fred wrote in message ...
In article , Alex
writes
fred wrote in message ...
In article , Alex
writes
The walls of my terrace house are made of two leaves of standard
bricks and the cavity is no more than 30mm.
Is there any way to install cavity insulation into such narrow gap?
I just found out about the YBS Airtec (aluminium foil + bubble wrap)
which promises the performance of a 50mm polystyrene (despite being
only 5mm thick) As I am redoing the innner leaf I would be tempted to
use the Airtec...
Has anyone come across similar issues?
Any suggestion?

Thanks

Alex
If you are rebuilding the inner leaf, I would suggest celotex (or Kingspan)
as it is available in a range of thicknesses and is regarded here as the best
insulation material, much better than polystyrene or others. I believe that
the claims of foiled bubblewrap brigade are to say the least optimistic.

OK, I have just found out about Celotex...it seems they do 25mm boards
which should do the job. I guess, I would also need some extra
insulation installed internally...what's the best way?
If the aluminium (from the cavity) reflects heat back into the room
another celotex installed internally would reflect this heat back into
the cavity and so on...
They also do 35mm but you may not be able to find a local stockist, worth
searching around for tho. I did a quick google & found that Travis Perkins
stock 12, 20, 25 & 55 in the cavity wall type so at worst you could add 20
+ 12 to make 32 but I'm sure you could special order 35 from someone. As
said by someone else, foil has no effect when in contact with a wall as the
heat transfer is by conduction. Also, for non contact gaps, unprotected foil
tranishes and loses its low radiation benefit.

Ideally, I would rather avoid any extra insulation (and waste of
space) and opt for using thermal blocks instead of bricks (for the
inner leaf) but I am not really sure if it is possible considering
that my property is a terrace house (end terrace...that probably would
help a bit). The rows of bricks from my neighbour change into blocks
into my property...any problem with it?
Yes, it would be a real faff to add more & the thermal blocks sound like a
good idea, but I am no expert in that area. Even if you had to build it in
brick, I would guess that a cavity with 35mm of celotex would be better
than a standard empty cavity or even one with rockwool batts. Maybe it's
time to put some figures into a central heating type calculator to see if it
will make that much difference, or do you have to satisfy a BCO that it
meets a certain figure?


When I refer to my concerns about using blocks I am not focusing on
the advantages in terms of insulation but about the possible drawbacks
of mixing bricks (from my neighbour) with blocks (my property), i.e.
is it structurally OK?
Anyhow, the work on the inner leaf has to be done on two external
walls purely for structural reasons (bulges and tie corrosion);
therefore it seems appropriate to grab the opportunity for installing
extra insulation.
By the way...as I just discovered the thickness of the old bricks is a
bit more than 110mm (these old bricks are very irregular and often and
reach 120mm)...by using the blocks (100mm thick) I can gain some extra
20mm cavity space which should add to a total of about 50mm.
Now really starts to make sense...

Thanks for your comments
Alex