We have just had a quote for cavity wall insulation for our 1989 built
detached out. With current schemes it comes out at £95, which sounds
quite good. The quote was for polybead insualtion which I beleive is
polystyrene balls.

I have been doing a bit of googling and there are lots of different/
conflicting opinions on the best type of material and whether cavity
wall insulation is a good idea or not. There are lots of people
reporting damp problems after they have had it done (some may have
been down to blocked air vents I guess). It appears that the prefered
material is the polystyrene beads but I have seen reports that it can
cause problems with cables that are in the cavity. We have satelite
and network cables running in our cavity and mains cable that pass
through the cavity to the attached garage and external lighting. Is
it still the case that this is an issue or was it just 'in the early
days'.

What are peoples general opinion on the different types of materials
and whether the cavity should be left as a cavity.

Thanks

Alan

AlanC wrote:
We have just had a quote for cavity wall insulation for our 1989 built
detached out. With current schemes it comes out at £95, which sounds
quite good. The quote was for polybead insualtion which I beleive is
polystyrene balls.

I have been doing a bit of googling and there are lots of different/
conflicting opinions on the best type of material and whether cavity
wall insulation is a good idea or not. There are lots of people
reporting damp problems after they have had it done (some may have
been down to blocked air vents I guess). It appears that the prefered
material is the polystyrene beads but I have seen reports that it can
cause problems with cables that are in the cavity. We have satelite
and network cables running in our cavity and mains cable that pass
through the cavity to the attached garage and external lighting. Is
it still the case that this is an issue or was it just 'in the early
days'.

What are peoples general opinion on the different types of materials
and whether the cavity should be left as a cavity.

Thanks

Alan

Could depend on where you are in the country. We are in Essex which is
very dry and have no problem with blown fibre.
Have also lived in houses with beads that were not stuck together.

If you want to change anything that involves making holes through cavity
walls do this first. Balls and blown fibre both have a habit of finding
their way out of small holes eg behind meters and consumer units.

AlanC wrote:

I have been doing a bit of googling and there are lots of different/
conflicting opinions on the best type of material and whether cavity
wall insulation is a good idea or not. There are lots of people
reporting damp problems after they have had it done (some may have
been down to blocked air vents I guess). It appears that the prefered

Some will be due to areas of uninsulated wall attracting heavy
condensation - either due to incomplete fill in the first place or the
filler slumping later. In areas with very wet outer walls then avaoiding
any material that can track moisture would also probably be a good plan.
(I would expect poly bead to be ok in that respect however)

material is the polystyrene beads but I have seen reports that it can
cause problems with cables that are in the cavity. We have satelite

Indeed it will. Polystyrene and PVC do not mix - it tends to leach the
plasticiser out of the plastic.

and network cables running in our cavity and mains cable that pass
through the cavity to the attached garage and external lighting. Is
it still the case that this is an issue or was it just 'in the early
days'.

Still the case. It would probably be easy enough to sheath any power
cables passing through the wall. I would be inclined to take a chance
with the LV wiring. As long as its not being moved about too much it is
unlikely to be a problem.

What are peoples general opinion on the different types of materials
and whether the cavity should be left as a cavity.

Generally most seem to find CWI worth having these days - especially now
the chemical foam products that used to be responsible for causing
irritation to the occupants don't seem to be used any more.

--
Cheers,

John.

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| Internode Ltd - http://www.internode.co.uk |
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| John Rumm - john(at)internode(dot)co(dot)uk |
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On Jul 3, 1:53*am, John Rumm wrote:
AlanC wrote:

I have been doing a bit of googling and there are lots of different/
conflicting opinions on the best type of material and whether cavity
wall insulation is a good idea or not. *There are lots of people
reporting damp problems after they have had it done (some may have
been down to blocked air vents I guess). *It appears that the prefered

Some will be due to areas of uninsulated wall attracting heavy
condensation - either due to incomplete fill in the first place or the
filler slumping later. In areas with very wet outer walls then avaoiding
any material that can track moisture would also probably be a good plan.

running a dehumidifier costs a fraction of the money saved by CWI.

(I would expect poly bead to be ok in that respect however)

I tested some, it sucks up water quickly. So not really suitable for
walls that do get water in the cavity.


material is the polystyrene beads but I have seen reports that it can
cause problems with cables that are in the cavity. *We have satelite

Indeed it will. Polystyrene and PVC do not mix - it tends to leach the
plasticiser out of the plastic.

and network cables running in our cavity and mains cable that pass
through the cavity to the attached garage and external lighting. *Is
it still the case that this is an issue or was it just 'in the early
days'.

Still the case. It would probably be easy enough to sheath any power
cables passing through the wall. I would be inclined to take a chance
with the LV wiring. As long as its not being moved about too much it is
unlikely to be a problem.

You could work out what it costs to reroute the cables, and compare to
the cost savings - or just use a compatible insulator.


What are peoples general opinion on the different types of materials
and whether the cavity should be left as a cavity.

Generally most seem to find CWI worth having these days - especially now
the chemical foam products that used to be responsible for causing
irritation to the occupants don't seem to be used any more.

Work out what it saves.


NT