Hello All ,
last year I got the cavity walls insulated and topped up the loft insulation
myself to save energy/ money etc ,but I now seem to have a problem that in
all the upstairs rooms at the joint of the ceilings and the walls I am
getting a lot of mould spores appearing this isprevalent on the outside
walls only .
My question is should the loft insulation go right up to the point where the
roof trusses meet the top of the walls or should I leave a gap and if so how
big a gap ? .
Its a semi house by the way / and we didnt have this problem last winter
Thx in advance for any replies Glenn
Hi Mike ,
There is only the normal sources of condensation ie shower/bath in the
bathroom (I have a ceiling extractor fan but this doesnt appear to draw much
moisture away !) and breath moisture in the bedrooms .
all the condensation spot appear on the walls with the windows below , this
probably has something to do with it due to the cold air possibly ?
thanks for your reply
If the damp spots are only above the windows it's likely that
condensation is forming on the lintel above the window. As this year
has been a very mild winter all over the UK and this didn't occur last
year it suggests the hse has become damper this year.
As the shower extractor doesn't seem to be working v well it could be
the insulation has blocked it, can you remove the grill and check the
vent for blockages. Plse remember to switch the fan off at the mains first!
The point of leaving a gap is to avoid blocking the roof ventilation.
How is your roof ventilated?
You should be able to run the insulation right up to the walls, but
you will probably have to reduce the tickness to keep at least an inch
(and preferably two inch) gap under the felt or tile backs.
If you have a real problem getting convensional loft insulation over
this area, you could get a sheet of 1" Cellotex and cut bits to fit
over the last few inches where you can't get the loft insulation to
fit. Glue it to the back of the plasterboard so air can't circulate
under the Cellotex (which would defeat it).
I guess this is the one remaining cold spot, due to no insulation on
top of it, so it's where condensation is going to form in the rooms.
Infra-red thermometers are very good at identifying cold spots like
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Theroof does not appear to be ventilated at any point itis tiled with black
tar? felt underneath .Icannot see any vents at any point within the roof ,
does this mean the roof is vented where the trusses meet the top of walls ?
do you think i have blocked the ventilation ?
thks for your help
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