Loft insulation: how deep?

[F]

We've got one of the energy companies coming to my father's house to survey for free loft insulation. Anyone know how deep it should be when they've finished?

[David]

IIRC it should be 12 inches.

[Harry]

Just had mine done to 10". Bum. Still, size isn't everything is it? ;->

[Doctor Drivel]

It is as deep as what they said it would be. Have the insulation as deep as possible. A minimum of 12" - put more in.

To use the loft. Fill with Rockwool up to joist level. Then fit 4" minimum, high performing rigid foam insulation over, then boards over that. Costs more, with a usable loft area.

[george (dicegeorge)]

More important than height of insulation is getting it airtight, not only will warm air piss out through the holes but it will condense as it moves up through the rockwool and create damp, rot, etc...

[g]

[F]

They haven't said anything yet: they're *coming out* to do a survey.

I would like to know what they should say before they say it so I can assess their suitability for doing the job...

[David J]

I've got flush-mounted ceiling lights in some bedrooms, and the loft insulation has been cut away over these fittings - presumably because of the rising heat from the lamps. So I cannot seal all gaps...

DJ

[RobertL]

I believe current buidling regulations require 280mm.

As it happens, we've just been looking into this as our loft has no insulation at present. Wickes have a 2 for 1 offer on some loft insulation with free delivery. We are doing our 6x7m loft to 300mm depth for =A3244 using space blankets (glass wool in polythene bags).

Robert

[dennis]

If you have none you can probably get a grant for it to be done free, check with your energy companies to see what they are offering.

[RobertL]

I had looked into grants and found that installation was covered by the grant but that I still had to pay for the materials.

But, more to the point, I would rather do the installation myself.

Robert