Insulation Calculator

- May 10, 2025
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Calculate the amount of insulation needed for your project, estimate costs, and determine R-values based on your climate zone. Enter your wall/ceiling dimensions, select insulation type, and get detailed estimates including material requirements and energy savings potential.

Project Information

Dimensions

ft
ft
in
sq ft
sq ft

Insulation Type

in
%

Cost Information

£ / sq ft
£ / sq ft
£ / kWh

Advanced Options

About Insulation and R-Values

Insulation is rated by its thermal resistance, or R-value, which measures how well it resists heat flow. The higher the R-value, the greater the insulating effectiveness. The R-value needed depends on your climate zone and the area being insulated.

Insulation Types Comparison
  • Fibreglass Batts: Common, affordable, and easy to install. R-value of about 3.1-3.4 per inch.
  • Mineral Wool: Fire resistant and good sound absorption. R-value of about 3.0-3.3 per inch.
  • Cellulose: Made from recycled paper, good for filling irregular spaces. R-value of about 3.2-3.8 per inch.
  • Spray Foam: Excellent air sealing properties. Open cell: R-3.5-3.6 per inch. Closed cell: R-6.0-7.0 per inch.
  • Rigid Foam Board: High R-value per inch (R-4 to R-6.5) and good for limited spaces.
Recommended R-Values by Zone
  • Zones 1-2: Attic R-30 to R-49, Walls R-13 to R-15, Floors R-13
  • Zones 3-4: Attic R-38 to R-60, Walls R-15 to R-21, Floors R-19 to R-25
  • Zones 5-7: Attic R-49 to R-60, Walls R-21 to R-28, Floors R-25 to R-30
  • Zone 8: Attic R-49 to R-60, Walls R-28+, Floors R-30+

What is the Insulation Calculator?

The Insulation Calculator is a handy tool that helps you figure out how much insulation you need for your home project. Whether you’re insulating walls, attics, or floors, this calculator provides clear estimates. Just enter your dimensions, pick the insulation type, and it will give you the details, including costs and energy savings. This makes planning your insulation project much easier and more efficient.

Understanding Insulation and R-Values

Insulation works by slowing down the flow of heat, and it’s rated by R-values. The R-value represents how effective the insulation is at resisting heat. A higher R-value means better insulation. Here are some common insulation types and their R-values:

  • Fiberglass Batts: R-3.1 to R-3.4 per inch.
  • Mineral Wool: R-3.0 to R-3.3 per inch.
  • Cellulose: R-3.2 to R-3.8 per inch.
  • Spray Foam: Open cell R-3.5 to R-3.6; Closed cell R-6.0 to R-7.0.
  • Rigid Foam Board: R-4 to R-6.5 per inch.

How to Use the Insulation Calculator

Using the Insulation Calculator is straightforward. You start by entering project details like the area to insulate and your climate zone. The tool will then guide you through selecting the right materials and even factoring in waste. It’s all about making your insulation planning as smooth as possible, so you get accurate results tailored to your specific situation.

Estimating Costs for Your Project

The calculator doesn’t just stop at insulation quantities; it also helps you estimate costs. You can input material costs and optional labour costs, giving you a total project cost estimate. This feature is especially useful for budgeting, ensuring you know what to expect financially before you start your project.

Climate Zones and Insulation Needs

Your climate zone plays a big role in how much insulation you need. The calculator allows you to choose your zone, which helps determine the appropriate R-value for your insulation. Here’s a brief look at recommended R-values based on climate zones:

  • Zone 1-2: Attic R-30 to R-49, Walls R-13 to R-15.
  • Zone 3-4: Attic R-38 to R-60, Walls R-15 to R-21.
  • Zone 5-7: Attic R-49 to R-60, Walls R-21 to R-28.
  • Zone 8: Attic R-49 to R-60, Walls R-28+.

Custom Options for Your Insulation Needs

Flexibility is key when it comes to insulation. The Insulation Calculator provides custom options like stud spacing and insulation thickness. This means you can tailor your inputs for a more accurate estimate. Whether you have standard or custom dimensions, the calculator can adapt to your specific requirements, making it a versatile choice for any project.

Advanced Features for Detailed Planning

The Insulation Calculator also includes advanced features, such as the ability to account for air sealing materials and vapor barriers. Users can adjust decimal places for precision, and even choose to see calculation steps. These features ensure that you’re not just getting a number; you’re understanding how that number was derived, helping you make informed decisions for your insulation project.