If you are lucky enough to have insulation in the floor bays of your attic, what is it made of?
If you are really lucky, you could have cellulose – stuff made of old newspapers. Cellulose insulation looks like dirty cottony paper-pulp.
You are also lucky if you have fiberglass (that pink cotton-candy-looking stuff.) These, fortunately, are the most likely things you will see in your attic floor, besides dust.
You might find one of the older insulating materials, UFFI. If you see it in an attic floor, it looks like Styrofoam. UFFI (Urea formaldehyde foam insulation) does a great job of insulating. But, when it was put in houses in the 1970s, it was found to out-gas enough formaldehyde to make people sick. It was outlawed in the 1980s. That was long-enough ago that the offending gas has dissipated. So, if you had UFFI in your house in 1985, you were pretty unhappy; now, it is a good thing.
Also in the old-insulation-that-does-you-harm category is vermiculite. It is rock that has asbestos in it. The web information on this varies from big bright alarm bells to just-never-touch-it-and-you’ll-be-fine. Asbestos is found in the attic and other places in your house.
Then there is the old stuff, usually wrapped in brown paper. Inspectors don’t think it is toxic, but they also don’t think it insulates all that much. I frequently see newspaper and cardboard (doesn’t do a thing except collect dust). Last week, I saw packing peanuts (maybe they were just spilled from a bag they were being stored in – I hope so!) Also, I see layers of what looks like aluminum foil without anything else; I think those are left over from old fiberglass that was removed.
There is also a growing trend to insulate attic ceilings. This is done with a foam called Icynene. It’s serious insulation and I see it in new construction not only on ceilings, but also behind basement walls and under basement floors. I am skeptical about new building materials, so I’d love to hear from anyone who is using this.
How much insulation is too much?
The problem with anything that seals a house against heat loss is that it also seals a house away from fresh air. Any super-tight house can have indoor air quality issues unless there is also good ventilation.
Roof shingles last longer if there is good ventilation in the attic. It’s a good thing that most old houses need. Heating costs and fuel waste are kept down by good insulation of the attic. It’s also a good thing that old houses need.
These two good-house-care items are at war with one another. If too much insulation is installed, it can shift over and block the ventilation. Then, the damp air from the house (caused by people breathing out, showers, and cooking) condenses in the cool surfaces in the attic. Without ventilation, the dampness can’t get out. This provides a happy environment for mold.
The homeowner’s lament is that you need to trust someone. If you aren’t going to crawl around in your attic yourself, how do you know if your attic ventilation-insulation system is working right? Even if you do crawl up there, would you know what you are looking at?