Insulation saves money, improves comfort and cools the planet.
Good Planning Saves Money
It's critical to understand both modern building science and how your building was constructed before deciding how best to tighten the "building envelope" (foundation, walls and roof). Learn more about building science here.
Regardless of our attention to detail, we can't see inside closed cavities, such as walls, finished attics, vaulted ceilings, interior soffits, etc. To determine how leaky your structure's envelope is and how best to tighten it, it's best to hire a building performance auditor to use an infiltrometer (or blower-door) and infrared (or thermographic) camera to identify hidden gaps, holes and voids. Ask for the photos so you can methodically address them.
Check LCAN's Events page. If our "B4UBuy Workshop" on Insulating isn't on the schedule, consider getting several friends together and contact us to schedule one. At minimum, review this one of its hand-outs: LCAN's Top Tips on Insulating.
Unless the building was built of an especially modern material, like stress skins, structural insulated panels (SIPs) or insulated concrete forms (ICFs), focus on blocking the building's stack effect -- the natural flow of air from warm to cool --- within a leaky building envelope.
After weatherizing around doors and windows, begin by sealing the attic and perimeter rim joists, where they intersect the foundation (see photo), to block the stack effect.
Then, if the building still is too leaky, consider insulating the walls, because they usually require messy and costly demolition and restoration. That said, if doing new construction or large-scale renovations of existing construction, there's no better time to insulate the attic, rim boards and walls.
Perimeter, rim joists sit atop the foundation and commonly leak if not insulated properly.
There are many types of insulation. Choosing which one to use depends on various factors, including how the building was constructed, available headroom, costs and whether you prefer a DIY product. The most commonly used products in our area are spray foam, Fiberglas and cellulose. Learn more here.
Spray foam insulation can be applied on the attic floor or, better, the underside of the roof. Choose a product without cyanate compounds or cover with drywall.
Fiberglas comes in batts, as shown, or loose fill. It usually is made partly of old glass bottles and jars.
Cellulose is a loose fill product and blown onto attic floors and into walls. It's made of recycled newspapers, treated with boric acid as a flame retardant.