Should you insulate interior walls? The answer is: It depends on where you live. If you live in a cold climate, the answer is yes, always. In most locations of the United States, insulation in exterior walls does nothing to improve your comfort or lower your energy costs. Suppose it’s cold enough outside to require insulating your exterior walls. In that case, you should probably be considering something a bit more robust than standard fiberglass batts.
- Interior vs. exterior insulation: comparing costs
- Blow-in vs. blown-in
- Should you insulate interior walls?
- Blown-in insulation vs. spray foam
- 2×4 Wall Cost to Insulate
- Can you insulate an interior wall?
- What are the most common materials to insulate exterior walls?
- What are the most common insulation materials for exterior walls?
- How many types of insulation are there for interior walls?
- What is the most cost-effective way to insulate a wall (Indoor and Outdoor)?
- What materials are used to insulate exterior walls?
- Can you insulate a wall with a window in it?
- Are there any insulating home products that reduce moisture?
- What are some materials used in wall insulation?
In warmer climates, interior wall insulation may seem like a good idea. Still, it is almost always a waste of money and material. Suppose your exterior walls are well insulated (which you should verify). In that case, the inside of your home will be naturally protected from outdoor temperatures. In addition, if you live in a hot climate, the air conditioning load will be reduced due to the lower temperature of your exterior walls. This reduces your need for interior insulation.
Interior wall insulation does have its place, despite these concerns. If you are building new construction or ultimately finishing your basement, placing insulation inside the wall cavity makes perfect sense.
Interior vs. exterior insulation: comparing costs
Before you decide to insulate your interior walls, it is crucial to understand what your options are. In most cases, blown-in insulation provides better results with less hassle at a lower cost than other methods. Fiberglass batts are the cheapest, but blown insulation is almost as inexpensive and much more effective. If you decide to install rigid foam, be prepared to spend a lot of money since the cost per square foot is significantly higher.
Exterior wall insulation requires additional framing because drywall cannot attach directly to plywood or OSB sheathing. In general, fiberglass batts are not an option since you cannot place the batts between studs and fall through the wall cavity. Blown insulation is an excellent alternative because it fills the entire hole, so you do not have to worry about finding a way to hold the insulation in place.
Blow-in vs. blown-in
There is one downside to blown-in insulation: getting the material through the holes in your wall. You will need a blower tool and hose, which can make the job more difficult if you have many nooks and crannies.
Blow-in insulation materials are available in two forms: loose fill or sprayed cellulose. Cellulose is made from recycled paper, so it is environmentally friendly. Still, you should always wear a mask and goggles since the fiber particles can irritate your lungs and eyes. It also takes longer to install because each stud cavity must be filled individually. Loose-fill insulation comes in batts or bags that are easily placed within the wall cavity.
Should you insulate interior walls?
The amount of insulation you need depends on the climate where you live and how much protection your exterior walls provide. In general, installing 1 inch of insulation in an outer wall will lower your heating bill by about 10% each year. You should expect these savings to accrue for nearly 10 years before the insulation begins to lose its effectiveness.
In warmer climates, insulating interior walls will help keep your home cooler. It also reduces your air conditioning costs. But be careful when evaluating quotes from insulation contractors. If they tell you that you need a lot of additional insulation because your exterior walls are poorly insulated or uninsulated, then you should be suspicious. This is a classic sales tactic because many homes in the South and Southwest have adequate insulation. It is costly to add additional insulation at this point.
If your exterior walls are uninsulated, adding R-20 of insulation will only reduce the heat loss through your walls by about 15%. The most significant savings will come from upgrading your windows and doors, which is what most homeowners should be doing anyway.
One inch of insulation might not sound like much, but the cost to cover a 2×4 wall can range anywhere from $150 for fiberglass batts up to $500 for blown-in cellulose. The average price of installing 1 inch of insulation for a 2×4 wall is about $200. This brings the total cost to insulate an exterior wall from $1,050 per wall up to $2,000 with blown-in insulation.
Installing more R-value than you need can reduce your energy costs because you are essentially wasting less heat in the winter and less cool air in the summer. This is only a good idea if you plan to stay in your home for more than 10 years, which is how long the insulation will remain effective before you begin to lose money.
Blown-in insulation vs. spray foam
Suppose you decide to insulate your exterior walls with spray foam. In that case, you need to have a contractor apply the foam because it can only be sprayed in place. The cost of spray foam insulation is much higher than blown-in insulation, which is why most homeowners do not use it.
The typical costs to insulate an exterior wall with fiberglass batts or cellulose are:
2×4 Wall Cost to Insulate
2×6 Wall Loose Fill $1,000 – 1,500 $1,500 – 2,000 Blown in Cellulose (R-19) $1,200 – 2,500 $2.400 – 3.000 Blown in Cellulose (R-20) $1,500 – 3,000 $2.600 – 4,000 Blown in Cellulose (R-38) $2,200 – 4.500 $3.200 – 6.000
Suppose you have two layers of drywall on your interior walls. In that case, it makes sense to add more insulation because you are also losing heat through the interior walls. The cost to insulate an interior wall is lower than insulating exterior walls. However, it is still a significant amount because of the labor involved in removing and reinstalling drywall.
Can you insulate an interior wall?
Yes, different insulation products can be applied to walls. Many homeowners choose insulated paneling for the inner walls of their homes. Check out this product page for more information:
What are the most common materials to insulate exterior walls?
Most homes have a variety of materials used in their construction as well as the siding. These materials include vinyl, aluminum, foam boards, and fiberglass.
What are the most common insulation materials for exterior walls?
The most common insulation material used on exterior walls is fiberglass batts. Other options include spray foam or rigid panels.
How many types of insulation are there for interior walls?
There are several different insulation types for interior walls. These include cellulose, fiberglass, and foam boards.
What is the most cost-effective way to insulate a wall (Indoor and Outdoor)?
Some of the least expensive insulation materials for walls are cellulose insulation as well as foam boards. They can usually be installed relatively easily in walls with little framing present.
What materials are used to insulate exterior walls?
The most common insulation materials for exterior walls are foam boards as well as spray foam. Insulating materials such as cellulose, polystyrene, and even recycled newspaper can also be used on exteriors.
Can you insulate a wall with a window in it?
Usually, yes. Most windows have gaps around them that allow you to seal and fill them with insulation. Check out this link for more information:
Are there any insulating home products that reduce moisture?
Yes, spray foam is one of the best ways to insulate a wall without increasing the risk of collecting moisture inside it. This product page explains: Are there any downsides to insulating exterior walls? The main downside to insulating exterior walls is the increased cost. A good quality insulation product for exteriors will usually be more expensive than one for an interior of a home.
What are some materials used in wall insulation?
Cellulose or fiberglass are both common materials used in wall insulation products. Other options include polystyrene and foam.