Loft insulation/flooring

[Mr-H]

I have recently topped up my loft insulation from (maybe) 50mm to perhaps as much as 250mm.However, with the loft flooring going back down on top of the insulation, it has compressed the total to the depth of the rafters - 150mm(?). By reflooring, and consequently compressing the insulation, does it reduce its effectiveness?

[SlackAlice]

Yes, insulation traps air between its fibres. By crushing it down you have reduced its effectiveness.

[Mr-H]

So - what's the recommeandation. Remove the flooring or now leave it alone? I suspect that like most people's lofts, it tends to be a storage area.

[Hymie]

Personally I think that if your loft has wooden flooring over the rafters, with fibre insulation filling the void between – this arrangement will be as good as a much thicker insulation filling only – if not better. When you consider that you are likely to store items on the loft flooring, adding to the insulation.

As SlackAlice says, by compressing the insulation you will have reduced its efficacy – but personally I would not go to the bother of removing the stuff now, for what I suspect would only be a marginal improvement in thermal insulation.

[The Builder]

.............. you probably don't want to hear this Mr H, but the best thing is to lay 100mm timbers across the joists ...... then re-lay the boards .......... then you have your 250mm :o)

[Mr-H]

Thanks builder!! Now I feel quite degected! What a great start to the year! :(