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What Is the First Step When Choosing Wall Insulation?
Start by working closely with your architect and contractor. The more energy-efficient the walls, the higher the price for the project. Contractors can explain the different strategies and materials and offer a report with other options. The same is true of a renovation – start by hiring a green contractor who embraces new technologies, strategies, and products.
What Should I Look for When Researching Wall Construction?
hen researching wall construiction, you may want to look at something beyond your city's building code unless you know that you have a sophisticated code - a few cities do. Following the most recent International Energy Conservation Code (IECC) and LEED residential codes will offer you ideas on state-of-the-art walls.
How Does Insulation Work?
Insulation is a barrier to heat flow. Heat moves through materials, like when you reach for a hot door handle warmed by the sun. Heat convection means hot air circulates through liquids and gases – warm air rises, and cooler air sinks. Radiant heat heats anything substantial in its path. Insulation slows convective and conductive heat.
What Is An R-Value?
An R-Value is a measurement that represents the ability of a specific type of insulation to resist heat flow. The higher the number, the better the insulation. High R-Values for walls in most of the country should be R-38, with northern climates at R-48.
What Are the Different Types of Insulating Materials?
We will discuss various types of high-performance insulation below, including SIPs and structured forms. There is a wide variety of other insulation types, the most common being blanket insulation that comes in batts or rolls. Blanket insulation can be made of fiberglass, plastic, mineral wool (from rock and slag), sheep's wool, or other natural fibers like cotton.
How Is Insulation Installed?
Several approaches exist. Expanding foam uses small amounts that expanding to fill space. It requires a professional. Loose-fill insulation gets blown in from holes drilled on the outside or inside of homes. Typically, insulation flows through 1"-2.5" diameter holes. Blown-in insulation comes as fiberglass treated or untreated with formaldehyde; cellulose, composed of about 80 percent ground-up newsprint and 20 percent the fire retardant borate and expensive mineral wool.
Let's talk about each of them.
What's the Best Way to Control Water in Walls?
The US Department of Energy suggests placing a water control layer either in front of or behind insulation, but not in-between. By having the barrier on the outside water has little chance of getting inside.
What Are the Best Practices for Air Control Layers in Walls?
Experts say air control layers separate conditioned (or inside air) with the outside environment. A sheet that stops air transfer can be placed either on the exterior or interior. Sheathing on the outside and gypsum board on the inside is one common approach.
What Are the Best Practices For Vapor Control in Walls?
Putting an insulating layer on the outside of the sheathing, especially in cold climates, reduces the vapor problem. When the exterior warms, water does not condense and enter the walls, removing the need for an interior vapor control layer.
How Much Thickness Does High-Performance Insulation Add to Exterior Walls?
High-performance insulation may add as much as 4 inches to the home's exterior. Though more than standard, it is not enough to be noticeable.
What Is the Advantage of External Home Insulation?
External home insulation allows a more continuous and more complete coverage of the framing. The approach provides minimal thermal bridging that causes unwanted heat loss or gain.
Will I Still Need Insulation on the Inside?
Frame walls have a cavity that can be insulated. Adding insulation insides creates an even better thermal seal. Look for insulation that helps you attain your sustainability goals - be it that they come from nearby sources, are renewable, or are made with natural fibers.
Which Are the Least Environmentally Friendly Types of Insulation?
The website Earth911 suggests that fiberglass insulation requires a lot of energy during its production, and some products still contain formaldehyde. Fiberglass often includes 20 percent of recycled materials. Look for products certified by GreenGuard, such as Ecobatt and Sustainable Insulation by Certainteed. Mineral wool production has been linked with air quality issues in the surrounding areas. Both fiberglass and mineral wool insulation, however, work better in humid climates than their more environmentally friendly counterparts. Homeowners considering polyurethane foam insulation and rigid foam insulation with fire retardants should research any issues related to off-gassing and global warming potential (GWP) factors.
Frank Jossi
Based in St. Paul, Frank Jossi is a journalist, editor and content strategist. He covers clean energy in Minnesota for Midwest Energy News and writes frequently for Finance & Commerce. His work has appeared in more than 70 local, national and international publications.
