Specialised construction activities (SIC division 43)
Division 43 of the UK SIC 2007 list. It holds 15 codes, listed in full below with the number of active UK companies filed under each.
What sits in division 43
This is the trades division, and one of the biggest classifications on the UK register. Electricians use 43210. Plumbing and heating engineers use 43220. Roofers use 43910. Plasterers, painters, glaziers, floorers and scaffolders each have a code of their own. Two broad codes swell the numbers further. Code 43999 covers specialised activities not elsewhere classified. Code 43390 covers other building completion and finishing. Both soak up general trades and multi-skilled firms. Most companies here are small. Many are one tradesperson who went limited for contracting or tax reasons.
Lots of firms sell to the trades, because their needs are predictable and repeat every year. They buy public liability insurance, accountancy for CIS refunds and company compliance, van leasing, tools and trade credit from merchants. Lead generation and website services aim at the poor-website filter. A tradesperson whose site fails basic checks loses local work to rivals who show up in search. New incorporations are the standout signal. They usually mark the jump from sole trader to limited company, when insurance, banking and bookkeeping all get chosen in a few weeks. Heating firms under 43220 also attract renewables sellers, especially heat pump distributors.
How to read a division 43 code
A UK SIC code is five digits and division 43 is the first two of them. Everything filed under 43 shares those digits: all 15 codes below begin 43, then the third digit narrows to a group, the fourth to a class and the fifth to the subclass a company actually picks. Division 43 sits inside section F, construction, which is the broadest tier of the classification. So a code is read left to right, from an industry down to a specific activity.
More on how division 43 codes are built
Companies choose their own codes at incorporation and can change them on any confirmation statement, and Companies House does not check the answer. A company may list up to four. That is worth knowing before you treat any division total as a headcount: the numbers here are what companies said about themselves, on the August 2026 register, and the largest single code in this division is 43999, other specialised construction activities n.e.c..
Working division 43 as a list
Division 43 holds 15 codes and 358,662 active companies between them. No single code dominates: the largest, 43999, is only 17 per cent and the top three take 48 per cent, with the rest spread across the remaining 12 codes. Companies here describe themselves in many different ways, so the division is the sensible filter and picking one code will lose you most of the market.
More on working division 43
A caveat that matters more in some divisions than others: a company may register up to four SIC codes, and the figures below count every position, not just the first. A business filed under two codes in this division appears under both. Treat the totals as reach rather than a headcount, and if you need a clean list, filter to companies whose FIRST code sits in the division. Every company you pull carries the Companies House record, the director's name, a verified website and a verified email, and the ones we cannot complete are not charged.
Every SIC code in division 43
43110, Demolition43120, Site preparation43130, Test drilling and boring43210, Electrical installation43220, Plumbing, heat and air-conditioning installation43290, Other construction installation43310, Plastering43320, Joinery installation43330, Floor and wall covering43341, Painting43342, Glazing43390, Other building completion and finishing43910, Roofing activities43991, Scaffold erection43999, Other specialised construction activities n.e.c.Prospecting this division
Division 43 companies, as leads
Tell us who you sell to. We find them, with a real email. 25 free leads, no card.
Division 43 questions
Should a multi-trade builder use 43999 or a specific trade code?
If one trade brings in most of your income, use its own code. That means 43210 for electrical work or 43220 for plumbing and heating. Specific codes read better to insurers and merchants. Genuinely multi-skilled firms use 43999 or 43390, or list up to four codes covering their main trades. The choice is yours. Companies House records it without judgement, and you can change it on any confirmation statement.
Does my SIC code need to match my trade qualifications or scheme memberships?
There is no formal link. Gas Safe registration, NICEIC enrolment and similar schemes are checked on their own registers, not at Companies House. Matching the code to your trade is still worth doing. Customers, insurers and finance providers do look at it, and a mismatch invites questions. If the business changes direction, update the code on your next CS01 confirmation statement.
Find companies across division 43
✓ No card · ✓ 25 free leads · ✓ Cancel anytime