Saw a home show on TV, either This Old House or one of the others. Anyway, this insulation was actually injected between the walls of an existing home without any wall or skin removal.
The material was similar looking on TV like that foam insulation in an aresol can that is so messy and sticky.
The walls had a 1/2 inch hole drilled into each cavity between the studs. The hole was very near the ceiling. This foam was injected into this hole and it was like filling a car at a gas station. The foam was in a liquid state until it contacted air, then it set up. It apparently filled the bottom up and then when the stuff came out of the hole, that particular area was done. This stuff, did not create a pressure buildup like the foam in a can. In other words it would not bow out the walls.
The draw back is that you have a 1/2 hole in the walls every 16inches. Then you have to plug up this hole.
This particular insulation was for exterior walls only. I guess that in some interior walls you could use it, I don't know why though.
Anyway, on TV this process took very little time. You might check into this process. Only one man was doing the work. The material could not be that expensive. Could save you some money.