VFI®-735 HFO Spray Polyurethane Foam

VFI-735 HFO Spray Polyurethane Foam is a two-component system that forms a rigid, closed-cell, 3 pounds per cubic foot density, HFO-blown roofing foam. A silicone or acrylic roof coating is applied over the spray foam to create a fully waterproofed and insulated layer on the roof. VFI-735 has excellent adhesion to most substrates and can help taper flat surfaces that may be at risk of ponding water. This product is approved for use in states that have restrictions on HFC blowing agents.

Two-part 3 PCF polyurethane HFO roofing spray foam that provides seamless coverage for uniform insulation.

Features & Benefits

  • Compatible as a full roof restoration system – when coated with acrylic or silicone coating, adds years of service
  • No tear off required – quick and easy application prevents complete roof replacement and costly labor shut downs
  • Self-flashing, seamless surface – creates a monolithic surface to prevent leaks from cracks, gaps, or seams
  • Improved R-Value – higher R-value means better insulation power to limit the amount of heat and cold air that flows into the building
  • Exceptional durability – protective barrier holds up in extreme weather
  • Environmentally friendly – HFO blowing agents have low global warming potential compared to existing HFC blowing agents

Instructions for Use:

Surface Preparation

Prior to applying SPF to the substrate, inspect the surface for needed preparations. Remove contaminants detrimental to adhesion, including dirt, dust, and debris. Any damaged structural components, including ducts, drains, flashing, or other penetrations, must be repaired before applying SPF. Repair gaps to be tight and flush by restricting them with additional screws and rivets. Tighten or replace loose or backed-out fasteners with oversized fasteners.

Power wash the roof as needed. Use a liquid cleaning detergent to scrub areas containing grease, oil, and animal fats. Clean mold, mildew, fungus, or algae spots with a concentrated chlorine solution. Rinse off the roof and allow it to dry before applying the spray polyurethane foam.


Premix VFI-735 HFO Spray Polyurethane Foam B side until uniform. Mix times will vary depending on the volume and mixing method. The temperature should be between 50°F – 100°F and the pot life will shorten if the temperature exceeds 72°F.

Protect objects from overspray and move portable objects to an acceptable area during application. Intake air vents must be turned off and covered before application. VFI recommends using a digitally controlled robotic SPF application device to improve the consistency, slope, and visual appearance of the spray.

At a minimum rate of 1-inch-thick passes per square, spray the polyurethane over the entire roof. The foam will expand and should reach a minimum thickness of 1.5 inches. Areas that have been tapered for proper drainage or areas that were brought to the existing roof level may vary in thickness. Check specifications for required wet and dry film thickness. Neatly terminate the foam a minimum of 4 inches above the finished surface at roof penetrations. Apply foamed-in-place cants for a smooth transition from horizontal to vertical surfaces. Complete the foam application process in a single day.

The finished surface should have a texture of “smooth to orange-peel,” with no voids, pinholes, or depressions. A “verge of popcorn” surface texture is acceptable if the foam can be completely coated. Popcorn or tree bark textures cannot be coated. The foam must be removed, and the surface will need to be re-foamed before coating. A top coat is required to protect the foam from UV degradation. Apply the top coat within 48 hours after the foam has cured.


Clean spray equipment with xylene, MEK, or a similar cleaning solvent. Flush the cleaning solvent through spray lines until the chemical mixtures are removed.


*Always read the safety data sheet before working with chemicals

Use chemicals only as directed and for their intended purpose. Do not dispose of chemicals down the drain. Most chemicals must be disposed of as hazardous waste.

PPE to avoid all unnecessary exposure:

  • Eye protection – wear safety glasses and any additional eye protection as necessary
  • Hand protection – wear chemically resistant protective gloves (nitrile, butyl, or neoprene)
  • Skin and body protection – wear suitable protective clothing
  • Respiratory protection – in case of insufficient ventilation, wear suitable respiratory equipment. Respirator selection must be based on known or anticipated exposure levels, the hazards of the product, and the safe working limits of the selected respirator

Product Limitations

VFI-735 is not UV color stable and has no long-term UV testing. The product contains a blowing agent and should be kept out of direct sunlight to prevent pressure buildup. Before using, release drum bungs slowly to relieve any built-up pressure within the container. Isocyanate (in A side) may be irritating to the skin and toxic if inhaled.

  • Incompatible materials – A side: oxidizers. B side: none known
  • Conditions to avoid – heat and incompatible materials
  • Chemical stability – stable under normal storage conditions
  • Reactivity & hazardous reactions – no dangerous reactions known under normal use
  • Hazardous decomposition products – may include, and are not limited to, oxides of carbon

Potential Health Hazards

  • May cause stomach distress, nausea, or vomiting if swallowed.
  • May cause skin irritation and sensitization: redness, edema, drying, defatting, or cracking.
  • May cause respiratory tract irritation, allergy or asthma symptoms, or breathing difficulties.
  • Causes serious eye irritation: discomfort, pain, excess blinking and tear production, with marked redness and swelling of the conjunctiva.

*If you are experiencing any of these symptoms, seek medical assistance or attention. Call a poison control center or doctor if swallowed.

Application Methods:

  • Spray

Available Packaging:

  • Drum

Physical Properties

  • Tensile Strength: 75 psi
  • Solid Material Density: 2.75 PCF
  • Closed Cell Content: 91%
  • Thermal Resistance: 6.9
  • Water Vapor Permeability: 1.1 perm
  • Water Absorption: 0

Liquid Properties

  • Liquid Density A Side: 10.18 lbs/gal
  • Liquid Density B Side: 9.73 lbs/gal
  • Mixed Liquid Density: 9.96 lbs/gal
  • Specific Gravity A Side: 1.22 g/ml
  • Specific Gravity B Side: 1.16 g/ml
  • Specific Gravity Mixed: 1.19 g/ml
  • Ratio by Volume (A:B): 1A:1B
  • Viscosity A Side: 175 cps
  • Viscosity B Side: 1200 cps
  • Cream Time: 10 seconds
  • Rise Time: 40 seconds
  • Tack Free: 29 seconds

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  • UL

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