Insulating an old place

Q: Can I use spray-on polyurethane foam to insulate the attic walls and ceiling in my 130 year-old frame house? I’d like to avoid batts or blown-in insulation.

A: You're right to be concerned about conventional insulation options within a roof frame because they typically require some sort of ventilation. And this condition would be difficult to build into a retrofit situation like yours. That's why you're on the right track with spray-on polyurethane. It would do a terrific job in your situation, but cost is a problem. A friend of mine shopped for a quote to insulate his garage with site-sprayed foam and the lowest price he could get from a contractor was $5000 for a roof area over a double-car space. But before you give up on the idea of foam, I can make a practical suggestion. Consider installing rigid sheets of extruded polystyrene foam, fastened to the roof frame with washers and nails, then sealed along the edges with beads of low-expansion polyurethane foam applied yourself. By intentionally leaving a 1/2-inch gap around the foam you install, there will be plenty of room for easy sealing. The most economical source of spray foam for this job comes in disposable canisters that screw on to a reusable, professional-grade gun. This method of dispensing is also much neater than those throwaway foam guns. Low-expansion poly foam is one of the most powerful air sealing tools available, useful for all sorts of renovation situations. If this were my home, I'd consider some form of batt insulation for conventional wall spaces, but switch to foam sheets for roof use. It would also be very effective to supplement the foam and batts with a layer of reflective foil insulation. One brand is called rFoil (www.tvmi.com; 888-313-3258). The best reflective foil products I've seen look like shiny bubble wrap.