Insulation Calculator

Calculating how much insulation you need for your project isn't as hard as you would think. All you need are some basic concepts and knowledge of how the insulation will be installed. The calculations for walls, floors, and ceilings are surely going to be different so don’t try and use one calculator for insulation on all surfaces. Insulation calculators can tell us the most effective insulation option and help us when comparing between options, and our advanced insulation calculator can take any kind of situation for insulating into consideration.

Types of Insulation

The most used types of insulation are:

  • Rolls
  • Batts
  • Faced insulation
  • Unfaced insulation

There are several things to take into consideration when calculating the right insulation for you. First, you need to know the zone and requirements of insulation for your area. 

The U.S. Department of Energy has established a specific guideline for R-values that are required depending on where the project is located. Zoning is broken up into zones 1 to 7. Check your zone requirements on the DOE map to figure out the R-value range for your area.

After figuring out your zone, you need to measure the room. Start by measuring the height and length of each of your room walls to determine the amount of insulation needed. Write down the spacing of the studs and multiply the wall’s length by the wall’s height so you can determine what kind of house insulation will be needed. This is important because insulation usually comes in pre-cut standard rolls designed to fit exactly in between studs. When measuring, make sure the window and door openings aren’t subtracted. These measurements will make up for odd cavities, nonstandard framing, and differences in framing. If your walls aren’t filled with batt insulation, it is recommended to put loose-fill insulation so your home will be adequately ventilated.

When you take measurements, first measure everything in inches. Then convert all of your measurements from square inches to square feet. All you need to do is divide the square inch number by 144 to get square feet.

When measuring floors, you’ll need to calculate the length and width of the floor of all the rooms the insulation will be installed. Doing this will help you know how many rolls of insulation or insulation material you’ll need to stop heat and moisture transfer in the flooring which causes ventilation and mold issues.

After measuring the floors and/or walls, calculating how much insulation you’ll need depends on the type of insulation you opt for, as there are several options. Rolls and blanket batts are typically the more budget-friendly options and are designed to fit between the width of standard dimension floor joists, wall studs, and attic rafters. One of the best insulation that comes in rolls is FAST ACTION Prodex Total 5M, which is excellent for metal buildings, homes, and even pole barns. Rolls can sometimes be very challenging to install in already built homes. The best solution for awkward spaces is blown-in insulation, whereas rolls or rigid foam panels are best for unfinished walls, floors, and ceilings. Attics, unfinished floors, walls, and ceilings in hot climates most commonly use radiant barrier house and roof insulation. Our insulation calculator can help you with choosing the best type of insulation for your needs.

How to calculate your attic area:

  • Measure the outside of your home.
  • Before measuring the first wall, walk around the exterior of your house to get familiar with the shape. Choose a corner of the house as a starting point, hook the end of the measuring tape to the starting point and begin measuring wall by wall.
  • Keep in mind that interior attic space may differ. Areas such as home additions may have different levels of insulation. Prior to measuring, group these areas separately if necessary.
  • Multiply the length and width of each rectangle to get the area.
  • (Area A+ Area B+ Area C) ÷ 144 = total square feet

How to calculate your wall cavity:

  • Measure the outside of your home.
  • Measure the height of the walls from the floor to the ceiling. If you own a multi-story home, measure from the floor to the ceiling of the top story.
  • Measure the length and width of all exterior windows and doors.
  • Subtract the area of windows, doors, and any walls you aren’t planning to insulate.
  • [(Exterior perimeter × height) − (window and door area + any walls/areas not insulating)] ÷ 144 = total square feet.

How to calculate basement or crawlspace area:

  • Measure the inside perimeter and the height of the walls from the floor to the underside of the subfloor.
  • Measure the length and width of all exterior windows.
  • Subtract the area of windows, doors, or walls you aren’t planning to insulate.
  • [(Interior perimeter × height) − (window and door area + any walls/areas not insulating)] ÷ 144 = total square feet.

Roll insulation calculator

Roll insulation is sold in standard sizes, suitable to insulate a certain amount of square feet per package. For example, 48 Prodex Total 5M is 48” in thickness and 700sq feet in size, so it’s best suited for metal buildings. Rolls, batts, or bales all describe these kinds of packages, the exact name depends on the type of insulation. Batts and rolls refer to fiberglass insulation sold in units of different sizes, with paper dividers between layers. Bales of insulation are used with shredding and blowing machines.

Insulation square footage calculators are available on most of the insulation manufacturers' websites. The pros and cons of each insulation type depend on the application, but the most important thing when choosing insulation is to know how much you’ll need to get. Insulation calculators on manufacturers' websites are geared towards calculating how much of their product you will need. Third-party insulation calculators, such as Omnicalculator, can provide a better idea of how much you will need, as they aren’t manufacturer specific.

How much insulation do I need?

Under-insulated homes are very common in the US. Regardless if you need ordinary home insulation or metal building insulation, performing a simple insulation inspection will help you determine how much insulation you need.

Firstly, you should inspect the insulation situation in your attic, because adequate attic insulation can help you maintain a comfortable temperature throughout your home, help save money on energy bills and prevent major issues like ice dams in the winter. If insulation measuring doesn’t add up and you need more, this can be done as a weekend DIY project, or you can call a professional to be sure it is installed correctly. Standard 1.5”x7.5” joists need R-values between 38 (for most southern climates) and 49 (for northern climates). That means the attic insulation will be between 13” and 18” deep, depending on the climate and type of insulation.

The exact amount of insulation you will need depends on a number of factors:

  • Where you live - different climates require different insulation R-values. Higher R-values are needed if you live in northern climates.
  • Home or building age - if the building is more than 10 years old, you will likely need to install more insulation. There are great options for installing insulation in already built buildings.
  • Your building type - house insulation, metal building insulation, and pole barn insulation all have different requirements.

Which Kind of Insulation is Best?

The best thing you can do for determining what insulation will fit your needs best is to get a professional to assess your situation and suggest the best type of insulation for your needs. Good contractors will do this with the intent to fulfill your needs rather than their sales quota. You can even evaluate this yourself using our advanced insulation calculator. You’ll need to know if the space is regular or whether it has an irregular shape (you need to measure it).

Batts and rolls like 10M Prodex Total Plus are usually suited for regular, sectioned-off spaces, such as the space between studs or rafters in walls, ceilings, and floors. Blown-in insulation is best for open spaces with a lot of awkward angles and hard-to-reach areas like crawl spaces or attics.

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