Green roof insulation

If you can afford the initial outlay, roof insulation is an absolute must for all houses. Roof insulation can reduce heating cost by approximately 13 percent; saving you money and greenhouse gas emissions. A well insulated roof can also substantially contribute to keeping your house cooler during the hotter months.

In one of our earlier houses, we had the standard fibreglass batts installed. They worked well, but I often felt guilty about using such a horrid, toxic substance. On one occasion when I was working up in the roof, I had troubles breathing for days afterwards and my skin was terribly itchy.

Fibreglass batts can incorporate adhesives that contain formaldehyde, a carcinogen. While fiberglass batts don’t burn easily, when they do, the fumes are quite toxic. The actual production of fibreglass is also very energy intensive.

Here’s some more environmentally friendly options:

Recycled cellulose fiber

In our new house, we opted for recycled cellulose fiber which is made from newspaper and other paper products. It was more expensive, but it has far better insulation quality than normal batts; therefore, over time there will be substantial cost savings – it’s also a greener option.

Recycled cellulose fibre comes in sheets, but in roof applications, it’s usually sprayed on using compressed air.

The insulation is treated to make it fire retardant – so fire resistant that if you scoop up a handful and apply a blowtorch to it, it won’t flame, just go black and your hand won’t be burned. Of course, this is something you should have the sales rep demonstrate :).

This fire retardant behavior gives recycled cellulose fibre the added value of helping to protect your house in case of a roof fire – it can slow the fire down. In most cases, as in ours, the flame retardant used is environmentally friendly  (boric acid) .

Another benefit of recycled cellulose fibre is that it’s treated to be a vermin repellent – no more mice and bugs in your roof! Finally, it also helps to deaden external sounds – particularly attractive if you live in a flight path.

Recycled denim

Another trash into insulation treasure is denim and cotton waste. In most of these products, the recycled content is around the 80% mark. Like recycled cellulose, the denim is treated with boric acid to give it fire retardant properties and repel vermin.

One of the advantages of the denim insulation over recycled cellulose is that it’s a little easier to handle. Whereas the cellulose insulation is blown into the roof and is loose, denim insulation comes in rolls – and is totally itch free.

Soy insulation

You can eat it, wear it, create biofuel from it – and insulate your roof with soy. Is there nothing it can’t do? Made from soybean oil, the insulation is sprayed into the roof area where it expands, filling cracks etc. before hardening. It will char but will not sustain a flame and will last the life of the building.

Sheep’s wool insulation

Wool insulation (sheep, not mineral wool) is considered one of the best (but most expensive) insulation options.

– R-value 10 – 15 percent higher than fiberglass
– moisture doesn’t affect it’s insulating abilities
– it is not a respiratory irritant
– is naturally flame retardant
– has excellent sound deadening qualities
– requires the least energy in production
– is mechanically bonded, no adhesives
– acts as a filter, traps toxic substances
– has a long life and can be reused
– can be composted

Borax may be used in wool insulation to discourage moths.

While fiberglass batts have ruled the insulation roost for many years, it’s great to see other more environmentally friendly options such as the above becoming more broadly available, economical and the choice of increasing numbers of builders.