Insulation batts and blow-in products – which one should you choose?

People often ask when we would recommend blow-in insulation instead of batts. Insulation batts and blow-in products both provide a thermal blanket however we recommend blow in for several applications.

Insulating your ceiling

Installing roof and ceiling insulation can save up to 45% on heating and cooling energy.

Jet Stream® MAX is a high performance, non-combustible Glasswool designed to be blown into floors, skillion roofs and ceilings. The system creates a thermal, acoustic barrier. The product completely fills gaps, voids and hard to reach areas around pipes, electrical wires and fixtures. 

Jetstream blow-in will help even the cover over existing loose fill in your ceiling.  Loose fill, such as cellulose, typically “grabs the beams” as it deteriorates leaving deposits and little product between the beams.  If you were to apply batts over the existing loose fill the batts would follow the contour of the loose fill and not join neatly, potentially reducing the efficiency of the thermal barrier.  The use of a blow-in loose fill insulation in your ceiling would provide an even thermal blanket .

Loose fill insulation can get into nooks and crannies where batts will struggle to fit, so we recommend blow in for low pitch tin roofs and roofs with considerable ducting.

If you require a full ceiling thermal bridging, covering the beams to minimise any heat transfer, blow in insulation provides a very cost-effective option at an approximate 15% additional cost than a single layer of batts.  To create the same coverage over beams with batts we would undertake a technique called cross thatching, where the initial batts are laid inside the joists, with an additional layer applied at a cross angle doubling the batt usage.

We would typically recommend a batt application where you had significant in roof work, such as rewiring to be done as it requires patience to restore the loose fill evenly, and if you simply preferred a solid mass to loose fill.

Insulating your walls

Most walls benefit from added insulation, and it is possible to add insulation to most construction types used in Australia. 

Cavity brick walls have high thermal mass, but without insulation are usually too cold in winter and often too hot in summer. If the cavity is insulated, the internal thermal mass (i.e. the internal brick skin) is protected from external temperature changes, and becomes highly effective at regulating temperatures within the home.

Blow-in insulation effectively fills the cavity between the internal plasterboard and external facade , with minimal disruption to your home. It can be installed either externally through brick, brick veneer, double brick and weatherboard, or internally through plasterboard (where external restrictions apply).

Retrofit cavity insulation also provides acoustic improvements and can be used for internal walls to ensure noise does not carry between rooms.

We recommend installing Knauf Supafil® CarbonPlus, an unbonded, non-combustible glasswool product which requires no mixing on site.

It is important to note that installing insulation in a new dwelling or adding insulation to an existing one can make a significant difference to the comfort and energy performance of the home, but it is vital that the insulation is installed correctly.