On Sun, 21 Dec 2008 23:50:50 GMT, "ARWadsworth"
wrote:


Bovvered? wrote in message
news
I've just had a survey by a cavity wall insulation company, they're
one of two approved companies under our local council's insulation
grant scheme. I'm confused over a couple of things they've said hence
this post.

I have a detached garage that is approx 4-5 feet away from one gable
end, they say that with this space for a ladder they can't safely
reach the roof apex and I'll have to pay extra for a scaffold
platform. I asked how high they could go on a ladder with the space
available and they said up to the gutter line. Not being an expert in
this field I'm wondering why do they need to insulate above the gutter
line anyway? Is there any reason why I need to have the wall cavity in
the loft insulated? If I don't is there a risk of damp?

I can quote Phil L (cheers mate) on this as he answered the same question I
asked earlier this year. His answer was

"All walls must be insulated to the top of the cavity, so the peaks on
gables
are always done, this is to prevent any water that may ingress from tracking
across the top of the 'stopped' insulation - if the cavity is 100% filled,
the water will simply make it's way down to the DPC naturally."

Thanks, I can see that now, although I can't see how water would
ingress in the first place unless I lost a ridge tile, and that isn't
something you wouldn't notice. At least they want to do a 'proper job'
which is a good thing

Could your gable peak be done from the inside to save on the scaffold costs?
If it is just a loft then that should not be a problem, if it is a bedroom
with plastered walls it could be a problem.

No it's just a loft space so it could be done from the inside, I
suppose it will just depend if they're willing to do that and if they
have a long enough hose to go through the house, up the stairs and
across the loft to the wall.

My next query is about our lounge which is 26 feet by 14 feet. It has
a gas fire with a normal flue and the room is double glazed with a bay
window at one end and patio doors at the other, the patio doors are
fitted with a permanently open trickle vent. The surveyor has told me
I'll need a 150mm square wall vent installed at extra cost. The reason
given being that CO2 produced by the gas fire won't be able to
permeate through the wall once the cavity is insulated. Is this
correct (and why) or just an unnecessary 'extra'.


I have never heard of a permeable wall that was used as a vent for a gas
appliance. I wonder if new this vent is required as the cavity wall
insulation would block up an existing vent.

There's no other ventilation from outside to in, just the trickle
vent?

Adam