Ayous treated with SaferWood Thermex-FR, Southern California. Shown with a factory coating. The fire classification applies to uncoated boards.
Ayous treated with SaferWood Thermex-FR, Southern California. Shown with a factory coating. The fire classification applies to uncoated boards.
Overview
What ThermoSafeFR is
ThermoSafeFR starts with ThermoCraft Ayous or ThermoCraft Nordic Pine and adds a second step: the boards are milled to profile, then Chemco pressure-impregnates them with Thermex-FR.
Fire-retardant-treated wood carries a surface-burning classification. It is not a fire-resistance-rated assembly and has no hourly rating.
Class A per ASTM E84, 30-minute test
D2898 Tested after weathering
Non-structural Interior and exterior
QAI listed Listing B1152-1, CERus-1031
Testing
How it is tested
- 01
Weathered first: ASTM D2898 wetting and drying cycles.
- 02
Tunnel test for 30 minutes: ASTM E84 extended (ASTM E2768).
- 03
Class A per ASTM E84: flame spread under 25, smoke under 450, flame front within 10.5 ft (QAI Listing B1152-1).
FR specs
What the listings cover
United States
| Item | Result | Source |
|---|---|---|
| Surface burning | Class A per ASTM E84: flame spread index under 25, smoke-developed index under 450, ASTM E84 extended to 30 minutes (ASTM E2768), after ASTM D2898 weathering | QAI Listing B1152-1, Table 2 |
| Flame front | No more than 10.5 ft past the burners; no significant progressive combustion | QAI CERus-1031 |
| Fire-retardant-treated wood | Evaluated as complying with IBC 2303.2 and IRC R802.1.5 | QAI CERus-1031 |
| Ignition-resistant material | 2025 California WUI Code 503.2.2 and 504A; IWUIC 503.2, item 3 | QAI CERus-1031 |
| Labels | Chemco's label with the QAI listing mark on each piece (IBC 2303.2.5) | QAI CERus-1031 |
| Use | Non-structural, interior and exterior; not for ground contact or standing water | QAI CERus-1031 |
Canada
| Item | Result | Source |
|---|---|---|
| Surface burning | CAN/ULC-S102 after ASTM D2898: flame spread rating under 25, smoke developed classification under 100. | QAI Listing B1152-1, Table 1, citing NBC 2020 3.1.4.5(b) and 3.1.4.8(3) |
| Use | Non-structural | QAI Listing B1152-1 |
QAI CERus-1031 is a US code evaluation. Canadian values come from QAI Listing B1152-1 (CAN/ULC-S102). No Canadian code evaluation (CCMC) is on file.
Applications
Where it goes
- ThermoSafeFR Ayous
- Cladding and siding, interior walls; soffits and ceilings where the authority having jurisdiction accepts them.
- ThermoSafeFR Nordic Pine
- Cladding and siding, interior walls; decking grade; soffits and ceilings where the authority having jurisdiction accepts them.Decking: listed in QAI's siding and decking (non-structural) grade; joist spacing and fastening TO CONFIRM
Installation
Working with it
Milled to profile before treatment.
No ripping or milling after treatment. Cross-cut and drill as needed.
Stainless steel fasteners, A2 (AISI 304) minimum.
Install uncoated. The fire classification is for uncoated boards.
Keep the label on each piece for the inspector.
Not for structural use, ground contact or standing water.
Species
Nordic Pine* treated with SaferWood Thermex-FR, Eagle, Idaho. Shown with a factory coating. The fire classification applies to uncoated boards. *Shown with fire-retardant treatment.
Specification
Specify it
Guide specification. The design professional is responsible for the project specification.
- Product, AyousFire-retardant-treated wood siding: ThermoSafeFR Ayous (listed as "Thermally Modified Ayous"), pressure-impregnated with Thermex-FR by Chemco, Inc.
- Product, Nordic PineFire-retardant-treated wood siding: ThermoSafeFR Nordic Pine (listed as "Thermally Modified Nordic (Scots) Pine"), pressure-impregnated with Thermex-FR by Chemco, Inc.
- ClassificationClass A per ASTM E84 on the 30-minute test after ASTM D2898 weathering (QAI Listing B1152-1).
- CodeEvaluated as complying with IBC 2303.2 (QAI CERus-1031).
- LabelsEach piece labelled per IBC 2303.2.5.
- UseNon-structural use. Install uncoated.
- MillingProfiles milled before treatment; no ripping or milling after treatment.
- FastenersStainless steel fasteners, A2 (AISI 304) minimum.
Tell us what you are working on.
Submittal packages, samples and quotes from our team.
Treated with
Fire-retardant-treated wood carries a surface-burning classification. It is not a fire-resistance-rated assembly and has no hourly rating. Fire performance applies to ThermoSafeFR Ayous and Nordic Pine as treated by Chemco, Inc. and labelled under QAI CERus-1031 and QAI Listing B1152-1, installed uncoated, unripped and in non-structural uses. Some stains, paints and coatings reduce fire performance; Chemco endorses no coating. Project acceptance rests with the authority having jurisdiction. Sources: QAI Listing B1152-1, Edition 3 (March 9, 2026) and QAI Code Evaluation Report CERus-1031, rev. March 2026 (report holder: Chemco, Inc.), at qai.org; the listing names the boards "Thermally Modified Ayous" and "Thermally Modified Nordic (Scots) Pine". Treated with SaferWood™ Thermex-FR™ by Chemco, Inc. SaferWood and Thermex-FR are trademarks of their respective owners.