under floor heating insulation

[pitza]

I am laying floor tiles with under floor heating in my bathroom which has floorboards, I was thinking of laying onto a waterproof plywood sheet but do I need to include some king of insulation so that the tiles warm up quickly?

[Rich]

Hi there

Funny that, just did ours last year the same, and we removed all the floorboards completely and replaced with waterproof plywood, bonded and sealed the joints, and made special lift up floor sections around pipe work.

Looked at several types of underfloor heating, and the specifications do vary from one manufacturer to the other.

Generally speaking, you wont need any special insulation, unless the underfloor heating itself comes with or recommends it, but you would always benefit from it if you did choose to put insulation under the actual floor itself, directly under your current floorboards, otherwise obviously heat will be lost warming the space under the floor too.

Depending on the size of your bathroom too, this could be expensive because building reg's specify you must use fireproof insulation, not that polystyrene rubbish.

Given a choice though, I would insulate the floor underneath anyway, even if it wasnt a requirement for the heating, but either way, the floor will always heat up fairly quickly, just how efficiently and how much heat is retained is what your insulation will affect.

Is your underfloor heating electric or water based?

[pitza]

Electric 'Warm up'

[Rich]

Electric 'Warm up'

Good choice, easier on maintenance and cheap to run too, and much thinner to roll out under the tiles.

They reckon underfloor heating is actually far cheaper than normal central heating too, costing only 0.07p p/hr to run. (Or about a grand if your with British Gas )

[sdlawson]

If you can find it the product you need is called SUPER THERM. It is a thin filmed multi-ceramic insulation coating that can be applied to the base substrate. This will better control heat from transfering into the base substrate. The floor and room will also heat up more quickly. The thickness is about the same as a business card. The product is also rated Class A fire rated in North America and does not burn.