When inspecting a 1940s colonial I noticed the roofing shingles had an unusual and uneven pattern of ageing. Viewing the home from the rear, the left side of the roof covering was distinctly more cupped, curled, and dried than the right side, which was fairly smooth.
Going into the attic I noticed there was only one gable end vent, which was on the right side of the home as viewed from the rear. This was the side with the better looking shingles as described previous.
I then look around on the floor of the attic for other tell tale signs of problems. I noticed the spots on the board in the first picture. Then on the attic scuttle cover in the second. Most often these water spots are thought to be from roof leaks. Actually they are from condensation dripping from the roofing nails. This is caused by inadequate attic venting. Moisture from the home is trapped in the attic and will condense on the cold metal roofing nails and drip.
If the moisture content is high enough it can cause mold or mildew to grow on the wood. A very easy way to spot a possible venting problem is to look at the wood surrounding the nails. If there is a black ring around the nails, this indicates moisture is condensing on the nails and the wood is absorbing the water and blackening.
Other problems are over heating of the attic, which can cause shingles to dry out, curl and prematurely age. As I saw on the back side of the roof.
The solution in this case was to add another end vent and if needed a ridge vent. This should prolong the life of the roof and stop the rain from pouring in the attic.
James Quarello
JRV Home Inspection Services, LLC
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