Vapour barrier under attic insulation

Postby DHY » Wed Feb 02, 2011 10:13 pm


We live in a modest three-bedroom terrace house. We are soon to be replacing the current insulation in the attic, which is negligible and in very poor condition. We had a problem in the very cold weather and snow in December with condensation in the attic. We found that the eaves were blocked with insulation, which we have since removed and we will be adding five soffit vents at the rear of the house spanning the width, which is approximately 8 metres.

We are planning to lay 100mm of insulation between the ceiling joists with a further 200mm across the joists possibly using the encapsulated Space Blanket.

Do we need to fit a vapour barrier between the joists before we lay the insulation?

We’d be very grateful to receive some sensible advice on this as the information we have found so far seems very contradictory.

Many thanks.
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Simply Build It

Postby welsh brickie » Fri Feb 04, 2011 8:20 pm

no you can lay the insulation without it its not needed
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