It could be either or neither, it could be double skin but no cavity, there
are no rules and all anyone in here can do is guess.
You can measure the brick panel outside, inbetween yours and next doors
downstairs windows or doors (the bit that spans the party wall) then knock
off the amount that belongs to you, plus the same amount that undoubtedly
belongs to them, and what you are left with is the thickness of the party
Can both parties agree to a test drilling into the brick? It should
be fairly soft "common" brick. Or if you have a region you can clean
the plaster off, the presence of "headers" will tell you it is a
double brick solid wall.
In those days regulations were considerably more lax than modern
dwellings are. A 5.5 mm masonry drill shouldn't do much damage. Though
you might have to use a 7mm to get the depth.
Once you are in 4 inches you will know. If it is still drilling solid
at 5" you have a single skinned double brick/ 9 inch wall.
A semi from the 60's is most likely to have a cavity party wall. The
party wall would normally be the same type as the external walls if
these are traditional contruction
You can't rely on looking in the loft, as it was common to change from
cavity to 9" or even 4 1/2" in the roofspace for simplicity and speed.
You could do a basic check by deducting the internal width from the
external width, and deducting the external wall thicknesses, and if
you have about 280mm you have a cavity and if you have less than 250mm
its a solid wall. This assumes the party wall is not dry-lined.
Looks like 4 1/2" in the loft.
I had found this first but did not mention it in my original posting to avoid
Plaster on brick.
54" from windowsill end to next door's (windowsill end).
20" from approx same point internally to plaster so looks like about 13"-14" for
Reason for asking was that we can hear nextdoors 13A plug being inserted - I
supposes there could be a wall tie nearby conducting the sound.
At least all my rawlplugs wont be fighting with theirs'.
Thanks to all who replied for the suggestions.
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