Modified Bitumen Roof Repair

A modified bitumen roof coating can extend the life of your roof by 10 or more years.

Why Consider a Modified Bitumen Roof Coating Application

Asphalt degradation is a growing concern. UV-rays oxidize the surface of the asphalt and produces a chalk-like residue. As plasticizers leach out of the asphalt, a modified bitumen or “mod bit” roof becomes brittle. Cracking and alligatoring inevitably follows, allowing water to penetrate the system causing blisters, and cracks. Seam failure inevitably follows causing leaks.

A black modified bitumen roof absorbs a lot of the sun’s heat in the summer. High temperatures and UV-rays accelerate asphalt degradation. To make matters worse, the heat build up raises plenum temperatures thereby increasing cooling costs in the building.

BEFORE: This modified bitumen roof has roof leaks in several locations. To make matters worse, the heat build up raises air temperature surrounding airconditioning units as well as the return plenum. This increases cooling costs in the building.

Modified Bitumen Roof Restoration Process

Cleaning and Surface Preparation

The entire modified bitumen roof was thoroughly washed using a 3,000 psi pressure washer. A biodegradeable degreaser was used to ensure a clean surface. All seams, flashings and penetrations were carefully sealed to render the roof watertight.

Priming
Priming ensures a good adhesion between the roof surface and the elastomeric coating.

Top Coating

30 dry mils of elastomeric roof coating is applied on the entire modified bitumen roof in 2 coats.

A fabric reinforced system is recommended for this job since there are plenty of seams that required sealing. The entire roof was primed with PrimeLock and while the coating was still wet, 40” wide SeamStitch roofing fabric was rolled out. PrimeLock was reapplied on the fabric to saturate it.

AFTER: A leak-free, seamless roofing membrane now covers the old, weathered modified bitumen roof. The cool roof coating reflects about 90% of the heat from the sun. The roof-top airconditioining units also operate more efficiently since the temperature intake air around the units have been noticeably reduced.

All these benefits for about half the cost of replacement. What more can you ask for?

Don’t Put It Off Any Longer.

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Types of Mod Bit Roof

• Atactic Polypropylene (APP)
• Styrene Butadiene Styrene (SBS)
• Self Adhered Modified Bitume

Roof Restoration Tools

Pressure Washer

A pressure washer is mandatory for preparing a roof’s surface for coating application. Pressure washing removes embedded dirt, chalking and poorly adhered material. In most cases, 2000 PSI can adequately clean the surface without damaging adhered roofing laps, masonry or flashings. Higher pressure ratings can speed up cleaning provided that a wider nozzle is used to prevent damage to the existing substrate.

Clear-rinsing detergents may be used to improve cleaning. Be aware of any local restrictions regarding how the wash-off water must be treated or released into storm sewers or swales.

Airless Sprayer

An airless sprayer pump capable of developing 1,800 to 2,500 PSI material output pressure should be sufficient to spray a variety of acrylic coatings. A siphon hose on the material inlet typically is used to draw material directly from 5-gallon pails or 55-gallon barrels.

A spray gun with an extender wand allows for comfortable coating application without having to hold the spray gun uncomfortably close to the surface. A 517 tip is usually recommended for roof primers and 631 for elastomeric coatings. Tips are reversible for easy cleaning and clearing of occasional tip clogs.

Proper spray technique involves keeping a gun level with a roof’s surface at all times, maintaining a consistent distance between the spray tip and surface. Use a overlapping, crosshatch pattern to ensure complete coverage and a uniform finish.