Self-adhering, waterproof underlayment is typically used under shingles on the eave, rake and valley areas of the roof and around any roof penetration. When properly installed, self-adhering roofing underlayment will minimize the chances of moisture penetration into critical areas of the roof system. However, once self-adhering underlayment has adhered to the roof deck for long periods of time, it can be very difficult to remove without damaging the deck material in the process.

If the existing layer needs to be removed or replaced, the roofing contractor should first attempt to pull away the underlayment that can be easily removed without damaging the roof deck. With less material on the roof, the contractor can more easily inspect the deck for signs of deterioration or damage.

Removing the self-adhering underlayment — without causing deck damage — reduces the buildup of excess materials that could generate a leak-producing water stop. It also eliminates unevenness that could produce aesthetic issues in newly installed shingles.

When more than one layer of underlayment is present, all layers should be removed. If removal cannot be accomplished easily, the contractor may be forced to replace the decking itself in the affected areas. However, if only one layer is present, and that layer cannot be easily removed without causing damage to the deck, roofers can install a second layer of underlayment over the existing membrane.

When a second layer is applied, the contractor should offset laps in the new and existing underlayment. The new layer should be “feathered in” by extending the new material a minimum of 8 inches beyond the edge of the existing material to reduce or eliminate chances of water stops and unsightly aesthetic issues.

Protecting the roof deck is paramount. If the self-adhering underlayment layer refuses to pull away from the deck easily, the contractor may be left with no choice but to remove and replace the deck itself. Failure to do so may cause bigger problems down the road.

Stuck In A Sticky Situation? Turn To Atlas!

Visit Atlas Roofing for more information about self-adhesive underlayment.