Keeping Comfortable and Saving Energy: A Guide to Insulating Your Walls

Walls play a significant role in the energy efficiency of your home. They can account for a considerable portion of heat loss, and uncontrolled air leakage through cracks and penetrations further exacerbates this issue. Adding insulation to your walls can significantly improve comfort, reduce energy consumption, and potentially lower your heating and cooling bills. This guide will walk you through the process of adding insulation to your walls, drawing on expert recommendations.

Understanding Your Current Situation

• Before you begin, it’s crucial to understand your home’s existing insulation. Many older homes have less insulation than modern constructions, but even newer homes can benefit from additional insulation.
• Assess what you already have: You’ll need to determine where your home is insulated, the type of insulation present, and its R-value and thickness. If you live in a newer house, the builder might have this information. For older homes, you’ll likely need to inspect yourself.
• Where to inspect: Check the attic, walls, and floors adjacent to unheated spaces like garages or basements, as structural elements are often exposed there. For exterior walls, you can try inspecting through electrical outlets (remember to turn off the power first). Just because one wall has insulation doesn’t mean they all do. Inspect unfinished basement ceilings and walls, and crawl spaces as well.
• Consider an energy assessment: A qualified home energy assessor can perform a whole-house energy assessment, including an insulation check, and identify areas needing air sealing. Air sealing should be done before insulating.

Choosing the Right Insulation

Once you know what you have, you can decide what type of insulation to add for maximum energy efficiency. Several insulation materials are available, each with its own advantages and disadvantages.

• Expanding Foam: This type of insulation excels at sealing air leaks and filling hard-to-reach areas. It has a high R-value per inch and can fill irregular spaces. However, it is generally more expensive and requires professional installation.
• Loose-Fill: Materials like cellulose or blown-in fiberglass are ideal for insulating existing wall cavities and attics without major demolition. They can be blown into wall cavities and are good for irregularly shaped areas. Cellulose is also often made from recycled materials. Specialized equipment is needed for installation, and it may settle over time.
• Batt: Typically made of fiberglass or mineral wool and sold in rolls, batt insulation is a common and affordable choice when walls are open, such as during renovations. It’s easy to install as a DIY project and comes in various R-values. However, it’s less effective at air sealing and can be challenging to install around obstacles.
• Rigid Panel: Made from materials like extruded polystyrene (XPS) or polyisocyanurate, rigid foam boards have a high R-value per inch and are moisture-resistant, making them effective for exterior walls and foundations. Careful installation is needed to prevent gaps.

Insulating Existing Walls

The approach to insulating existing walls depends on whether the walls are finished or if you are undertaking a more extensive renovation.

• Insulating Finished Walls: Drill-and-fill: Small holes are drilled into the wall cavities, and loose-fill insulation is blown in. This is less invasive and works well with cellulose or blown-in fiberglass. The holes must be plugged and sealed afterwards.
• Injection foam: Similar to drill-and-fill, but uses expanding foam for better air sealing, though it is more expensive.
• Insulating Open Walls During Renovation: When walls are open, you have more options. Batt insulation can be easily installed between studs, ensuring a proper fit. Spray foam can provide excellent insulation and air sealing in one step. A combination approach using spray foam to seal gaps and batt insulation for cost-effectiveness can also be considered.

Insulating During Renovations

Major renovations offer ideal opportunities to add or upgrade wall insulation.

• Interior Renovations: You can rebuild the existing wall by removing the wallboard, adding insulation, and installing a new vapor barrier and finish. Adding horizontal strapping to the studs can reduce thermal bridging. Another option is to build a new insulated wall on the inside of the existing one, ensuring all cavities are filled with insulation and a well-sealed vapor barrier is installed.
• Exterior Renovations: Removing the existing siding allows for upgrades to the structure, wiring, plumbing, and insulation before installing new insulation and siding. Rigid board or batt insulation can be applied over the old siding. This provides an opportunity to add significant amounts of insulation. Remember to account for extending window and door jambs and other penetrations.

Important Considerations

• Moisture Management: Addressing moisture issues before insulating is critical to prevent mold and structural damage. Use vapor barriers appropriately for your climate zone and ensure proper ventilation. Attic spaces and bathrooms/kitchens especially need adequate ventilation.
• Air Sealing: Sealing air leaks is crucial for the effectiveness of insulation. Focus on areas around windows and doors, where different materials meet, and around penetrations for pipes and wires. Use caulk, weatherstripping, or expanding foam.
• R-Value: The R-value measures an insulation material’s resistance to heat flow; higher R-values mean better insulation. Determine the recommended R-values for your climate zone.
• Safety: Always prioritize safety by wearing protective gear like goggles, gloves, and a respirator. Ensure proper ventilation and turn off electricity when working near wires.
• Professional Help: Consider hiring professionals for tasks like spray foam installation, dealing with hazardous materials, insulating hard-to-reach areas, or if you are unsure about moisture management. Professionals can often complete the job efficiently and ensure proper installation.

Cost-Effective Strategies

• Prioritize areas: Start with the attic, as it’s often the most cost-effective area to insulate. Focus on air sealing first.
• Combine projects: Insulate walls when undertaking other renovations like replacing siding or roofing to save on labor costs.

By carefully assessing your needs, choosing the appropriate insulation materials and methods, and paying attention to important considerations like air sealing and moisture management, you can effectively insulate your walls, leading to a more comfortable and energy-efficient home.