STL HOME INSPECTOR TIPS: DETECTING ATTIC DAMPNESS

The St. Louis Brick Kick'n Blog

ST. LOUIS HOME INSPECTOR TIPS: DETECTING A DAMP ATTIC

DETECTING MOISTURE

So, we’ve still got cool enough weather in the St. Louis area that it’s not too uncomfortable to get some projects done in the attic, and you want to take a look to see what else might be needed.  We’ve covered wiring, insulation concerns, and a couple of other things, but what else should you look for?  One of the biggest problems that can occur in an attic is too much humidity, but how can you tell if you might have that problem?

Never mind the obvious stuff.  An active water leak, rotting and moldy roof sheathing, or catch containers half full of water are all dead giveaways.  There is no mystery there.  But, what if none of these are in visible?  Are there any other clues that you might be getting excessive moisture in your attic from time to time?  Well, in the words of a certain, somewhat controversial ex-vice presidential candidate, “You betcha!”

It’s important to be aware of this moisture for several reasons.  Excessive humidity can lead to mold, damaged sheathing, saturated insulation, and ceiling stains.  The good news is that there are fairly simple steps to get rid of it.

If your roof sheathing is made from plywood, you can bet that it is not an exterior grade material.  The glue holding the wood layers together can be damaged from too much humidity, resulting in delamination.  I have shown this in one of the photos. 

The individual layers or laminations of the plywood literally start coming apart, and the plywood loses its strength.  Since this is the main support for the roofing, leaks can result, and the roof can become a hazard for anyone walking on it.

Another good indicator of excessive humidity is dark streaks where the roofing nail tips are sticking through the sheathing.  Excessive humidity in an attic can condense on these nails during periods of really cold weather.  The condensed moisture will soak up into the sheathing, following the grain of the wood, and it will take a little of the nail plating with it.  This is identifiable because of the darkening in the wood where this has occurred.  Some of this condensation can also drip off of the ends of the nails, leaving drip stains on any exposed surface in the attic.  Look for these on any exposed wood, on attic fan housings, and on the upper surface of your attic hatch cover. 

Examples of these dark streaks and drip marks are also included with this article.  Maybe one of them was taken during your home inspection.


AUTHOR:
Michael Chambers – St. Louis Area Home Inspector
BrickKicker Home Inspections
Email: Michaelc@brickkicker.com
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