underfloor Insulation

[Steve London]

Hi
Can anyone help, I have a victorian terraced house

I am considering fitting some type of underfloor insulation on the ground
floor to cut down on heat loss through the wooden suspended floor.

I would prefer to fit the insulation from underneath the floor
(there is a gap under the floor boards where it is possible to crawl along, although sheets would need to be cut down due to the restricted space) rather than having to lift the floor boards & re-fix them (I would not cover the air bricks to allow free air flow to the joists etc.,)

My questions are:
1. Would you recommend insulating this type of floor & if so, what
type/brand & thickness would be recommended

2. Should there be a gap between the under side of the floor boards &
the insulation, if so what size gap would you recommend

3. Please advise whether a fire retardant grade is recommended, the
area to be covered is approx 40 sq metres in area

4. Is it ok if the insulation comes into contact with pvc covered electrical
cables & copper central heating pipes?

I would be grateful for any advice anyone can give especially if they
have done anything similar

regards
steve

 

[MdB]

4. Is it ok if the insulation comes into contact with pvc covered electrical cables & copper central heating pipes?

Polystyrene + PVC don't go together well so don't use polystyrene as your insulation (not that you would due to it being highly flammable). You also want to be careful about encasing your wiring in insulation as it can cause the cable to overheat. It is not generally a problem if the wiring is fixed to a beam or resting on the surface of the insulation as this causes less of a heat rise. You might want to read up on the appropriate wiring regs on this.