UK construction companies in 2026: a count from the Companies House register

By size: the accounts each company files

The register records the Companies Act filing regime a company used for its last accounts (AccountCategory). It is an exemption, not a turnover. The census groups the categories into the bands below, each listed with the categories it holds. “Very small” includes TOTAL EXEMPTION FULL, which means full accounts filed with audit exemption claimed: a filing choice, not a measure of size. Read the bands as filing regimes, not as sizes.

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By trade: the SIC codes

Section F of UK SIC 2007 has 25 codes. A company can carry up to four SIC codes, so it is counted under each Section F code it carries, and the rows below add up to 632,251, more than the 518,002 companies. The census treats 18 codes as subcontractor trades: every code in group 43, and the utility and water project codes. A company is in the 319,161 if it carries at least one of them, even where it also carries a code for developing building projects, constructing whole buildings or civil engineering.

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By the trade the company name declares

UK SIC 2007 has no code for bricklaying, groundworks, drylining, steel erection, cladding or passive fire, so the census also reads each company’s name for trade keywords such as BRICKWORK, GROUNDWORK or SCAFFOLD. Each company counts under one trade at most, the first that matches. 116,283 of the 518,002 names declare a trade; the rest are not in this table. A name is a heuristic: it says what a company called itself, not what it does now.

Method, and the limits of the data

• Source. The Companies House Free Company Data Product, snapshot of 1 September 2026. Every row of its seven parts was read, 5,689,368 records, and counted on 10 September 2026.
• Active. A company counts only where the register’s CompanyStatus field reads Active. A company with any other status, such as one in liquidation, is not counted.
• Section F. Construction in UK SIC 2007, the 25 codes from 41100 to 43999 in Companies House’s SIC list. A company counts once if any of its codes is in Section F.
• Up to four SIC codes per company. A company is counted under each Section F code it carries, so the per-code figures add up to more than the company total.
• No primary activity. The register has no field for a company’s main activity, and its SIC codes are stored in numeric order, so the first code is not the main one. SIC codes are chosen by the company itself.
• Size is a filing regime. The bands come from the register’s AccountCategory, the Companies Act regime a company filed under. That is an exemption, not a turnover, and a company that has not yet filed shows as no accounts filed.
• Nation. Taken from the registered office’s country field where the register carries one (321,089 companies), otherwise inferred from a postcode area that lies wholly within one nation (19,058). Areas that straddle a border (CH, SY, HR and TD) are never inferred, and England is never inferred at all, so 177,855 companies stay unstated and the English figure is a floor rather than a count.
• Companies, not businesses. Sole traders and ordinary partnerships are not on the register. A group’s companies are counted one by one, so the band of the company that does the work can say little about the size of the group behind it.