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Material profile  ·  Timber and wood  ·  Construction & Interior Design

Reclaimed Wood: Carbon, Grading and Certification for Designers

Sourced data on carbon, structural grading, fire, safety and FSC claims for people who specify reclaimed timber.

ArchitectsInterior designers

By Pilar Flores· Published October 7, 2026· Updated October 8, 2026· 7 min read

Reclaimed wood properties at a glance

Family
Timber and wood: solid timber (reused, not recycled into a new composite)
Origin
Deconstructed buildings, barns, piers, railway and marine structures. Species depend on the source: for example Ashwells in the UK reclaims tropical hardwoods such as Jarrah, Greenheart and Keruing from piers and sleepers.[3]
Production
Selective deconstruction or salvage, then cleaning, metal removal, cutting out rotten ends, and re-milling or resawing. The UK interviewees named the time and logistics of careful deconstruction and the reconditioning of the wood among the main challenges.[2]
Forms
Beams and posts · floorboards and parquet · cladding · boards for furniture and joinery[2][3][4][5]
Thermal conductivity (λ)
Same physics as new wood: structural softwood at 12 % moisture content is 0.10–0.14 W/(m·K); the handbook table runs from 0.094 (northern white cedar) to 0.21 (hickory) across species, and actual values can differ by up to 20 %.[6] No measurement specific to reclaimed timber was found. A wall of solid timber is not insulation.
Density
Depends on the species: among the species in the handbook table, specific gravity runs from 0.31 (northern white cedar) to 0.78 (mockernut hickory).[6] Measured density of reclaimed lots is not published by the suppliers we checked.
Reaction to fire
The EU default class D-s2,d0 applies to visual- and machine-graded structural timber with a mean density of at least 350 kg/m³ and a thickness of at least 22 mm.[7] Reclaimed pieces are usually ungraded, so whether that default can be used is a question for a fire engineer. We found no fire data for ungraded reclaimed timber.
Embodied carbon (A1–A3)
No EPD for reclaimed timber was found. A US Forest Products Laboratory study (cradle to construction site, including transport) gives fossil CO₂ of 23.9 kg/m³ for recovered softwood framing lumber against 109 for new, and 49.7 against 228 for hardwood flooring.[1] US data, 2013; not an A1–A3 figure.
Emissions
Not measured for reclaimed timber in any source we read. Old finishes and treatments matter: lead-based paint is the documented hazard.[8] We found no emission tests of finished reclaimed flooring or cladding.
Moisture behaviour
UK practitioners describe mature timber as dimensionally stable and lower in moisture content, but the authors say more research is needed to compare it with new wood.[2] We found no measured moisture or movement data.
Certifications seen
FSC Recycled claims for reclaimed material rest on FSC-STD-40-007 (pre- and post-consumer classification).[9] Supplier certificate codes, checked in the FSC public search on 7 and 8 October 2026: Ashwells is a valid group member (site INT-COC-005535-452) of group certificate FSC-C007915, held by Enviaudits Ltd and valid until 14 June 2031 (FSC UK's article prints the code as C007195), and reSAWN holds FSC-C122513 itself (valid until 10 September 2029).[16][3][5] The Ashwells group certificate lists FSC-STD-40-007 V2-0 among the standards assessed, but its product list is the whole group's; reSAWN's lists only FSC-STD-40-004 V3-1, and none of its 11 product entries is labelled FSC Recycled.[16] We found no CE mark for reclaimed timber, and the general grading standards do not apply to it. Standard Norge lists NS 3691-3:2025 (published 10 January 2025), rules for visual strength grading of reused rectangular softwood (spruce or pine) from Nordic and Baltic sources for load-bearing use; we read its catalogue entry, not the standard.[17][2]

Reclaimed wood is old timber given a second life: the beams of a demolished mill, the boards of a barn, the planks of a pier. Designers choose it for its look and its low impact. The useful questions are how much carbon it really saves, what you can legitimately specify, and what the risks are.

This guide sets out the sourced numbers and the gaps. It covers reuse of solid timber, not recycling into chipboard or biomass.

How much carbon does reclaimed wood save?

What the US study found

The US Forest Products Laboratory compared recovered and new softwood framing lumber and hardwood flooring, including transport to the construction site. Making the new products took 6,440 and 7,750 MJ/m³ (fossil plus biomass energy, mostly mill residues burned on site); recovering the old ones took 418 and 859 MJ/m³ of fossil energy.[1] Fossil CO₂ for new products was about four times higher (109 against 23.9 kg/m³ for framing lumber; 228 against 49.7 for flooring).[1] This is a US study from 2013 on two products, so treat the ratios as indicative.

What changes the result

The same study shows that the benefit depends on what would otherwise happen to the old wood. With standard GWP accounting (biogenic CO₂ excluded), reuse beat new wood in the base case, but could be worse than new wood if all the old timber were burned to displace coal or natural gas.[1] In the UK, 65 % of waste wood (a 2023 figure cited by the authors) already goes to biomass, and demand for it competes with reuse.[2]

Can you specify reclaimed timber structurally?

Grading depends on where you build

New structural timber is strength-graded (for example C24) and CE-marked. Current grading methods do not apply to reclaimed wood, and the UK interviewees named the lack of re-certification as the principal barrier; the cited advice was to use an experienced timber grader or engineer.[2] The EU project RECOWERS (a Marie Skłodowska-Curie action, 2022–2023, now closed) set out to develop a grading system for recovered timber and a European standardised framework; we have not read its results.[10] The authors report that in Norway a draft standard, prNS 3691 "Evaluation of recycled wood", was under consultation.[2] Standard Norge now lists NS 3691-1 to -3:2025, published 10 January 2025: terminology and general rules, impurities, and visual strength grading of "returtre" (reclaimed wood). Per its catalogue entry (read 12 October 2026), part 3 sets rules for visual strength grading of rectangular reused softwood, spruce or pine from Nordic and Baltic sources, for use in load-bearing structures, and does not cover glue joints. We have not read the standards themselves, and we did not confirm whether a published standard exists in your country, so check with your national standards body.[17]

Insurance, fixings and yield

The same interviews raise insurance (harder for commercial buildings), warranties and treatment history, and note that hidden rot may not be visible.[2] The authors name metal in reclaimed wood as one of the principal challenges when it is used as feedstock for new products.[2]

Is reclaimed wood safe to use indoors?

Old wood may carry lead-based paint or past preservative treatments. A 2005 USDA Forest Products Laboratory report states there was no regulatory or policy guidance at the US federal level that permits, prohibits or qualifies salvaging and reusing building materials coated with lead-based paint.[8] A 2005 study of remilling Douglas-fir siding from Army barracks, with standard machinery and dust collection, measured worker lead exposure below one-tenth of the OSHA limit.[11] Treat that as one case, not clearance for any lot. Ask the supplier for the building's origin and treatment history.

What does "FSC Recycled" mean for reclaimed wood?

FSC-STD-40-007 sets how certificate holders buy, verify and classify reclaimed material, splitting it into pre-consumer and post-consumer.[9] A Recycled claim therefore tells you the supplier followed that classification, not that the wood has a structural grade or is free of treatments. Check the certificate on the FSC database before you specify it.

What is reclaimed wood used for?

Flooring, cladding and joinery

Best for: interior designers · architects

Suppliers list parquet, panelling, cladding and structural timber from deconstructed buildings.[3][4][5] Ashwells' tropical hardwoods come from structures such as Southend and Boscombe piers, and from sleepers and marine piles.[3]

Structural timber

Best for: architects · engineers

Possible but uncommon: in the UK study only one participant gave an example of structural reuse, from one listed building to another.[2] Plan an audit before demolition, a grading route and a buyer early.[2]

Reclaimed wood in use: projects

Redfox Commons

Lever Architecture · Portland, Oregon, USA · 2019

More than 6,500 linear feet of 4x12 inch boards were reclaimed from an overbuilt mezzanine during demolition and used to build a new timber and glass entrance structure joining two historic buildings. The page does not mention grading or testing.[12]

(P)RECAST Pavilion

GXN · Copenhagen, Denmark · 2023 UIA World Congress of Architects

Five modules of salvaged concrete walls are framed by 200-year-old timber beams. ArchDaily says the elements came from the demolition of a school in Vanløse and of Jagtvej 169 in Østerbro, and describes the beams as having aesthetic and structural value.[13]

Barn Again pavilion

THISS Studio and Tom Svilans, with Bollinger+Grohmann · Gammel Strand, Copenhagen · 2025 · temporary

Stacked beams of salvaged timber from disused Norwegian barns form the pavilion; the engineer describes reused timber elements with reversible connections that allow full disassembly. The sources do not mention grading or testing.[14][15]

Where to buy reclaimed wood

Suppliers selected by our editors and checked against company documents and registry records where available.

SupplierProductsCountryCertifications
Ashwells Reclaimed Timber Reclaimed tropical hardwoods (Jarrah, Greenheart, Keruing) · parquet and panelling · structural timber United Kingdom (Essex) Valid group member (INT-COC-005535-452) of FSC group certificate FSC-C007915, held by Enviaudits Ltd, valid until 14 June 2031; FSC-STD-40-007 V2-0 among the group's standards assessed; the registry shows the group's products, not Ashwells' own claims (FSC public search, 7 and 8 October 2026). FSC UK's article prints the code as C007195. No carbon figures given.[16][3][4]
reSAWN TIMBER co. Reclaimed and new wood for flooring, wall cladding, furniture and exterior siding United States FSC-C122513 (own certificate SCS-COC-005058), valid until 10 September 2029, assessed against FSC-STD-40-004 V3-1 only; its 11 listed product entries carry FSC Mix or FSC 100 % claims, none FSC Recycled (FSC public search, 7 and 8 October 2026). The company says most products are available as FSC-certified and that all qualify for LEED credits (company claims); no EPD found.[16][5]

Opalis lists professional retailers of building materials from dismantled buildings.[4] Certificate codes were checked in the FSC public search on 7 and 8 October 2026; confirm status again before specifying. Listing policy: editorial selection, not paid.

Frequently asked questions about reclaimed wood

Is reclaimed wood more sustainable than new wood?

In US life-cycle data, recovered framing lumber and flooring emitted about four times less fossil CO₂ than new products. The advantage shrinks if the old wood would otherwise have been burned for energy.

Can reclaimed timber be used structurally?

Yes in principle, but the general grading standards do not apply to reclaimed timber and we found no CE mark for it. Norway has published a visual grading standard for reused spruce and pine (NS 3691-3:2025), so check what applies where you build. Use an experienced grader or engineer and agree the risk and insurance early.

Is reclaimed wood safe?

It depends on the lot. Old paint may contain lead and old timber may have been treated. Ask for the building's origin and treatment history; one study of remilling lead-painted siding found worker exposure under a tenth of the OSHA limit.

What does FSC Recycled mean?

That the supplier classified the reclaimed material as pre- or post-consumer under FSC-STD-40-007. It does not certify strength or absence of treatments.

What is the thermal conductivity of reclaimed wood?

Like any wood: about 0.10–0.14 W/(m·K) for structural softwood at 12 % moisture content, higher for dense hardwoods. No reclaimed-specific measurement was found.

Does reclaimed wood have an EPD?

We found none for reclaimed timber. Ask suppliers directly; the US study is the only quantified comparison we read.

The bottom line on reclaimed wood

The one life-cycle study we read, from the US and dated 2013, found much lower fossil CO₂ for recovered framing lumber and flooring than for new products, which supports reclaimed wood as a low-carbon option for those uses. For structure it is still a project-by-project decision, because grading and certification routes are only starting to emerge and insurance is a concern. Ask each supplier for origin, treatment history and certificate numbers.

Related materials

CorkBio-based BambooBio-based Hemp & hempcreteBio-based MyceliumBio-based

Sources

  1. Bergman, R.D., Falk, R.H., Salazar, J., Gu, H., Napier, T.R. & Meil, J. (2013). "Life-cycle energy and GHG emissions for new and recovered softwood framing lumber and hardwood flooring considering end-of-life scenarios." Res. Pap. FPL-RP-672, USDA Forest Service, Forest Products Laboratory. US data; includes transport to the construction site and end-of-life scenarios; GWP excludes biogenic CO₂ by standard practice. Full text read. Treesearch
  2. Godina, M., Gowler, P., Rose, C.M., Wiegand, E., Mills, H.F., Koronaki, A., Ramage, M.H. & Shah, D.U. (2025). "Strategies for salvaging and repurposing timber elements from existing buildings in the UK." Journal of Cleaner Production 489:144629. Interviews with UK supply-chain stakeholders; source for grading, certification, insurance, fixings, UK waste-wood shares and reclamation barriers. Full text read. doi:10.1016/j.jclepro.2024.144629 · PDF
  3. FSC UK, "Ashwells Reclaimed Timber" (3 June 2020; prints the code as FSC C007195, which differs from the registry code FSC-C007915 in [16]): reclaimed tropical hardwoods from sleepers, marine piles and piers; no carbon figures in the article. Certifier-side news item. uk.fsc.org
  4. Opalis (Rotor vzw/asbl and Bellastock), "About" page and the listing for Ashwells Reclaimed Tropical Timber (parquet, panelling, structural timber; Upminster, UK). Directory of reuse dealers; listings are self-described. opalis.eu · listing
  5. reSAWN TIMBER co., "Sustainable wood" page: most products "available as FSC-Certified", all products said to qualify for LEED credits, FSC C122513 in the page footer. Company claims; no EPD or product-level certificate linked. resawntimberco.com
  6. USDA Forest Products Laboratory (2021). Wood Handbook: Wood as an Engineering Material, FPL-GTR-282, Chapter 4, "Thermal conductivity" text and Table 4–7 (values at 12 % moisture content; up to 20 % variation). Full text read. Treesearch
  7. Commission Decision 2003/593/EC of 7 August 2003 amending Decision 2003/43/EC, Official Journal L 201, 8.8.2003, Table 4: structural timber, minimum mean density 350 kg/m³, minimum thickness 22 mm, class D-s2,d0 (excluding floorings). Applies to graded structural timber; its application to ungraded reclaimed pieces is our reading and should be confirmed. EUR-Lex lists the Decision as in force with no end date (checked 8 Oct 2026). EUR-Lex · PDF (copy hosted by Buildwise; text read)
  8. Napier, T.R., Falk, R.H., Guy, G.B. & Drodz, S. (2005). "Regulatory and policy issues for reuse and remanufacture of wood materials coated with lead-based paint." Gen. Tech. Rep. FPL-GTR-164, USDA Forest Products Laboratory, 6 pp. Full text read. Treesearch
  9. Forest Stewardship Council, FSC-STD-40-007 V2-0 EN, "Sourcing reclaimed material for use in FSC Product Groups or FSC Certified Projects" (approved 1 April 2011): definitions of pre-consumer and post-consumer reclaimed material and verification on receipt. Full text read from a regional FSC site copy; FSC's Document Centre lists V2-0 (approved, effective 1 April 2011) as the current version (checked 8 Oct 2026). Applies to organisations certified to FSC-STD-40-004 or -006. PDF · Document Centre
  10. European Commission CORDIS, "REusing COnstruction Wood through a common EuRopean Standard (RECOWERS)", H2020 grant agreement 101025786. Project objective as described by CORDIS (fact sheet read 8 Oct 2026): a grading system and a European standardised framework for recovered timber; project closed 31 Dec 2023, Marie Skłodowska-Curie action; CORDIS lists two publications, results not read. cordis.europa.eu
  11. "Remilling of salvaged wood siding coated with lead-based paint. 1. Lead exposure." Forest Products Journal 55(7/8):76–80 (2005). About 2,180 m of Douglas-fir siding from deconstructed Army barracks. Abstract read on the journal knowledge-base page; authors not shown there and full text not accessed. forestprod.org
  12. Lever Architecture, "Redfox Commons" project page: location, year, quantities and on-site origin of the reclaimed boards. Architect's page. leverarchitecture.com
  13. ArchDaily, "GXN and MEE Studio's pavilions in Copenhagen explore circularity and regeneration for the 2023 UIA Congress of Architects": architect, city, year and timber origin. Independent trade press. www.archdaily.com
  14. Bollinger+Grohmann, "Barn Again" project page: designers, engineer, client, year and reuse of timber. Engineer's page. www.bollinger-grohmann.com
  15. Building Design (BD), "Pavilion gives barns new life at Copenhagen Architecture Biennale" (2025): Norwegian barn origin, stacked beams, location and structural engineer. Independent trade press. www.bdonline.co.uk
  16. Forest Stewardship Council, FSC Search (public certificate database), records opened 7 and 8 October 2026 (database last updated 8 Oct 2026): (a) group certificate INT-COC-005535, licence FSC-C007915, held by Enviaudits Ltd (Halesworth, UK), first issued 1 Nov 2006, last status update 15 Jun 2026, valid until 14 June 2031, standards assessed FSC-STD-40-007 V2-0, FSC-STD-40-003 V2-1, FSC-STD-40-004 V3-1; its member list (EnviAudits list of 1 Oct 2026) includes Ashwells Reclaimed Timber Ltd, INT-COC-005535-452, Wick Place Farm, Bulphan, Essex, status Valid; the product list on the record is the group's (for example cork, bamboo, paper), so Ashwells' own product scope is not shown; (b) reSAWN TIMBER Co. Inc (Telford, Pennsylvania), licence FSC-C122513, certificate SCS-COC-005058, first issued 11 Sep 2014, valid until 10 September 2029, standard assessed FSC-STD-40-004 V3-1 only, 11 product entries (flooring, wall cladding, beams, solid wood boards and others) with claims FSC Mix and/or FSC 100 %, none FSC Recycled. Ashwells (group) · reSAWN
  17. Standard Norge, online.standard.no catalogue entries NS 3691-1:2025 "Evaluering av returtre - Del 1: Terminologi og generelle regler", NS 3691-2:2025 "Del 2: Urenheter" and NS 3691-3:2025 "Del 3: Visuell styrkesortering", each edition 1.0, published 10 January 2025, committee SN/K 267 (catalogue pages read 8 Oct 2026; part 3 re-read 12 Oct 2026; the standards are paid and were not read). Standard Norge presentation slides ("Evaluering av returtre", filed as 250320) describe the series as ready for use. NS 3691-1 · -2 · -3
Reclaimed wood Bio-based Circular construction Flooring Structural timber FSC Recycled