What does Class A mean on fire treated lumber?

Class A is the top surface-burning classification under ASTM E84: a flame spread index of 25 or less and a smoke developed index of 450 or less. FireProShop lumber is tested on the extended thirty-minute schedule and to ASTM E2768, which is the test regime used to qualify fire retardant treated wood.

Is FireProShop Class A lumber the same as FRTW?

It is a code-evaluated alternative to pressure-treated fire retardant treated wood. DrJ TER 2504-101 is the evaluation report, written against the alternative materials provision of the IBC and IRC, and it is what the building official reviews when the lumber is submitted in place of FRTW.

Can my crew use regular nails and tools?

Yes. Bright uncoated steel nails are permitted under the report's conditions of use, and the lumber is cut, nailed and hung the same way as untreated Douglas Fir.

Where can Class A fire treated lumber be used?

Interior and above-ground framing covered by AWPA use categories UC1, UC2 and UCFA, under the IBC, IRC and IECC 2018, 2021 and 2024 editions referenced in the evaluation report.

How does the lumber arrive and where does it ship?

Every piece arrives stamped. Dimensional lumber and turn-key framing packages ship from NorCal Lumber north of Sacramento across the Western United States, or as prefabricated walls and trusses built from the same material.

01 · DrJ TER 2504-101

Class A Fire Treated Lumber

Name: Class A Fire Treated Lumber
Brand: FireProShop
SKU: lumber

MFB-34 EPA Safer Choice Fire Retardant treated Douglas Fir. Treated at the mill, arriving stamped and code-evaluated.

MFB-34 EPA Safer Choice Fire Retardant Treated Wood: No. 2 structural Douglas Fir, treated at the mill and arriving code-evaluated as an alternative to FRTW. A topical coating, not a pressure treatment, so the wood is not incised and allowable design stresses in dry use are the same as before treatment. Bright uncoated steel nails are permitted under the report's conditions of use.

Ask about this product Spec sheet (PDF)

The short answer

Class A lumber is framing lumber with a Class A surface-burning rating: a flame spread index of 25 or less and smoke developed of 450 or less under ASTM E84. FireProShop Class A fire treated lumber is No. 2 Douglas Fir coated at the mill with MFB-34 EPA Safer Choice Fire Retardant, evaluated under DrJ TER 2504-101 as an alternative to pressure-treated FRTW, and it arrives stamped on every piece.

Specifications

Flame spread index≤ 25 · ASTM E84 ext. / E2768

Smoke developed≤ 450

AWPA use categoriesUC1 · UC2 · UCFA

CodesIBC · IRC · IECC 2018 / 2021 / 2024

ArrivesStamped, per member

FAQ

Questions about Class A Fire Treated Lumber.

What does Class A mean on fire treated lumber?: Class A is the top surface-burning classification under ASTM E84: a flame spread index of 25 or less and a smoke developed index of 450 or less. FireProShop lumber is tested on the extended thirty-minute schedule and to ASTM E2768, which is the test regime used to qualify fire retardant treated wood.
Is FireProShop Class A lumber the same as FRTW?: It is a code-evaluated alternative to pressure-treated fire retardant treated wood. DrJ TER 2504-101 is the evaluation report, written against the alternative materials provision of the IBC and IRC, and it is what the building official reviews when the lumber is submitted in place of FRTW.
Does the fire treatment reduce the lumber's strength?: No. MFB-34 is a topical coating applied at the mill, not a pressure treatment, so the wood is not incised and allowable design stresses in dry use are the same as before treatment. The framing plan does not change when a project switches to it.
Can my crew use regular nails and tools?: Yes. Bright uncoated steel nails are permitted under the report's conditions of use, and the lumber is cut, nailed and hung the same way as untreated Douglas Fir.
Where can Class A fire treated lumber be used?: Interior and above-ground framing covered by AWPA use categories UC1, UC2 and UCFA, under the IBC, IRC and IECC 2018, 2021 and 2024 editions referenced in the evaluation report.
How does the lumber arrive and where does it ship?: Every piece arrives stamped. Dimensional lumber and turn-key framing packages ship from NorCal Lumber north of Sacramento across the Western United States, or as prefabricated walls and trusses built from the same material.