Support Spacing
Use furring at least 3/4 inch thick and no more than 24 inches on center; confirm the final layout for the profile and project.
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Architectural Cladding · Division 07 46 23 · Issaquah project guide
Thermo Ashfor Siding & Cladding.
Thermo Ash is the dense hardwood option in the Maximo collection, with pronounced grain, a deep brown tone and a published Class 1 durability rating. End-matched profiles can help plan long runs efficiently when installed according to the current profile guidance.
APPLICATION SYSTEMThermo Ash · Siding & Cladding
1,320Janka Hardness
38.5Dry Density
Verify ProductDurability Rating
20 YearMaximo Warranty
Hardware & Nails
Exterior-grade stainless steel fasteners selected for the profile, substrate and exposure; pre-drilling is recommended.
Sub-framing Details
Water-resistive barrier, coordinated flashings and a continuous ventilated space behind the siding.
Air Cavity Specs
Keep drainage and airflow continuous from the base to the top of the cladding assembly.
Material & assembly planning
Key advantages &
installation rules.
End-Matched Layout
The cataloged end-match can simplify joint planning and may reduce offcuts when the installation instructions allow joints between supports.
Dense Hardwood Character
Thermo Ash offers a substantial feel and pronounced grain for high-visibility exterior surfaces.
Through-Modified Tone
Thermal processing creates a deep brown tone through the board rather than applying a surface-only stain.
Assembly Guidelines for Siding & Cladding:
- Install over a drained, back-ventilated rainscreen cavity with minimum 3/4" airspace.
- Pre-drill fastener locations and take particular care near board ends and edges.
- Apply end-grain sealer immediately to all field cuts prior to fastening.
- Follow the current Maximo profile instructions for fastener quantity, placement and substrate penetration.
Reduced tangential movement supports more consistent joints through seasonal changes.
Thermal modification reduces moisture uptake and changes nutrients used by decay fungi; confirm the rating for the selected profile.
Real wood modified without added wood-preservative chemicals.
Consultation and order coordination through BFS Issaquah.
Cataloged Profiles
2 Profiles available for
Thermo Ash siding & cladding.
5/4x6S4S E4E End MatchWhere to buy in Issaquah
Builders FirstSource Issaquah
Catalog available by consultation. Contact the Issaquah team to confirm availability, sample kits, and lead time for your selected Maximo profile.
Issaquah, WA 98029
(425) 391-8000
Monday–Friday, 7:00 AM–4:00 PMDealer information verified August 31, 2026. No in-stock claim is made on this site.
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on your project.
Tell us what you are building. Our team will review your wood selection and contact you to coordinate a Maximo consultation with Builders FirstSource Issaquah.
Frequently Asked Questions
Thermo Ash · Siding & Cladding
Why choose Thermo Ash siding over Western Red Cedar?+
Thermo Ash offers a denser hardwood surface, a published Class 1 durability rating and reduced moisture response after thermal modification. Cedar performance varies by grade and heartwood content; compare the exact products, finish plan and warranty rather than the species names alone.
Can Thermo Ash siding be oriented vertically?+
Yes. For vertical installation, install horizontal furring over vertical drainage spacers to ensure uninterrupted vertical airflow behind the cladding.
Product and installation references