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Posted to uk.d-i-y
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Loft ventilation
wrote:
Broadback wrote:
Recently I have had loft insulation installed, the "surveyor" maintained
that even though there was no obvious form of ventilation it was not
needed because the roof felt was a breathable membrane, looks like
ordinary roof felt to me.
Do you have other reasons to doubt the surveyor?
Anyway 2 questions, when is the best time to check for condensation, in
warm damp weather, cold, or when?
When the roof is cold enough for condensation to form, I found it worse
in the winter.
Second if I need ventilation I intend to put through air bricks at
either end of the gables, does it matter how high they are placed?
TIA
As low as possible but I doubt a few air bricks are sufficient. You
need continuous eaves vents (or equivalent) so that the air enters at a
low level and flows across the roof space.
See
http://www.stockton.gov.uk/resources/environment/BldgControl/BCGuideNotes/condroof.pdf#search=%22roof%20ventilation%20site%3 Agov.uk%22
and many other such pages.
MBQ
Thanks all for your replies. No the insulation is on the floor of the
loft. It was not that I did not believe the surveyor, just that he was
not a surveyor in the true sense, so thought I would keep an eye on it
myself. I was offered (by a different installer) the option of simple
plastic wedges that hold the roof felt away from the tiles. If I
install the vents the plan was one in both gable ends, which are at
either ends of the rather long and narrow loft. If I need to do that I
cannot complain as I had full loft insulation and cavity wall insulation
installed free!
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