Water infiltration under shingles is a common issue faced by homeowners with pitched roofs. This troublesome problem occurs when water finds its way beneath the protective shingle layer, potentially leading to substantial damage if not addressed promptly. In this article, we will delve into the primary causes behind this occurrence and explore the potential consequences when water infiltrates beneath shingles. By understanding the root causes, you can take proactive measures to prevent such water intrusion, safeguarding your home’s structural integrity and avoiding costly repairs.

Common Causes of Water Getting Under Shingles

Improper Installation

Improper installation of shingles is a leading cause of water infiltration. Several factors contribute to this issue. Improper nailing, where the nails are not driven fully into the decking, can create gaps for water to seep underneath the shingles. Incorrect underlayment, such as using the wrong type or not using any at all, can prevent proper water drainage and contribute to water accumulation beneath the shingles. Additionally, insufficient overhang, where the shingles do not extend far enough over the edge of the roof, can allow water to easily flow underneath.

Damaged or Missing Shingles

Damaged or missing shingles can also lead to water penetration. Cracked shingles provide a pathway for water to seep through, especially during heavy rainfall. Loose shingles, caused by improper installation or natural wear and tear over time, can create gaps that let water underneath. In more severe cases, shingles blown off during storms expose the underlying roof structure, leaving it vulnerable to water damage. Finally, missing shingles simply leave gaps in the roof where water can easily enter.

Clogged Gutters

Clogged gutters are a common issue that can result in water getting under shingles. Debris buildup, such as leaves, twigs, and dirt, can clog the gutter system, preventing proper water flow away from the roof. When water cannot properly drain, it can overflow or back up onto the roof, potentially finding its way under the shingles. Additionally, if the gutter slope is improperly installed, it can lead to stagnant water, increasing the chances of water infiltration. Regular maintenance and cleaning of gutters are essential to prevent this problem.

Faulty Flashing

Flashing is an integral part of a roofing system that helps to prevent water infiltration. However, faulty flashing can compromise its effectiveness. Improper installation, where flashing is not securely attached or not placed correctly at critical roof junctions, can create gaps for water to enter. Damaged flashing, such as corrosion or holes, can disrupt its waterproofing capabilities, allowing water to penetrate the roof system. In some cases, missing flashing altogether leaves vulnerable areas exposed to water infiltration.

Ice Dams

In colder climates, ice dams can pose a significant risk for water infiltration under shingles. Poor insulation and inadequate ventilation in the attic can lead to temperature fluctuations on the roof, causing snow to melt and refreeze at the eaves. This creates a dam-like structure that traps water on the roof. As the trapped water continues to accumulate, it can find its way under the shingles, leading to leaks and potential water damage. Clogged gutters exacerbate this issue by preventing proper drainage of melted snow.


Condensation can be a hidden cause of water getting under shingles. Inadequate ventilation within the attic can result in excessive moisture buildup. High humidity levels, often caused by poor ventilation, can lead to condensation on the underside of the roof deck. Over time, this moisture can seep through the decking and infiltrate the shingles from below. Temperature differences between the attic and the external environment can further contribute to condensation and water accumulation beneath the shingles. Improper installation of a vapor barrier can also allow moisture to pass through and reach the shingles.

Wind-Driven Rain

Severe weather conditions, particularly wind-driven rain, can cause water to get under shingles. During storms, strong winds can force rainwater to be driven upward and horizontally against the roof. Damaged or loose shingles provide an entry point for water. Inadequate underlayment, such as using an insufficient layer or low-quality material, can allow water to penetrate through and reach the underlying roof structure. Additionally, insufficient overhang, where the shingles do not extend far enough over the edge, can make the roof more prone to wind-driven rain infiltration.

Aging and Wear

As a roof ages and undergoes natural wear and tear, it becomes more susceptible to water infiltration. Shingle degradation, caused by exposure to the elements over time, can lead to the loss of their waterproofing properties. This makes them more vulnerable to water penetration. Loss of granules, the protective layer on the shingles’ surface, exposes the underlying material, making it easier for water to seep through. Brittle or cracked shingles can also provide pathways for water to enter, especially during heavy rainfall. Additionally, warping or curling of shingles can create gaps, allowing water to find its way underneath.

Roof Penetrations

Roof penetrations, such as chimneys, vents, or skylights, can become sources of water infiltration if not properly sealed. Improper installation or damaged flashing around these penetrations can create gaps for water to enter. Additionally, worn-out sealants or deteriorated caulking can compromise the waterproofing around these areas. Regular inspection and maintenance of roof penetrations are essential to ensure their integrity and prevent water from seeping beneath the shingles.

Inadequate Ventilation

Inadequate ventilation in the roof system can contribute to water getting under shingles. Excessive heat and moisture trapped within the attic can create a conducive environment for water accumulation. Improperly sized attic vents, which may not allow for sufficient airflow, can contribute to moisture buildup. Blocked ventilation channels, often caused by debris or insulation obstruction, can impede air circulation and promote the retention of moisture. The lack of sufficient intake or exhaust vents can also hinder proper ventilation, leading to excessive humidity levels and potential water infiltration.

In conclusion, multiple factors can contribute to water getting under shingles. From improper installation and damaged or missing shingles to clogged gutters and faulty flashing, each issue poses a risk for water infiltration. Additionally, ice dams, condensation, wind-driven rain, aging and wear, roof penetrations, and inadequate ventilation can all contribute to this problem. Regular inspection, proper maintenance, and timely repairs are crucial in preventing water from seeping under shingles and protecting the integrity of the roof.