Leading Basement Contractors in London
Your Trusted Partner for Basement Construction in London
CSMANLTD is a trusted name among basement contractors in London, offering expertly planned and executed basement construction services. Whether you are a homeowner expanding your living space or a developer preparing a new site, we deliver strong, safe, and cost-effective results.
Our experienced team includes engineers, designers, surveyors, and builders who work closely with clients throughout the entire project. We help you plan efficiently, build smartly, and maximize value at every step.
Experienced Basement Builders London Property Owners Trust
As one of the most experienced basement builders in London, we assess the unique challenges of each site and deliver practical, tailored solutions. From under-house basements to garden-level extensions, we ensure every build meets structural, planning, and safety requirements.
London Basement Contractors with a Developer-Focused Approach
We regularly work with developers from the early stages of planning. Our team prepares the site while architectural designs are finalized, which speeds up the overall construction process and helps reduce project costs.
We also offer flexible working models, including labour and plant-only services, depending on your requirements.
Smart and Affordable London Basement Renovations
Already have a basement that feels underutilized or outdated? Our London basement renovations team helps you transform it into a modern, functional space. Whether it’s a gym, home office, guest suite, or media room, we design and deliver spaces that are practical, compliant, and ready to use.
Our Core Services
Basement Construction
We provide complete basement construction services including under-house and garden basements. Our team manages excavation, waterproofing, and structural stability for long-term safety and performance.
Basement Conversion, Extension and Excavation
If you already have a basement, we can convert or expand it. From cellar conversions to full basement extensions, our team ensures structural safety and compliance with all building regulations.
Underpinning
We provide underpinning to strengthen existing foundations before or during basement construction. Each solution is designed based on your property’s soil and structural profile.
Precision underpinning ensures your building remains stable and safe.
Demolition
We carry out controlled demolition of buildings or sections before construction begins. Our team handles all permits and safely manages disposal for both partial and complete clearances.
Groundworks
CSMANLTD provides full groundwork services including drainage, ducting, site clearance, and access roads. We prepare the site with safety, efficiency, and full regulatory compliance.
Piling Contractors London
As experienced piling contractors in London, we offer methods such as mini piling, CFA piling, and rotary bored piling. These solutions are ideal for challenging ground conditions and tight access spaces.
Piling ensures strong, deep foundations for all building types.
Super Structure
We build reinforced concrete frames and structural steelwork. Our super structure services support safe vertical expansion while ensuring load-bearing and fire resistance standards are met.
Why Choose CSMANLTD as Your London Basement Contractor
- Transparent, honest advice at every stage
- Full project planning and execution support
- Trusted by homeowners and developers across London
- Flexible contracts and scalable teams
- Practical, buildable solutions that reduce complexity
- Delivered by a skilled in-house team
We help you save time, reduce costs, and build better.
Proudly Serving All Areas of London
CSMANLTD serves all London boroughs. Whether your site is in North, South, East or West London, we are your dependable London basement contractors for high-quality construction and renovation services.
Start Your Basement Project Today
Looking for reliable basement contractors in London? Contact CSMANLTD for a free consultation. We are ready to help you plan, design, and build your next basement project with confidence.
Frequently Asked Questions (FAQs)
The cost of building a basement in London depends on several factors, including the size, depth, site access, soil conditions, and design requirements. On average, it can range from £2500 to £4000 per square metre. Contact CSMANLTD for a tailored quote based on your property.
In many cases, basement construction or excavation under your home in London will require planning permission, especially if it involves structural changes, external alterations, or changes to drainage. Our team can help you assess what permissions you need and guide you through the application process.
Most basement construction projects take between 12 to 24 weeks, depending on complexity, access, and whether the space is being excavated or simply renovated. CSMANLTD provides clear timelines during the planning phase to help you stay informed and on schedule.
Yes. We specialise in basement conversions, including turning existing cellars into fully functional living areas. Whether you need extra storage, a home office, gym, or additional bedroom, we ensure structural safety, waterproofing, and high-quality finishes.
CSMANLTD offers experience, transparency, and a practical approach to every project. We are trusted basement builders in London with a proven track record of delivering safe, affordable, and high-quality basement construction and renovation services.