Steven L. Smith, Bellingham, WA Home Inspector (King of the House)

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Insufficient Roof Slope

The composition shingles that we see on houses are designed for sloped roofs. They will shed water but they are not waterproof membranes. Ideally, a roof will have a slope of 4/12 or better, but generally, if a roof is 3/12 or steeper, the inspector probably won't say much about it.

This is a roof slope gauge. It is on a composition roof. The slope is about 1.25/12. Now, as an inspector, I have to cite that as a potential problem. In some cases, like at manufactured homes, the factories use minimal slope but we hope that they use a good system of underlayments and felts below the surface. But, even at a manufactured home, the roof better have more slope than this.

Some sellers might think that the inspector is a bad guy for referring to this as a worry. After all, the average home owner and do-it-yourselfer has no clue about slope. In this case, it was a pretty easy call. The low slope was resulting in leaks and rot at the underside of the sheathing.

This photo was taken at an attached shed where the problem was obvious, but parts of the house were equally low sloped. A roofer needs to be called in to remedy the roof problems here.

 

Steven L. Smith

If you enjoy nostalgia and music of yesteryear, click on Elvis' gold record to visit This Day In History. To explore The Stories Behind The Music blog posts click on the electric guitar. 

 

        

 

 

 

 

Comment balloon 6 commentsSteven L. Smith • June 04 2011 05:53PM
Insufficient Roof Slope
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The composition shingles that we see on houses are designed for sloped roofs. They will shed water but they are not waterproof membranes. Ideally, a roof will have a slope of 4/12 or better, but generally, if a roof is 3/12 or steeper, the inspector… more
Electric Safety and GFCI's -- The Basics
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In the State of Washington, regardless of the age of the house, an inspector must recommend that the clients upgrade to GFCI protected receptacles in those areas where they are, today, standard. The state standards of practice dictate that… more