When it comes to keeping a house warm, one of the most important factors is the insulation and air sealing in the walls. The walls of a home play a crucial role in regulating indoor temperatures and keeping heated or cooled air where it belongs – inside. In this article, we’ll explore what types of insulation work best, how insulation keeps heat in, and some tips for choosing the right insulation for your climate and home.
What is insulation and how does it work?
Insulation is any material that resists heat flow. Good insulators have tiny pockets of air or gas trapped within them, which prevent heat energy from escaping. When heat tries to pass through insulation, it gets trapped in the air pockets rather than being conducted through the material. This helps keep the heat inside your home in the winter, and keeps hot outdoor air from overheating your house in the summer.
The effectiveness of insulation is measured by its R-value. The higher the R-value, the better the insulation is at resisting heat flow. Most homes today should have R-13 to R-23 in the walls and R-30 or more in the attic. Adding insulation to meet these recommendations can make a dramatic difference in home energy efficiency and comfort.
Types of Insulation
There are several types of insulation commonly used in home construction and remodeling projects:
- Fiberglass – Made from melted glass spun into fibers, fiberglass insulation comes batts or rolls for walls and floors. It has an R-value of approximately R-3 per inch.
- Mineral wool – Similar to fiberglass but made from natural materials like basalt or slag. It has a slightly higher R-value of R-3 to R-4 per inch.
- Cellulose – Made from recycled newspaper, cellulose is blown into wall cavities as loose-fill insulation. R-value is around R-3.7 per inch.
- Spray foam – Foam insulation comes in two types: closed-cell spray foam has a high R-value of R-5.5 to R-6.5 per inch but higher cost. Open-cell spray foam has an R-value of R-3.7 to R-4.3 per inch.
- Rigid foam – Rigid foam panels made of polystyrene, polyurethane or polyisocyanurate can be installed on exterior walls or roof. R-value ranges from R-5 to R-6.5 per inch.
- Reflective insulation – Uses a reflective material like aluminum between wall studs to reflect heat back into the house. Effective when combined with other insulation materials.
Of these different types, fiberglass batts, cellulose, and spray foam are among the most common and cost-effective insulation solutions for walls in many homes.
How does insulation keep heat in house walls?
Insulation works by slowing conducted heat flow through the building materials in your home’s walls, attic, floors, and crawl spaces. Here are the main ways it helps retain heat in the cooler house walls during winter:
- Forms a thermal barrier – The tiny air pockets within insulation materials resist and slow down the transfer of heat through the wall assembly.
- Traps air – Insulation traps air, which is a poor conductor of heat, further hampering heat loss.
- Reduces convection – Insulation reduces air leakage so there is less convection pulling warm air out through gaps in walls.
- Minimizes thermal bridging – Stops heat loss through studs, joists, and other conductive materials that act like thermal bridges.
The same principles apply for keeping house walls cooler in the summer by resisting heat gain from hot outdoor air. Properly installed insulation creates a continuous thermal envelope around the conditioned space inside your home.
Tips for choosing insulation
Consider the following factors when selecting insulation for your home walls:
- Climate – The colder your winters, the higher the R-value you should aim for. Cold climates like the northern U.S. and Canada may require R-21 or more in walls.
- Wall construction – Different wall types (2×4, 2×6, solid masonry, etc.) accommodate different insulation thicknesses and materials.
- Air sealing – Seal air leaks before insulating to maximize effectiveness. Look for gaps around windows, doors, pipes, wires, etc.
- Vapor retarders – Depending on your climate, a vapor barrier on the warm-in-winter side prevents moisture issues.
- Contractor expertise – Find an insulation contractor familiar with your local building codes and climate.
- Fire safety – Ensure flammability ratings meet building code requirements.
- Lifespan – Fiberglass and mineral wool insulation will last for the lifetime of the home. Other types may degrade over decades.
- Eco-friendliness – Seek greener, recycled insulation materials when possible.
Also consider upfront material and labor costs, long term energy savings, DIY vs professional installation options, and health factors like risk of airborne fibers or off-gassing of chemicals for some types of insulation.
Conclusion
Keeping your home comfortably warm in winter starts with proper insulation and air sealing. The walls of your home play a key role in regulating indoor temperatures and reducing heating bills. By understanding how insulation works along with following best practices for selecting and installing insulation, you can create a warmer and more energy efficient home this winter.