Before you decide on the best insulation for exterior walls, it’s good to know the facts. The Department of Energy (DOE) lists the full spectrum of exterior wall insulation options. I have studied the types of wall insulations, and I can tell you there is no shortage of exterior wall insulation options.
Best Insulation for Open Exterior Walls
The best insulation options for open exterior walls are foam board insulation, injection foam insulation, blown-in cellulose insulation, spray foam insulation and fiberglass insulation.
Insulated Exterior Wall Panels
Insulated exterior wall panels improve and protect continuous air barriers with a simple installation. Homeowners install insulated exterior wall panels because they drain better and perform better than other exterior wall insulation solutions on the market.
Insulated exterior wall panels are ideal for industrial, architectural, institutional, cold storage, and commercial applications. They are available in many colors and applied finishes.
Exterior Thermal Insulation
Exterior thermal insulation is used to improve the thermal performance of exterior walls while minimizing energy costs. In addition, exterior thermal insulation offers an excellent solution for insulating the exterior walls of buildings without cavity walls and new houses.
Homeowners install exterior thermal insulation to insulate exterior walls from the outside. This type of exterior wall insulation protects older homes with solid walls without cavities and new and existing homes built with stud-and-sheathing framing.
Best Insulation for 2×4 Exterior Walls
Kraft-faced fiberglass insulation rolls are the best insulation for 2×4 exterior walls. In most exterior wall applications, it’s best to use R-13 or R-15 kraft-faced fiberglass insulation. These two types of exterior wall insulation materials are close enough in thickness to fit (since modern 2×4 are actually 3.5 inches instead of 4) into modern two-by-four wall systems.
Older homes may employ 2×4 that actually measure four inches instead of 3.5 inches. In this case, you can still use R-13 or R-15 fiberglass insulation even though there is no 4-inch thick-faced fiberglass insulation in batts or rolls on the common market.
Best R-Value Insulation for Exterior Walls
The best R-Value insulation for exterior walls is R13 to R15. These insulation solutions have a lot of similarities. Both R13 and R15 are sold faced and unfaced. Unfaced insulations are ideal for use on top of existing insulations. Faced insulation is sold with a barrier on the head.
Modern homes are built to have 2×4 walls. But, the wall is not exactly four inches deep because modern 2x4s are only 3.5 inches wide. Regardless, both R13 and R15 work for 2×4 exterior walls.
Even though they have different R values, they offer equal thermal protection. However, it would be best if you used them correctly. Refer to the manufacturer’s installation guidelines before installation.
Best Fiberglass Insulation for Exterior Walls
The best fiberglass insulation for exterior walls offers flexibility, is energy efficient and is fire retardant. They are also noise-cancelling and eco-friendly.
Fiberglass exterior wall insulation is available in rolls, loose-fill, and pre-cut panels. It is a flexible exterior wall insulation offering a simple installation; you can install fiberglass insulation between joists, studs, rafters, blocks, and other areas that require insulation.
Its flexibility makes fiberglass a great option for exterior wall insulation projects.
Fiberglass is so energy efficient. If installed correctly, this type of insulation can reduce your cooling and heating bills by up to 50%. Because fiberglass insulation is made of about 30% recycled materials, it’s an eco-friendly exterior wall insulation option.
Best Insulation for Exterior Walls in Texas
Fiberglass is the best insulation for exterior walls in Texas. More specifically, you can use R13-R15 for exterior wall insulation if you live in Texas. It is the most effective and perfect for filling tight nooks and crannies. It is installed around pipes, wiring, and hard-to-reach areas.
This insulation is fire retardant, offers flexibility, and is efficient. More importantly, R13-R15 exterior wall insulation is noise-canceling and eco-friendly.
Best Insulation for Exterior Walls in New Construction
R-19 to R-21 is the best insulation for 2″x 6″ exterior walls in new construction. The 2″ x 6″ studs allow for more energy-efficient insulation than 2″ x 4″ walls.
For new construction, you have many options for exterior wall insulation. For sheathing, rigid foam insulation is a fine choice. For the interior side of those exterior walls, batt insulation is ideal. For new construction, use
R-5 to R-6 insulated sheathing under the exterior finish of the home.
With exterior walls, blown-in fiberglass or wet-sprayed cellulose are better insulators.
Is it worth insulating exterior walls?
It is worth insulating exterior walls, especially since about 9% of heat loss occurs through walls. Exterior wall insulation allows for proper air sealing. It’s worth the cost, especially if you live in a climate with cold winters.
Insulating exterior walls helps you keep the heat inside the walls of your home, which makes financial sense, especially with today’s high energy prices.
Insulating Exterior Walls From Inside
Insulating exterior walls from the inside is possible by drilling holes between the studs. Through the holes, you can spray cellulose or foam exterior wall insulation. Alternatively, you can insulate with loose-fill insulation. Once applying the insulation, the holes must be plugged and refinished to match your home’s interior finish.
Foam Board Insulation for Exterior Walls
Foam board insulation is effective for exterior walls because of its R-values from 3.6 to 8.0. It’s especially effective for cold and damp climates. Since foam board insulation is applied to exterior walls, it prevents thermal bridging.
This type of insulation is better at controlling moisture. Foam board protects the framing or wood sheathing from any rain or moisture that could leak in under the siding. And it warms the interior framing or sheathing enough to prevent water accumulation from the heated interior air during cold weather.
Foam board exterior wall insulation is better at preventing air leaks.
When properly installed, foam board works as an excellent air barrier. The same feature mentioned above prevents thermal bridging also applies to air transfer.
Spray Foam Insulation for Exterior Walls
Spray foam insulation is effective for exterior walls because it creates an air seal that will maintain a constant temperature in your house. It is an environmentally friendly exterior wall insulation option. The spray foam is generally mixed with either water or some chemical agent.
Open-cell spray insulation is used for residential projects. Once applied inside the exterior walls, the insulation expands and fills the cavity. For exposed walls, homeowners should use closed-cell foam insulation. Because of its durability, closed-cell foam is the better option for exposed walls.
Spray foam will stop air movement through the exterior walls, improving your home’s energy efficiency.
Best Insulation for Walls
The best insulation for walls is fiberglass insulation, injection foam insulation, foam board insulation, blown-in cellulose insulation, and spray foam insulation.
When to use exterior acoustic wall panels?
You should use exterior acoustic wall panels if your home is located in a noisy environment. It will improve the acoustic comfort and well-being of the residents. Use exterior acoustic wall panels to reduce sound pollution and absorb sound.
When to use laminate wall panels?
You should use laminate wall panels if you want:
- Simple installation
- Low maintenance
- Stylish walls
- No mold or bacteria
- An inexpensive wall covering
Sealing Exterior Cinder Block Walls
Sealing exterior cinder block walls is a must to protect them from water intrusion. Once moisture intrudes into a cinder block, it creates even larger pores, reinforcing the cycle of water damage to the external wall.
The easiest way to seal cinder block is to apply the coating directly on the exterior wall. It is an effective defense against moisture intrusion and air leakage. The sealants are generally water-based materials. You can spray it on or roll it on your exterior walls.
You can also use a peel-and-stick weather-resistant elastomeric layer to insulate exterior cinder block walls. This type of sealing, if installed correctly, creates an impenetrable moisture barrier.