Vaulted ceiling insulation can take a very long time to do properly, however it's worth taking the time to do the job the best you possibly can. Vaulted ceilings are also known as cathedral ceilings and will not have an attic space above them.
Although it is possible to work from a latter when installing ceiling insulation it will be much safer if you use a scaffold tower. This makes it possible to have a stable platform which you can stand on while you are installing the insulation. These can be hired from your local hire shop.
To work out how much insulation is required measure the distance between the roof trusses, then count the number of trusses to work out how much insulation you need to purchase. When cutting the insulation it must span the trusses so that it can be fixed in place.
The insulation is very easy to cut using a knife, cutting the insulation on a sheet of plywood will ensure that you don't damage your knife. If you're working on long lengths then consider cutting the insulation in two so that installing it is much easier.
Fixing Ceiling Insulation
Ceiling insulation should be stapled in place using the tags at the side of the insulation. The staples should fix the insulation into the trusses.