Spray Foam Spec & QA Standard

How we spec and verify closed-cell spray polyurethane foam (ccSPF) in wall and roof assemblies — assembly design, R-value, code barriers, PPE, and equipment-verified quality control. Written for general contractors, builders and inspectors who want documentation they can hand the AHJ. Veteran-owned, BPI-certified.

✔ ICC-ES documented ✔ Blower-door verified ✔ Thickness QA ✔ BPI Certified

1. Assembly design — spec foam where it earns its keep

All-foam everywhere is usually over-spec'd. We optimize the assembly so closed-cell does the air/vapor/structural work and cheaper fill carries the rest of the R.

Walls — flash-and-fill (hybrid)

1.5–2″ ccSPF direct to sheathing: continuous air + vapor control, plus it bonds sheathing to framing (racking / load-path stiffness).
Fill the remaining cavity with fiberglass or dense-pack cellulose to reach the assembly R-target.
Result: foam-grade air sealing + structure, batt-grade cost on the balance of the R.

Roofs — unvented deck (IRC R806.5)

ccSPF to the underside of the roof deck: conditioned attic, deck protection, and an adhesive bond that adds wind-uplift resistance beyond fasteners alone.
In cold climates the ccSPF layer must be thick enough to keep the condensing surface warm if air-permeable insulation is added below it — under-spraying that ratio is the #1 cause of hybrid-roof moisture problems.

Verify: wind-uplift ratings require an engineer + a tested assembly. Condensation-control ccSPF ratios and R-targets are code- and climate-zone-specific — confirm the adopted IECC/IRC edition and any local amendments with the AHJ before it goes in writing.

2. R-value framework (Climate Zone 6–7 region)

Our territory (MT/ND/SD/WY) is largely CZ 6–7. Typical targets below — framework only; verify the current adopted code + AHJ.

Assembly	Typical CZ 6–7 target*	ccSPF note
Attic / roof	~R-49 to R-60	~R-6.5–7 per inch (aged/LTTR)
Above-grade wall	~R-20+ or R-13 + R-10ci	2″ ccSPF ≈ R-13 flash layer
Air leakage	Blower-door ACH50 per code	ccSPF is the air barrier

*Illustrative targets, not a code citation. R-value is a rated aged (LTTR) value per the product's ICC-ES report.

3. Code barriers — budget them, don't get caught

Thermal barrier over foam in occupied space: 15-minute rated — ½″ gypsum or an approved coating (e.g. DC315). (IRC R316.4 / IBC 2603.4)
Ignition barrier in attics/crawlspaces without regular access, or an approved coating. (IRC R316.5)
ICC-ES report (ESR/ER): we provide the evaluation report for the specific foam so the inspector has the code basis in hand.

Section numbers renumber between code editions. Confirm the edition your AHJ has adopted, plus local amendments.

4. Applicator PPE & exposure control (SPFA-aligned)

SPF chemistry (MDI isocyanate + amine catalyst + blowing agent) is hazardous during spray and cure. Our protocol:

Respiratory: supplied-air respirator (SAR) for interior high-pressure spraying; cartridge APR (organic-vapor + P100) only where an exposure assessment and ventilation support it.
Skin/eye: full coverage suit + hood, nitrile gloves, sealed goggles — MDI is a skin/respiratory sensitizer.
Lift discipline: spray to the manufacturer's max lift thickness in multiple passes. Over-thick lifts trap exothermic heat → scorching, degraded cell structure, and extra off-gassing — worse for both quality and exposure.
Ventilation + re-occupancy: ventilate during and after; honor the product's re-entry time (per TDS) before other trades return.

5. Equipment-verified quality control

Realized R-value = the product's rated R × install quality. We control the variables that decide in-situ cell structure and adhesion:

Ratio: 1:1 A:B, with daily ratio / AB-draw checks. Off-ratio foam = poor cell structure, friability, odor, lost R and adhesion.
Temperature: drum, heated-hose, and substrate temps to spec; substrate at least 5°F above dew point (no-go under 5°F spread).
Pressure: balanced A/B at the proportioner.
Thickness verification: depth checks / cores to confirm installed thickness meets the R-target.
Air-sealing proof: blower-door ACH50, before/after where the scope calls for it.

On "nominal vs. verified" R: code sets R by the product's rated (aged/LTTR) value — that stays. The real-world gap is install quality, and it's closed cheaply by verifying installed thickness + air sealing (blower door), not by lab-testing every job. That documentation is also the proof an owner or inspector can actually trust.

📞 GCs & builders — spec a job or request our ICC-ES docs: 406-939-8301

For homeowners, in plain English

Foam does two jobs at once — it stops the air leaks that drive your bills and insulates — and on roofs it even helps hold the deck down in the wind. We spray it to the manufacturer's spec, protect our crew with proper gear, and prove the result with a blower-door test and thickness checks. You get a tighter, more comfortable building and the paperwork to back it up.

Spec & QA — common questions

Do I have to foam the whole cavity, or can we do a hybrid?

You don't have to foam everything. We run a flash-and-fill hybrid: 1.5–2″ of closed-cell against the sheathing for continuous air/vapor control (plus racking stiffness), then fill the rest of the cavity with fiberglass or dense-pack cellulose to hit the assembly R-target — foam-grade air sealing at batt-grade cost on the balance of the R.

What thermal or ignition barrier does code require over spray foam?

In occupied space, foam needs a 15-minute thermal barrier — ½″ gypsum or an approved coating like DC315 (IRC R316.4 / IBC 2603.4). In attics/crawlspaces without regular access, an ignition barrier or approved coating applies (IRC R316.5). Section numbers renumber between editions — confirm the edition your AHJ adopted plus any local amendments.

Will you provide code documentation for the inspector?

Yes — we hand over the ICC-ES evaluation report (ESR/ER) for the specific foam so the AHJ has the code basis in hand, along with our installed-thickness and blower-door QA records.

How do you verify the installed R-value and quality?

Realized R = rated R × install quality. We run daily 1:1 ratio/AB-draw checks, hold drum/hose/substrate temps to spec (substrate ≥5°F above dew point), verify installed thickness with depth checks/cores, and prove air-sealing with a before/after blower-door ACH50 where the scope calls for it.

Machine Gun Spray Foam & Concrete Lifting, LLC · Veteran-Owned · 2402 N Anderson Ave, Glendive, MT 59330
📞 406-939-8301 · Serving MT / ND / SD / WY · BPI Certified
Reference only — not a substitute for the product TDS, ICC-ES report, a design professional, or your local AHJ. Verify all code figures against the adopted edition.