Learn About Wall Insulation Solutions

Generally, builders install wall insulation in two general ways. In the first method, technicians remove the interior surface (usually sheetrock or wall-board). Also, at times, technicians remove the exterior surface (less common). Next, technicians, insulate the wall cavities before re-installing the interior surface. Typically, the industry calls the process a gut rehab or wall renovation. However, the process and project remains very invasive and expensive.

Conversely, the second method of insulating exterior walls of homes requires drilling holes in each wall framing cavity. Next, technicians blow the insulation in with a machine. This method provides improved insulation faster and cheaper. However, the process requires experience with various steps, such as

• removing exterior siding.
• use of insulation machines.
• working on ladders.
• knowing the technique for properly insulating a closed wall cavity.

Furthermore, many different types of insulation can be used to insulate exterior walls. Here is a brief overview of the different insulation options and how they are used to insulate exterior walls of homes:

Fiberglass Insulation

• Fiberglass Insulation. Primarily composed of glass used as a thermal insulator, it slows the transfer of heat by trapping pockets of air. This insulation keeps rooms warm in the winter and cool in the summer. Blown-in fiberglass often works as an insulation for walls, but specific types of blown fiberglass are necessary to be blown into exterior walls with an insulation machine. When dense-packed, this special formula of fiberglass provides highly resistant materials and prevents air movement. Blowing fiberglass insulation into existing walls continuously grows in popularity. However, it remains a relatively uncommon practice. Fiberglass also comes in rolls or batts that insulate exterior walls. To install fiberglass batts in walls, the interior (or exterior) wall surface must be removed to gain access to the wall framing cavity. Then, install the fiberglass batt insulation in the wall framing cavity. When installed correctly, fiberglass provides an R-Value of approximately 3.0 to 3.5 per inch.

Cellulose Insulation

• Cellulose Insulation. Primarily made from recycled materials such as newspaper and cardboard. Cellulose is treated with fire retardants and is manufactured to repel insects and rodents. However, cellulose only comes in loose-fill form. It cannot be purchased in a roll or batt for like fiberglass. But, cellulose works well in enclosed spaces, such as exterior walls of existing homes. When dense-packed, cellulose offers high resistant against air movement and yields an R-Value of approximately 3.2 to 3.5 per inch.

Styrofoam Insulation

• Styrofoam Insulation. Typically installed installed on the exterior of the wall framing. In other words, styrofoam insulation boards are commonly installed between the 2 by 4 framing and the exterior siding to provide a higher insulating capacity for the wall. The two main types of styrofoam insulation boards include Extruded Polystyrene Foam (XPS), also known as blue board or pink board. It is one of the most widely used foam board insulation products in the residential construction industry today. XPS maintains an R value of 4.5 to 5.0 per inch of thickness. The second type of Styrofoam insulation board is Expanded Polystyrene Foam (EPS). EPS remains a common foam packing material in the shipping industry today. But, EPS offers an R-Value of 3.6 to 4.0 per inch thickness. Also, technicians generally prefer extruded polystyrene insulation over expanded polystyrene insulation when insulating homes due because it maintains a higher R-value per inch and ease of use.

Polyisocyanurate Insulation

• Polyisocyanurate Insulation. Polyiso (for short) is a closed-cell foam core bonded on each side with foil facers. Polyiso provides one of the highest R-values per inch of any rigid insulation board (R-6.0 to R-7.0 per inch). As a result, polysio remains widely used in the insulation industry today.

Spray Foam Insulation

• Spray Foam Insulation. This insulation combines excellent air tightness and high insulation R-values. The basic types of spray foam, insulate and air seal today’s homes. One-component spray foam works best as  a sealant for small joints and cracks roughly the size of an inch or less. 1-part spray foam requires no hoses or large tanks. However, this type does not work well when sealing larger openings. Two-component spray foam works well for filling large voids and cavities in your home. Since 2-part spray foam expands rapidly as soon as it leaves the applicator, insulating large sections of walls, attics, basements or crawl spaces are common uses for 2-part spray foam. Two component spray foam is also available in open cell and closed cell formulas. Open cell foam maintains a lower density (1/2 lb per cubic foot) and an R-value of 3.5 to 4.0 per inch. Closed cell foam offers a higher density (2 lbs per cubic foot) and yields an R-value of 6.0 to 7.0 per inch.

Regardless of the insulation type, R-value measures insulation performance. R-value measures the resistance of heat flow of any material (or insulation). The higher the R-value, the better the insulating capability. GreenHomes recommends a minimum of R-15 insulation for exterior walls (or the amount of insulation sufficient to fill the framing cavity).