| Aburns Engineering Ltd | Builders | DL3 0UN | 2026 |
| Advanced Inspections Ltd | Builders | DL3 0SL | 2016 |
| Affordable Homes Group Ltd | Builders | DL3 9AZ | 2015 |
| Ah Windtech Ltd | Builders | DL2 2ZF | 2026 |
| Allan Oliver Reinforcing Ltd | Builders | DL3 7EH | 1999 |
| Alwyn Doors Ltd | Builders | DL3 7SD | 2023 |
| Amira Construction Ltd | Builders | DL3 7SP | 2025 |
| Arnco Building Services Ltd | Builders | DL3 7AR | 2025 |
| Aspire Property Management Services Ltd | Builders | DL3 7RX | 2025 |
| B & C Building Contractors Ltd | Builders | DL3 9AU | 2012 |
| Bba North East Ltd | Builders | DL2 2PT | 2024 |
| Bh Blinds & Shutters Ltd | Builders | DL2 1QR | 2024 |
| Borthwick Construction Ltd | Builders | DL3 0TW | 2019 |
| Brass Holdings Ltd | Builders | DL3 7EH | 2023 |
| Broken Homes Ltd | Builders | DL3 0HD | 2025 |
| C & S Paving Services Ltd | Builders | DL3 6QE | 2017 |
| C&C Construction Consultants Ltd | Builders | DL2 1FE | 2024 |
| C.T. Steel Site Services Ltd | Builders | DL3 8NE | 2001 |
| Cherry Tree Home Improvements Ltd | Builders | DL2 1QZ | 2025 |
| Clinton Building Services Ltd | Builders | DL3 0PX | 2020 |
| Cm Door Services Ltd | Builders | DL2 2WS | 2025 |
| Cm Site Services Ltd | Builders | DL3 7BJ | 2023 |
| Cna Rigging and Lifting Solutions Ltd | Builders | DL2 1AX | 2026 |
| Commercial Electrical Contractors Ltd | Builders | DL3 7SD | 2025 |
| Commercial Maintenance Contractors Ltd | Builders | DL3 7SD | 2022 |
| Complete Home Inspections Guaranteed Ltd | Builders | DL2 2FD | 2024 |
| Csm Bolting Ltd | Builders | DL2 1GJ | 2025 |
| Cws Fabs Ltd | Builders | DL3 0ER | 2026 |
| D B Site Services Ltd | Builders | DL2 2JS | 1998 |
| D Wright Groundworks Ltd | Builders | DL3 7BJ | 2017 |
| Daa Groundworks Ltd | Builders | DL3 0XY | 2026 |
| Darlington & Tees Blinds Ltd | Builders | DL2 2WB | 2026 |
| Darren Grahams Building Ltd | Builders | DL3 6EN | 2025 |
| Design4 Ltd | Builders | DL2 2UF | 2019 |
| Dk Gell Construction Ltd | Builders | DL3 8LF | 2012 |
| Dmw Brickwork Ltd | Builders | DL3 7SD | 2018 |
| Doggy Access Ltd | Builders | DL2 1LW | 2017 |
| Dorserve Ltd | Builders | DL3 7BJ | 2008 |
| E.A Render Systems Ltd | Builders | DL3 0UN | 2020 |
| Elm Integrated Services Ltd | Builders | DL2 2QY | 2016 |
| Emmanuel General Services Ltd | Builders | DL3 7JT | 2023 |
| Eton Environmental Group Ltd | Builders | DL3 0PH | 2004 |
| F & E Trade Services Ltd | Builders | DL2 2ZL | 2025 |
| Factorial Solutions Ltd | Builders | DL3 0HU | 2025 |
| G D Services (N.E.) Ltd | Builders | DL3 7JJ | 2017 |
| Gdl Access Ltd | Builders | DL3 7JJ | 2019 |
| Graham Everett Rope Access Ltd | Builders | DL2 1HJ | 2014 |
| Gsm Maintenance Solutions Ltd | Builders | DL2 3DE | 2017 |
| Harpers Construction & Groundworks Ltd | Builders | DL2 1JH | 2015 |
| Harrogate Developments Ltd | Builders | DL3 7EH | 2018 |
| Heffs Ltd | Builders | DL3 7AR | 2024 |
| Heritage South Ltd | Builders | DL3 8QJ | 2003 |
| High-Tech Access Ltd | Builders | DL3 7JJ | 2015 |
| Highthorn Developments Ltd | Builders | DL3 7SP | 2018 |
| Hssg Inspections Ltd | Builders | DL3 7JJ | 2016 |
| I G Inspection Ltd | Builders | DL3 7JJ | 2019 |
| Industrial Coatings North East Ltd | Builders | DL2 1UL | 2015 |
| Iq Building Services Ltd | Builders | DL3 7PR | 2016 |
| J & C Boardline Ltd | Builders | DL3 7SD | 2015 |
| J Foster Building Services Ltd | Builders | DL3 7SD | 2015 |
| J R Humble Building Services Ltd | Builders | DL3 9DY | 2022 |
| J. Arkle Ltd | Builders | DL2 1UA | 2019 |
| James Cameron Joinery Ltd | Builders | DL3 7SD | 2019 |
| Jamie Bryant Rope Access Ltd | Builders | DL3 7JJ | 2019 |
| Jay'S Technical Services Ltd | Builders | DL3 7BJ | 2016 |
| Jig UK Drainage Solutions Ltd | Builders | DL2 1RJ | 2021 |
| Jsa Rope Access Ltd | Builders | DL3 8LX | 2019 |
| Kes Design Ltd | Builders | DL3 7EH | 2024 |
| Kestrel Kitchen Installations Ltd | Builders | DL3 9AU | 2022 |
| Keystone Architectural Surveying and Developments Ltd | Builders | DL3 7RG | 2024 |
| L&M Race Paving Ltd | Builders | DL2 3LA | 2017 |
| Lt Access & Maintenance Ltd | Builders | DL3 0SB | 2025 |
| M&M Total Property Services Ltd | Builders | DL3 7BJ | 2019 |
| Matthew J Brown Ltd | Builders | DL3 0QF | 2020 |
| Mds Joinery & Building Ltd | Builders | DL3 9EW | 2014 |
| Merrybent Project Management Ltd. | Builders | DL2 2LF | 2004 |
| Mph Electrical Contractors Ltd | Builders | DL3 7HJ | 2019 |
| Mulholland Builders Ltd | Builders | DL3 8SE | 2020 |
| Mw Rail Ltd | Builders | DL2 1FJ | 2026 |
| Nova Construction & Site Services Ltd | Builders | DL3 7BJ | 2025 |
| Oakwood Construction (Darlington) Ltd | Builders | DL3 7SD | 2008 |
| Olympia Property Solutions Ltd | Builders | DL3 8QF | 2024 |
| Opdoc Ltd | Builders | DL3 8NA | 2016 |
| Partek Site Services Ltd | Builders | DL2 2LF | 2014 |
| Paul Townend Ltd | Builders | DL3 7SD | 2026 |
| Peaks Construction Services Ltd | Builders | DL3 7SD | 2024 |
| Perspective Blinds Ltd | Builders | DL2 3US | 2026 |
| Plasterboard Recycling Group Ltd | Builders | DL2 3RR | 2019 |
| Premier Solutions Interior Specialists Ltd | Builders | DL3 8FD | 2021 |
| Proassemble Ltd | Builders | DL2 2BX | 2025 |
| Proformance Ltd | Builders | DL3 7EH | 2007 |
| Q9 Cladding Solutions Ltd | Builders | DL2 3PX | 2011 |
| R W Fencing Ltd | Builders | DL2 2XT | 2008 |
| Rennyco Ltd | Builders | DL3 0XE | 1986 |
| Renowork Group Ltd | Builders | DL3 6NE | 2025 |
| Retrofit Coordinators Ne Ltd | Builders | DL3 0GY | 2022 |
| Richard Mands Safety & Training Solutions Ltd | Builders | DL3 7SD | 2025 |
| Rjb Consultants Ltd | Builders | DL3 6EN | 2026 |
| Robson Granite Worksurfaces Ltd | Builders | DL2 2TT | 2017 |
| Rps Civil Engineering Ltd | Builders | DL3 7BJ | 2003 |
| Rtl Energy Consultants Ltd | Builders | DL2 1QR | 2025 |
| Rw Access Ltd | Builders | DL3 0SL | 2022 |
| Simple Renovation Ltd | Builders | DL3 6NE | 2023 |
| Srb Quality Building Services Ltd | Builders | DL3 7SD | 2023 |
| Stephen Oliver Living Ltd | Builders | DL2 1RA | 2025 |
| Steven Bowes Construction Ltd | Builders | DL2 2PS | 2019 |
| Stoneriver Housing Ltd | Builders | DL3 8DE | 2020 |
| Storefit (UK) Ltd | Builders | DL3 6EU | 2015 |
| Sw Lunnon Construction Ltd | Builders | DL3 7EH | 2018 |
| Sylvan Glade Spv Ltd | Builders | DL2 1PD | 2024 |
| T & K Building Maintenance Ltd | Builders | DL3 7SD | 2023 |
| The Craft Man+ Ltd | Builders | DL3 0QP | 2025 |
| The Luxury Wood Floor Company Ltd | Builders | DL3 9AU | 2025 |
| The Strays Building Services Ltd | Builders | DL2 2GE | 2024 |
| Thistle Solutions Ltd | Builders | DL2 1AS | 2013 |
| Thompson Bros Ltd | Builders | DL3 7EH | 2026 |
| Thurston Construction Ltd | Builders | DL3 0XQ | 2019 |
| Total Solution & Service Ltd | Builders | DL3 7SD | 2010 |
| Trunghao Estate Agent Ltd | Builders | DL2 2RY | 2023 |
| Unique Doors and Shutters Ltd | Builders | DL3 0QT | 2018 |
| Upright Ltd | Builders | DL3 7EH | 1984 |
| Vgd Ltd | Builders | DL3 6NE | 2024 |
| Wade Brothers Ltd | Builders | DL3 7BJ | 2013 |
| West End Tree and Landscaping Ltd | Builders | DL3 0TW | 2019 |
| Whessoe Road Aggregates Ltd | Builders | DL3 7BJ | 2025 |
| Wycliffe Grange Estates Ltd | Builders | DL3 7SD | 2021 |