Insulation in Older Homes

Heating and cooling old houses presents many challenges. We try to reduce air infiltration as much as we can and add more insulation where it makes sense to do so. This often means reworking windows and doors, sealing and re-insulating attics, and detailing housewrap and the interior vapor barrier so there are good seals around all wall penetrations.

We sometimes use spray foam to seal inherently-leaky old walls and foundations. On masonry buildings, we will sometimes frame out the interior walls, run new wiring, install HVAC lines and ductwork, insulate and install the appropriate vapor barriers, and then re-plaster and re-trim the interior. On wood frame structures, we may remove the siding, repair the structure, rewire as needed, and then re-insulate and re-side, leaving the original interior wall surfaces intact.

There are different schools of thought regarding the ideal method of insulating older buildings, and there is no across-the-board perfect solution for all projects. The customer's budget is one factor that comes into play when choosing from the many options available. Some customers prefer cellulose insulation instead of, or in combination with, icynene or another type of foam. Others prefer fiberglass insulation. We can and do help advise our customers as to their different options for the project.

Icynene foam has been applied to the exterior walls and ceiling on the interior of this old stone building. Note the new studs and the new wiring. The walls will now be re-plastered and trimmed out anew.

Icynene foam is applied to exterior walls. The two parts of the foam application are mixed in the spray gun tip. The water blown solution sticks to the cavity as a warm, thick liquid, and an exothermic reaction occurs causing the water to give off gas, which, in turn, makes the solution foam up. The insulation is fully cured ten seconds after the foam is applied. The excess can be trimmed with a serrated knife. The worker on the left is trimming the foam as the worker on the right applies the foam.

The picture below shows how fast the spray foam sets up. Eric Olson of ETO Contracting is applying at seven feet above the ground and the foam at the bottom of the wall cavity has already foamed out and set up. Half pound, open-cell foam is usually used above grade and and out of the weather. Two pound, closed-cell foam is often used below ground and can resist some exposure.