Specially-Formulated Liquid Rubber Roof Coating. Extend the life and repair the roof of your commercial building and storage buildings

Use PRC500 Seam Sealer over joints, seams, and penetrations. Then apply two coats of PRC550 Top Coat. Reinforce with fabric mesh or seam tape where called for. No primer needed and no mixing.

  • Use PRC 500 Seam Sealer

    - Use PRC 500-Pella Premium Seam Compound for when thicker material is required—over joints, pinholes, screw heads, seams, protrusions, brackets, and around HVAC installs.

    - PRC 500 Seam Sealer is meant to be used in conjunction with PRC 550 Pella Roof Coatings Top Coat.

  • Then Use PRC 550 Top Coat

    - Roll or Brush on PRC 550 to begin application of Top Coat.

    - As 1 Gallon of PRC 550 covers approx. 100 sq ft at 10 mils, you'll want to roll on 100-500 sq ft at a time.

    - 1 coat will provide protection, 2 coats for a total of 20 mils thickness is recommended.

  • Complete Protection for your Roof

    - No primer needed

    - Indefinite pot life (with lid secured)

    - Will take standing water 365 days/year

    - ASTM Tested and Energy Star Approved

    - Proven to outlast standard roof coatings 4x longer

    - Elastomeric liquid rubber forms a seamless membrane

    - Waterproofs within 2-4 hours of application

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Key Benefits

1) No primer needed

2) Indefinite pot life (with lid secured)

3) Will take standing water 365 days/year

4) ASTM Tested

5) Energy Star approved formulas

6) Proven to outlast standard roof coatings 4x longer

7) Elastomeric liquid rubber forms a seamless membrane

8) Will reduce dirt accumulationReduces mold and mildew (contains mildewcide)

9) Conforms to any shape or protrusion

10) Reduces heat buildup and noise

11) Easy application

12) Will withstand significant temperature swings

13) Waterproofs within a couple hours of application

Use PRC 500 Pella Premium Seam Compound

Where thicker material is needed. Seal seams and joints before applying PRC 550 Top Coat.

Also Use PRC 500 Pella Premium Seam Compound

Over nuts/bolts/washers/screws/nails before applying PRC 550 Top Coat.

Finally, Use PRC 500 Pella Premium Seam Compound Around Roof Penetrations

Seal around the edges of any/all hardware that pentrates the roof of your building with PRC 500 Pella Premium Seam Compound. You'll then be ready to apply PRC 550 Pella Elastomeric Liquid Rubber Roof Coating.

Once Ready for Top Coat - Mark-Off 100-500 Square Foot Sections

Coverage Rate = 1 Gallon of Pella Elastomeric Liquid Rubber Roof Coating covers approx. 100 sq ft of roofing at 10 mils thick. (5 gallons = 500 sq ft.)

Apply Two Layers of Liquid Rubber Top Coat

Aim to apply two coats of Pella Elastomeric Liquid Rubber at 10 mils thick each (20 mil thickness total.) In total, you'll need 2 gallons of top coat for every 100 sq ft you plan to cover. Allow time to dry in-between coats.

Surface Preparation

After inspecting and repairing structural faults and under skin corrosion, any silicone type of caulking on the roof surface should be removed. Silicone is not compatible with elastomeric liquid rubber.

Any holes, gaps, seams, or tears (of more than 1/16″ wide) must be repaired or reinforced. Any potential weak areas must be reinforced. Holes and low spots must be filled with non-silicone caulking or epoxies. Before coating, clean and wash the surface with detergent (soap) and water, ensuring that surface is free of oils, dirt, debris, and flaking paints.

If the surface has fungus, molds, algae, or other biologicals, soak these areas in one-third bleach and water solutions to kill the biologicals. Let it soak until the solution evaporates. You will still need to scrub (with a stiff brush) these areas with soap and water after soaking with the bleach solution, as some biologicals anchor onto certain types of surfaces and must be mechanically removed even after killing.

Thoroughly dry the roof before applying elastomeric liquid rubber. Unwanted splatters and drippings can be removed with rags and xylene or mineral spirits when wet (within 20 minutes after application). Use a short nap roller and a chip brush to apply elastomeric liquid rubber manually. Use a brush for hard-to-reach areas.

Broadcast and spread using a short nap roller to release trapped air and rubber squeegee to evenly distribute the elastomeric liquid rubber. Using a squeegee with a long mop-type handle and roller will allow you to apply the product standing and not on your knees.

It is important to apply an even distribution of elastomeric liquid rubber at the correct thickness. Too little material will produce too thin of a membrane, with inadequate adhesion and inadequate film strengths. Too much material will be wasteful, may cause under-cure situations/long cure situations ad may cause excessive swelling with some types of sheet rubber roofs.

The optimum thickness for most purposes (non-immersion conditions) is two coats at 20 mils.

Clean with Pella Super Clean Degreaser/Cleaner and prepare the surface to be coated as directed.Reinforce with seam tape & fabric mesh, if needed (gaps, tears, seams, pin-holes, defects, etc.) Check with our Technical Service Department for procedures.Apply elastomeric liquid rubber on surface/roof as described, and use as a squeegee, roller, and brush to ensure an even application of 10-mils. To achieve a 10-mil thickness, conduct a spreading rate calculation. For fairly smooth surfaces, such as EPDM sheets, unpolished metals, fiberglass roofs, etc., use a spreading rate of about 100 sq. ft. per gallon. Reduce this for rougher surfaces, e.g., steel troweled concrete surfaces, and use a spreading rate of about 50 sq. ft. per gallon.

Surface Area

When calculating the applied surface area, ensure you measure true surface areas. For example, if a panel is corrugated, take into account the corrugations when calculating the surface area of the panel. If you have not applied elastomeric liquid rubber before, apply it in several premeasured sections. The first section will give you a feel for the product and how quickly you are able to apply it. You can then do larger areas in subsequent sections.

We recommend you apply 1 gallon at first, over a pre-measured 100 sq. ft. section. When applied evenly, you will form a 10 mil. thickness after it’s cured. Spread the product evenly—not thick in some sections and thin in others. In 65°F to 85°F, the product will start to thicken in about four hours. Plan your work sections within a four hour time frame or less.

Corrosive Environments

Corrosive environments are created by many industrial operations where acids are used. Similar conditions can also be produced organically in poultry and hog production operations, which generate high volumes of manure. Coatings can protect steel and other construction materials from rapid deterioration in these environments.

One component thermoset. Non-thermoplastic materials, regardless of shape, can now be coated with butyl liquid rubber as protection against corrosion or chemical attacks. The coating can be applied by spray, roll-on or brush-on methods.

Apply to Flat Roofs to Protect from Standing Water -Withstands Ponding Water 24/7/365

Pella PRC 550 Elastomeric Liquid Rubber Roof Coating is great for flat roofs.

Apply Coating Under and Around Building Pillars

Light foot traffic is easily handled.

Top Coat Application Procedures

- Mix the product for approximately 3–4 minutes. In the event you have to stop the job for the day, simply put the lid on securely so air will not get in. This will stop the curing process.

- Apply masking tape to the perimeter of the roof or wherever straight edges are desired. The tape can also act as a catch basin for sags if only one edge is attached to the roof and the rest is formed into the shape of a gutter.

- We suggest chalking off the roof in 25×10 ft. areas or 250 sq. ft. When you are done applying the product in that area, you should have used up a five-gallon pail.

- Pour some material onto the roof. Follow with the roller to even out the wet film. The product will self-level. Use a brush around vents, A/C pipes, ladders, and antennas. Brush and roller marks will disappear when sufficient material is applied. Work from front to rear.

- Masking tape can be used to create clean lines and should be left on until the rubber is solid enough to be touched.

To Repair Rips & Tears in Your Metal Roof

1) Trim ragged edges of damage.

2) Cut new aluminum plate to overlap damaged area by 3″.

3) Drill rivet holes ½” from edge 1½” apart.

4) Remove plate and apply rubber over holes.

5) Pop rivet plate and coat with butyl liquid rubber.

6) Coat seams of new aluminum plate with Pella Premium Seam Compound, overlapping both edges of the seam by 2 inches.

7) Apply Pella Liquid Rubber Top Coat - 2 coats at 10 mils thick each.

To Stop Leaks

1) Use a wire brush to clean edge-strip, seams and flashings. Use sharp edged spatula to remove cracked or brittle caulk. Rough up smooth surfaces with sand paper.

2) Apply masking tape when a straight edge is desired, leaving 1½” on either side of the seam for coating.

3) Apply one coat of butyl liquid rubber with a brush on all seams, flashings, and remaining caulk.

4) Remove masking tape the following day after rubber has undergone a partial cure.

Acceptable Roof Types

Pella Elastomeric Liquid Rubber can be applied to a variety of roofing materials without the need for a primer.

1) Weathered aluminum

2) Weathered copper

3) Weatherized galvanized steel

4) Fiberglass

5) Acrylic sheet & any acrylic based products

6) Weathered vinyl

7) Polyurethane foam

8) Roofs that were coated with a prior roof coating- prior coating must be adhering well to roof substrate

9) EPDM - Flash Coat Needed

10) Hot-mopped mod bitumen

11) Hypalon

12) PVC, if over 20 years old.

*Product is not for use over silicone.*

*Product is not for use over Metal Roofs with aluminum coatings.*

Outstanding Application Characteristics

Extremely high resistance to water penetration

Ultraviolet and ozone stable

Built-in mildewcide

Excellent long-term aging properties

Extremely broad temperature tolerance range (from -40°F to 200°F)

Acid and alkali resistant

Excellent in salt-water environments 

Withstands ponding water 365 days/year

Film Integrity

The curing process of elastomeric liquid rubber gives it outstanding surface wetting properties. The product will fill the smallest cracks and irregularities. This enables it to be applied in a single coat over non-porous surfaces, and still result in complete film integrity. Elastomeric Liquid Rubber can withstand water immersion within the first few hours of its cure cycle. Elastomeric Liquid Rubber should not be used where the material does not have exposure to oxygen such as between two impervious materials. When oxygen is available, curing takes place from both top and bottom of the film. There is sufficient oxygen available on most surfaces to initiate cure from the bottom. Oxygen readily penetrates films 20mil thick. Elastomeric Liquid Rubber is extremely easy to work with and, unlike other catalyzed products, as long as the lid is on tight, the product does not cure. This means no loss of materials if you get into a bind on the roof due to unforeseen interruptions.

The Curing Mechanism

The elastomeric rubber cross-linking takes place at ambient temperatures. Free radicals resulting from the decomposition of solvent cause cross-linking to take place. The rate at which the solvent decomposes determines the rate at which the system will cure. This rate is governed by the temperature and the availability of oxygen. Oxygen is necessary to activate the solvent which promotes peroxide decomposition. The cure mechanism in Elastomeric Liquid Rubber will vary from active to inactive as determined by temperature. Faster cures and slower cures over extended periods of time result in identical physical properties. Broad day-night temperature swings in spring and fall will not compromise the final results of the elastomeric liquid rubber membrane.