# Mean Roof Height

Don’t be Mean, be Average

At Hansen Pole Buildings, every building plans is originally drafted to meet the client’s specific needs and what they ordered. Every once in a while they receive some interesting feedback. Like this:

“Project #15-05xx has declined plan approval for the following reason: page S-0 under code data mean roof height should be 22.67”

Let’s begin with a refresher course on what “mean” is mathematically:

mean

(mēn) an average; a numerical value that in some sense represents the central value of a set of numbers

In the case of this particular building, it has a 32’ width gabled roof, 12 foot eave height and an 8/12 roof slope. Taking ½ of the building width (16 feet) x the slope 8/12 gives us a rise in the center of 128 inches (or 10’8”). Adding the 10’8” to the eave height of 12’ makes the overall building height 22’8” (or 22.67’).

The mean roof height would be the average of 12’ plus 22.67’ or 17.33’ as shown on the building plans. It appears there may have been some confusion, on the client’s part, as to the definition of “mean roof height”.

So why is mean roof height even important and why is it even listed on the plans? Wouldn’t the Planning Department care more about the overall building height, to make sure I don’t have a building which is too tall for my zoning?

Building plans deal with the structure of your building, how it is put together. The design wind speeds are based upon the mean (or average) height of the building roof, with a minimum of 15 feet. This mean roof height is stated on the building plans as well as the design wind loads for each sector of the building which corresponds to this mean roof height, as well as wind speed and exposure.

And yes, overall height can be important to a local jurisdiction with specific height restrictions. But not to be mean…this is not what mean roof height is all about.

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