You don't anticipate seeing this, but I have never seen a completely rotting roof.
I smelled something funny when we got to the upper level. But we saw nothing amiss moisture wise anywhere.
Then opening the attic access I got a whiff and wow, lots of something was going on up there!
Everywhere I shined my light the roof was rotting.
The ENTIRETY of the roof!
This is an older town house, but the older, bad FRT roof sheathing had been replaced. Around here that would have likely been in the mid 80s to mid 90s.
Getting up there it smelled strongly of mushrooms.
None were visible, but it really smelled a lot like mushrooms!
And when they put in the new FRT plywood, they did not add separator clips, so the sections were sagging where they abutted one against another.
Looking around the attic I saw many conditions, which certainly contributed to the evident moisture problems -
1. When in bloom the house would be completely shaded by large, leafy trees.
2. The roof had two layers of shingles. The second layer is not brand new.
3. Someone had added an extra layer of 6" of fiberglass insulation inside the attic.
4. There is a ridge vent visible from the outside, but there was no slot cut to allow air out. The roofer of the second layer of shingles knew this.
5. This extra insulation had been pushed to the very edge of the roof, seen in the lower left photo, completely covering the soffit vents.
6. There was no ridge vent, or smaller scoop vents.
7. The only bathroom vents into the attic space. The tubing can be seen in the lower left photo.
You add all this up and so much general moisture, held in place by extra shingles and insulation, with no air flow, and this would be the expected result.
I have never before seen roof sheathing so generally rotten, but have heard it is possible.
AND IT IS!
My recommendation: moisture has to be controlled, everything needs to breath and a do-it-yourself homeowner, no matter how good the intentions, can cause a lot of damage. Combining an unprofessional roof installation with a homeowner trying to increase the insulation and you have a recipe for moisture retention. The ultimate result is a roof that looks like the above.
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560