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Posted to uk.d-i-y
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Cavity wall insulation - cavity too large ????
wrote:
huh? damp? You lost me with that one... I wasn't told that damp was
the issue.
Damp isn't the issue - yet, the issue is trespass, which could lead to damp.
Can you explain how damp penetrates through the insulation if only
half the wall is done?
It can't get *through* the insulation because it's waterproof, but it can
travel across the top of the insulation if it stops halfway up a wall, which
is why it's installed to the top and also why one flat out of a block cannot
be insulated, unless it's ringbeamed.
Water naturally passes through the outer leaf, IE the brick, and it runs
down the inside of the brickwork until it reaches the DPC or a lintel (which
usually have weep holes for this very reason)....if the cavity is partially
filled, this water runs across the top of the insulation and soaks into the
inner leaf, causing damp.
I presume you mean half done as in vertically? who could it cause damp
for - me or the neighbour?
The neighbour, because yours would be 100% filled, but you would be
responsible when it went to court and then instead of paying thousands out
in damages, you would naturally blame the installer, which is why he isn't
doing it.
I remember looking through the original surveyor's scope - I would
guess it to be around 170mm - not much more than 6" but definately
more.
The largest brushes I ever seen during 14+ years of installing it were 6
inch (150mm), and these were used in a four inch (100mm) cavity, because
they have to stay in place by compresion of the bristles....I suppose they
could twist 2 or even 3 of these together as they are only thin gauge wire
with nylon bristles
--
Phil L
RSRL Tipster Of The Year 2008
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