Roof Valley Termination

By John Turner, P.E. | October 10, 2019

One reoccurring theme we often see is poor termination of roof valleys.  We’ve seen a bunch of these recently – both in existing homes and in new designs that we were asked to review. Here’s a few examples that we’ve come across that you could look out for in your own home…

In the first example, note the brown stained icicles.  This is a tell-tale sign that water is penetrating the structure and causing rot/deterioration!  Terminating a valley at a corner like this makes for challenging flashing details.

In our second example, water streaking down the wall is indicative of valley termination at the exterior corner board.  The problem here is that even wit

h perfect underlayment and flashing, water will still find ways to penetrate the wall assembly and cause damage. Water will prefer to travel in narrow spaces by capillary action.

The best design to avoid this condition is shown in the sketch.

Are you contemplating a construction project?  Let us perform a design review.  More often than not, we can catch these overlooked details that can result in major repair costs later on!

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