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Common Roofing Mistakes

It’s essential to understand that when selecting a roofing contractor, the workmanship elements are often more important than the quality materials you choose. Many homeowners mistakenly believe all roofs are installed equally, but the reality is that proper installation techniques make the critical difference in your roof’s performance and longevity.

Unlike purchasing a television with standardized manufacturing, roofing involves numerous skilled techniques that vary significantly between contractors. At Dayus Roofing, we employ only the most experienced roofers in Windsor-Essex County, ensuring your installation meets the highest standards in the industry.

Below we outline some of the most common roofing mistakes and workmanship errors that less experienced contractors frequently make:

  • High Nailing & Low Nailing
  • Over or under driven roofing nails
  • Mixed Ventilation
  • Over or under ventilating
  • Venting a bath or kitchen exhaust fan
  • Misused vent types
  • Misused or Forgotten underlayments
  • Re-using or omitting flashings
  • Re-using or omitting drip edge
  • Wrong shingles for hip & ridges
  • Plugged Soffit Ventilation
  • Installing shingles over old boards

The Foundation of Proper Shingle Installation

High Nailing & Low Nailing:
Precision Matters

High Nailing & Low Nailing

One of the most critical yet frequently overlooked aspects of roof installation is proper nail placement. Unfortunately, this fundamental error is extremely difficult for homeowners to detect without specialized knowledge.

The Nailing Strip

Shingles feature a designated nailing strip ranging from ½ to 1 inch wide where fasteners should be placed. When nails hit this specific zone, they should penetrate both the shingle being installed and the course below it. With four nails per shingle, each shingle ultimately receives eight fasteners for maximum wind resistance and stability.

Common Installation Errors

Many contractors compromise quality for speed to reduce costs, resulting in fasteners placed outside the designated nailing strip. High nails frequently miss the underlying shingle and fail to penetrate the shingle's reinforced core, dramatically reducing wind resistance. Conversely, low nails leave heads exposed to the elements, leading to corrosion, expansion/contraction issues, and eventual leakage points.

Laminated Shingle Consideration

With modern dimensional shingles, proper nailing becomes even more critical. Nails must penetrate both the base sheet and the second lap to achieve maximum strength and performance. Improper placement compromises the entire roofing system's integrity, often voiding manufacturer warranties and reducing your roof's effective lifespan.

Understanding Proper Attic Airflow Design

Mixed Ventilation: A Critical System Error

One of the most consequential mistakes made by inexperienced roofing contractors is combining different types of ventilation within a single attic space. This fundamental error undermines your roof’s performance and can lead to serious structural issues.

Proper Airflow Design

Your attic ventilation system is designed to create a specific airflow pattern, with fresh air entering through soffit vents at the eaves and exiting through exhaust vents at or near the peak. This continuous airflow helps regulate temperature, remove moisture, and extend shingle life.

Different vent styles create airflow through distinct mechanisms. Ridge vents provide linear exhaust along the roof peak, while whirlybirds use wind to create suction. Static vents rely on natural convection, and power vents use motors to force air movement. When combined, these systems work against each other rather than in harmony.

Mixing vent types can “short-circuit” your ventilation system, drawing conditioned air from your living space rather than from the soffits. This not only wastes energy but can actually pull moisture and even snow into your attic during winter months, leading to insulation damage, mold growth, and structural deterioration.

The Critical Element of Fastener Installation

Over or Under Driven Roofing Nails:
Precision Depth Control

Beyond proper placement, the precise depth of roofing nails is crucial for long-term roof performance. Over-driven fasteners that penetrate too deeply can tear shingles or break through entirely, creating potential leak points and reducing wind resistance. Conversely, under-driven nails that sit proud of the surface create bumps and air pockets in subsequent shingle courses, making your roof vulnerable to wind damage and compromising its appearance.

Understanding Proper Material Applications

Using Asphalt Shingles in Low Sloped Areas: Design Limitations Matter

Standard asphalt shingles are specifically engineered for roof slopes of 4/12 and steeper, with special installation techniques sometimes permitting use on 3/12 slopes (often with reduced warranty coverage). Despite these clear manufacturer specifications, many contractors install standard shingles on inadequately sloped surfaces, creating inevitable future failures and costly repairs.

When shingles are installed on too shallow a pitch, water drains slowly or pools on the surface, accelerating deterioration and leading to premature failure. Additional problems include increased vulnerability to wind damage, penetration from wind-driven rain, and winter ice creep beneath shingles. For proper low-slope applications, specialized materials designed specifically for these conditions should be installed instead of standard asphalt shingles.

Common Ventilation Mistakes and Solutions

Over or Under Ventilating: Balanced Airflow Matters

Over or Under Ventilating

Proper attic ventilation requires precise calculation rather than guesswork. Many contractors incorrectly determine ventilation requirements or add excessive vents at a homeowner's request, disrupting optimal airflow patterns. The industry standard calls for 1 square foot of ventilation per 300 square feet of attic space, though roof design may alter this ratio. A balanced system is essential—exhaust ventilation should never exceed intake ventilation.

Venting Bath or Kitchen Exhaust Fans

Many homes, especially older ones with retrofitted ventilation, have improperly connected interior exhaust systems. When bathroom or kitchen fans aren't properly ducted through the roof or exterior walls, they discharge moisture directly into the attic space. This hidden issue creates ideal conditions for condensation problems, wood rot, and potentially dangerous mold growth that can compromise your home's structure and indoor air quality.

Misused Vent Types

The fundamental difference between intake vents (designed to draw air into the attic) and exhaust vents (designed to expel air) is frequently misunderstood by contractors. A surprisingly common error involves installing exhaust vents in intake positions, particularly when retrofitting older homes. This critical mistake creates ventilation conflicts that can draw conditioned air from your living space and compromise your roof's moisture management capabilities.

Misused or Forgotten Underlayments

The proper use of underlayments provides crucial secondary protection against water infiltration. Code and manufacturers recommend ice and water shield at eaves, valleys, and vulnerable areas, with No. 15 felt covering remaining deck surfaces. While some contractors install complete ice and water coverage, this can trap moisture in poorly ventilated attics. Conversely, omitting underlayments entirely eliminates a critical component of your roofing system's water protection strategy.

Re-using or Omitting Flashings

Wall and chimney transitions represent the most problematic areas of any roofing system when improperly addressed. Some contractors reuse deteriorated flashings or rely on caulking and tar to save time and materials costs. Proper step and counter flashings at all wall junctions aren't just code requirements—they're essential for long-term waterproofing. Always ensure your contract specifically addresses flashing details and installation methods.

Re-using or Omitting Drip Edge

Drip edge serves multiple essential functions: supporting shingle edges, protecting the fascia-to-roof transition, and enhancing your roof's finished appearance. Reusing this component typically results in bent metal with existing nail holes that compromise water protection. Without proper drip edge, shingles at roof edges bend into gutters, creating collection points for water infiltration that can damage fascia boards and lead to structural deterioration.

Undermining Roof Integrity

Common Roofing Mistakes That
 Compromise Performance

Ensuring Complete Ventilation Systems

Plugged Soffit Ventilation: Intake Airflow Matters

Even properly installed soffit vents can become functionally useless if blocked from the interior. A common mistake occurs when insulation is installed directly against soffit openings, completely obstructing essential airflow into the attic space. This ventilation blockage traps moisture within your attic, creating perfect conditions for condensation problems, wood rot, and potential mold growth.

Proper installation requires either the use of Moore vents (Styrofoam baffles that create channels for airflow) or carefully pulled-back insulation to maintain clear air passages. Remember that balanced ventilation requires both proper exhaust and intake—blocked soffits effectively disable your entire ventilation system regardless of how many roof vents are installed.

Understanding Specialized Capping Requirements

Wrong Shingles for Hip & Ridges: Material-Specific Applications

The evolution of shingle technology has created important distinctions in ridge cap application that many contractors overlook. While traditional 3-tab shingles can be cut into three pieces for effective ridge capping, today’s thicker dimensional and designer shingles require different treatment. These premium products don’t bend properly over ridges and hips, often cracking when forced into this application and creating immediate vulnerability.

Professional installers use manufacturer-designed specialty ridge cap shingles that coordinate with premium shingle lines or, alternatively, matching 3-tab shingles specifically for ridge applications. This seemingly minor detail significantly impacts both your roof’s appearance and its critical weatherproofing at these highly exposed transition points.

The Importance of Proper Decking

Installing Shingles Over Old Boards: Stable Foundation Required

Many contractors install new shingles over existing decking regardless of type or condition, creating significant future problems. Spaced board decking (common in older homes) presents particular challenges as it creates inconsistent nailing surfaces that result in improperly secured shingles with varying nail penetration depths.

More critically, seasonal temperature changes cause these boards to expand and contract at different rates than modern materials, creating shingle buckling and gaps that allow water penetration. Professional installations include covering old board decking with approved 3/8″ plywood to provide a consistent, stable surface for proper fastening and long-term performance in Windsor-Essex’s challenging climate conditions.

Delivering expert roofing solutions and reliability to Windsor-Essex homes and businesses since 1920.

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