yes, any kind of insulation weather it be, polly foam, cellulose or fiberglass insulation, is always a good idea. no matter what you put inside your walls there is always a chance that something will leak. fiberglass will absorb water and rot your walls just as quick as any other tipe of insulation. a leak is a leak.
For years the traditional method of insulating walls in an existing home was blown in cellulose. This created some pretty sizable holes in the side of the house that were then plugged. Eventually, re-siding is the only way to restore the cosmetic appearance of the home. If spray foam is used it must be a slow-rising foam to allow gravity to pull it into the cavities before expansion. In general, spray foam is a wonderful and efficient product, but it is difficult to fill every void in an old house, but the results should be substantial. Enormous improvement in energy efficiency and quiet. Certainly not cheap, but a substantial improvement with energy costs certain to rise in our lifetimes.
The spray in foam sounds great,, BUT it's not cheap and here is the REAL PROBLEM. If your house ever gets a leak, the foam will not absorb the water, nor will the aluminum. If there is any wood in the walls, it will absorb the water. If the leak is not detected, the wood will eventually start to rot. If the wood is a structural member of your home,things will start to fall apart. This may take awhile, but it will show It's ugly head and by the time it does, it may be too late to save it.
