A common question we get from folks installing wool insulation (or at least thinking about it) is “How much wool will I need?” Insulation measurement can be a daunting task. In this week’s blog we make it simple, real simple.

Let’s do a little bit of measuring

A few things you will need  before getting started :


  • Measuring tape
  • Pencil and paper

At a high level all we want to do is measure the square footage of what needs to be insulated. It is a simple  process.

Let’s use a 10’ by 20’ room with 8’ high walls and a 3’ by 4’ window for our example.

Step One : Measure the Room Dimensions

The first 2 walls are 10’ by 8’ which is 160 s/f . 2*(10*8) = 160
The other 2 walls are 20’ by 8’ which is 320 sf. 2*(20*8) = 320
160+320 = 480 s/f is the room dimension and also our Initial Amount to be insulated.

Step Two : Measure and Adjust for Windows and Doors

The dimension of the window is 12 s/f (3×4). Subtract that 12 s/f from the above Initial Amount to get the Adjusted Amount. 480 s/f – 12s/f = 468 adjusted s/f. This is the square footage of wool insulation you need for that room. Follow the same exercise for any doors in the room.

Step Three : Note Cavity Depth of your Walls

If you are using 2×6”’ studs the actual depth is 5.5”. You do not need to incorporate this into your calculation but stud depth needs to be defined.

A few additional notes :

The space occupied by each stud in your wall can be calculated and then subtracted from the Initial Amount. But let’s keep it simple and avoid this step. Any slight overages can be used to cover for any miscalculations.

To measure floor and ceiling just use the dimensions of the room – 200 s/f (10×20′). The cavity will probably be larger eg 2×10 or 2×12 thus requiring more depth in insulation. Attics and roofs can add challenges with knee walls, and pitch angles but your general contractor can help, or you call us and we will!

And finally, please review our Where to Use Wool Insulation doc for some helpful guidance on insulation measurement.

Thanks for reading and keep well,

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2 comments on “Insulation Measurement Doesn’t Need to be Complicated. The Easy Step-by-Step Process.

  • THANKS! Andrew for all the helpful information. I will be starting on my 2019 Dodge Promaster Van conversion in early 2020 and will look forward to using your wool insulation!!

  • Both side walls 270 sqft and the ceiling 156 sqft. And the wall cavity depth is 4 1/2 inches, the ceiling is about 1 – 2 inches.

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