Micafil Loose Fill loft insulation

Someone asked us this week whether or not Micafil loft insulation is worth installing.

Micafil is different to most loft insulation in that it is loose fill – i.e. instead of coming in a big roll, this insulation comes as small particles in bags which can then be poured into the required spaces.

Micafil is made from vermiculite, which is a naturally occurring mineral. The vermiculite is heated to extremely high temperatures, and this then expands to produce ultra-lightweight aerated particles which consist of about 90% air.

How does Micafil perform?

In the following section we are going to compare Micafil to more traditional rolls of loft insulation (Earthwool).

Energy performance of Micafil loft insulation

Micafil has a thermal conductivity of 0.063 W/mK. A roll of Earthwool (which is the loft insulation more commonly used to do the loft insulation job) has a thermal conductivity of 0.044 W/mK which is a little higher. In order to reach building regulations you would require a 380mm layer of Micafil, but only 270mm of Earthwool, so while the insulating properties are very good, they are not as high as the more commonly-used rolls of loft insulation.

Price of Micafil loft insulation

The price of Micafil is approximately £20 per bag – and one bag of this will cover 1m2 to a depth of 100mm.

The price of a roll of Earthwool is £18 per roll (at B&Q) and will cover about 8.30m2 to a depth of 100mm. Therefore the Micafil loft insulation is considerably more expensive!

Ease of install of Micafil loft insulation

Obviously having read the first two comparisons, things are not looking good for Micafil, but it does have a real advantage over the rolls of loft insulation – and that is the ease of installation.

The Micafil comes in easy-to-handle bags and can be poured in to any space where it is required. This makes it incredibly easy to install. It’s fibre-free, non-irritant and safe, so there is no need to wear gloves, masks or take special precautions when handling it.

We insulated a loft just before Christmas using the Earthwool and it is far more difficult to install – the rolls are relatively heavy and the wool needs to be cut to fit spaces. The worst thing about the rolls of insulation is that the wool fibres are so itchy, and regardless of how well you cover your skin, the itch continues for the next day or so!

In conclusion, Micafil is the ideal product for topping up any existing loft insulation you have. It is extremely lightweight, so it won’t compress the underlying insulation, but also the small particles fill in gaps where the rolls of insulation don’t quite butt up to one another, giving you complete coverage.

It is also the perfect product if you have uneven joist gaps, but to be honest, even then the rolls of wool can be cut relatively easy with the Stanley knife!

If you are insulating your loft for the first time, we would always recommend using rolls of loft insulation due to the improved thermal performance of this type of insulation, coupled with the fact it is easier and cheaper to achieve the required depth of insulation.

Have you used Micafil to insulate your loft? Let us know what you thought below!