The construction sector in Northern Ireland features a mix of established firms and more recent entrants. GRAHAM Group, founded in 1778, specializes in a wide range of construction and development projects across the UK and Ireland. McLaughlin & Harvey Ltd, established in 1853, also provides construction, civil engineering, and fit-out services. Newer companies like Alternative Heat Ltd, founded in 2003, focus on offsite fabrication for MEP solutions, while Kane Group, also from 2003, delivers building-service solutions. Omexom UK, founded in 1998, specializes in electricity infrastructure.
Many of these companies, such as FP McCann Ltd, the UK's largest precast concrete manufacturer, and McMullen Facades Limited, a specialist facade contractor, demonstrate a strong focus on specialized construction materials and components. A notable pattern is the concentration of headquarters in a few key locations, with Belfast, Magherafelt, and Banbridge each hosting multiple significant construction firms.
| # | Company | Employees | |||
|---|---|---|---|---|---|
| 1 |
GRAHAM Groupgraham.co.uk
Specializes in delivering construction and development projects across the UK and Ireland, encompassing building, civil engineering, interior fit out, facilities management, and investment projects. |
1,933 | |||
| 2 |
FP McCann Ltdfpmccann.co.uk
UK's largest manufacturer of Precast Concrete Solutions also offers Quarrying, Ready Mix, and Construction services with award-winning projects in various sectors |
592 | |||
| 3 |
McLaughlin & Harvey Ltdmclh.co.uk
Construction, civil engineering, and fit-out projects and facilities management services for public and private clients across diverse sectors throughout the UK and Ireland. |
557 | |||
| 4 |
Omexom UKomexom.co.uk
Specializing in electricity generation, transmission, distribution, and substation design and construction to support the energy transition for clients in the UK and Ireland |
394 | |||
| 5 |
Alternative Heat Ltdalternativeheat.co.uk
A market leader in offsite fabrication for MEP solutions, offering high-quality products through experienced design engineers and skilled trades personnel |
330 | |||
| 6 |
MJM Marinemjm-group.com
A global marine outfitting company based in Northern Ireland, specializing in crafting high-spec, bespoke spaces for leading cruise liner brands worldwide |
320 | |||
| 7 |
Kane Groupkanegroup.co.uk
Designing, developing, and delivering building-service solutions across the UK and Ireland with a focus on quality, health, and safety. |
302 | |||
| 8 |
H & J Martin Limitedhjmartin.co.uk
A construction company with over 175 years of experience, specializing in asset management, construction, and fit out services within Ireland |
183 | |||
| 9 |
McMullen Facades Limitedmcmullenfacades.com
Leading specialist facade contractor, provides full design, fabrication, and installation of aluminium curtain wall and window systems for medium to large building projects. |
178 | |||
| 10 |
Dowdsdowdsgroup.com
A leading specialist contractor providing building services, construction, facilities management, and energy solutions in the UK & Ireland since 1978 |
177 | |||
| 11 |
Lagan Specialist Holdingslaganscg.com
Undertakes specialist contracting activities including Aviation & Infrastructure, Piling, Operations and Maintenance, Facilities Management, Fit Out, civil engineering, and building projects globally. |
175 | |||
| 12 |
Heron Brosheronbros.com
An award-winning construction and property development entity operating throughout the UK, Ireland, and Europe, focused on delivering excellence and sustainability |
163 | |||
| 13 |
Irwin M&Eirwinm-e.com
Provides mechanical, electrical, energy, and renewables installation and maintenance services to clients in public and private sectors across the UK and Ireland. |
160 | |||
Want more companies than this list?This page shows the largest ones only. Connect to Tamtam to see every company that matches, filter by size, industry or growth, and reach their decision-makers. | |||||
| 14 |
Keystone Lintelskeystonelintels.com
The Keystone Group specializes in manufacturing steel lintels, roof windows, and masonry support systems, with a focus on innovative design and exceptional customer service |
151 | |||
| 15 |
Keylite Roof Windowskeyliteroofwindows.com
A leading supplier of roof windows, blinds, loft ladders, and accessories, committed to innovation, quality, and value for customers in Europe |
112 | |||
| 16 |
Copius Groupcopiusgroup.com
Provides comprehensive electrical, mechanical, and construction services for offshore and onshore projects, focusing on power, renewables, oil & gas, and critical infrastructure globally. |
96 | |||
| 17 |
Premier Electricspremierelectrics.com
Delivering comprehensive electrical services for prestigious clients in commercial, industrial, leisure, and retail sectors within Ireland, UK, and Europe since 1993 |
72 | |||
| 18 |
Kilwaughter Minerals Ltdk-rend.co.uk
A family-owned company investing in people, offering secure employment, development opportunities, competitive benefits, and a range of career options in various fields |
66 | |||
| 19 |
Charles Brand Group Limitedcharlesbrand.com
The company offers customized Civil Engineering, Process, and M&E solutions to a range of public and private clients |
57 | |||
| 20 |
SA3 POWERsa3power.com
Provides specialized electrical services for data centers across Europe, including installations, fit-outs, lighting design, and inspection testing, adhering to high professional standards. |
55 | |||
| 21 |
Tinnelly Grouptinnelly.com
A family-owned group specializing in recycling metals, removing asbestos, and handling demolition projects with over 60 years of experience |
35 | |||
| 22 |
CP Hire Ltdcphire.com
A construction equipment rental company with 10 depots, providing top-notch customer service and support throughout the UK for 45 years |
25 | |||
| 23 |
National Building Servicesnbsni.co.uk
This company offers Facilities Management services across multiple locations, allowing clients to focus on core business while outsourcing support services |
25 | |||
| 24 |
Sustainable Homes By Bayviewbayviewcontracts.com
Leading provider of whole house energy solutions, specializing in central heating, renewable energy, home insulation, and building maintenance with extensive experience in energy efficiency projects |
20 | |||
| 25 | 
Premix Concretecreaghconcrete.com
Leading producer of innovative concrete products since 1976, serving diverse markets with high-quality solutions for construction projects |
12 | |||
| 26 |
O'Hanlon Electrical Ltdoelni.com
An experienced electrical contractor offering a wide range of services for public, commercial, industrial, and private sectors in the UK and Ireland |
9 | |||
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Every company on this list has a Tamtam company profile. The industry is the one the company gives on LinkedIn; categories such as SaaS or fintech are classified by Tamtam's AI from the company's website and LinkedIn page; and the headquarters city must match the company's own address. Companies are ranked by the number of employees on LinkedIn, and the list is refreshed every night. Classifications can be wrong, so treat the list as a starting point rather than an official ranking. Last updated Nov 12, 2026.
More company lists in Northern Ireland
- The largest companies in Northern Ireland 354
- Multinational companies in Northern Ireland 84
- Manufacturers in Northern Ireland 48
- Retail chains in Northern Ireland 40
- Software Development companies in Northern Ireland 30
- Companies with in-house R&D in Northern Ireland 28
- Retail companies in Northern Ireland 27
- Family-owned companies in Northern Ireland 27
- Financial services firms in Northern Ireland 26
- Food and Beverage Manufacturing companies in Northern Ireland 25
The same list elsewhere in United Kingdom
- Construction companies in the United Kingdom 797
- Construction companies in England 667
- Construction companies in Scotland 51
- Construction companies in London 125