Patching Compound

Video | MSDS |Product Brochure |Product Data

Swepco Heavy Duty Patching Compound is widely used for the repair and
sealing of roof areas subject to leakage.

Particularly suitable for the repair of gutter joints and other areas with possible movement it can be used in conjunction with SWEPCO Patching Fabric.

Many Roll Roofing Installers are using Heavy Duty Patching for end finishing and finishing off around penetrations, it is a perfect replacement for Bostik 1313 Mastic.
Bostic 1313 Mastic is a heavy bodied, semi stiff trowel application, bitumen based mastic compound.
Heavy Duty Patching Compound has many additional benefits such as NON-flammable when cured, does not melt or run, will NOT support combustion, UV stable, will provide a long term positive seal.
It is one of the few products which will seal Butyl Rubber Membranes.

Swepco Heavy Duty Patching Compound® Product Information

  • Versatile, all-purpose fibred patching compound.
  • Stays flexible longer.
  • Resistant to cracking and splitting.
  • Ideal for new or old flashing work and all types of spot repairs.
  • UV Stable.

Formulated for the tough waterproofing jobs.

Heavy Duty Patching Compound is a thick, black, waterproofing compound manufactured from “Heart of Texas” Asphalt®, High Strength Micro Fibers, Dia-SealTM, finely milled blue-black slate and two highly effective chemical additives, ZHD-7TM and ZonamineTM. It is used with other SWEPCO Roofing Products in a number of various applications to provide complete roof protection. Consult the appropriate application literature for more information. It is also used as a highly versatile adhesive, sealer and filler in general roof maintenance.
It takes a tough product to provide reliable waterproofing at edge, wall and protrusion flashings. Stresses concentrated in these areas can quickly destroy inferior patching materials. Just as difficult is finding a patching materia that works well in all repair situations… tough ones such as blisters, cracks and metal seams. Heavy Duty Patching Compound is the answer for both new roof construction and routine HEAVY DUTY maintenance… a heavy-duty, asphalt-base waterproofing mastic, manufactured from specially selected and refined “Heart of Texas” Asphalt, High Strength Micro Fibers, select mineral stabilizers and reinforcers and two special SWEPCO additives which inhibit oxidation and promote better bonding. Used before leaking occurs, Heavy Duty Patching Compound seals, reinforces and waterproofs problem areas.

Superior resistance to cracking & tearing.

Heavy Duty Patching Compound has superior resistance to cracking and tearing
under normal roof stresses because it stays flexible and pliable longer.

The specially selected “Heart of Texas” Asphalt provides flexibility,
bondability and weatherability not found in common waterproofing asphalt. As a result, Heavy Duty Patching Compound has more resistance to the normal roof stresses which cause most repairs to fail.
Stays flexible longer because it’s fortified with ZHD-7.
Oxidation is one of the major causes of failure of asphalt waterproofing materials, causing age hardening, embrittlement and cracking. But Heavy Duty Patching Compound is formulated with ZHD-7, SWEPCO’s highly effective chemical oxidation inhibitor. ZHD-7 slows down the natural aging process. In the heated state produced by ultra-violet radiation, the free oxygen molecules which cause oxidation react more readily with the ZHD-7 than with the asphalt. Much of the available oxygen is actually consumed by ZHD-7 before it can harm the asphalt. And the process is a continuous one, because, as ZHD-7 reacts with the available oxygen, it forms a new molecular arrangement which continues to consume more of the harmful free oxygen molecules. Result — the completed repair or flashing assembly retains its flexibility and pliability longer.

High Strength Micro Fibers add strength & durability. High Strength Micro Fibers are added to increase strength and durability, as well as enhance

temperature stability.Heavy Duty Patching Compound
The fibers stay evenly distributed throughout Heavy Duty Patching Compound, both in the container and on the roof, to provide uniform strength, durability and temperature stability.

Two other superior mineral stabilizers, Dia-Seal and Finely Milled Blue-Black Slate, are also added to further improve tensile strength and resistance to erosion and abrasion. This highly effective combination of three of the finest mineral stabilizers and reinforcers available adds measurably to the overall durability and weatherability of Heavy Duty Patching Compound.

Zonamine promotes superior bondability. Another special SWEPCO additive, Zonamine, promotes formation of a tight, strong, durable and uniform bond every time . . . the kind of strong bond that resists peeling, shrinking and delamination. Zonamine also permits effective use of Heavy Duty Patching Compound for temporary emergency repairs on clean, wet surfaces.

Exceptional ease & versatility.
Use it for long lasting roof maintenance and new flashing work. Works on asphalt, concrete, masonry, metal and wood. Seal cracks, blisters, open seams and either new or deteriorated flashings at vents, skylights, pitch pans, metal seams, gravel guards and flashing flanges. Caulk small cracks, copings, counter flashings, drainage gutters and other common trouble spots. The smooth troweling consistency makes it easy to use straight from the container.


Heavy Duty Patching Fabric is a strong reinforcing material designed for use with Heavy Duty Patching Compound. It reinforces Heavy Duty Patching Compound repair work just as steel is used to reinforce concrete. Embedded between layers of Heavy Duty Patching Compound, it strengthens repairs to help prevent cracking and splitting. It exceeds the requirements of U.S. Federal Specification H-C-466, Type 1 and ASTM Designation D-1668, Type 1.

Tough, glass fiber mesh.

Heavy Duty Patching Fabric is an inorganic mesh, coated with a high quality waterproofing resin. It is many times stronger than most original roofing felts and is highly resistant to heat, rotting, mildew, tearing and other forms of deterioration. The open weave design allows Heavy Duty Patching Compound to thoroughly penetrate the fabric for a strong, durable repair job.

Ideal for all patching jobs.

Heavy Duty Patching Fabric is the perfect material for strengthening repairs of edge, wall and protrusion flashings at vents, skylights, pitch pans and other roof fixtures. It is also excellent for repair of blisters, cracks, open seams and seams in metal roofs.

Easy to use.

Rolls on smoothly without warping, shrinking, wrinkling or tearing. Conforms to most shapes and is easily cut to fit those hard-topatch places on the roof.

%d bloggers like this: