrene) followed by a screed with teh pipes in it.

Even if you lay a suspended floor just over the top of that, it may be
easier than e.g. infilling your joists with insulation, and laying pipes
over that. The pattern of contra rotating spirtals that gives the most
even heating really doesn't fit in with parallel joists.

(ii) UF and wood floors are NOT happy bedfellows. You will need to use
narrow planks, pre shrunk to very low humidity, or 'engineering' wood
floors, and either lay fully floating or expect some gapping warping and
cupping.

If its a modern style you want I would 100% recommend what I did -
screeded floor-with-pipes and real wood engineering type surface.

If you really want a suspended floor feel, it can be done, but expect to
have to adjust the odd plank and/or sand bits down after the first year.

Ther is no problem by the way, in filling up an extension floor to get
it up to level. Usually the foundation spoli is used to get it roughly
right...and any surplus bricks, slabs, bits of dead rate etc etc...are
just bunged in and tamped down before casting the first slab :-)



Or should I just
install a radiator (using precious wall space)? Any recommendations
for products and suppliers (considering DIY since did all the building
work)? Useful web sites? Will underfloor heating work?

Advise, experiences, possible problems and suggestions welcome.
Dave