Brick/Block cavity + cellulose

[NandM]

After reading the DIY blown-in EPS beads thread, I started looking into DIY blown-in cellulose. I was/am planning to use it for the cavity walls and also flat/pitches roofs....but:

 

1) I've had a very helpful chap (Jasper) over at X-Floc tell me that cellulose is not suitable for brick/block cavity as "There is too much of a risk of interstitial condensation and risk of water penetration from the outer layer." 

 

When I asked for more information, he said " When it is a timber frame there is always a ventilated void on the outside before the brickwork or indeed any other rainscreen layer.  Also, the frame itself has a vapour control level on the internal side at least 5x higher than the external side which helps prevent the interstitial condensation risk.

The other equally risky factor for a fully filled brick and block cavity is that external brickwork can leak, water gets through mortar cracks or porous bricks into the insulation layer.  Worst case this causes degradation to the insulation and dampness internally or just diminishing  the insulation performance if it is wet."

 

2) I also read the FAQ in the Thermofloc website, which again doesn't recommend using cellulose for brick/block cavity (last FAQ in the list)

 

I know forum members here have used it in a timber frame - but has anyone used cellulose in brick/block? Does the reasoning from Jasper make sense and would it be less riskier with EPS beads?

[ADLIan]

Do NOT inject any insulation in the cavity between a brick/block outer and the timber frame. Simply not a recognized system/method of insulating walls. Cellulose cannot be used in external masonry cavity walls.

[joe90]

I didn’t use cellulose but used rockwall batts full fill in brick and block. It has a bba certificate for this and yes the outer brickwork was damp but did not penetrate the insulation ( I found this when when drilling for the ASHP pipes).

[NandM]

I've just had an email from warmcell also advising not to use it.  So EPS it is then