Thermal Barrier

The International Building requires the installation of an approved thermal barrier over all foam plastics (including spray foam insulation) separating the foam insulation from the interior space of the building.

 The IBC specifically lists 1/2" gypsum wallboard as an acceptable thermal barrier material. However, most recently new technology has emerged for more cost effective thermal barrier solutions such as a spray applied in tumescent coating. Royal Rahimi has tested and qualified an in tumescent coating, DC-315 as an approved spray applied thermal barrier over Polyurethane foam K-span building.

 This provides architects, designers, and commercial building owners with a cost effective option for exposed applications such as acoustical ceiling plenums, exposed roof assemblies, and attics connected to habitable space.            

DC315: Your one step solution for Polyurethane Foam "15 Minute Thermal Barrier" and "Ignition Barrier" ratings.

DC315 is a Certified Warnock Hersey listed and rated product which has passed certified testing for both the (UL-1715) 15 minute Thermal Barrier and the NFPA 286 (AC-377 standards) as an Ignition Barrier.

What is truly amazing about DC315, it applies as easy as regular latex paint and being a water base it cleans up in a snap. Using DC315 will satisfy code compliance on"15 Minute Thermal Barriers" and "Ignition Barriers" on your next foam job means:

  • Large single coat spread rate
  • UL 1715 Thermal Barrier - varies, 70-90 sq ft per gallon / 350-450 sq ft per 5 gallon pail
  • NFPA 286 (AC377) Attic Crawl Space Ignition Barrier - 400 sq ft per gallon / 2,000 sq ft per 5 gallon pail
  • Reduced labor cost, reduced material cost and higher profits
  • Fast turnaround time
  • Easily applied with a sprayer, brush or roller
  • No complicated mixing- just stir the paint before application
  • No waste
  • Fast and easy clean up of our water based latex product, tools & equipment
  • Will not gum up or block spray equipment
  • Passed strict EPA - VOC and AMQD tests
  • Non Toxic, Low Vapors, Low VOCs
  • Two year shelf life
  • Certified Code Compliant Coating

Recommended Uses

This product is designed for use on interior polyurethane foam surfaces


Adequate ventilation must be provided during and after application until the coating has dried. Avoid breathing vapors or spray mist. Close container after use.
Read MSDS before opening containers.

Surface Preparation

Can be applied directly to fully cured polyurethane foam surfaces. All surface preparation should be carried out in accordance with good painting practices. Remove all loose, peeling or powdery existing paint from the surface. All dirt, grease, oil, wax, and other foreign matter MUST be removed with a detergent, rinse surface thoroughly with clear water, and allow drying.

Application Equipment: DC315 can be applied by brush, roller or airless sprayer.
Brushing: Use top quality polyester/nylon blend brushes such as those supplied by Purdy, Wooster, or equivalent.
Rolling: 3/8" polyester blend nap roller covers generally work well.


  • Pump: (Graco) for best results use Graco 795 airless sprayer, with a minimum 2000 PSI
  • Tip: 526 - 529 or equivalent.
  • Filter: 60 mesh
  • Hose: Use minimum size of 3/8" airless spray line for the first 50' from pump.

Airless Spray:

  • Fluid Pressure: 2,000 PSI or higher
  • Strainer: 60 Mesh
  • Fluid Hose: 3/8 diameter with a 1/4" whip
  • Tip: .021 - .029

Conventional Spray

  • Air Supply: 12 CFM, 50 psi at nozzle
  • Fluid: 15-20 psi
  • Gun: Graco 217-800 to 217-816
  • Type: External Mix
  • Reduction: Up to 7%


Stir thoroughly and apply WFT per test. Do not apply in temperatures below 50°F (10°C).


  • Finish: Flat
  • Color: Off-White
  • Spreading Rate: For 15 minute Thermal Barrier - varies, 70-90 sq ft per gallon / 350-450 sq ft per 5 gallon pail
  • Spreading Rate: For AC377 Attic Crawl Space- 400 sq ft per gallon / 2,000 sq ft per 5 gallon pail
  • V.O.C.: (47 g/l)
  • Volume Solids: 65%
  • Drying Time @ 77°F & 50% RH: To touch 1-2 hours to recoat 2 to 4 hours
  • Type of Cure: Coalescence
  • Flash Point: None
  • Reducer/Cleaner: Water
  • Shelf Life: 2 years (unopened)
  • Packaging: 1&5 gal. Containers
  • Shipping weight: 1 gal - 13 lbs, 5 gals - 58 lbs
  • Application: Brush, roller, conventional and airless spray

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Building Code Requirements For Use Of Spray Polyurethane Foam

A prescriptive ignition barrier is required within a residential application over the surface of the polyurethane foam insulation when used within accessible attics or crawlspaces.
Interior surfaces in inhabited buildings should be covered with a "15 minute" thermal barrier for fire protection.
Ignition and thermal barriers are defined within the International Building Code and International Residential Code as the following:

  • 1.5 inch-thick (38 mm) mineral fiber insulation
  • 0.25 inch-thick (6.4 mm) wood structural panels
  • 0.375 inch-thick (9.5 mm) gypsum board
  • Corrosion resistant steel having a base metal thickness of 0.016 inch (0.406 mm).
  • Any product which meets testing performed under NFPA 286, FM-4880, UL-1040 or UL-1715; such as DC315. DC315 is a Certified Warnock Hershey listed and rated product which has passed certified testing for both the (UL-1715) "15-minute" Thermal Barrier and the NFPA 286 (AC-377) standards as an Ignition Barrier. Consult your local building code authorities regarding requirements of installation of polyurethane spray foam insulation in your application.