Thermally modified wood siding and rainscreen cladding
American-made Ash and Poplar siding, heat-treated to resist rot and insects without chemicals, in vertical-grain and flat-sawn profiles.
Thermally modified wood
Grown, harvested and modified worldwide. Installed on homes everywhere
Choose Ash for a bold, pronounced grain or Poplar for a smooth, even face. As the manufacturer’s distributor, profiles are your call.
siding
Rot and insect proof
Class 1 durability without preservatives.
Stable boards
Up to 50% less movement than untreated Ash.
Finish optional
Leave to silver or oil to keep the brown tone.
Rainscreen ready
Profiles sized for furring and hidden clips.
Why specify thermowood
Siding that outlasts the finish
Thermal modification drives moisture and sugars out of the cells, so boards stop feeding decay fungi and insects. Class 1 durability with nothing added but heat and steam.
Tight vertical grain reduces checking and keeps lap and shiplap profiles flat, which is why architects specify it for rainscreen assemblies.
63+ species in stock
Solid and engineered wood products in over 63 species, veneer in over 203.
Established 1920
Over a century in the wood trade, with custom millwork and finishing in-house.
Metal detected & kiln dried
Every reclaimed board is metal-detected, kiln dried and milled.
Samples & trade pricing
Samples on request; architects, builders and designers welcome.
Profiles, species
Vertical grain or flat sawn
Shiplap, channel, T&G and open-joint rainscreen profiles in 1×6 and 1×8, milled from thermally modified Ash or Poplar.
Tight-grain Ash
Quarter-sawn vertical grain for the flattest, most stable siding board. Pronounced figure that greys evenly to silver.
Smooth Poplar
Flat-sawn Poplar for a calm, uniform face that takes oil and pigment finishes well. Lighter weight, easier to hand-nail.
Siding profiles and species
Thermally modified siding and rainscreen is 100% grown, harvested and manufactured in Pennsylvania. Choose the profile and the species; we are the manufacturer’s distributor, so it is your call.
Pronounced grain
Thermally modified Ash
Ash gives a bold, open grain that reads clearly from the street and greys to an even silver. Quarter-sawn vertical-grain boards stay the flattest of any siding we sell.
Smooth face
Thermally modified Poplar
Poplar is calm and uniform, lighter to handle and hand-nail, and takes pigmented oils evenly for a painted look without paint.
Nordic Pine
Lunawood Luna Triple 32x140
A Finnish facade panel with two deep grooves that gives a batten look from a single board and installs faster than individual battens. Architecture MasterPrize 2021 sustainable product winner.
Shiplap
Horizontal or vertical, 1x6 and 1x8
Channel siding
Shadow-line profile, 1x8
Tongue & groove
Tight joint for soffits and ceilings
Open-joint rainscreen
Gapped boards on furring with clips
Species
Ash
Widths
1x6, 1x8
Durability
Class 1
Made in
USA
Standard profiles
13 profiles, sizes and drawings
Standard board sizes for thermally modified Ash, Ayous, Iroko, Pine, Western Red Cedar, VG Hemlock, Shou Sugi Ban style and Rhino Wood. Every order is milled to the thickness, width and profile the project needs.
| Thickness | Width | Length |
|---|---|---|
| 13/16″ | 3-5/8″, 4-13/16″, 5-9/16″ | 2.6 to 9.8 ft |
| 1″ | 3-5/8″, 4-13/16″, 5-9/16″ | 2.6 to 9.8 ft |
| 1-5/8″ | 3-5/8″, 4-13/16″, 5-9/16″ | 2.6 to 9.8 ft |
A fire-retardant treatment backed by ASTM and ULC test reports is available on request; classification depends on species, profile and application.
Thickness: 1-5/8"
Width: 3-3/4" to 4-3/4"
Length: 2.6 to 10.2 ft (0.8 to 3.1 m)
Thickness: 9/16" to 13/16"
Width: 3-9/16" to 5-1/2"
Length: 2.6 to 10.2 ft (0.8 to 3.1 m)
Thickness: 9/16" to 13/16"
Width: 3-9/16" to 5-1/2"
Length: 2.6 to 10.2 ft (0.8 to 3.1 m)
Thickness: 9/16" to 13/16"
Width: 3-9/16" to 5-1/2"
Length: 2.6 to 10.2 ft (0.8 to 3.1 m)
Thickness: 9/16" to 13/16"
Width: 3-9/16" to 5-1/2"
Length: 2.6 to 10.2 ft (0.8 to 3.1 m)
Thickness: 1"
Width: 5-1/2"
Length: 2.6 to 10.2 ft (0.8 to 3.1 m)
Thickness: 9/16" to 13/16"
Width: 3-9/16"
Length: 2.6 to 10.2 ft (0.8 to 3.1 m)
Thickness: 9/16" to 13/16"
Width: 3-9/16" to 5-1/2"
Length: 2.6 to 10.2 ft (0.8 to 3.1 m)
Thickness: 1-1/8" to 1-1/4"
Width: 4-5/8" to 4-3/4"
Length: 2.6 to 10.2 ft (0.8 to 3.1 m)
Thickness: 9/16" to 13/16"
Width: 3-9/16" to 5-1/2"
Length: 2.6 to 10.2 ft (0.8 to 3.1 m)
Thickness: 9/16" to 13/16"
Width: 3-9/16" to 5-1/2"
Length: 2.6 to 10.2 ft (0.8 to 3.1 m)
Thickness: 1"
Width: 3-3/4" to 4-3/4"
Length: 2.6 to 10.2 ft (0.8 to 3.1 m)
Thickness: 9/16" to 13/16"
Width: 3-9/16" to 5-1/2"
Length: 2.6 to 10.2 ft (0.8 to 3.1 m)
Siding questions
Common questions
Installation guides for siding and rainscreen are on our guides page.