How to tell whether cavity block or cavity wall construction

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pbyrne

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Hi,

Please don't laugh!

I am wondering what the most simple method is for telling whether a house has cavity wall or cavity block construction. I am trying to determine whether we have a cavity wall which may be suitable for insulation via filling (what/how/who to fill is a different question for another day).

I reckon I know what the difference is now between the two construction methods, I know what a cavity block looks like and can imagine what the cavity wall setup looks like (a gap between two walls - interior/exterior). However I am wondering where would you go to take a proper look - would you actually need to start drilling the wall?!? (or is there a point up in the attic that I should be looking at).

Many thanks
 
the easiest way to tell....

tap on the inner of the external walls..... if they sound 'hollow'..... most likely its cavity block construction.... to make sure, measure the thickness of the wall at the back door jamb.... cavity block walls with dry lining generally tend to be about 300mm thick...

if the inner of the external feels solid, and the thickness is approx 350-370mm then you probably have a cavity wall house.
 
There has been a lot of previous discussion of this subject on AAM - see

It was mentioned once that you might be able find out by looking inside your ESB box.

There is also some discussion in those previous threads about getting advice from There have advisors who call you back and give you some general advice.
 
Hi sydthebeat,

Any idea off the top of your head what a depth of ~ 210-240mm would indicate. The wall seems to be solid at all points I gave my scientific knock to so would I be correct in guessing that this is a single block of 210mm thickness?

(sueellen - thanks for those links - was scanning through them earlier today and got some useful info from them)
 
pbyrne said:
Hi sydthebeat,

Any idea off the top of your head what a depth of ~ 210-240mm would indicate. The wall seems to be solid at all points I gave my scientific knock to so would I be correct in guessing that this is a single block of 210mm thickness?

(sueellen - thanks for those links - was scanning through them earlier today and got some useful info from them)
Click to expand...

A standard hollow block is 215mm thick; in the case of an uninsulated (i.e. not drylined) hollow block wall this would mean an overall wall thickness of (13mm internal plaster +215mm block+ 19mm external render) about 247mm, give or take.
 
Hi Carpenter,

That sounds exactly like my setup then - rules out the cavity fill type insulation - darn!

Thanks to all for the replies.
 
Hi,

Another way to check is to take off one of your room vents and inspect from there.

Been down this road myself and opted for drylining the exterior walls.

Regards,
majj
 
Hi Clubman, You presumed correctly. Our drylining was done inside the home and was applied to the 3 exterior walls.
 
pbyrne said:
Hi sydthebeat,

Any idea off the top of your head what a depth of ~ 210-240mm would indicate. The wall seems to be solid at all points I gave my scientific knock to so would I be correct in guessing that this is a single block of 210mm thickness?

(sueellen - thanks for those links - was scanning through them earlier today and got some useful info from them)
Click to expand...

depending on year of construction...
210 - 240mm might indicate cast concrete walls....

either way, there is probably no insulation anywhere....
there are many threads on insulating walls here.... if the house is a one off--- perhaps consider external insulation... much better performance...
 
Hi syd,

Year of construction is approximately 1968 if that makes any difference. As you say though - no insulation regardless. It is not a one-off house, part of an estate (although I believe that back in those days the builders built the houses in groups of 10 or so each).

Think the external might not be an option for the following reasons:

(1) looks expensive (say mention of ~16k on other threads)
(2) there is a possibility we will be extending in a few years so it would have to be re-done
(3) some of the stuff I have been reading indicates that you get better performance from the internal method

However the nightmare now is that we have (foolishly?!) done alot of work internally (wooden floors, tiled bathroom, fitted wardrobes) against all of the walls that would be potentially dry-lined. So not sure where to go next - read about this stuff last night:

[broken link removed]

This led me to here (SOLID WALL INSULATION section):
[broken link removed]

There is a mention there of "[FONT=Trebuchet MS, Geneva, Arial, Helvetica, SunSans-Regular, sans-serif]Internal Flexible Thermal Linings" any knowledge of them as an option? The reason I would consider them is that it would not require radiators/electrics to be moved (I think)


[/FONT]
 
pbyrne, that product doesnt look like it would make a huge difference to heat loss... it actually looks more like a damp proof product....

i havent got the u value calculator with me right now but 10mm with a TC value of 0.158 is not good.....
for example, to meet current min. regs you need to incorporate 75mm of insulation with a TC value of 0.023...
that product is 7 times thinner with a TC value 6 times worse....
 
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