Friday, June 11, 2010


Remember all that math you did through high school that, depending on the method of instruction you encountered, you always wondered what use it could possibly be in real life? Well, I think the local high schools should get the trigonometry classes out building a house. I use basic arithmetic, geometry, trigonometry, and even a bit of light algebra on a near daily basis.

We've still be applying foam to the house, waiting, as per usual, for a dry spell with warm temperatures. Tuesday I put the foam on this crazy triangle wall above the greenhouse and put my 3-dimensional geometry skills to the test.

Here are the criteria I was working with:

  • The wall is a triangle
  • The foam is 8 inches wide, so I have to take into account the front and back dimensions
  • The roof above is at a 5/12 pitch
  • The roof above has rafter tails coming through that must be notched for
  • The roof of the greenhouse has a compound angle of 22° in the north-south axis and 25° in the east-west axis
  • We had to cut out one window opening in the little wall
  • I was using funny end pieces of foam that I had to piece together

We started by putting a temporary "roof" on the greenhouse so we had something to stand on.

Then we measured and marked and cut with the wire cutter and dry fit. Miraculously, after the kinks were worked out with the first course, my other pieces fit perfectly on the first go! I was giddily proud.

Then we glued and screwed nailer boards on, all while standing precariously on the compound pitch roof. (My feet and lower legs got sore up there!)

Here's the wall section when all complete:

If your math skills are in need of a little brush up, build something! you don't have to jump right in with a house. Maybe a garden box, a sandbox, a pea shooter for your nephew, a spice rack for the kitchen, or you could get fancy with a tool shed. You'll be so glad you did.


  1. And Lee always says he's bad at math. go figure:)

  2. Julie, In my experience, it's applied math that is required in building, very different from the kind of math we all did in school. And the best builders I know (including Lee, I'm sure) have all sorts of beautiful little "tricks" they use to calculate measurements quickly and accurately that don't require numbers at all!