Structural bay depth discipline
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docs(building-design): add 6 new TOPICs from redaction-reviewed design-collaboration source (4:1 parking ratio, design sequence priority, Common Building Code, water management system, tile-level climate zoning, structural bay depth discipline), plus Sub-Prototype and Campus Design BIM-massing supplements
@@ -0,0 +1,41 @@ --- schema: foundry-doc-v1 title: "Structural bay depth discipline" slug: structural-bay-depth-discipline category: building-design type: topic content_type: topic quality: pre-build status: active audience: customer-woodfine bcsc_class: current-fact language_protocol: PROSE-TOPIC last_edited: 2026-08-24 editor: pointsav-engineering short_description: "A structural-grid discipline requiring leasehold bay depth to be set by tenant space requirements rather than the cheapest available beam span, since unleasable depth from an oversized bay is never recoverable over the life of a lease." paired_with: building-design/structural-bay-depth-discipline.es.md --- Woodfine sets leasehold bay depth from tenant space requirements, not from the maximum span a beam can economically cover. Letting the cheapest available beam span set bay depth is, in Woodfine's own assessment, a design decision severe enough to threaten the asset's performance. Depth a tenant does not need and will not pay for cannot be recovered once the building is built and leased. ## What it replaces The discipline replaces sizing leaseholds to whatever depth the most economical beam happens to produce. That approach reads as a construction saving at the time the beam is chosen. But the saving is realized at the wrong stage of the asset's life: many commercial developers have built bays too deep for what their tenants' business models actually require, believing a cheaper structural system left them ahead. It does not. Certain tenant formats — the frontage-driven retail and quick-service formats that know precisely the depth their layout requires are the clearest case — will lease only the footprint that matches their business model and no more. The landlord absorbs whatever additional bay depth the structural grid produced. That absorbed depth is unleasable for the life of the lease; it cannot be recaptured mid-term, and small per-square-foot inefficiencies of this kind compound over a lease term of a decade or more into a material effect on the building's capitalized value. ## Depth follows Key Plans and Tiles, not the reverse Woodfine's own design experience across multiple buildings and jurisdictions using the same [[fixed-floor-plates|Fixed Floor Plate]] for the Building Core reinforced the same conclusion. Beam sizing should be set from the [[key-plans-and-tiles|Key Plans and Tiles]] and the resulting variance in office floor counts, not the other way around. Letting available beam spans dictate Floor Plate sizing across a multi-building rollout is the more damaging version of the same mistake, since it repeats a single bad depth decision across every subsequent deployment of the prototype rather than confining it to one building. ## Column-free is a leasehold property, not a Floor Plate property The discipline also reframes what "column-free" should mean. Woodfine treats a leasehold as column-free when its structural columns line up with the demising boundaries the [[key-plans-and-tiles|Key Plans and Tiles]] already define — not when the Floor Plate as a whole has the fewest possible columns. Minimizing columns across the whole Floor Plate is worth pursuing only where it does not compromise the ability to expand or contract a prototype's floor count. It is also worth pursuing only where the building's façade design is kept free of structural dependency, so it can still be changed later. Where those two goals conflict, getting the demising right at the leasehold level takes priority over a column-free Floor Plate. ## Consequence for underwriting and asset value Rent and capitalization rate are directly linked in determining what a building is worth at sale. Bay-depth slippage is not a cosmetic design flaw for that reason — it is a recurring drag on realized rent per leasable square foot that shows up at the point of a future sale, not at the point the beam was chosen. Setting bay depth from tenant requirements before construction is committed is the only stage at which this loss is avoidable; it cannot be engineered away afterward. ## See also - [[key-plans-and-tiles]] — the leasehold geometry bay depth must be set from - [[fixed-floor-plates]] — the floor plate discipline this principle protects - [[design-sequence-priority]] — why Structural is sequenced after the Leasing Plan