The first steps in home renovations are tests that show you exactly, which are the necessary steps to be made to have an accurate and quality work. One of these tests, which otherwise is extremely important, is the blower-door test that shows the house air leaks. If there are, you should take all the measures for a professional air sealing.
It is obvious that you can effectively seal all air leaks where you can reach them. Unfortunately, if a previous owner have blown too much loose cellulose into the house attic without any regard for air leaks, then the possibility of sealing these leaks will be quite limited.
Of course, you can shovel the loose cellulose out of the way and seal all the leaks you can find, but it is more than likely to omit some.
A better option is to vacuum completely the insulating material and then to seal the entire attic surface with a closed-cell foam layer. In this case, the question is if it is possible and especially if it worth to reuse the original loose-fill cellulose.
Reusing the Original Loose-Fill Cellulose
You can use without problems the original loose-fill cellulose, if it is not mixed with dirt and debris such as old plaster and lumber scraps.
There are several ways to vacuum the cellulose:
a) You can find large vacuum bags, which have a capacity of several cubic yards to any insulation supplier. You can also rent a gasoline-powered vacuum.
b) However, a better and easier way is to call a professional contractor with a special truck that can spray cellulose. These trucks usually include a professional vacuum that can suck and deposit all the excess insulation material in its hopper ready for the reuse.
Once, your attic has been vacuumed, you need to clean thoroughly its surface. Then, you can apply closed-cell foam layer and blow the original cellulose back over the attic surface.
However, in some cases, this method may not be the best economical solution. It is the best solution when you have indeed an extremely leaky attic on the largest part of its surface.
Otherwise, the best solution is to find and seal the leaks from inside your living space. You can find them easily running a blower door test and a smoke pencil. Anyway, some problem spots such as chimneys, partitions, light fixtures or vents should be sealed from within your house attic and will definitely require some sweeping and shoveling. Nevertheless, even if it requires some work and time, is still a smart solution, given that vacuuming and replacing the original cellulose layer may cost you at least $ 1,500.
Essentially, the best thing is to test, before you start working and after sealing, to make sure your home is airtight.