Voids and debris


I bought a cheap Depstech endoscope from amazon. It's an impressive bit of kit for £30. The camera head is thin enough to fit though a lot of the little holes drilled in the wall for pipes and cables and heating vents.
As your mobile phone is the viewing screen. Photos and videos can be taken while rummaging through a nook.
For very narrow holes, there is a mirror attachment allowing you to survey the expanse of the cavity.

I tried it out on the cavity above the combustion vent in the living room. The installers had neglected to put a sleave on the vent which means the cavity is easily accessible. 

A correctly insulated cavity should be difficult to see anything due to presence of dense insulation. But here there was a large void above the combustion vent.
The picture below shows a reason for the void:




A long wooden baton sits in the cavity obliquely and rests against a fish tail walltie.
The baton has probably fallen into the cavity when the roof was constructed.  The narrow cavities mean that the insulation can't pass the batton and the filling machine triggers to say it's full.
This falls foul of the BBA certificate for Cosytherm (Agrément Certificate No 01/3789) which specifies :

5.2 When installed the target mean density for this product, is 18 kgm􏰀3. Local areas within the wall, when sampled over an area of 0.5 m2, may have a density variation of ±5 kgm􏰀3.

Another feature that can be seen in the photo is the mortar lying on top of the walltie which seems to be bridging the cavity.

Here is photo of a typical walltie used in the 1920-1950s.

Mild steel 'fishtail walltie

Wall ties of this area are usuallly made from mild steel susceptible to corrosion which can cause them to expand to several times their original size. The force can be enough to move whole sections of  bricks above the tie or cause cracking and with catastrophic failure a complete peeling of the external skin.
Wetness and wallties do not go well together, so wet insulation surrounding the tie will accelerate the corrosion.
CIGA won't let you take out the wet insulation yourself it out without forfeiting your claim even after they have carried out their 'thorough inspection'. It has been 6 months since we raised the concern. CIGA are stonewalling.

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