If you're working up in the roof, the right preparation can save you from constantly climbing up and down the ladder. Start by turning off the power. You will also need a sharp knife for trimming the insulation, a tape measure, a non-conductive insulation stick, a kneeling board and a torch. Make sure you wear rubber soled shoes and suitable loose fitting clothes, including a long sleeved shirt, long pants, cap, gloves and dust mask.
Work out how much insulation you'll need by calculating the square metres of your roof space. Measure the length and width of your roof space then multiply to two. The area each insulation roll covers is usually marked on its packaging. It can also be useful to draw a diagram of your roof space that includes lighting and electrical fittings.
Lay the crawling board across three joists. This will give you a stable work platform and also somewhere to place your tools. Take the insulation bags up into the ceiling space before you cut them open. Insulation batts come in different sizes, so make sure you choose the one that fits snugly between your roof joists. And unless you have a very small access hole, make sure you measure first prior to cutting.
Cut open a bag of insulation and let the batts expand to their original size. Cut the batts so they're the right length and width. Start laying the insulation furthest away from the access hole then work your way back from the outside edges in. Install the insulation between the ceiling joists and butt pieces together at all joins. Save any off-cuts to fill in any remaining spaces.
The spaces around the edges and in the corners of your roof can be too low to safely install the insulation. When you find yourself in this situation, cut the insulation to size and use the non-conductive stick to put the batt into place and press it down.
Safety is paramount when you are installing insulation. Make sure you put all your weight on the joists as you work. If you need to install around downlights, cut a semi-circle out of two ends of the insulation and butt them together, leaving a 200mm gap either side of the light. Also make sure that any electrical cords and cables in the roof are sitting on top of the insulation and not under it.