What I'm Seeing Now

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Poor Gutter And Downspout Design

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

www.jaymarinspect.com


Comment balloon 10 commentsJay Markanich • January 05 2015 02:21AM

Comments

Jay, you science teacher might think this problem was too easy to detect! Nice catch anyway. Enjoy your day!

Posted by Wayne Martin, Real Estate Broker - Retired (Wayne M Martin) about 6 years ago

All very easy to see, if one knew what they were looking at.

Posted by Lenn Harley, Real Estate Broker - Virginia & Maryland (Lenn Harley, Homefinders.com, MD & VA Homes and Real Estate) about 6 years ago

When you said look carefully before I went on I saw the issue.  You are a great teacher on what to look for and I for one am learning when I read your posts.    

Posted by James Dray, Exceptional Agents, Outstanding Results (Fathom Realty) about 6 years ago

Maybe Wayne, but then he would ask me to calculate the specific gravity of the water as it is absorbed by the surrounding soil.  I'm screwed there...

Lenn - then why doesn't the gutter/downspout company designer see it?  Or supervisor?  I understand from my clients that the supervisor said I was just looking for things to report.  Ummm....

James - that is why I come to AR.  I learn stuff every day.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 6 years ago

I too like to pout about downspouts

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) about 6 years ago

I think in your neighborhood they recommend against downspouts draining onto roof surfaces Charlie.  Not so much said about that over here.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 6 years ago

Don't get me started on gutters! For as important as they are... I see waaay too many installations that looks like they were given no thought whatsoever!

Posted by Fred Hernden, CMI, Albuquerque area Master Inspector (Superior Home Inspections - Greater Albuquerque Area) about 6 years ago

Sorry Fred, but the purpose of the post was to get you started on gutters.

So get started.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 6 years ago

I thought so you rascal! So let me tell you.... 

Posted by Fred Hernden, CMI, Albuquerque area Master Inspector (Superior Home Inspections - Greater Albuquerque Area) about 6 years ago

Like everything, Fred, if principles are not obeyed, like fluid dynamics, the gutter system won't work.  The Mississippi River works to drain most of the country because it obeys the principles of fluid dynamics, naturally.

That's what you were going to say, right?

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 6 years ago

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