True-Cost Index · Charleston Tri-County
One number for cost-of-ownership pressure over 10 years.
Composite 0-100 score blending FEMA flood zone + 2027 NFIP re-rating + SC's 5-year reassessment cycle + post-2022 carrier exits + utility rate-case trajectory + lowcountry foundation risk + HOA escalation. Higher = more cost pressure. Quote it on every showing — “asking price is $X, true-cost is Y” — and clients start using the number themselves.
Properties scored
0
avg 0.0 · median 0.0
High pressure
0
composite ≥ 70
Moderate
0
40-69
Low pressure
0
< 40 · safer 10-yr cost
Top-driver
—
market-wide
Hottest zips · ranked by avg True-Cost
concentrate broker triage — these are the zips where every showing needs the disclaimer
| Zip | County | Properties | Avg True-Cost | High pressure | Most-cited driver |
|---|---|---|---|---|---|
| No zip-level rollup yet — score table needs ≥2 properties per zip. | |||||
Highest True-Cost · the “buyer-beware” list
hand a buyer this row at the showing — they'll thank you in 5 years
| Address | Zip | Last sale | Top driver | 10-yr lift | True-Cost |
|---|---|---|---|---|---|
No True-Cost scores yet. Run worker:python -m worker.processing.true_cost | |||||
Lowest True-Cost · “buy-with-confidence” list
flip the script — these are the addresses to actively recommend
| Address | Zip | Last sale | Driver | True-Cost |
|---|
Methodology · Charleston Tri-County recipe
Seven sub-scores, each independently 0-100, weighted into a single composite. The recipe is calibrated to specific Charleston levers — which is why it's not just a re- rendered FEMA map.
- flood_risk · 30% — FEMA zone (VE / AE / AO / X) + 2027 NFIP rerating uplift for properties within 12 months of the deadline.
- insurance_volatility · 25% — zip-level YoY claim delta + count of paused/exited carriers (post-2022 SC market).
- tax_trajectory · 15% — YoY assessment growth + jump_alert (≥25% YoY = imminent reassessment shock).
- reassessment_proximity · 5% — SC Code §12-37-3140 5-year cycle anchored to last sale; properties within 18mo of next reappraisal score high.
- utility_pressure · 10% — Dominion (Charleston Co.) > Santee Cooper / co-op (Berkeley/Dorchester) per recent SC PSC rate-case dockets.
- foundation_repair · 10% — waterfront flag + flood zone + year-built (pre-1990 lowcountry homes).
- hoa_creep · 5% — master-planned + new-construction neighborhoods (Daniel Island, Carnes Crossroads, Nexton, Cane Bay, etc.).
Recipe + weights live in apps/worker/processing/true_cost.py. What the score deliberately excludes: school-district scores, demographic data, neighborhood-quality subjective metrics — kept ECOA-clean.