Water repelling properties of my cavity wall insulation (or lack of)

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Since the incompetent installers left a pile of insulation in the loft, I decided to examine the water repelling properties of the material

Cosytherm® white wool material description


Here is the salient information from the Cosytherm White wool BBA Agrément Certificate No 01/3789:

5 Description
5.1 Cosytherm White Wool Cavity Wall Insulation consists of granulated glass wool fibres which are treated with an inert water repellent during manufacture. The length of the fibres and degree of granulation are subject to regular quality control checks by the manufacturer.

In relation to Building regulations Section C4 (England and Wales) .
Resistance to weather and ground moisture
Tests for water resistance carried out by the BBA indicate that a wall filled with the product meets this Requirement provided the wall complies with the conditions set out in sections 7.2, 7.4, 7.6 and 9.2 of this Certificate.
The product does not absorb water by capillary action and may therefore be used in situations where it bridges the dpc’s of the inner and outer leaf 

My tests on cosytherm



Test 1 water repellent



I took 2.2g of dry insulation  and splashed some cold tapwater over it for  8 seconds.
During the test it showed no water repellency and in fact in short exposure had increased in weight to 18.1g.
I was able to then squeeze out some of the excess water but it still remained wet.

Test 2 Capillary action




I took a small sample of dry insulation to test for capillary action (i.e ability to wick against gravity).
I used beetroot powder as a water soluble dye but I also tried with plain water which produced the same results but not easily viewed on camera.

There is 2mm of coloured fluid in the plastic container. The video clearly shows 10mm of capillary wicking within a matter of seconds.

Test 3 Evaporation Test


Using the beetroot juice above, I placed several pieces of insulation into the liquid until it was completely absorbed.

At 24 hours sitting on a hot windowsill on a sunny day it was still visibly wet and compressed: (please not the red colour is from the beetroot water).


Even after 72 hours in a sunny window sill with outside temperatures in the range 12-25 degree Celsius, the insulation was still very wet as seen on the following video.

Conclusions


  1. Product has no water repellant properties - a single exposure is enough to saturate it to 8 times its original weight.
  2. Product demonstrably shows capillary action
  3. Product retains water for days in a vented and sunny area and readily retransmits the moisture to a more absorbent surface in direct contact with it. Scaling this up to a whole wall It seems unlikely that a whole section of wall filled with saturated insulation would be able to dry off at all.

Questions

Given the large discrepancy between the BBA certificate and the demonstrably poor water repelling performance of this material I would like to question the quality/content of this product.

  1. Is this material actually what it claims to be and if so was it subject to a batch test for quality control?
  2. Is there presence of an adulterant during or after manufacture
  3. Is there presence of a water repellant additive? And If so has stopped working over time?.
  4. To what degree do the BBA certificate test 'aged' product - I.e are products revisited after 10 years or more in situ to recheck their water repelling properties?


The wool manufacturer aka the  'system designer' is no longer trading defaults back to CIGA under the 25 year guarantee.


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Comments

  1. Unknown11 July 2018 at 07:22

    Brilliant. You have just showed us yet another example of the misleading rubbish that are the BBA agrement certificates - issued by a private company, making serious cashflow from suppliers to issue meaningless certificates used to dupe the public. I've got the same problem with certificates issued for sprayfoam insulation - they claim polyurethane sprayfoam is breathable!!!! Need to check the exact methodology of each test - whether BBA will give that information on request I have no idea..

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