Constructability Review

Overview

Review a construction documents package against eight constructability axes — trade sequencing, tolerance stack, MEP coordination, install access & rigging, lay-down & site logistics, temporary works, materials procurement & lead times, and phased operations — and produce a written review that lives in docs/constructability/.

This is the CM-side / owner's-rep / preconstruction perspective. It catches the "looks fine on paper but cannot be built without rework" failures during DD or 50% CD, when redesign is still cheap. Aligned with NA practice: AGC of America constructability review checklists, CMAA preconstruction services scope, AIA Document G701 (Change Order) economics on what should-have-been-caught issues cost when caught later, and ASHRAE / ANSI / SMACNA installation tolerance standards.

When to use

Trigger on:

• Pasted CD set details, plan/section excerpts, RCP/MEP overlays, or schedule-and-logistics narratives with a constructability question.
• Project file paths to a CD set the user wants reviewed.
• Explicit asks: "constructability review", "can this be built", "sequencing check", "install access for the AHU", "MEP coordination clearance", "lay-down on this site".
• Hand-off from bid-review when low bidder flagged a constructability concern in their qualifications.

Do NOT trigger for:

• Pure code/egress compliance (use code-review).
• Drawing-set completeness audit (use drawing-checklist).
• Submittal review during CA (use submittal-review).
• General design critique (use design-critic).
• Cost estimating (this skill flags constructability-driven cost risk; it does not produce independent estimates).

Workflow

Step 1 — Bootstrap if needed

Check that docs/constructability/index.md exists. If not:

python scripts/init_constructability_workspace.py

Step 2 — Anchor the project context

Constructability findings are project-specific. Pin context before applying axes.

• Read docs/project.md if it exists for delivery method (DBB, CMAR, DB, IPD), construction type (Type I-V per IBC §602), structural system (steel, CIP concrete, mass timber, hybrid), envelope system (curtain wall, panelized, brick veneer), site constraints (urban-infill, owner-occupied, weather-restricted), and CD phase (DD, 50% CD, 100% CD, GMP set).
• Identify the dominant constructability risk category for the project: occupied-building renovation, urban high-rise lay-down constraint, mass-timber procurement, expedited fast-track, etc. The dominant risk drives axis weighting.
• Pull lead-time benchmarks from references/long_lead_items_2026.md for current procurement realities (electrical switchgear, AHUs, custom glazing, elevators, structural steel deck).

Step 3 — Apply eight-axis review

Load references/constructability_axes.md for the full framework with sub-criteria. Quick reference:

1. Trade sequencing & critical path — Is the implied sequence physically possible? Out-of-sequence work, predecessors blocked by later trades, unrealistic concurrent work in the same volume?
2. Tolerance stack-up — Cumulative tolerance from structure to finish exceeds the detail's accommodation? Steel ±¼" + deck ±½" + topping ±⅛" + acoustic substrate ±⅛" can defeat a 1/8" reveal at the wall-to-floor joint.
3. MEP coordination & rack space — Above-ceiling clear height accommodates duct + sprinkler + cable tray + lighting in real (not BIM-clashed-but-resolved) coordination? Riser stack alignment story-to-story? Shaft enclosure penetrations within rated-assembly limits?
4. Install access & rigging — Crane / boom-truck reach for steel and pre-cast erection? Hoisting paths through future façade openings? Equipment-room dimensions for AHU / chiller / switchgear installation and future replacement (the "removal route" question)?
5. Lay-down & site logistics — Material storage area on a constrained urban site? Truck deliveries through restricted streets? Crane swing radius respects neighbor airspace? Pedestrian protection per IBC §3306, OSHA 1926 Subpart M, and local DOB / DSA requirements?
6. Temporary works — Shoring for excavation? Dewatering capacity vs. groundwater rate? Weather enclosure for winter concrete or interior finishes? Life-safety path during construction (egress paths, sprinkler activation, fire watch)?
7. Materials procurement & lead times — Long-lead items (electrical switchgear 40-60 weeks 2026, AHU 30-50 weeks, custom curtain wall 24-40 weeks) ordered with lead-time buffer? Decisions for those items frozen at the schedule date that procurement requires?
8. Phased operations & owner occupancy — If the building is occupied during construction (renovation, expansion, school during summer break), are temporary-condition floor plans coordinated with infection-control risk assessments (ICRA in healthcare), means of egress, mechanical of patient/student transitions (MOP), neighbor noise/vibration limits, and security boundaries?

Focus on the 3-5 axes with real signal for the project. An urban high-rise reads heavily on 4, 5, 6. A healthcare renovation reads heavily on 1, 7, 8. A suburban greenfield reads heavily on 2, 3, 7.

Step 4 — Write the review

Read assets/constructability-template.md, fill placeholders. Filename:

docs/constructability/<YYYY-MM-DD>-<slug>.md

Slug rule: lowercase, [^a-z0-9-] removed, max 40 chars, derived from project + CD phase or dominant risk (acme-hq-50pct, harbor-school-occupied-phasing). If a review with the same date+slug already exists, suffix -<n>.

Step 5 — Update the constructability index

python scripts/append_to_index.py \
  --date 2026-05-09 \
  --slug acme-hq-50pct \
  --cd-phase "50%" \
  --primary-axes "sequencing,mep-coordination,install-access" \
  --severity-high 3

The script appends a row to docs/constructability/index.md. Do NOT edit the index manually with the Edit tool.

Step 6 — Report

Tell the user:

• Path to the review file.
• The 2-3 highest-severity findings (each with a recommended design move and an estimated change-order avoidance value when caught now vs at CA).
• Any long-lead items where the procurement decision is already late.
• Whether a follow-up submittal-review checklist should pre-load for the long-lead items called out.

Rules

• Every finding cites a specific drawing detail or sheet, plus the assembly tolerance / clearance / lead-time number being violated. "MEP coordination is tight" is not a finding; "AHU-3 corridor clear height of 8'-2" leaves 6" above 24" round duct + 8" lighting, no sprinkler reserve" is a finding.
• Severity tag each finding: High (will cause a change order or schedule slip if not addressed before CD), Medium (likely to surface as RFI in CA), Low (worth noting; resolvable without redesign).
• Lead-time claims cite a date source (RSMeans 2026 Q2, manufacturer's published lead time, prior project benchmark). Lead times have moved a lot since 2020; do not use pre-2023 numbers.
• Tolerance findings cite the contributing assemblies' tolerances and where they are sourced (AISC 303 for steel, ACI 117 for concrete, SMACNA for sheet metal, glazing manufacturer's installation guide).
• Phased-occupancy findings always reference the AHJ rule that drives the constraint (NYC DOB occupied-building protocols, CA HCAI for healthcare, school-district summer-only windows, GSA tenant-occupied protocols).
• Refuse to assert "this can't be built." If a detail is hard, the finding is "this drives the schedule / cost / coordination as follows" — constructors find a way; the review's job is to surface the cost.

Anti-patterns

• Reviewing every axis when only 3-4 carry the project's risk. Pick the dominant risk axis first and weight others against it.
• Generic findings ("coordinate MEP", "tight tolerance") without the specific detail / dimension / lead-time number. Useless to the design team.
• Treating BIM clash detection as constructability review. Clash detection is necessary, not sufficient — clearance for installation tools (the wrench arc, the crane hook, the lift table) is a separate analysis.
• Ignoring the temporary condition. Many projects have life-safety and egress that are compliant in the final state but non-compliant in mid-construction; that gap is a real risk.
• Out-of-date lead times. Switchgear at 12 weeks (2019 reality) vs 40-60 weeks (2026 reality) is the kind of error that derails a schedule.
• Editing index.md manually instead of using append_to_index.py.

Resources

• scripts/init_constructability_workspace.py — bootstrap docs/constructability/ and the constructability index
• scripts/append_to_index.py — append a row to docs/constructability/index.md
• references/constructability_axes.md — eight-axis framework with sub-criteria, NA tolerance / clearance / lead-time benchmarks, common failure modes, example findings
• references/long_lead_items_2026.md — current (2026 Q2) lead-time table for switchgear, AHUs, chillers, custom curtain wall, structural steel, mass timber, elevators, with sourcing notes
• assets/constructability-template.md — review markdown template with severity-tagged findings block