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Roof Underlayment

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Self Adhering Starter Roll 33 lin. ft. 1

Self Adhering Starter Roll 33 lin. ft.

$32.98 - $32.98
$32.98
$32.98 - $32.98
$32.98
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About This Product Starter Roofing Shingle Roll - the essential first layer of a weather-tight roof. This product is compatible with all Owens Corn...

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Membrane Roll for Low Slope Roofs, Tri-Ply APP Smooth Modified Bitumen, 3 ft. x 33 ft. (100 sq. ft. net) 1

Membrane Roll for Low Slope Roofs, Tri-Ply APP Smooth Modified Bitumen, 3 ft. x 33 ft. (100 sq. ft. net)

$109.00 - $109.00
$109.00
$109.00 - $109.00
$109.00
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About This Product Tri-ply APP Smooth is a sturdy, durable membrane suitable for both new roofing projects and reroofing, as well as for use as fla...

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Membrane Roll for Low Slope Roofing, Tri-Ply APP Granular Cap Sheet, White, 39.625 in. x 32.25 ft. (100 sq. ft. net) 1

Membrane Roll for Low Slope Roofing, Tri-Ply APP Granular Cap Sheet, White, 39.625 in. x 32.25 ft. (100 sq. ft. net)

$109.00 - $109.00
$109.00
$109.00 - $109.00
$109.00
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About This Product Tri-ply app Granule is a robust, durable membrane ideal for new constructions or reroofing projects, and can also be used as fla...

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Membrane Roll for Low Slope Roofs, Tri-Ply #75 Base Sheet, 3 ft. x 100 ft. (300 sq. ft. Net) 1

Membrane Roll for Low Slope Roofs, Tri-Ply #75 Base Sheet, 3 ft. x 100 ft. (300 sq. ft. Net)

$58.97 - $58.97
$58.97
$58.97 - $58.97
$58.97
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About This Product Self-Adhering Roofing Systems are installed without the use of torches, open flames, hot asphalt, or solvent-based adhesives. Ke...

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Roof Underlayment Roll, Synthetic, ProArmor, 1001 sq. ft. 1

Roof Underlayment Roll, Synthetic, ProArmor, 1001 sq. ft.

$104.00 - $104.00
$104.00
$104.00 - $104.00
$104.00
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About This Product Synthetic Roof Underlayment with Fusion Back Coating Technology is robust, long-lasting, and water-repellent. It is also lightwe...

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Cap Roll Roofing, White, Fiberglass, Mineral-Surfaced, 3 ft. x 36 ft., 100 sq. ft. Coverage 1

Cap Roll Roofing, White, Fiberglass, Mineral-Surfaced, 3 ft. x 36 ft., 100 sq. ft. Coverage

$54.97 - $54.97
$54.97
$54.97 - $54.97
$54.97
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About This Product Fiberglass mineral surfaced roll roofing is a product coated with asphalt and reinforced with glass fibers. The surface made of ...

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Roof Underlayment, Felt, 216 sq. ft. 1

Roof Underlayment, Felt, 216 sq. ft.

$35.98 - $35.98
$35.98
$35.98 - $35.98
$35.98
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About This Product APOC organic felts are crafted with specialized technology that ensures rain and water stay outside your home while allowing wat...

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Roof Underlayment: What You Need to Know

Roof Underlayment: What You Need to Know

Roof underlayment, also known as roofing felt, membrane sheets, or protective roofing barriers, serves as a critical moisture-resistant layer between the roofing deck and shingles or panels. Designed for added durability and leak prevention, underlayment enhances weatherproofing, UV protection, and insulation efficiency. Available in various materials and configurations, it ensures long-term structural integrity for both residential and commercial roofing systems.

Types:

  • Synthetic Underlayment: A lightweight, high-performance alternative to traditional felt, synthetic underlayment provides superior tear resistance, waterproofing, and UV stability. It is ideal for steep-slope roofing applications requiring extended exposure before shingle installation.
  • Felt Underlayment (Asphalt-Saturated): A cost-effective and time-tested option, felt underlayment offers basic water resistance and reinforcement under shingles. Available in 15-pound and 30-pound grades, it provides varying levels of durability and thickness.
  • Self-Adhering Membrane: Featuring an adhesive backing for secure attachment, self-adhering underlayment offers exceptional water resistance and wind uplift protection. Often used in low-slope roofing systems and ice-prone regions, it acts as a secondary waterproofing layer in critical areas.

Technical Applications:

  • Waterproofing Barrier: Roof underlayment serves as a secondary moisture defense, preventing water infiltration from wind-driven rain, ice dams, and roof leaks.
  • Slope Compatibility: Synthetic and felt underlayment can be used on steep-slope roofing, while self-adhering membranes are designed for low-slope applications where added sealing is necessary.
  • Fire & UV Resistance: Many synthetic underlayment options feature fire-resistant coatings and UV protection, allowing longer exposure before final roof installation.
  • Enhanced Roof Longevity: By preventing deck rot, mold growth, and premature material degradation, underlayment extends the lifespan of the roofing system.

Why Choose Supply Ontime?

At Supply Ontime, we offer reliable materials designed to meet your project’s needs. With same-day delivery across the Greater Los Angeles area, we make it easy to keep your projects on schedule. Order Roof Underlayment now and get it delivered today!