Insulation is an important factor to maintain a comfortable home. It is mostly unseen because it is behind finished walls and ceilings. The attic is an area that needs attention because there will be issues that must be addressed. Insulation is meant to do two things: insulating and air sealing. The older the house the more work that is to be done.
Insulation comes in many forms. Fiberglass, cellulose and spray foam are the most common types of insulation. Fiberglass insulation comes in batts or blown in. Batts are easier, cheaper, and can be installed by a homeowner using proper tools and protection. Most times these batts come with a paper vapor barrier. This vapor barrier is installed on one side of the batts and faces the heated surface. Installed backwards or incorrectly the exposed vapor barrier is a fire hazard. Blown in fiberglass insulation is small pieces of fiberglass blown in evenly to the space needing insulation. Contractors use a truck mounted power blower and a long tube to distribute the insulation. Fiberglass insulation >40 years old begins to settle and lose effectiveness.
Cellulose is ground up news print and treated with a fire retardant. It is loose and is blown in using a truck mounted power blower. Contractors put an additional chemical in it to us it in vertical applications. Cellulose insulation >40 years old begins to settle and lose effectiveness.
Spray foam insulation is the state of the art of insulation. It is a two part polyurethane solution that is sprayed directly on the surfaces to be insulated. It also air seals doing two jobs at once. Installed properly there is little expansion. Do not use the spray foam insulation in a single can, it can expand and damage the structure.
Fiberglass batts, loose fiberglass and cellulose insulate but do not air seal. Air sealing the gaps prevents unconditioned air from being drawn into the conditioned space. A good sealant is used to seal these gaps. Air sealing is done first, then the insulation is added.
Insulation has an R-value, the higher the R-value the more effective the insulation. In Michigan, attics are insulated to R-38, walls are insulated to R-13 and crawl spaces are insulated to R-13. Spray foam is most effective, followed by cellulose, blown fiberglass and fiberglass batts. To get an R-38, the spray foam is 5-6” thick, cellulose is 8-1/2” thick and fiberglass is 10” thick. Spray foam is the most expensive, followed by cellulose and fiberglass. Added insulation has the fastest pay back in terms of energy costs.
The best way to determine the insulation needs of the home, hire a contractor to perform an energy audit. 1-2 people show up, take measurements, look at the furnace, a/c system, water heater, basement, crawl space, attic, windows and doors. They run a blower door test that depressurizes the house. They have an app that tells them what air flow is best for the house. They take photos, wrap up the work and return to their office to write a recommendation report. When the work starts they run another blower door test to guide them where air sealing is needed.
Vermiculite insulation installed in the 50s and 60s most likely contains asbestos. It is yellow and gold pellets. If suspicious of it do not disturb it, in a licensed asbestos mitigation contractor for safe correction.
In my nearly 25 years in the industry I have seen Styrofoam, hay, packing peanuts and aluminum foil used as insulation. They were all well intended, but mostly ineffective.
Here are some tips. Roofers do insulation work because they are there. Need a new roof? Consider a contractor who does both. HVAC contractors have their own auditors and insulation installers. Need a new HVAC system? Consider a contractor who does all of it.