Assistant Site Manager

Assistant Site Manager / Site Administrator – Permanent Role Luxury Residential Projects – Flagship Build in Sunningdale & Surrounding Prestige Areas (Berkshire, Surrey)
At Castellum, we are award-winning luxury construction specialists delivering exceptional, high-end residential projects across prime locations in London, Surrey, Berkshire, and the Cotswolds. With over two decades of expertise in new builds, sensitive refurbishments, extensions, listed buildings, and sustainable retrofits, we partner closely with discerning clients, architects, and designers to create homes of lasting distinction — many under strict confidentiality.
We are now seeking a proactive, highly capable Assistant Site Manager to join our experienced team on a flagship luxury residential project in the exclusive Sunningdale area. This permanent position offers genuine long-term career progression, with a strong pipeline of prestigious schemes and the opportunity to work on some of the most desirable properties in the South East.
Key Responsibilities

• Provide comprehensive daily support to the Site Manager, overseeing all site operations including coordination of skilled labour, specialist subcontractors, plant, and premium materials to ensure flawless programme delivery
  
• Lead, inspire, and mentor multi-trade teams to consistently achieve the exceptional standards of craftsmanship and finish that define Castellum projects
  
• Champion best-in-class health, safety, and environmental performance — delivering toolbox talks, dynamic risk assessments, and full compliance with CDM 2015 regulations
  
• Proactively monitor progress against programme, identify potential risks or delays early, and collaborate effectively to deliver robust solutions
  
• Build and maintain strong, professional relationships with subcontractors, suppliers, architects, and clients to secure timely, high-quality contributions
  
• Maintain meticulous site records, including daily logs, progress photography, quality checklists, and comprehensive handover documentation
  
• Enforce rigorous quality assurance protocols to deliver exquisite, high-specification finishes that surpass the exacting expectations of our clients and design teams
  Essential Requirements
  
• Demonstrable site supervisory experience in UK construction (Assistant Site Manager, Site Supervisor, Foreman, or strong progression from Trainee/Graduate level)
  
• Valid CSCS card
  
• Current SMSTS certificate
  
• Strong understanding of residential construction techniques, CDM 2015, and contemporary site management best practices
  
• Outstanding leadership, communication, and problem-solving abilities — comfortable managing diverse teams in fast-paced, high-expectation environments
  
• Full UK driving licence and own transport (essential, given the semi-rural and prestige nature of our sites)
  Highly Desirable
  
• Previous experience on high-end, luxury, or bespoke residential projects (new build, refurbishment, or listed buildings)
  
• Additional certifications (SSSTS, First Aid at Work, or similar)
  
• Exposure to premium finishes, client-facing environments, and working with high-profile stakeholders
  What Castellum Offers
  
• Highly competitive permanent salary, commensurate with experience
  
• Long-term job security with a robust pipeline of exclusive luxury residential projects
  
• A supportive, professional culture with director-level involvement, ongoing training, mentorship, and clear pathways to Site Manager and beyond
  
• The privilege of contributing to landmark homes in the UK's most sought-after locations
  
• The satisfaction of delivering work that consistently earns industry recognition and client pride
  If you are safety-first, quality-obsessed, and ready to build a rewarding career within a respected, award-winning team specialising in prime residential construction, we would be delighted to hear from you.
  Please submit your CV along with a brief covering note highlighting your most relevant experience (particularly any luxury or high-end residential projects) and your current notice period/availability