Solved! How Much Insulation Do I Need?
Wondering, “How much insulation do I need?” These tips will take you through the basics, from R-value to insulation calculators to the different types of insulation.
Q: Help! My home feels cold in the winter and too hot in the summer, and I think I need to add insulation. But how much insulation do I need?
A: Several factors affect the amount of insulation you’ll need, including the areas you’re insulating, the type of insulation, and where you live. Some tips below can help you understand the best way to insulate your home and when to contact an expert to assist you in installing or purchasing proper materials. Before you head to the home improvement store, inspect your home and check to see what kind of insulation you already have and what its condition is.
Determine what areas of the house you want to insulate.
The amount of insulation you’ll need to install will depend partly on where you intend to put it. The most common areas homeowners use insulation are attics, walls, and floors. Since it’s best to overfill attics with insulation to prevent an updraft that draws cooler air in, you may need more insulation for an attic or roof insulation than you would with flooring. If you’re adding wall insulation to existing batting or adding blown-in insulation to an older home, you’ll typically need more insulation than you would for insulation under flooring but less than you would with attic insulation.
If cold air is getting sucked through gaps in the floorboards, add insulation to the floors to keep moisture from warping the wood or encouraging mold growth. You can hire a professional to install the insulation, or you can glue or fasten rigid foam sheets to joists beneath the floor or use spray foam from a can to fill small gaps.
Talk to a local contractor or building authority to learn the minimum required R-value for insulation in your area.
You may not know what an R-value is if you’ve never dealt with insulation. In simple terms, the R-value of a material describes its capacity to insulate. Although it’s essential as a homeowner to have a basic understanding of what insulation does and what R-value means, a local contractor or building authority will have the expertise to tell you what R-value is required for the specific region you live in.
For instance, if you live in a southern state, the R-value for the insulation needed in your attic will probably be around R-30, as opposed to homes in northern areas, which need R-38 insulation for their attics, since winters are colder and summers can still get hot. Once you know the R-value of your home’s insulation needs, you will have a better idea of how much material you need to meet a professional’s recommendation for proper insulation.
For walls, measure the height and width of the wall and multiply the numbers together. Subtract the area of any windows or doors.
When calculating the amount of insulation you’ll need, you need to know the area of the space being insulated. Start with one wall, and measure the height and width of the wall. Multiply those numbers for the area. If there are any windows or doors in the wall, measure the height and width of those to calculate their areas. Subtract the areas of any windows and doors from the entire wall’s area because they won’t need to be insulated. If your walls aren’t already filled with batt insulation, it’s also recommended to fill wall cavities with loose-fill insulation so your home will be adequately ventilated. An online insulation calculator can help you determine and keep track of your home’s measurements.
If you live in an older home, you’ll probably need more insulation than if you live in a new build. This is because insulation tends to settle in walls over time. For these situations, blown-in insulation through holes in the wall will be the best option to optimize the home’s comfort.
For floors, measure the length and width of the floor to get the area.
To know exactly how much insulation you’ll need to fill flooring, you will need to calculate the length and width of the floor in the specific room or rooms it will be installed in. This will provide a better idea of how many rolls of insulation or insulation material you’ll need to ensure cold air and moisture don’t seep through any cracks or holes, which can cause issues with ventilation and also encourage mold growth.
You will likely not need as much insulation for flooring as you would for other areas of the home, such as interior walls or attics. If you live in a southern climate, an expert would probably recommend a value of R-13 for your insulation, and if you live in the northern region of the United States, that recommendation would likely be R-30. Remember that if you’re hiring a professional for insulation installation, they will do all the calculations for you and determine the appropriate R-value.
The amount of insulation you need will also depend on your existing insulation and the type of insulation you choose.
If you have existing insulation in your home, you won’t need as much as you would if you were starting from scratch. Even if the insulation you have meets Department of Energy guidelines, it may need to be beefed up if you’re feeling cold in the winter and hot in the summer when you’re indoors. Depending on where the extra insulation is being installed, you may just need blown-in or spray insulation foam in a few areas.
How much insulation you need depends on the type of insulation you install, as there are several options. Blanket batts and rolls are typically on the budget-friendly end and are designed to fit in between the width of standard wall studs, attic rafters, and floor joists. However, rolls of insulation are challenging to install in homes that are already constructed. On the other hand, spray foam insulation fills leaks and gaps in wall cavities. Blown-in insulation is excellent for awkward-shaped spaces, whereas rigid foam panels are best for unfinished walls, floors, and ceilings. Radiant barrier insulation is most commonly used in attics, unfinished walls, ceilings, and floors in hot climates. An insulation pro will tell you which type is best for your home and situation and ensure that there’s enough insulation to get the job done.