What Happens If You Don’T Use Underlayment on a Roof?

If you don’t use underlayment on a roof, you risk water damage, reduced insulation, and shortened roof lifespan. Underlayment serves as a protective barrier against moisture and contributes to the overall integrity of the roofing system.

Without it, your roof becomes susceptible to leaks, mold growth, and premature deterioration. Proper underlayment installation is crucial in ensuring the longevity and performance of your roof. Neglecting this essential component can lead to costly repairs and structural issues in the future.

Use Underlayment on a Roof

What is Roof Underlayment?

Roof underlayment, often referred to simply as underlayment, is a vital component of roofing systems. It is a protective layer installed between the roof deck and the outer roofing material, such as shingles or tiles. Underlayment serves as an additional barrier against water infiltration and helps to prevent leaks by providing an extra layer of defense beneath the outer roofing material.

There are several types of roof underlayment available, each with its own characteristics and benefits. The two primary categories of underlayment are:

  • Asphalt-Saturated Felt: Commonly known as felt paper, this traditional underlayment is made from organic or fiberglass materials saturated with asphalt. It offers moderate water resistance and is suitable for use in most roofing applications.
  • Synthetic Underlayment: Made from polyethylene or polypropylene materials, synthetic underlayment offers superior durability, moisture resistance, and UV protection compared to traditional felt paper. It is lightweight, easy to install, and often preferred for high-performance roofing systems.

Read Also: Why Roof Material Matters to a Homeowner?

Consequences of Omitting Underlayment

The decision to omit underlayment from a roofing system can have significant consequences, impacting both the short-term and long-term performance of the roof. Here are some of the potential outcomes of neglecting to install underlayment:

Increased Risk Of Water Damage

Without using underlayment on a roof, there is an increased risk of water damage. The absence of this protective layer leaves the roof vulnerable to leaks and potential structural issues.

Without underlayment, any small gaps or cracks in the roof surface can become major entry points for water to seep into your home. Water can then penetrate through the roof deck and potentially spread to other areas, causing damage to your ceilings, walls, insulation, and even your home’s structural integrity.

Not having underlayment also increases the risk of leaks occurring during heavy rainfall or snowmelt. When rainwater or melted snow reaches the roof’s surface, it can easily find its way into your home without underlayment to provide a barrier. Leaks can drip unnoticed into your attic or walls, leading to mold growth, rotting of wood, and even compromising the stability of your roof.

Compromised Structural Integrity

Underlayment plays a vital role in reinforcing the structural integrity of the roof. By distributing the weight of the roofing materials evenly across the surface of the roof deck, underlayment helps to minimize stress and prevent sagging or buckling. Without this additional support, the roof structure may be more susceptible to damage from heavy snow loads, wind uplift, and other external forces.

Lack Of Durability And Longevity

When underlayment is not used on a roof, the lack of durability and longevity becomes a pressing concern. The roof is directly exposed to the elements and is more susceptible to premature aging due to direct exposure to rain, snow, and UV rays. This can lead to the deterioration of the roofing materials, causing cracks, warped shingles, and weakened structure over time.

The absence of underlayment also contributes to a reduced lifespan of the roof. The protective qualities of the underlayment, such as moisture resistance and temperature regulation, are crucial for maintaining the integrity of the roof. Without these safeguards, the roofing materials are more prone to decay and damage, ultimately diminishing the overall lifespan of the roof.

Reduced Energy Efficiency

Without proper underlayment, there is a lack of insulation which can result in significant heat loss in the winter and increased heat gain in the summer. This affects the energy efficiency of your home, making it more difficult to maintain a comfortable indoor temperature.

When underlayment is neglected, it leads to higher cooling and heating costs. The lack of insulation allows air to escape, causing your HVAC system to work harder to maintain the desired temperature. This results in increased energy consumption and subsequently, higher utility bills.

Decreased Noise Reduction

Another consequence of omitting underlayment from a roofing system is the decreased ability to reduce noise transmission into the home. Underlayment serves as a sound barrier, absorbing and dampening external noises such as rain, hail, and wind. Without this additional layer of insulation, these sounds can penetrate more easily through the roofing materials and into the interior of the home.

Roofing materials, such as shingles or tiles, alone may not provide sufficient noise reduction properties, especially during inclement weather or in areas with high levels of ambient noise. Underlayment helps to muffle these sounds, creating a quieter and more comfortable living environment for occupants.

In addition to enhancing comfort, noise reduction provided by underlayment can also contribute to better sleep quality and overall well-being. Excessive noise pollution has been linked to increased stress levels, sleep disturbances, and adverse health effects. By reducing noise transmission, underlayment helps to create a more peaceful and tranquil indoor environment, promoting relaxation and restful sleep.

Weakened Protection Against Fire Hazards

Underlayment also contributes to the overall fire resistance of the roofing system. Certain types of underlayment are designed to meet fire safety standards and provide an additional layer of protection against the spread of flames in the event of a fire.

Omitting underlayment can weaken this protection, increasing the vulnerability of the roof to fire hazards and potentially endangering the safety of occupants and property.

Voided Warranties and Insurance Coverage

Many roofing manufacturers require the installation of underlayment to validate their warranties. Failure to comply with these requirements may result in the voiding of any warranty coverage, leaving homeowners liable for the cost of repairs or replacements in the event of damage.

Similarly, insurance companies may view the omission of underlayment as negligence, potentially complicating the claims process and reducing coverage for roof-related issues.


Underlayment plays a crucial role in protecting your roof from damage. Without it, your roof is vulnerable to leaks, moisture buildup, and reduced insulation. Choosing the right underlayment is key to ensuring the longevity and effectiveness of your roof. Don’t overlook its importance in your roofing project.