Functions Of Roofing Underlayment

October 19, 2021

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The underlayment is one of the most critical layers of the roof. The underlayment material, which slots between the roof deck and covering, can be asphalt-saturated felt, rubberized asphalt, or non-bitumen synthetic. Each underlayment material has its pros and cons, but they all serve the same critical purposes. Below are some of these functions.

Moisture Barrier

The roof protects your house from weather elements, and moisture is one of these elements. Moisture can pass through some of the smallest openings, thus the underlayment requires multiple layers to prevent its penetration. Water from melting snow, rainfall, or melting ice dams are some of the things to worry about.

The roof covering, such as asphalt shingles, is the primary moisture barrier on the roof. The underlayment provides a secondary moisture barrier. You can install either a water-resistant underlayment that allows vapor to pass through or a waterproof underlayment that blocks both liquids and vapor. The latter is suitable for leak-prone areas of the roof, such as the valleys.

Temporary Protection

Roofing underlayment provides temporary protection for your house whenever the roof covering is not in place. For example, the underlayment will protect your roof:

During roof installation or replacement, before the roofers install the roof covering

If a disaster, such as a storm, damages the roof covering

Without the underlayment, sunlight, rainfall, and snow would damage the house whenever the roof covering is not in place.

Fire Resistance

The underlayment contributes to your roof’s over all fire resistance. In fact, many tests for fire resistance ratings include underlayment. Asphalt shingles with Class A fire resistance ratings, for example, might lose their ratings if tested without underlayment in place.

Note that underlayment’s contribution to fire resistance depends on its compatibility with the roofing material. For example, underlayment for asphalt shingles is not necessarily suitable or useful with wood shakes. Your roofing contractor will help you choose the right underlayment for your roof.

Resin Stain Resistance

Some roofing materials are not compatible with some sheathing materials. For example, some houses have pine boards as roof sheathing. The boards leak resin that can react with roofing materials, such as asphalt shingles. The interaction can discolor the shingles and accelerate their deterioration.

In such a case, you can use the underlayment as a barrier between the two materials. The underlayment will prevent the resin chemicals from reaching the roof covering.

Curb Appeal

The underlayment also contributes to your roof’s curb appeal by providing an even surface for roof coverings. The even surface is necessary since the roof deck does not always lie flat. Installing shingles on an uneven deck would lead to raised sections on the roof. Roofing contractors use the underlayment to provide a perfectly flat surface for the shingles.

Building Code Requirements

Local authorities use building codes to enforce safety requirements. Many jurisdictions include roofing underlayment as part of their building codes. The codes even specify the underlayment to use. Thus, constructing a roof without an underlayment is a code violation, attracting multiple penalties, including monetary fines.

Heat Barrier

The underlayment material also provides a heat barrier between your house’s interior and the roof coverings. The heat from the house would rise and reach the roof coverings without the underlayment. Heat deteriorates most roofing materials, including asphalt shingles. Thus, the underlayment contributes to your roof’s durability.

A durable roof requires good design, installation, and maintenance. All the roofing materials should be of good quality. Barrier Roofs promises you all that and more. We can handle every aspect of your roofing project – we even assist with homeowner’s insurance claims. Contact us today for all your roofing needs and enjoy our professional services.