Risk Register

Ranked by Likelihood × Impact. Pin numbers correspond to the risk heatmap.

Risk heatmap — likelihood × impact, top-right is worst.

Top 5 risks to act on now (revised after Round 2 builder rebuttals)

R1 Budget gap reduced. PEMB-efficient at $1.87M is $120K over $1.75M, fully closeable. Conservative at $2.23M. Get 2–3 line-item GC bids.
R2 Island vent — Korean BBQ engineering. Cost basis corrected ($25–40K vs $50–100K). Build a mockup ($1–3K) before ceiling closes.
R12 ERV/balanced ventilation — must be sized for boost mode (1,000–1,500 CFM) since now doing double duty for kitchen MUA. See LDD-05.
Floor 2 + ballet/rebound walls deserve their own LDDs — implicit in drawings + rebuttals; document formally.
R10 spine threshold formwork — specify 2–4mm step-down on gym side at formwork stage.

Full register

Pin	Risk	L	I	Mitigation
R1	Budget overrun above $1.75M	High	High	Decide: grow budget, cut scope, or phase. See budget.
R2	Island vent under-performs at Korean BBQ load	Med	High	Hood specialist + mockup before slab pour.
R3	Lift mechanical failure	Very Low ↓	Low ↓	Reclassified: material lift (Asgard Press inventory), not passenger. Failure = inventory stays on ground for a day. No life-safety, no building egress impact.
R4	Site prep cost blowout	Low ↓	Med ↓	Downgraded: site plan confirms FFE 252.4 / pier foundation / above floodplain (study line 246) / sewer lateral identified / FEMA floodway is east-downhill off footprint.
R5	Gypcrete cost + drying delays schedule	Med	Med	Lock gypcrete vs dry-panel early; bake drying into Gantt.
R6	Trade coordination fails on exposed ceiling	Med	Med	Coordinated RCP before rough-in; weekly photo verification.
R7	Spine wall acoustic separation underperforms	Med	Low	Spec STC target; accept 18' glass door as limit.
R8	Make-up air → backdrafting	Closed ↓	None	Closed: all-electric building has no atmospheric combustion to backdraft. ERV boost-mode interlock replaces dedicated tempered MUA. See LDD-05.
R9	Manifold accessibility lost in construction	Low	Med	Photograph + label all manifolds before drywall.
R10	Spine threshold flush mandate violated at slab pour	Low ↓	Med	Softened: specify 2–4mm step-down at formwork stage on gym side. Cleaner solution than retrofit overlay; standard practice.
R11	LVP slab temp exceeds 85°F → warranty void	Low ↓	Med	Softened: tight IMP envelope + 30kW PV thermal-battery + low-temp curve = slab unlikely to approach 85°F. Confirm in writing with LVP manufacturer.
R12	Missing ERV/balanced ventilation in tight envelope	High	Low–Med	Add ERV LDD entry now.
R13	Mech room undersized (70 sqft)	Med	Med	Bump to ≥90 sqft.
R14	West gym solar gain exceeds cooling capacity	Med	Med	Manual J + exterior shades or selective Low-E.
R15	South bay dimensions don't close at 60'	High	Low	Reconcile W→E widths before structural drawings.
R16	Korean BBQ classified as Type I commercial	Closed ↓	N/A	Closed Round 3: per builder pushback — UL-listed residential induction + removable cast-iron plate is mechanically + electrically identical to teppanyaki plate. Type I applies to open-flame gas commercial ranges, charbroilers, restaurant continuous-duty cooking — none describe R-3 residence. Permit-submission language ("residential UL-listed induction with removable accessory plates") is sufficient.
R17	Lightning protection / grounding not specified	Low	Med	Add LDD entry; coordinate with envelope.
R18	HPWH in 70 sqft mech room loses efficiency	Med	Low	Vent ducts or different water heater type.
R19	Construction sequencing not Gantt-documented	Med	Med	GC builds Gantt before mobilization.
R20	No acoustic treatment in gym	High	Low	Acoustic baffles in ceiling hierarchy now.
R21	~~Pier foundation × radiant assembly mismatch~~	Withdrawn ↓	N/A	Withdrawn 2026-05-15 PM: PEMB "piers" = column footings, not wood-subfloor-on-piers. Slab-on-grade with integrated radiant remains the assembly. No cascade.