What Exactly Is DC315?

DC315 is a water-based intumescent coating engineered to be applied over spray polyurethane foam (SPF) insulation. It meets the requirements of ICC-ES AC377, the acceptance criteria for spray-applied foam plastic insulation systems in North America.

How Does It Actually Work?

The coating contains intumescent compounds that expand significantly when exposed to heat. When a fire breaks out:

The coating swells — expanding to many times its original thickness
A char layer forms — acting as insulation between the flame and the foam
Flame spread is slowed — satisfying the code's thermal barrier intent

Without a thermal barrier, exposed SPF foam can ignite quickly and produce thick, toxic smoke. DC315 significantly slows the spread and buys critical time.

Why Is DC315 Preferred Over Drywall?

In crawlspaces, mechanical rooms, garages, unfinished basements, and Muskoka cottage spaces, drywall is often:

Impractical — too heavy, moisture-sensitive, or structurally unsuitable
Space-consuming — critical in low-clearance areas
Expensive — especially when the space doesn't warrant a full interior finish

DC315 is sprayed directly onto the foam surface. No framing. No fasteners. No additional structure.

Application Requirements

DC315 must be applied at the correct wet film thickness using appropriate commercial spray equipment by a qualified installer. Under-application means the coating won't perform as intended.

Common Applications in Muskoka

We regularly apply DC315 in:

Basements — foam on walls or rim joists left exposed
Garages — especially attached garages adjacent to living space
Crawlspaces — where drywall isn't feasible
Cottage renovations — year-round and seasonal properties
New builds — after spray foam is applied, before other trades proceed
Inspector-flagged corrections — resolving compliance issues fast

Pricing for DC315 Application in Muskoka

Typical pricing ranges from $2.50 to $3.50 per square foot, with a minimum service fee of $1,500 depending on the size and scope of the project.

Pro Tip: The square footage of foam surface is not the same as the floor area of the room — it includes walls, rim joists, and any ceiling areas with exposed foam.

Local Insight

Muskoka has a higher-than-average rate of spray foam usage in residential construction — largely because of the region's extreme temperature swings, older cottage stock, and the prevalence of remote properties where air sealing is critical. That means DC315 demand in Muskoka is also higher than in many other parts of Ontario.

If you need DC315 applied professionally in Muskoka, contact us today. We'll assess your project, provide clear pricing, and get the work done right.

DC315 Thermal Barrier Coating: What It Is, How It Works, and When You Need It