same slab, four rulebooks

Problem statement

Reusing whole precast concrete elements — hollow-core slabs, wall panels, beams and columns lifted intact from a building being taken down — avoids almost all of the carbon of making new ones, and the EU-funded ReCreate project has demonstrated it in real deconstruction pilots in Finland, Sweden, the Netherlands and Germany. But its legal-requirements study found that the rulebook was written for new products and disagrees with itself across borders. On waste status: "it is unclear how the EU Waste Framework Directive and its national implementations should be interpreted when it comes to the waste status of deconstructed components intended for reuse: are they waste or not? Some actors consider such components as waste, others argue the opposite, and there is no consensus." Finnish environmental authorities treat deconstructed elements as waste (requiring environmental permits and end-of-waste procedures), in Sweden "it is still ambiguous," Germany has explicit legal routes to avoid waste status, and the Netherlands does not treat them as waste at all — "these differences are noteworthy in that all the countries' waste legislation is based on the same EU Waste Framework Directive." On technical approval: "technical requirements for reused elements are presently the same as for new elements," but the properties of a reused element cannot be controlled in manufacture, "documentation about the original manufacture is rarely available," existing assessment standards were "not devised to consider the reuse of a building's parts in a new kind of assembly," and "the necessary sample size for testing ... is still the authorities' case-by-case decision." The unsolved problem is a product-approval and waste-status pathway sized to a reused structural element — one that neither the CE-marking regime nor national existing-structure assessment codes were built to provide.

Why this matters

Concrete is the most-used material on Earth and precast systems from the 1960s–1980s — Finnish BES, Swedish A-system, Dutch VAM, East German WBS-70 — are now reaching demolition age across Europe in the millions of tonnes; the ReCreate blog notes that reuse's climate benefit far exceeds the small offset from carbonation. The new Construction Products Regulation, in force since December 2024, concedes the gap in its own recitals: "the second-hand market for construction products is currently not very developed and requirements for construction products which have previously been used vary widely amongst Member States," and used products are to be brought under harmonised technical specifications only through "long-term harmonisation." Until then, every reuse project must negotiate approval case by case — a bureaucratic burden that, the study warns, "may hinder small or medium-sized enterprises from entering the reuse market and so slow down the circular economy transition of the whole sector."

What’s been tried and why it hasn’t worked

The pathway that exists is national and improvised. In Finland the ministry clarified in June 2022 that reused components are approved by local building supervisors through "construction site-specific approval," but as of the report "it is still unclear how the approval process is conducted for different reused building components — including precast concrete elements." Sweden lacks established procedures, "assign[ing] a heavy responsibility on developers when it comes to proving the technical properties"; the authorities "have not elaborated on which substances should be analysed" for hazardous content, and a sister project (Återhus) has proposed methods that remain unadopted. Germany and the Netherlands have institutionalised alternatives — German case-by-case approvals and Dutch product certificates from certified bodies — but even there "the special requirements for reused building components add complexity to the planning and approval process and therefore increase the costs of the project." CE marking is not a route: harmonised standards "contain requirements for quality control during manufacture that are not possible for reusable building components" (a Finnish ministry-commissioned study quoted in the report), so "reused construction products cannot normally be CE-marked" (a Danish reused-brick company's voluntary ETA is the rare exception). Existing-structure assessment standards (used to check a building in place) set "minimum required testing methods and sample sizes" for the present use, not for redesign of individual elements into a new assembly, so "new kind of standards are required for assessing the properties for redesign of reusable elements, as the current methods may not be safe enough." Waste hierarchy enforcement compounds it: regulatory attention "lies in the stages 3–5 of the waste hierarchy (recycling, recovery, disposal)," so "regulations and market structures are incentivising the building industry towards recycling, rather than reuse." The 2024 CPR opens a door — used products can be covered by future harmonised specifications, and on-site reuse without re-placing on the market falls outside the regulation — but no dedicated specification for reused precast concrete yet exists.

What would unlock progress

Two enablers, both within reach: (1) a statistically grounded, element-type-specific sampling and testing protocol for reclaimed precast (how many slabs from a batch to core, hardness-test or load-test, which hazardous substances to screen, how to document provenance) that national authorities and eventually a CEN standardisation request could adopt as the "product category of their own" the study calls for; and (2) an inverted default for waste status — "a product would become waste only if it could not be reused" — implemented through a common EU interpretation. Adjacent precedents: aircraft-part re-certification (traceability plus condition-based inspection instead of manufacturing QC), the reused-steel route where SCI P427/P440 and CEN/TS 1090-201 now define testing and declaration, and Denmark's ETA for reclaimed bricks.

Entry points for student teams

A structural-engineering team could design and pilot a sampling-and-testing protocol for one element type (e.g., hollow-core slabs from a specific 1970s system), using reliability theory to derive how many elements must be tested for a target confidence, and validate it against published ReCreate pilot data. A law/policy team could produce a comparative map of waste-status and product-approval rules for reused precast across EU member states and draft the model interpretation or standardisation-request scope the CPR now permits. A digital team could prototype the provenance-and-test record (a "reuse passport") that would travel with an element from deconstruction survey to permit. Relevant skills: structural reliability, materials testing, EU regulatory law, information systems.