Useful Tool When You Find Yourself Asking: Honey, How Steep is That Roof Slope?!

Useful Tool When You Find Yourself Asking: Honey, How Steep is That Roof Slope?!

One of the classic tools of a well-equipped truss designer or supplier is the ubiquitous, hand-held, transparent plastic “pitch finder.”  This tool is used for answering one question and only one, when either visiting an existing building or glancing over a set of plans: “How steep is that roof?!”


Roof pitch, or steepness of slope, is a great visual cue in building design.  It gives off layers of subtle communication regarding the building as a whole:

  • How formal a design is it
  • How proud or pretentious is it meant to be
  • How striking or mild the initial impression was intended
  • What architectural style is the building meant to emulate
  • How much area did the owner intend to reserve for “attic” space under the roof.

When examining existing buildings or new plans it is often a lively topic of conversation, how steep is (or should be) a particular roof line, and what would it look like with a different “pitch”? More practically, exact pitches become a serious topic of debate where the possibility of interference between rooflines and windows, or other roof elements, becomes possible.

Roof truss designers are required to inspect plans and elevations (even photographs for additions) for clues regarding the roof pitch.  Often a pitch is mismarked on a plan, where the labeling of the pitch isn’t represented by the angle of the actual lines.  Other times, roof plans are drawn without any particular pitch indicated.  Sometimes the only indication of the pitch of an existing roof is a photograph taken at 90-degree angles to the building, where a customer wants to get an approximate price quote on matching new trusses to the existing construction.

In each of these cases, the plans or photographs are not on paper, but rather in digital format!  Whether a PDF or digital photo, the classic plastic “pitch finder” can sometimes be used with difficulty on flat LCD computer monitor to check pitch, by comparing the slope visually to a horizontal line, like the bottom of the screen.

However, there is an easier way!  To check a roof pitch on digital plans or photographs on a computer, my favorite method is to “print” a PDF of a “pitch finder” CAD drawing and save to a memorable location.

With the use of a tiny, free program called “Ghost-It!” this PDF can be overlaid on your screen using a “transparency” setting which enables you to reference your drawing or photograph against the digital “pitch finder” you highlighted.  The degree of transparency can be adjusted by the user in the very simple “Ghost-It!” settings menu, until both the “pitch finder” and the underlying drawing are easily visible.


The “pitch finder” overlay is whisked away with the click of a button in “Ghost-It”, which runs in the system tray on the lower-right corner of your desktop.


As you might imagine, this method works very well for checking any photograph, as well as being a speedy and convenient way to “double check” pitches marked on a PDF plan which require some sort of verification.  This process of methodical checking and re-checking plans is important for careful and thorough component design, and we at GDI are dedicated to using every tool at our disposal to make sure that we are working with the correct information.  We hope that you also can make use of this handy tool in your own design process, or when surfing the web looking at plans or photos.

Jonathon Landell – Design Professional

Gould Design, Inc.