How to Spray an RV Roof With Polyurea: Prep, Primers, Masking and Cure

RV owners are tired of resealing the same roof every spring. A seamless spray polyurea roof is a real answer, and it is a service more coating shops are adding. The spray itself is the easy part. The prep is where RV roofs are won or lost, because RV membranes are some of the hardest surfaces in the business to bond to.

Step 1: Identify the roof

You cannot prep correctly until you know what you are standing on. ArmorThane's RV roof guidance lists these common roof types:

• EPDM rubber: pull a vent trim ring and look underneath. EPDM is white or dove gray on top with a black backing, and it chalks with age.
• TPO: the same color on both faces, with a smoother, heat-weldable surface.
• Fiberglass (FRP): a hard, glossy gelcoat with a solid knock.
• Aluminum: seamed metal panels where fasteners and seams cause most leaks.

Step 2: Prep by substrate

Every roof starts the same way: wash thoroughly with soapy water to remove dirt and chalky residue, rinse, and let it dry completely. Repair soft decking, tear out failed sealant, and address seams, cracks and penetrations. Then prep by roof type.

EPDM

• EPDM has very low surface energy and is neither porous nor reactive, so standard primers do not bond well to it. Use an EPDM-compatible bonding primer, applied at the primer maker's coverage rate and fully cured before you spray.
• Keep petroleum solvents and citrus-based cleaners off EPDM. Both attack the rubber.
• Do not use a TPO primer on EPDM. The chemistries are different.

TPO

• New TPO is slick and resists adhesion. Aged TPO develops a matte surface that coats better.
• Clean thoroughly and use a primer rated for TPO when the membrane or your adhesion test calls for it.

Fiberglass

• Remove wax, mold release and road film with a wax and grease remover or alcohol before sanding, so you do not grind contaminants into the surface.
• Scuff until the gloss is completely gone, then clean again and wipe dry. Do not let cleaners air dry on the surface.
• ArmorThane's Primer 41 is a two-component, non-isocyanate primer listed for adhesion to fiberglass, plastic, aluminum, galvanized steel, metal and wood.

Step 3: Mask like you mean it

Polyurea overspray travels and does not come off easily. Before the rig is even warm:

1. Mask or remove vents, AC shrouds, skylights, antennas, solar panels and ladders.
2. Tape a clean edge along the roof perimeter and awning rails.
3. Drape the sidewalls, windows and slides in plastic sheeting all the way to the ground.
4. Cover anything parked nearby, and check the wind before you start.

Masking film, tape and dispensers are in spray supplies.

Step 4: Spray the roof

• Confirm the substrate is dry and at least 5°F above the dew point.
• Bring the material to the temperature its TDS calls for, and verify ratio and pressure before you move onto the roof.
• Detail around penetrations and seams first, then spray the field in even, overlapping, multidirectional passes.
• Build to the thickness your material and warranty call for, and check it with a gauge as you go.

Material choice depends on your rig. On high-pressure equipment, ArmorThane lists ArmorFlex UV, an aliphatic polyurea it describes as suited to roofs and RV roofing. On low-pressure equipment, ETS-110 is ArmorThane's 1:1, 100% solids, fast-set modified polyurea liner for metal, concrete, fiberglass and wood. Ask the tech team which LP material and primer they recommend for your roof type.

Step 5: Cure and topcoat

Polyurea goes tack-free fast, but follow the material's TDS for return to service before anyone walks on the roof. If you sprayed an aromatic material, topcoat it for UV. ETS-110 yellows or darkens in sunlight and can be topcoated within 12 hours with an aliphatic polyurethane or polyurea. UV ColorCoat, an aliphatic polyurethane topcoat, covers 1 gallon per 300 square feet in two coats, with a third for maximum protection. A white topcoat keeps the roof bright and cooler.

Step 6: Turn RV roofs into a profitable service

Here is where it gets interesting for your shop. ArmorThane has released a new 1:1 low-pressure spray system that lets applicators spray RV roofs and spray-on bedliners, with complete setups starting as low as about $20,000. That is a much lower barrier than a full high-pressure rig.

ArmorThane's ArmorLine LP line gives a sense of what low pressure offers: the 1:1 Series 4111 uses the EZ static mix gun to control material flow at the gun, runs line sets up to 150 feet, sprays from 5 or 55-gallon containers, and changes colors quickly with easy cleanup. Call us for the current configuration of the new system.

• Two services, one machine: bedliners fill weekdays, RV roofs fill the season.
• Real demand: ArmorThane's RV roof guide puts a typical polyurea roof on a 30-foot rig at roughly $3,500 to $7,000, against owners who reseal every year.
• Support: ArmorThane trains applicators with no franchise fee or royalty.

Materials, primers and topcoats are in coatings and chemicals, low-pressure equipment is in spray equipment, and E-Z Gun parts are in parts and rebuild kits. Approved applicators get account pricing through the Applicator Program. Ready to price a system? Call (417) 831-5090 or use our contact page.