Common Roof Defects found during inspection

I’m sure it’s varied by geographical area… but what are some of the most common Roof Defects found in your area during a Residential Home Inspection?

As I’m surrounded by vast amounts of Concrete Tile… day after day, I’d say the most common defect I find in this roofing system is lack of maintenance, including gaps/voids around plumbing and heat vents, metal valleys impacted with debris, cracked/slipped tiles that have allowed the membrane below them to become damaged by sun/elements. Installation defects aren’t too hard to find either, you can usually find ridge tiles acting as a bird’s mouth for water under the tile system.

The toughest part of inspecting in-place concrete tile roofing systems is that fact that the membrane is concealed below the tile. I’ve gotten familiar enough with these systems that certain ages of homes are likely closer to the “edge” of their service life, but… catching a glimpse of the paper below can be very informative, as would be the condition of the underside of the sheathing. Especially on a 30+ year old concrete tile install.

As we also have a fair amount of composition roofs here as well… I find a lot of “shiners” along the perimeter and ridge/hip that are begging to be covered… along with the typical stuff.

What are common roofing defects in your area that you across day in and day out… along with “stuff” that’s not so easy to spot?

One common mistake is to find continuous sidewall flashing installed with comp shingles. It’s always wrong. They always require step-flashing.

Another is comp shingles that are poorly bonded or have never bonded. The adhesive strip bond is the most important component in wind resistance, more important than fasteners, so it should always be checked.

Another defect common with a variety of roof covering materials is that at sidewalls and headwalls, there is inadequate clearance between the roof-covering material and the bottom of the exterior wall-covering material.

Lack of crickets above chimneys 30" or wider is relatively common.

Batch problems are relatively common on older homes with comp shingles, especially those with organic shingles.

Here is one Shingles nailed too low. Another is improper exposure causing poor adhesion.

Ditto here Tim…but the underlayment generally lasts about 18-20 years if their lucky…the extreme heat cooks the hell out of it.

Poor ventilation, vaulted ceilings, I’ve seen complete failures at 14 years.

Good post. We also have a lot of flat roofs. Ponding and mumpimg seem to be two issues I see on almost every installation. If the A/C is on the roof I usually see condensate drains that drain to the roof cover and improper covering around the A/C stand. Most of the time You can’t access the attic of the flat roof but I bet there would be moisture stains in many cases.

I agree.
Great point Mr. Spargo.
Butumin caulking compounds are inexpensive and used by all roofers around Montreal Quebec.
Roof protrustiuons, flashing and copping, openings, seams, or gaps.
Improper proceedure to applocation,IE; thin, poorly placed, improper tooling after applocation andf as little as 3 years water ands weather infultration is apparent.
Maintenance on roofing systems is number one deficiency.
After that.
In my area, zone 5a PHZ ( plant hardness zone ) Ply decks before 2000 lack underlay or adequate underlay.
Start course is deficient, attic ventilation.
Good thread.

John, are you referring to underdriven nails?

In Fort Pierce we find a lot of underdriven, overdriven and angle-driven shingle nails as well as a lot of exposed nails.

  1. Poorly or improperly installed shingles, particularly in valleys (apparently some people do not know what “woven” means).

  2. Flashing at intersecting walls, chimneys, etc. Lack of or the use of caulking instead of an approved flashing material. Always, always fails.

  3. Shingles installed over rotted wood, holes left when some type of through the roof stack or vent has been removed, or damaged wood.

  4. Shingles installed while too hot, badly damaged or smudged from some knucklehead walking on it…removes the mineral surface.

  5. Shingles installed too tight together. Buckles in summer.

  6. Ridge vents installed improperly or not at all. Find many ridge vents installed over a solid ridge…no cut out for air to escape. Ridge vents missing end caps…allows critters and vermin to enter and take up housekeeping in the attic…yes, even squirrels can squeeze through an open ended ridge vent…see it all the time. Ridge vent caps costs $1.50

  7. Exposed roofing nails…these eventually rust away, leaving tiny holes that continuously seep water, rots out the sheathing. See this one a lot. Nails standing proud on the roof surface.

Another common problem is nails placed above the adhesive strip, although if the shingles are bonded you won’t discover until they blow off.

Over and under driven nails are from air guns. You have to set the pressure for every deck substrate. Thickness, density, species, always differ in rigidity.
Under driven nails are never set and over driven nails loss the sealing ability when windy conditions arise.
I am an old nailer. Hammers and soars on your hands.
Kenton I to was taught above the nailing strip until I learned why.
Very, very common problem. They think it stops the chance of leakage.
Good point.