This article discusses the appearance, cause, and impact on roof life of nails that "pop up" or push up from underneath a roof shingle enough that we can see the shingle lifting from the roof surface.

Page top photos: lifted asphalt shingles on this roof are probably being pushed upwards by nails in each shingle course below.

Page top photo courtesy of Dov Ber Kahn, a New York home inspector.

Nail Pops in Asphalt Shingle Roofs

Roof shingle nails that are not driven flush with the surface of the shingle or that have worked their way upwards are more than a cosmetic defect on a roof. They can lead to roof damage and roof leaks as we'll explain.

Our page top photo shows how you might spot this condition on a roof. Individual shingles are seen as pushed upwards from below, arcing or bending over a roofing nail that sticks up below the shingle.

Here we include photos illustrating shingle nail pop conditions on roofs and clues to help you recognize this condition.

Why are Roof Shingle Nail Pops a Concern?

Sketch (above/left) of common roof shingle nailing errors is a detail from FEMA's , Asphalt Shingle Roofing for High Wind Regions cited at the end of this page.

Notice that the second nail from right (circled in red, our addiition to the image) is not fully driven.

This type of "nail pop" will hold up the lower edge of the next course of shingles above and thus increases the risk of wind blow-off or of damage from foot traffic.

Shingle nail pops can reduce roof life by lifting and curling shingles, increasing the risk of wind damage.

If someone walking on the roof steps on one of these popped-up shingle nails the result can also be an immediate hole in the shingle, also reducing roof life and increasing the risk of a roof leak.

More subtle, shingle nail pops can, by creating a raised pressure point under a shingle, lead to early granule loss on the exposed or weather side of the shingle, reducing roof life.

Roofing product manufacturers are careful to specify where shingle nails should be placed in each shingle and the number of nails required.

How nails are driven is critical to a shingle's ability to stay on the roof.

Causes of Nail Pops or Raised Nails in Asphalt Shingle Roofs

These "asphalt shingle nail pops" may be due to several causes including

• Failure to drive the shingle nail fully
  
  when the shingles were first installed. The roofing nail should be driven so that its head is flush with the top of the shingle surface.
  
  The nail should not stick up above the shingle surface, and it should not be over-driven such that it cuts into the shingle.
• Bent-over roofing nails
  
  from sloppy use of a nail gun, such as by the roofer reaching out too far to drive a nail rather than moving her or his body closer to the nailing location
• Crooked roofing shingle staples,
  
  leaving one end sticking up above the shingle, also caused by over-reaching while stapling shingles to the roof deck.
  
  See ASPHALT SHINGLE STAPLE vs NAIL 
• Roof decking in poor condition,
  
  soft or rotting so that nails are not retained in place.
  
  Roof sheathing rot damage or plywood delamination damage may be due to roof leaks (LEAKY ROOF DIAGNOSIS & REPAIR ) or to attic condensation traded to inadequate ventilation (ATTIC CONDENSATION CAUSE & CURE)
• Poor choice of roof deck material -
  
  fiberboard roof sheathing (FIBERBOARD SHEATHING) or gyupsum board roof sheathing (SHEATHING, GYPSUM BOARD) may have less nail withdrawal resistance than wood or plywood.
• Improper roofing nail choice:
  
  shingle nails that are too short or wrong type.
  
  At ASPHALT SHINGLE NAIL TYPES we explain that a shingle nail must be long enough that its tapered point actually extends through the inside surface of the roof decking.
  
  This requirement is to address the problem of use of relatively thin roof decking (often 1/2" CDX but on some older homes even as thin as nominal 3/8" thick plywood).
  
  By making the nail tip show up on the underside of the roof deck we are assured that the roof deck grasps the full-width shaft of the roofing nail throughout the thickness of the roof decking itself - thus improving nail withdrawal resistance.

We note that roofing nail pops may occur in other roof installations such as roll roofing or roofs using other shingling materials, but their impact and effect is in our (DF) OPINION most commonly observed in asphalt shingle roof installations.

Examples of Shingle Nail Pops Lifting Asphalt Shingles

Below, courtesy of reader Jim S we see asphalt strip shingles being held up above the roof surface.

Jim asked: Can you tell me what kind of shingle this is and who makes it. It looks like a 3 tab but the tabs are much wider? The house was built in 2002.

Also what do you think is causing the lifting on the shingles. They are on all the slopes? - Jim S. Aug 2, 2020.

We said: To diagnose the cost of those lifting shingles you'll need on roof access. Gently lift up without damaging the shingle in an area of uplift. I suspect you will see a nail pushing up from the roof deck below.

At the top of this page and below are photos of what we think are nail pops in an asphalt shingle roof on a New York home, courtesy of Dov Ber Kahan.

Dov's first photo shows multiple areas of lifted shingles on two slopes of this home. More detail follows.

Below we see a closer view of lifted shingles on this roof that we think are being held up by raised roofing nails that were either not fully driven or that are pushing their way upwards. Our photo also notes some other questions about this roof and its ventilatin system.

In Dov's third photo below at the right side our circle with a white arrow is pointing to what looks like granule loss above exactly were we expect to find a nail head below the shingle surface.

Below is a closeup of that damaged Shingle

 

Roof Shingle Nail Pop Damage Research

• ASPHALT SHINGLE ROOFING FOR HIGH WIND REGIONS, HOME BUILDERS' GUIDE TO COASTAL CONSTRUCTION [PDF], FEMA 499, August 2005, Technical Fact Sheet No. 20.
• Donan, JL,  SELF-SEALING ASPHALT SHINGLES – TECHNICAL BULLETIN 1.0 SEAL STRIP DESIGN, EXPECTATIONS, AND FAILURE ANALYSIS [PDF] J. Lyle Donan, P.E., C.F.E.I. President Donan Engineering Co., Inc ​ 
  
  
  
  Excerpts from photos and text above and below:
  
  Regardless of seal strip performance, be wary of the roof that has many nail pops!
  
  While nail pops may occur for a variety of reasons, when they cause the overlying shingle to become raised, they may not only puncture the shingle or cause its seal strip to fail, but because they elevate the overlying shingle’s profile, they also make a roof inherently more prone to wind damage.
  
  
  
  Donan Engineering Co., Inc. is a forensic engineering and fire investigation company headquartered in Louisville, Kentucky with offices throughout the central United States.
• Esmay, Merle L. Factors affecting the durability and wind resistance of asphalt shingles. Iowa State University, 1951.
• Williams, Chad T. "Use of the Repairability Assessment Method for Evaluating Asphalt-Composition Shingle Roof Repairs." Journal of the National Academy of Forensic Engineers 37, no. 1 (2020).

Thanks for photos and technical consulting from

• Dov Ber Kahn, a home inspector in Rockland County, NY has contributed photographs of various building features to InspectApedia. Mr. Kahn is a licensed home inspector in New York and New Jersey, and can be reached at Website: Kahnbhomeinspectors, Tel: 845-445-8234, Email: kdovber@googlemail.com

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Continue reading at ASPHALT ROOF SHINGLES, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

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• ASPHALT ROOF SHINGLES - home
• ASPHALT SHINGLE INSTALLATION
• ASPHALT SHINGLE LIFE / WEAR FACTORS
• ASPHALT SHINGLES on LOW SLOPE ROOFS
• ASPHALT SHINGLE NAIL POPS - nails pushing up from below damage the roof shingles
• ASPHALT SHINGLE NAIL TYPES
• ASPHALT SHINGLE STAPLE vs NAIL
• ASPHALT SHINGLE TEMPERATURES
• LADDERING vs STAIR STEPPING SHINGLES
• ROOF INSTALLATION WORKMANSHIP
• SHINGLE EXPOSURE AMOUNT
• BEST ROOFING PRACTICES
• WARRANTIES for ROOF SHINGLES

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