In article ,
"Fergus O'Rourke" writes:
Just adding to my attic insulation, and I notice that there is no vapour
barrier under the existing stuff which has been there for c.25 years. There
seems to have been no deterioration in the 25 year old stuff.

Should I now add a barrier or just leave things be ?

It's not required. The amount of moisture which will come through a
ceiling (barring outright holes which should be filled) is negligable
compared with the ability of even a small amount of loft ventilation
to to disperse it. Moisture in lofts is caused by holes in the ceiling
(e.g. downlighters, around pipes, etc), uncovered loft tanks, leaks
in the roof, all combined with very poor loft ventilation.

--
Andrew Gabriel
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