Gorilla Guard® 30 Engineered Roof Underlayment

Gorilla Guard EVERFELT Roof Underlayment

Designed for any type of roof covering, Gorilla Guard®  30 is a high performance engineered roof underlayment. In fact, engineered felt underlayment outperforms traditional organic felt through innovation and technologically advanced substrates. Its proprietary formulation and manufacturing process create unique water shedding characteristics that allows it to lay flatter and resists wrinkling compared to traditional shingle underlayment products. Also important, Atlas’ engineered felt underlayment gives your roof added UV protection. Meaning, if exposed, it will not be as susceptible to deteriorate after being exposed to the sun’s ultraviolet rays. And Atlas’ Gorilla Guard® 30 Engineered Roof Underlayment is a rugged and reliable walking surface for your installers. Unlike traditional felt, you won’t have to worry about it tearing easily.

Benefits of Gorilla Guard Roof Underlayment

  • 36% Lighter than Traditional Organic #30 Felt
  • 28% Stronger Substrate Means No More Re-Work Before Applying Shingles
  • Four Square Roll Means Half the Handling & Half the Time
  • Increased Performance for the Same Price Per Square Basis
  • Increase Water Shedding Characteristics
  • Lays Flatter than Traditional Organic Felt

Take advantage of the lighter, stronger, smoother underlayment. Unroll a sheet today for an added layer of protection that actual lives up to its name. Gorilla Guard® 30, the toughness you need to guard the place you call home.

Installation Instructions

Gorilla Guard® shall be applied to a properly prepared dry deck that is smooth, clean and free from any depressions, projections, or protruding nails. Roof decks shall be structurally sound and meet or exceed minimum requirements of the deck manufacturer and local codes.

Always lay the Gorilla Guard® parallel to the eaves, lapping each course at least 2" over the underlying course. Apply the drip edge underneath the Gorilla Guard® along the eaves and over the Gorilla Guard® along the rakes. Gorilla Guard® should never be applied perpendicular to the eaves. Secure the Gorilla Guard® with fasteners every 12" across the lower and upper edge to hold it in place. If more than one piece is required to continue a course, lap the ends at least 4". End laps in succeeding courses should be located at least 6' from end laps in the preceding course. Lap the Gorilla Guard® a minimum of 6" from both sides over all hips, ridges and valleys. Where a roof meets a vertical surface, carry the underlayment at least 4" up the surface.

On decks having a slope greater than 4" per foot, one layer of Gorilla Guard® should be applied. Some local codes may require specific underlayments. On slopes 2" to 4" per foot apply a double layer of Gorilla Guard® over the entire deck surface. Starting with a 19" wide strip at eaves, overhanging the eaves 1/4" to 3/8", cover with full 36" strips providing a 17" exposure. Continue with 36" strips lapping each course 19" over the preceding course. End laps for low slopes shall be 12" and staggered 6' apart.

The use of Gorilla Guard® along with the proper decking materials and shingles will help in meeting Class A and or Class C Fire ratings. A shingle by itself is not fire-rated, although it is part of the roofing assembly.


KEEP ROLLS DRY AND COMPLETELY PROTECTED FROM THE WEATHER. If work is to be done in cold weather, rolls of roofing should be placed in a warm place for 24 hours prior to application.

*Tip: Cut Gorilla Guard® into manageable lengths for safety on the roof.