Non-destructive ways of finding out if you have cavity wall insulation

Ergates

Our house is around 20 years old, so falls into the bracket of may or may not have had cavity wall insulation installed when built.  Our last home energy report (now out of date, but the walls won't have changed) states that it is *assumed* it had cavity wall insulation installed when built - and we've always assumed that too.

However, knowing what they say about assumptions, I'd rather know for sure.   The walls are rendered (all the houses on this estate are) so wouldn't show any drill holes (and, presumably, if it was installed on build there wouldn't be any anyway).

Short of drilling a hole in the wall is there any way to tell?

FreeBear

Ergates said: Short of drilling a hole in the wall is there any way to tell?

Short answer, no.

If you do drill a hole, it need not be a big one - I have a small USB camera that will fit down an 8mm hole - https://www.ebay.co.uk/itm/154715346925 - Pick a spot behind a down pipe, and a hole will never be noticed once filled.

Doozergirl

If you do know when it was built then you should be able to check the building regulations in place at the time.  

There will also be building control records of the build - somewhere.  

And drilling a hole isn't really destructive.  You do it somewhere discreet and fill the hole with silicone.  You'll quickly forget about it.  

Or hire a thermal imaging camera - you'll get a VERY good idea of where any problem areas are.  Probably the best idea if you're worried about something. 

DRP

any wall lights or similar you can unscrew and take a peek? You might be able to open up the hole a bit even, and recover ti with the fitting.

stuart45

The odds are that it's got insulation. There are no building regs that state it must have, or even be a cavity, but using a brick/100mm cavity with part or full fill/ 100mm block were probably the most efficient way of meeting the regs. In the 80's thicker AAC blocks were sometimes used on the inner skin instead of insulation. 
Can you see anything from the meter box?
If you look at the eaves you might have a fire sock closing the cavity.

Ergates

DRP said:

any wall lights or similar you can unscrew and take a peek? You might be able to open up the hole a bit even, and recover ti with the fitting.

Not on an external walls.   All internal are stud.

Ergates

Ergates said: Short of drilling a hole in the wall is there any way to tell?

Short answer, no.

If you do drill a hole, it need not be a big one - I have a small USB camera that will fit down an 8mm hole - https://www.ebay.co.uk/itm/154715346925 - Pick a spot behind a down pipe, and a hole will never be noticed once filled.

Bummer.   How deep would the hole have to be?  (that's probably a dumb question).  I don't actually know what the external walls are made of (as they're rendered) but the inner walls are (I think) made of concrete blocks (the large ones with square holes in the middle).   I'm assuming the outer layer would be something smaller?   Probably not clay bricks as that would be a waste of money if you were going to render it.

Ergates

Doozergirl said:

Or hire a thermal imaging camera - you'll get a VERY good idea of where any problem areas are.  Probably the best idea if you're worried about something. 

I have a thermal camera, but there is a degree of "all the gear and no idea".  I can spot a localised hot/cold spot, but don't really know what a whole wall not being properly insulated would look like.

stuart45

The external skin would normally be 100mm blocks. Very unusual to use 215mm hollow blocks for the internal skin. I've never seen houses built like that in the UK. They are generally used for reinforced masonry.
What is the width of your walls at the jambs?

FreeBear

stuart45 said: The external skin would normally be 100mm blocks.

Plus another 15mm or so for a layer of render. So as long as the drill bit is long enough to go right through. Something like this should do the job - https://www.toolstation.com/dewalt-multi-material-drill-bit/p10042

Ergates

stuart45 said:

The external skin would normally be 100mm blocks. Very unusual to use 215mm hollow blocks for the internal skin. I've never seen houses built like that in the UK. They are generally used for reinforced masonry.
What is the width of your walls at the jambs?

Probably my mistake then - maybe they just looked like that from the side and my brain filled in the blanks (incorrectly).  I'll go up in the loft later and have a look.


I think I have a masonry bit long enough for that - and if not I'm planning on running some ethernet cables externally at some point so I'll need one anyway.