It would be a fair statement to say that I often see poor gutter and downspout design.
Who am I to think this, you ask?
To quote Descartes, "I think, therefore I am." So there.
And when I see new, and old, construction, I often think about and evaluate the gutter and downspout design and discharge. This is brand new construction.
And I see a problem here. Do you see it? Look carefully.
What is going on here that would be of poor design?
Look at what's going on.
Before you do, you have to remember a little 8th grade lab science.
I can tell you assuredly that Mr. Levondowsky would faint to be told that I actually got something out of his lab science class, but that's another matter.
You will notice on this roof that 2/3 of the upper roof on the house drains onto the shed roof over the garage. From there the water is collected into one gutter over the garage doors and is discharged down one small-sized downspout on the right.
By my calculations that is approximately 1200 square feet of roof surface. A gallon of water is contained in an area 11" x 21" x 1". So during a 1" rain storm that entire roof surface is draining about 748 gallons into that one gutter. If I remember my lab science, a gallon of water weighs 8.34 pounds. So, during a rain storm dropping 1" of rain, that gutter is expected to handle 6238 pounds of water. That is over 3 tons!
The gutters on this house have not been in place for long, less than 2 months. Perhaps hard to see, but the gutter over the garage doors is bowing downward somewhat over the left door. Gee, why would that be? Reason 1 - it isn't inclined properly toward the downspout, and reason 2 - it is handling a whoooole lot of weight! Too much weight, by my thinking.
What would have been a better design?
That the upper roof
- the upper right roof would drain by itself off to the right side of the house,
- the gutter over the garage doors could be larger (6"),
- the gutter over the garage doors would incline appropriately toward the downspout on the right.
If the gutter over the garage is already bowing downward, it will only get worse over time.
I know, the spot in the box is lacking a kick-out flashing detail. That's another matter.
My recommendation: if things start out being a problem they will continue to be a problem. Often the problem gets worse. It's best to start out with a good design so that a poor one does not exacerbate circumstances. Will anything be done about this matter? Maybe not. But still, the home inspector is to think, observe and report. And I did. Cogito ergo sum.
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560