{
  "sources": {
    "bati_materiaux_annees": {
      "source": "Base nationale des bâtiments (CSTB)",
      "url": "https://open-data.s3.fr-par.scw.cloud/bdnb_millesime_2026-02-a/millesime_2026-02-a_dep44/open_data_millesime_2026-02-a_dep44_csv.zip",
      "extracted_at": "2026-10-13T18:13:21.286613+00:00",
      "licence": "Licence Ouverte 2.0"
    },
    "centres_communes": {
      "source": "API Découpage administratif",
      "url": "https://geo.api.gouv.fr/communes?codeDepartement=44&fields=nom,code,centre,codesPostaux,anciensCodes&format=json&geometry=centre",
      "extracted_at": "2026-10-13T18:26:08.353698+00:00",
      "licence": "Licence Ouverte 2.0"
    },
    "reconnaissances_inondation": {
      "source": "Géorisques, catastrophes naturelles",
      "url": "https://files.georisques.fr/GASPAR/gaspar.zip",
      "extracted_at": "2026-10-13T18:22:24.866776+00:00",
      "licence": "Licence Ouverte 2.0"
    }
  },
  "date": "2026-10-13",
  "licence": "Licence Ouverte 2.0",
  "source": "https://open-data.s3.fr-par.scw.cloud/bdnb_millesime_2026-02-a/millesime_2026-02-a_dep44/open_data_millesime_2026-02-a_dep44_csv.zip",
  "perimetre": "31 communes étudiées de Loire-Atlantique ; pas une estimation de tout le département",
  "communes": [
    {
      "insee": "44003",
      "nom": "Ancenis-Saint-Géréon",
      "lat": 47.382,
      "lon": -1.1681,
      "url": "/secteur/couvreur-ancenis-saint-gereon/",
      "groupes": 5817,
      "materiaux_connus": 3661,
      "materiaux_absents": 2156,
      "materiaux": {
        "ardoise": 2791,
        "tuiles": 438,
        "zinc_aluminium": 53,
        "autre": 179,
        "mixte": 200
      },
      "taux_materiaux_pct": 62.9362,
      "avant_1997": 2739,
      "annee_1997": 37,
      "depuis_1998": 1366,
      "annees_connues": 4142,
      "annees_absentes": 1675,
      "catnat_inondation": 1
    },
    {
      "insee": "44009",
      "nom": "Basse-Goulaine",
      "lat": 47.2134,
      "lon": -1.4628,
      "url": "/secteur/couvreur-basse-goulaine/",
      "groupes": 4817,
      "materiaux_connus": 3262,
      "materiaux_absents": 1555,
      "materiaux": {
        "ardoise": 61,
        "tuiles": 3041,
        "zinc_aluminium": 8,
        "autre": 36,
        "mixte": 116
      },
      "taux_materiaux_pct": 67.7185,
      "avant_1997": 2090,
      "annee_1997": 91,
      "depuis_1998": 1250,
      "annees_connues": 3431,
      "annees_absentes": 1386,
      "catnat_inondation": 2
    },
    {
      "insee": "44015",
      "nom": "Blain",
      "lat": 47.4562,
      "lon": -1.7817,
      "url": "/secteur/couvreur-blain/",
      "groupes": 6840,
      "materiaux_connus": 3928,
      "materiaux_absents": 2912,
      "materiaux": {
        "ardoise": 3371,
        "tuiles": 114,
        "zinc_aluminium": 41,
        "autre": 255,
        "mixte": 147
      },
      "taux_materiaux_pct": 57.4269,
      "avant_1997": 2687,
      "annee_1997": 30,
      "depuis_1998": 1513,
      "annees_connues": 4230,
      "annees_absentes": 2610,
      "catnat_inondation": 4
    },
    {
      "insee": "44018",
      "nom": "Bouaye",
      "lat": 47.1478,
      "lon": -1.6687,
      "url": "/secteur/couvreur-bouaye/",
      "groupes": 4267,
      "materiaux_connus": 2653,
      "materiaux_absents": 1614,
      "materiaux": {
        "ardoise": 47,
        "tuiles": 2362,
        "zinc_aluminium": 37,
        "autre": 98,
        "mixte": 109
      },
      "taux_materiaux_pct": 62.1748,
      "avant_1997": 1633,
      "annee_1997": 26,
      "depuis_1998": 1226,
      "annees_connues": 2885,
      "annees_absentes": 1382,
      "catnat_inondation": 1
    },
    {
      "insee": "44020",
      "nom": "Bouguenais",
      "lat": 47.171,
      "lon": -1.6181,
      "url": "/secteur/couvreur-bouguenais/",
      "groupes": 9808,
      "materiaux_connus": 6003,
      "materiaux_absents": 3805,
      "materiaux": {
        "ardoise": 222,
        "tuiles": 5094,
        "zinc_aluminium": 134,
        "autre": 336,
        "mixte": 217
      },
      "taux_materiaux_pct": 61.2051,
      "avant_1997": 4617,
      "annee_1997": 41,
      "depuis_1998": 1872,
      "annees_connues": 6530,
      "annees_absentes": 3278,
      "catnat_inondation": 1
    },
    {
      "insee": "44026",
      "nom": "Carquefou",
      "lat": 47.2968,
      "lon": -1.4687,
      "url": "/secteur/couvreur-carquefou/",
      "groupes": 8690,
      "materiaux_connus": 5833,
      "materiaux_absents": 2857,
      "materiaux": {
        "ardoise": 4413,
        "tuiles": 656,
        "zinc_aluminium": 151,
        "autre": 409,
        "mixte": 204
      },
      "taux_materiaux_pct": 67.1231,
      "avant_1997": 4033,
      "annee_1997": 98,
      "depuis_1998": 2220,
      "annees_connues": 6351,
      "annees_absentes": 2339,
      "catnat_inondation": 3
    },
    {
      "insee": "44043",
      "nom": "Clisson",
      "lat": 47.0936,
      "lon": -1.2654,
      "url": "/secteur/couvreur-clisson/",
      "groupes": 4428,
      "materiaux_connus": 2715,
      "materiaux_absents": 1713,
      "materiaux": {
        "ardoise": 67,
        "tuiles": 2470,
        "zinc_aluminium": 10,
        "autre": 55,
        "mixte": 113
      },
      "taux_materiaux_pct": 61.3144,
      "avant_1997": 1977,
      "annee_1997": 47,
      "depuis_1998": 1056,
      "annees_connues": 3080,
      "annees_absentes": 1348,
      "catnat_inondation": 2
    },
    {
      "insee": "44047",
      "nom": "Couëron",
      "lat": 47.2391,
      "lon": -1.7472,
      "url": "/secteur/couvreur-coueron/",
      "groupes": 11189,
      "materiaux_connus": 7268,
      "materiaux_absents": 3921,
      "materiaux": {
        "ardoise": 3733,
        "tuiles": 2314,
        "zinc_aluminium": 226,
        "autre": 638,
        "mixte": 357
      },
      "taux_materiaux_pct": 64.9567,
      "avant_1997": 5511,
      "annee_1997": 79,
      "depuis_1998": 2164,
      "annees_connues": 7754,
      "annees_absentes": 3435,
      "catnat_inondation": 3
    },
    {
      "insee": "44071",
      "nom": "Haute-Goulaine",
      "lat": 47.1951,
      "lon": -1.4097,
      "url": "/secteur/couvreur-haute-goulaine/",
      "groupes": 3814,
      "materiaux_connus": 2234,
      "materiaux_absents": 1580,
      "materiaux": {
        "ardoise": 45,
        "tuiles": 1998,
        "zinc_aluminium": 21,
        "autre": 99,
        "mixte": 71
      },
      "taux_materiaux_pct": 58.5737,
      "avant_1997": 1492,
      "annee_1997": 68,
      "depuis_1998": 891,
      "annees_connues": 2451,
      "annees_absentes": 1363,
      "catnat_inondation": 2
    },
    {
      "insee": "44074",
      "nom": "Indre",
      "lat": 47.1993,
      "lon": -1.6701,
      "url": "/secteur/couvreur-indre/",
      "groupes": 2018,
      "materiaux_connus": 1239,
      "materiaux_absents": 779,
      "materiaux": {
        "ardoise": 492,
        "tuiles": 592,
        "zinc_aluminium": 12,
        "autre": 73,
        "mixte": 70
      },
      "taux_materiaux_pct": 61.3974,
      "avant_1997": 1172,
      "annee_1997": 6,
      "depuis_1998": 181,
      "annees_connues": 1359,
      "annees_absentes": 659,
      "catnat_inondation": 0
    },
    {
      "insee": "44035",
      "nom": "La Chapelle-sur-Erdre",
      "lat": 47.3041,
      "lon": -1.5621,
      "url": "/secteur/couvreur-la-chapelle-sur-erdre/",
      "groupes": 8956,
      "materiaux_connus": 6173,
      "materiaux_absents": 2783,
      "materiaux": {
        "ardoise": 4811,
        "tuiles": 229,
        "zinc_aluminium": 95,
        "autre": 704,
        "mixte": 334
      },
      "taux_materiaux_pct": 68.9259,
      "avant_1997": 4698,
      "annee_1997": 80,
      "depuis_1998": 1769,
      "annees_connues": 6547,
      "annees_absentes": 2409,
      "catnat_inondation": 4
    },
    {
      "insee": "44101",
      "nom": "La Montagne",
      "lat": 47.1858,
      "lon": -1.6826,
      "url": "/secteur/couvreur-la-montagne/",
      "groupes": 3765,
      "materiaux_connus": 2181,
      "materiaux_absents": 1584,
      "materiaux": {
        "ardoise": 391,
        "tuiles": 1598,
        "zinc_aluminium": 9,
        "autre": 56,
        "mixte": 127
      },
      "taux_materiaux_pct": 57.9283,
      "avant_1997": 1986,
      "annee_1997": 6,
      "depuis_1998": 360,
      "annees_connues": 2352,
      "annees_absentes": 1413,
      "catnat_inondation": 0
    },
    {
      "insee": "44084",
      "nom": "Le Loroux-Bottereau",
      "lat": 47.2325,
      "lon": -1.3272,
      "url": "/secteur/couvreur-le-loroux-bottereau/",
      "groupes": 4802,
      "materiaux_connus": 2814,
      "materiaux_absents": 1988,
      "materiaux": {
        "ardoise": 80,
        "tuiles": 2548,
        "zinc_aluminium": 16,
        "autre": 58,
        "mixte": 112
      },
      "taux_materiaux_pct": 58.6006,
      "avant_1997": 1616,
      "annee_1997": 28,
      "depuis_1998": 1409,
      "annees_connues": 3053,
      "annees_absentes": 1749,
      "catnat_inondation": 0
    },
    {
      "insee": "44120",
      "nom": "Le Pellerin",
      "lat": 47.2341,
      "lon": -1.8377,
      "url": "/secteur/couvreur-le-pellerin/",
      "groupes": 3146,
      "materiaux_connus": 1863,
      "materiaux_absents": 1283,
      "materiaux": {
        "ardoise": 218,
        "tuiles": 1410,
        "zinc_aluminium": 16,
        "autre": 105,
        "mixte": 114
      },
      "taux_materiaux_pct": 59.2181,
      "avant_1997": 1364,
      "annee_1997": 21,
      "depuis_1998": 642,
      "annees_connues": 2027,
      "annees_absentes": 1119,
      "catnat_inondation": 2
    },
    {
      "insee": "44198",
      "nom": "Les Sorinières",
      "lat": 47.142,
      "lon": -1.5195,
      "url": "/secteur/couvreur-les-sorinieres/",
      "groupes": 4712,
      "materiaux_connus": 2912,
      "materiaux_absents": 1800,
      "materiaux": {
        "ardoise": 70,
        "tuiles": 2543,
        "zinc_aluminium": 54,
        "autre": 153,
        "mixte": 92
      },
      "taux_materiaux_pct": 61.7997,
      "avant_1997": 1818,
      "annee_1997": 48,
      "depuis_1998": 1330,
      "annees_connues": 3196,
      "annees_absentes": 1516,
      "catnat_inondation": 1
    },
    {
      "insee": "44087",
      "nom": "Machecoul-Saint-Même",
      "lat": 47.0057,
      "lon": -1.8063,
      "url": "/secteur/couvreur-machecoul-saint-meme/",
      "groupes": 5933,
      "materiaux_connus": 3236,
      "materiaux_absents": 2697,
      "materiaux": {
        "ardoise": 123,
        "tuiles": 2870,
        "zinc_aluminium": 5,
        "autre": 105,
        "mixte": 133
      },
      "taux_materiaux_pct": 54.5424,
      "avant_1997": 2341,
      "annee_1997": 32,
      "depuis_1998": 1212,
      "annees_connues": 3585,
      "annees_absentes": 2348,
      "catnat_inondation": 3
    },
    {
      "insee": "44109",
      "nom": "Nantes",
      "lat": 47.2382,
      "lon": -1.5603,
      "url": "/",
      "groupes": 57330,
      "materiaux_connus": 36992,
      "materiaux_absents": 20338,
      "materiaux": {
        "ardoise": 19994,
        "tuiles": 10527,
        "zinc_aluminium": 766,
        "autre": 2841,
        "mixte": 2864
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      "taux_materiaux_pct": 64.5247,
      "avant_1997": 35030,
      "annee_1997": 337,
      "depuis_1998": 6319,
      "annees_connues": 41686,
      "annees_absentes": 15644,
      "catnat_inondation": 6
    },
    {
      "insee": "44110",
      "nom": "Nort-sur-Erdre",
      "lat": 47.4454,
      "lon": -1.5239,
      "url": "/secteur/couvreur-nort-sur-erdre/",
      "groupes": 5943,
      "materiaux_connus": 3442,
      "materiaux_absents": 2501,
      "materiaux": {
        "ardoise": 2964,
        "tuiles": 104,
        "zinc_aluminium": 33,
        "autre": 217,
        "mixte": 124
      },
      "taux_materiaux_pct": 57.9169,
      "avant_1997": 2167,
      "annee_1997": 25,
      "depuis_1998": 1495,
      "annees_connues": 3687,
      "annees_absentes": 2256,
      "catnat_inondation": 2
    },
    {
      "insee": "44114",
      "nom": "Orvault",
      "lat": 47.2745,
      "lon": -1.6195,
      "url": "/secteur/couvreur-orvault/",
      "groupes": 9933,
      "materiaux_connus": 7206,
      "materiaux_absents": 2727,
      "materiaux": {
        "ardoise": 4387,
        "tuiles": 1661,
        "zinc_aluminium": 174,
        "autre": 616,
        "mixte": 368
      },
      "taux_materiaux_pct": 72.5461,
      "avant_1997": 5934,
      "annee_1997": 70,
      "depuis_1998": 1675,
      "annees_connues": 7679,
      "annees_absentes": 2254,
      "catnat_inondation": 4
    },
    {
      "insee": "44143",
      "nom": "Rezé",
      "lat": 47.1733,
      "lon": -1.5573,
      "url": "/secteur/couvreur-reze/",
      "groupes": 16141,
      "materiaux_connus": 9885,
      "materiaux_absents": 6256,
      "materiaux": {
        "ardoise": 1107,
        "tuiles": 7455,
        "zinc_aluminium": 141,
        "autre": 620,
        "mixte": 562
      },
      "taux_materiaux_pct": 61.2416,
      "avant_1997": 8538,
      "annee_1997": 89,
      "depuis_1998": 2206,
      "annees_connues": 10833,
      "annees_absentes": 5308,
      "catnat_inondation": 0
    },
    {
      "insee": "44162",
      "nom": "Saint-Herblain",
      "lat": 47.2246,
      "lon": -1.6306,
      "url": "/secteur/couvreur-saint-herblain/",
      "groupes": 12006,
      "materiaux_connus": 7827,
      "materiaux_absents": 4179,
      "materiaux": {
        "ardoise": 4616,
        "tuiles": 1990,
        "zinc_aluminium": 138,
        "autre": 760,
        "mixte": 323
      },
      "taux_materiaux_pct": 65.1924,
      "avant_1997": 6832,
      "annee_1997": 87,
      "depuis_1998": 1873,
      "annees_connues": 8792,
      "annees_absentes": 3214,
      "catnat_inondation": 1
    },
    {
      "insee": "44166",
      "nom": "Saint-Jean-de-Boiseau",
      "lat": 47.1919,
      "lon": -1.7198,
      "url": "/diagnostic-toiture/?commune=44166",
      "groupes": 3307,
      "materiaux_connus": 2124,
      "materiaux_absents": 1183,
      "materiaux": {
        "ardoise": 66,
        "tuiles": 1843,
        "zinc_aluminium": 18,
        "autre": 75,
        "mixte": 122
      },
      "taux_materiaux_pct": 64.2274,
      "avant_1997": 1528,
      "annee_1997": 18,
      "depuis_1998": 711,
      "annees_connues": 2257,
      "annees_absentes": 1050,
      "catnat_inondation": 1
    },
    {
      "insee": "44188",
      "nom": "Saint-Philbert-de-Grand-Lieu",
      "lat": 47.0689,
      "lon": -1.6443,
      "url": "/secteur/couvreur-saint-philbert-de-grand-lieu/",
      "groupes": 6126,
      "materiaux_connus": 3538,
      "materiaux_absents": 2588,
      "materiaux": {
        "ardoise": 90,
        "tuiles": 3174,
        "zinc_aluminium": 9,
        "autre": 98,
        "mixte": 167
      },
      "taux_materiaux_pct": 57.7538,
      "avant_1997": 1986,
      "annee_1997": 43,
      "depuis_1998": 1731,
      "annees_connues": 3760,
      "annees_absentes": 2366,
      "catnat_inondation": 1
    },
    {
      "insee": "44190",
      "nom": "Saint-Sébastien-sur-Loire",
      "lat": 47.2065,
      "lon": -1.5023,
      "url": "/secteur/couvreur-saint-sebastien-sur-loire/",
      "groupes": 11928,
      "materiaux_connus": 7540,
      "materiaux_absents": 4388,
      "materiaux": {
        "ardoise": 435,
        "tuiles": 6219,
        "zinc_aluminium": 61,
        "autre": 379,
        "mixte": 446
      },
      "taux_materiaux_pct": 63.2126,
      "avant_1997": 6819,
      "annee_1997": 65,
      "depuis_1998": 1156,
      "annees_connues": 8040,
      "annees_absentes": 3888,
      "catnat_inondation": 2
    },
    {
      "insee": "44172",
      "nom": "Sainte-Luce-sur-Loire",
      "lat": 47.2529,
      "lon": -1.4704,
      "url": "/secteur/couvreur-sainte-luce-sur-loire/",
      "groupes": 6019,
      "materiaux_connus": 4320,
      "materiaux_absents": 1699,
      "materiaux": {
        "ardoise": 3185,
        "tuiles": 521,
        "zinc_aluminium": 81,
        "autre": 378,
        "mixte": 155
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      "taux_materiaux_pct": 71.7727,
      "avant_1997": 2892,
      "annee_1997": 112,
      "depuis_1998": 1622,
      "annees_connues": 4626,
      "annees_absentes": 1393,
      "catnat_inondation": 1
    },
    {
      "insee": "44194",
      "nom": "Sautron",
      "lat": 47.275,
      "lon": -1.6839,
      "url": "/secteur/couvreur-sautron/",
      "groupes": 3938,
      "materiaux_connus": 2777,
      "materiaux_absents": 1161,
      "materiaux": {
        "ardoise": 2353,
        "tuiles": 112,
        "zinc_aluminium": 60,
        "autre": 149,
        "mixte": 103
      },
      "taux_materiaux_pct": 70.518,
      "avant_1997": 2104,
      "annee_1997": 34,
      "depuis_1998": 806,
      "annees_connues": 2944,
      "annees_absentes": 994,
      "catnat_inondation": 2
    },
    {
      "insee": "44195",
      "nom": "Savenay",
      "lat": 47.3542,
      "lon": -1.9203,
      "url": "/secteur/couvreur-savenay/",
      "groupes": 4376,
      "materiaux_connus": 2820,
      "materiaux_absents": 1556,
      "materiaux": {
        "ardoise": 2349,
        "tuiles": 129,
        "zinc_aluminium": 53,
        "autre": 227,
        "mixte": 62
      },
      "taux_materiaux_pct": 64.4424,
      "avant_1997": 1739,
      "annee_1997": 23,
      "depuis_1998": 1393,
      "annees_connues": 3155,
      "annees_absentes": 1221,
      "catnat_inondation": 2
    },
    {
      "insee": "44204",
      "nom": "Thouaré-sur-Loire",
      "lat": 47.2755,
      "lon": -1.4294,
      "url": "/secteur/couvreur-thouare-sur-loire/",
      "groupes": 4480,
      "materiaux_connus": 3092,
      "materiaux_absents": 1388,
      "materiaux": {
        "ardoise": 2196,
        "tuiles": 480,
        "zinc_aluminium": 55,
        "autre": 244,
        "mixte": 117
      },
      "taux_materiaux_pct": 69.0179,
      "avant_1997": 2025,
      "annee_1997": 31,
      "depuis_1998": 1238,
      "annees_connues": 3294,
      "annees_absentes": 1186,
      "catnat_inondation": 3
    },
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      "insee": "44209",
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