I had a few comments that Blow In Insulation was not covered, and the pros and cons were evident when I was involved with a building inspection yesterday with Rod Harris from the Building Industry Advisory Services.
There are some advantages of utilising Blow In Insulation (Cellulose is recycled paper with Borax and Boraxic acid added to it for fire and insect protection) with difficult to get to roof spaces, however, if not properly installed i.e, inconsistent coverage, it just does not perform. A 5% gap in insulation can equate to a 50% loss of efficiency.
A requirement of R4 insulation means 150 mm thickness which covers the joists and there- in provides a problem for any trades coming in after. Batts are easier to lift or shift if new wiring is needed. Most tradespeople will prefer batts if they are working in the roof space. What we generally see is that owners organise the installation of downlights after handover to save costs. LED downlights must be installed correctly with shrouds to avoid hotspots and what is going to happen now is that the insulation will be moved around changing the coverage.
As the picture reveals, these owners have poor performing insulation which is not helping those power bills. A wasted investment!