Blown Fiberglass Insulation

Using blown fiberglass to insulate your home is an ideal way of saving yourself money and reducing your carbon footprint. Blown fiberglass insulation is most commonly associated with cavity wall insulation, but under the right conditions it can also be used in a loft space. Although generally a cheaper option for installing cavity wall insulation in an already completed building is the use of urethane foams, they have a drawback in that the fumes given off from them, can affect some people and they can be prone to seepage through the inside wall. Additionally, in some areas they are no longer legal to use, due to their carcinogenic nature.

Fiberglass Cavity Wall Insulation

Installing blown fiberglass insulation into your home’s cavity walls can easily be accomplished within one day. However, apart from purchasing the blown fiberglass you’ll also need to hire an air compressor and pipes; as the blown fiberglass needs to be injected into the cavity wall through holes drilled into the outside of the wall. The holes should be drilled about every 10 feet, along and up the wall.

Start filling the cavity wall from the bottom up and make sure that at the top of the wall you drill an extra set of holes if necessary. You can then use the highest set of holes to make sure that the cavity wall is filled with the blown fiberglass to the maximum; as being particulate in nature it will settle over time. After all, there’s no point in a few weeks time ending up with an un-insulated gap at the top of the wall.

Blown Fiberglass Loft Insulation

Providing your loft is ventilated but not prone to having ‘winds’ blowing through it, using blown fiberglass for loft insulation is quite acceptable. To reduce fiberglass particles from becoming airborne during the installation process a barrier, referred to as a blanket, needs to be fitted across the joists in the loft space. The blown fiberglass insulation can then, in effect, be poured through slits in the blanket; which are then sealed when the process is complete.

The ‘blanket’ remains in place - solely to prevent the fiberglass becoming airborne. Being a particulate substance using blown fiberglass, if fitted correctly, will not leave any gaps or spaces around: pipes, cables or the joists themselves. (The same is also true of course in a cavity wall.) When laying any form of insulation in a loft you must make sure that there is good ventilation in the loft after you’ve finished the installation. Without ventilation in the loft you’ll leave it prone to condensation, which could lead to wood rot in the joists later.

The golden rule here is - do not cover the eaves with insulating material. You also need to be careful how you approach any loft insulation around, or near, water pipes or tanks that might be in the loft. Whilst insulating your loft will reduce heat loss, it also means that the loft will be colder - meaning any water conduits are more likely to freeze in cold weather. This potential problem is easily dealt with by adequately insulating any water tanks or pipe-work and not installing loft insulation directly beneath a water tank. Instead, insulate around it and above it.

Safety First

Fiber glass materials are irritants to the skin, eyes and respiratory systems. When working with fiberglass wearing fully protective clothing (including gloves), a mouth & nose mask and goggles is essential. An ‘all-in-one’ face mask/visor is not recommended unless it is a ‘hood’ type that also has an air filtering system. Whilst at one time fiberglass was considered to be a carcinogenic material - that is now no longer the case.