Dimensional Asphalt Shingle Roof Inspection Guide


The International Standards of Practice for inspecting the roof system is located at www.nachi.org/sop.


To learn about inspecting roofs, please visit Mastering Roof Inspections.

Also called “laminated” or “architectural” shingles, their main characteristic are:

  • they consist of multiple layers.
  • they typically come in metric sizes (39”x13”);
  • have 30 to 50-year warranties;
  • weigh 250lbs to 300lbs per square
  • designed with a maximum wind resistance of 70 to 110 MPH

Note: In this display, shingles on the left side are not bonded and can be lifted to examine sealant and fastening.

Drip Edge


The section on the left (1) is correct for Florida, with the drip edge covering the underlayment at the eave. Shingles at the eaves are especially vulnerable to wind damage. This installation method helps resist underlayment uplift from wind. If you find this does not comply on a house you inspect, your report would mention it and state that it may reduce the wind resistance of the roof slightly (don’t recommend correction).

The section on the right (2) is correct for most other jurisdiction in North America and is the method recommended by shingle manufacturers. If you find this does not comply on a house you inspect, your report would mention it and state that it increases the chances of damage to roof sheathing slightly, and mention whether you saw any sheathing decay at the eave that appeared to relate to this condition.

Starter Course

The starter course is the underlying row of shingles in the first course. It should be fastened along the roof edge to resist uplift.


Starter shingles in this display are not securely fastened at the roof edge. Your report would mention this and state that this condition reduces the wind resistance of the asphalt shingle roof.

Typical correction would require:

  1. breaking the bond of full-bonded first course, fastening starter shingles, then hand-sealing shingles in the first course;  or
  2. bonding the starter shingles to the drip edge with sealant

Work to be completed by a qualified contractor. Do not recommend either correction. Your job is to identify the problem alert your client to the potential results.

First Course

Shingles in the first course should be bonded to the underlying starter shingles at the roof edge, but are not. Your report would mention this and state that this condition reduces the wind resistance of the asphalt shingle roof. Correction would require hand-sealing the shingles. Recommend that:

  1. In areas designated “high-wind”,  correction be performed to reduce the chances of wind damage.
  2. In areas designated “normal-wind”, correction be “considered”.

Field Shingles

Shingle Bonding

Bonding of the asphalt shingle sealant strip of is the single most important component in the wind resistance of asphalt shingle roofs. It allows the entire shingle roof to act as a single membrane.

Field shingles on the left side are not bonded. 


Lifting the butts, you can see that the sealant strip has been contaminated and the shingles can never fully bond. You would mention this in your report and recommend hand-sealing. It would be a strong recommendation in areas designated “high-wind”.

Shingle bonding always fails first where shingles bridge the joints between shingles in the course immediately below.

Shingles Fastening

Lifting shingles on the left, you can see that many are high-nailed or have too few fasteners. On a fully bonded roof you would not be able to see the fasteners. One indication is shingles that are slipping downhill or are missing. Shingles with over-driven or too few fasteners can me dangerous to walk. The only correction is removal and replacement of shingles.  Inspector recommendation would depend on the severity of the condition.


These shingles were fastened too high.


Excessive Exposure


Installers left too much shingles exposed in certain areas.

Sidewall Flashing

Sidewall flashing on the right side is step-flashing. This is recommended by most manufacturers and is common over most of North America.  In jurisdictions designated “high-wind” (like Florida) regulations require continuous flashing to be installed because of its better wind resistance. Its disadvantage is that it directs runoff beneath the shingles.

The left side has no sidewall flashing. This is a defective installation.

Headwall Flashing

Headwall flashing on the left side directs water beneath the shingles. Headwall flashing should keep runoff of the shingle surface. The right side is correct.

Penetration Flashing

The plumbing stack vent on the left routes runoff beneath the shingles, increasing the chances of leakage. Your report should state that this condition increases the chances of leakage, mention whether you saw any sign of leakage related to this condition, and recommend sealant be applied and flashing be installed correctly when re-roof happens. Immediate correction may be expensive and may cause trouble with the transaction, so this recommendation may cost you work.

The stack vent on the right is better, but best is if no fasteners are visible. This type of vent is not common in Florida. Look for cracks in the rubber boot.