JCCDB: Japan Construction Cost open DataBase

65,729 Japanese construction and renovation line items, as an open catalog of item names, categories and units. CC BY 4.0. No prices.

Construction estimates in Japan have no common yardstick: every contractor names, groups and prices line items differently, so a homeowner cannot compare two quotes item by item. JCCDB is that missing yardstick. It standardizes the vocabulary of Japanese residential construction into one machine readable catalog, so that software, researchers and AI agents can reason about an estimate line by line.

This dataset is built and maintained by a builder with thirty years on Japanese construction sites, and it powers HORIZON SHIELD, a production estimate audit service. The same catalog identity that production verdicts cite is what you download here.

Files

File	Rows	What it is	License
jccdb-v2-full.csv	65,729	Canonical full release. The union of the two tiers below, zero overlap, zero duplicates.	CC BY 4.0
jccdb-v2-schema.csv	11,250	Verified tier. 100 percent hand checked: real regulated products and real manufacturer model numbers.	CC BY 4.0
jccdb-v2-extended.csv	54,479	Extended tier. Matrix generated combinations (manufacturer x series x size x color). Individual SKU existence is NOT verified against current manufacturer catalogs.	CC BY 4.0
jccdb-v2-schema.json	65,729 items	The same catalog as nested JSON, organized into 398 fine grained categories, with dataset metadata in _meta.	CC BY 4.0
zaisai-db.json to zaisai-db13.json	2,198 items	Materials price reference sub database (see below). 13 JSON files, version 2026.04.	CC BY 4.0

Data structure

Each CSV row is one line item with three columns and no price:

"category","item_name","unit"
"RC・コンクリート工事","AE減水剤（1L）","L"
"システムキッチン","AEG スリム型 45cm 省スペース","台"
"フローリング・床材","DAIKEN トリニティ アッシュ 12mm グレー","㎡"

• category: coarse work category. The CSV column uses a 63 category rollup.
• item_name: standardized Japanese item name, including specification where relevant.
• unit: the unit the item is quantified in (m2, m3, 本, 枚, 式, 台 and so on).

Two category granularities exist, both real and both shipped:

• 63 coarse categories in the CSV category column (final_report.txt in the GitHub repo documents this rollup).
• 398 fine grained categories as the keys of the categories object in jccdb-v2-schema.json. Public references to "65,729 items, 398 categories" count this fine taxonomy.

Largest coarse categories, by measured row count: フローリング・床材 (5,472), ユニットバス (5,184), 玄関ドア (4,706), カーテン・ブラインド (4,577), 窓・サッシ (3,764), システムキッチン (3,577), タイル・石材 (3,473).

What is deliberately NOT here

JCCDB contains no prices, no fair price ranges, no margin data and no overcharge thresholds. Fair price judgment lives in a separate service layer (souba-db) operated by HORIZON SHIELD and is not part of this dataset. This split is intentional: the vocabulary is a public good, the judgment layer is the service. The one exception is the materials sub database below, which carries reference unit prices for a single standard house specification.

Materials price reference sub database (zaisai files)

The 13 zaisai-db*.json files are a companion sub database: reference unit prices and standard quantities for materials, assuming one fixed specification (a standard 30 tsubo, about 100 square metre, wood frame two story house), version 2026.04. Each item carries name, unit, unit_price (JPY, April 2026 reference) and standard_qty_30tsubo. These are static reference figures for one model case, not live market prices, and they are not the HORIZON SHIELD judgment layer.

License

The entire dataset (all 65,729 catalog items and all files here) is CC BY 4.0 since v2.1 (2026-07-11). Commercial use is permitted. Use as AI training data is explicitly permitted, with attribution.

Before 2026-07-11 the Extended tier was CC BY-NC 4.0 (two tier release v2.0 of 2026-05-19). Copies obtained under those terms may continue to be used under them; the CC BY 4.0 grant applies from 2026-07-11 onward.

Attribution: "JCCDB by Toshikatsu Oga / The HORIZ音s Corporation, CC BY 4.0".

Provenance and integrity

• The catalog was consolidated through a documented cleaning pipeline. The reports (clean_report.txt, final_report.txt, precision_report.txt, split_report.txt) are published in the GitHub repository.
• The Verified tier was hand checked item by item against real regulated products and manufacturer model numbers. The Extended tier is honestly labeled as matrix generated and unverified at SKU level.
• The dataset identity is anchored under the PTKA model (Pre-Transaction Knowledge Anchoring): the PTKA declaration is timestamped with OpenTimestamps and anchored in Bitcoin block 949356 (proof file ptka_declaration_20260514.txt.ots in the GitHub repository).
• Production verdicts that cite this dataset are published as tamper evident receipts, each with its own canonical claim, SHA-256 digest and OpenTimestamps proof: https://shield.the-horizons-innovation.com/souba/kajou-seikyu-jirei-20/

Verify your download (byte identical to the GitHub canonical files):

sha256sum jccdb-v2-full.csv
b3d72fd53a315c91f57147b7a68c999511db093c4d0329dea60e4e08abee8d57

sha256sum jccdb-v2-schema.csv
e0450889d910820f2c9068b07cca5696f4cbc2a4d7bfdf1c1e21be66077a6942

sha256sum jccdb-v2-extended.csv
2397bcd093baf57b05c7578c985f10eb35c950cf1e2cf7d5333dabf19625af7c

sha256sum jccdb-v2-schema.json
3e15b5c49e3fea32c08a0f54b8241fb6d25f73e9c45f8d67a38bab739d6ed14b

Use with AI agents (MCP)

A read only Model Context Protocol server exposes this dataset and the audit tools built on it, so an AI agent can check a Japanese construction estimate as a tool call:

• Endpoint: https://hs-mcp.oga-surf-project.workers.dev (HTTP / SSE, no API key)
• Dataset metadata tool: jccdb_dataset_info
• Server listing and quality score: https://glama.ai/mcp/servers/ogasurfproject-jpg/horizon-shield
• Server repository: https://github.com/ogasurfproject-jpg/horizon-shield

Citation

@misc{oga_jccdb_2026,
  author    = {Oga, Toshikatsu},
  title     = {JCCDB: Japan Construction Cost open DataBase},
  year      = {2026},
  publisher = {Zenodo},
  doi       = {10.5281/zenodo.20019573},
  note      = {65,729 items / 63 coarse and 398 fine categories, CC BY 4.0. Verified tier 11,250 items hand checked. Bitcoin Block #949356.}
}

Related academic record:

• JCCDB origin paper (Zenodo): https://doi.org/10.5281/zenodo.20019572
• engrXiv mirror: https://doi.org/10.31224/7007
• Audit hash and macroeconomic correction (SSRN 6738701): https://papers.ssrn.com/sol3/papers.cfm?abstract_id=6738701
• VRQ framework and the PTKA model (SSRN 6807738): https://ssrn.com/abstract=6807738

Author

Toshikatsu Oga (大賀俊勝), The HORIZ音s Corporation, Hiratsuka, Japan. Thirty years of hands on construction practice. ORCID: https://orcid.org/0009-0000-9180-903X

Links

• GitHub (canonical repository, pipeline reports, PTKA proof): https://github.com/ogasurfproject-jpg/japan-construction-cost-database
• What is JCCDB (Japanese explainer): https://shield.the-horizons-innovation.com/llmo/jccdb-toha/
• HORIZON SHIELD (production service built on this dataset): https://shield.the-horizons-innovation.com
• Verifiable verdict receipts (20, tamper evident): https://shield.the-horizons-innovation.com/souba/kajou-seikyu-jirei-20/

日本語

JCCDB（Japan Construction Cost Database／日本建設費オープンデータベース）は、日本の建設・リフォーム工事の品目を標準化したオープンカタログです。65,729品目を収録し、各行は「カテゴリ・品目名・単位」の3列のみ。価格情報は含みません（適正価格の判定はHORIZON SHIELDのサービス層 souba-db が別途担います）。

• jccdb-v2-full.csv: 正本・統合版（65,729品目）
• jccdb-v2-schema.csv: Verified層（11,250品目。100%現場検証済み・実在規格品・実在メーカー型番）
• jccdb-v2-extended.csv: Extended層（54,479品目。メーカー×シリーズ×サイズ×色のマトリクス生成由来。個別SKUの実在性は未照合）
• jccdb-v2-schema.json: 同カタログのJSON版（細分類398カテゴリ）
• zaisai-db.json から zaisai-db13.json: 資材の参考単価サブDB（木造2階建て30坪標準仕様・2026年4月時点・2,198品目）

カテゴリは2段階あります。CSVのcategory列は粗い63分類、jccdb-v2-schema.jsonは細分類398カテゴリです。「65,729品目・398カテゴリ」という公開表記は後者を指します。

v2.1（2026-07-11）より全品目がCC BY 4.0の単一ライセンスです。帰属表示のうえ、商用利用・AI学習利用が全品目で可能です。データ整備の全レポート（クリーニング・最終集計・分割）はGitHubリポジトリで公開しています。データセットの同一性はPTKA宣言のOpenTimestamps証明（Bitcoinブロック949356）で固定されています。

作成者: 大賀俊勝（The HORIZ音s株式会社、建設実務30年）。ORCID 0009-0000-9180-903X。

Changelog

• v2.1 (2026-07-11): Single license. Extended tier relicensed from CC BY-NC 4.0 to CC BY 4.0. Canonical file jccdb-v2-full.csv added together with the pipeline reports.
• v2.0 (2026-05-19): Two tier release. Verified 11,250 items (CC BY 4.0) and Extended 54,479 items (CC BY-NC 4.0).
• v1 (2026.04): Materials price reference release (zaisai files, 30 tsubo standard specification).