Green Addition Remodel – Insulation

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Green Insulation for Additions

Insulation is a major cornerstone in the world of green building. Poorly insulated homes waste enormous amounts of energy. Fiberglass batts are still the most popular, but other products such as cellulose or spray-foam perform much better and provide greater comfort, saving resources and money.

When should you insulate:

  • When you live in a house built before 1980.
  • When the temperature in your house is uncomfortable.
  • When you are already remodeling.
  • When you pay higher energy bills than your neighbors in a similar-sized home.
  • When you can hear the neighbors from inside your home.

Insulation Types

Fiberglass is the standard insulation in the industry today. High-density fiberglass makes the same wall cavity 15-20 percent more effective than low density R=11 batts in reducing heat loss. Fiberglass can incorporate 10-30 percent recycled material in its manufacture. However, the problem of microparticulate shedding – the release of invisible fiberglass particles that can irritate people’s skin, eyes, and lungs has become controversial. Loose fill is a greater risk than batts. In addition, fiberglass batts often use formaldehyde as a binder. Some newer products, though, employ alternative binders or no binders at all.

Cellulose insulation is environmentally friendly because it is primarily made from newsprint and recycled wood fiber from pre-and post-consumer waste. It has another advantage in that when it is sprayed, it forms a good infiltration barrier, which adds to the tightness of the house and reduces drafts. It is less contractor-dependent for quality control in filling voids. Cellulose can be blown dry, mixed with a binder, or sprayed wet.

Mineral/Rock Wool Insulation  is made of molten slag, a waste product of steel production, or natural rocks (rock wool) such as basalt and diabase (or a mix of the two). Has a higher density than fiberglass.

Bio-based insulation – or soy bean-based, insulation is an open-cell, semi-rigid, water-blown foam that penetrates every cavity and even the tiniest crevices, expanding 100x its orignial liquid size for a perfect air-sealed fit. Although relatively new to the market, this insulation has been hailed as one of the most environmentally friendly insulations.

See Chapter 6, Room Additions in the book Green Remodeling for more details.


Green Insulation for Additions Checklist

  • Seal all wall penetrations such as wires or pipes or electrical outlets with expansion foam
  • Add additional insulation to the attic if applicable
  • Pay careful attention to sealing around windows and doors
  • Insulate the crawl space and between floor joists
  • If the rest of the house has poor insulation, do as much as possible to improve the thermal envelope.