To the real estate editor: I recently finished insulating the wood walls of my house with W. R. Grace's masonry fill (Zonolite). I built my own pumping machine, using a 55-gallon drum , an old vacuum-cleaner motor (mounted on the outside which pumped air into the drum), and 15 feet of 1 1/2-inch flexible rubber hose reduced to five-eighths of an inch at the end.
I drilled 5/8-inch holes in the siding of the house and pumped in the Zonolite. Then I replugged the holes with 5/8-inch dowels. M. L. Young Miami