Groundworks & Drainage London
Reliable groundworks and drainage solutions for residential and commercial projects across London, from foundations to complete site preparation.
Professional Groundworks Contractors in London
Alstruct provides comprehensive groundworks and drainage services across London. Every construction project starts below ground, and getting the foundations and drainage right is critical to the success of the build above. Our experienced groundworks team handles everything from site clearance and excavation to foundation construction, drainage installation and service connections.
Whether you need foundations for a house extension, a new drainage system for a renovation, or complete site preparation for a new build, Alstruct delivers on time, to specification, and within budget.
Groundworks Services We Deliver
Foundations
Strip foundations, trench-fill foundations, raft foundations and piled foundations designed by our structural engineers. We excavate, pour concrete, and construct foundation walls to support extensions, new builds and structural alterations.
Drainage Systems
New foul and surface water drainage, soakaways, drainage diversions, and connections to the public sewer. We install complete below-ground drainage systems compliant with Building Regulations and water authority requirements.
Site Clearance & Excavation
Demolition of existing structures, removal of vegetation, excavation to formation level, and spoil removal. We prepare your site ready for construction, including temporary works, hoarding, and site access.
Service Connections
Installation and diversion of underground services including water mains, gas, electric ducting and telecommunications. We coordinate with utility providers and ensure all connections are compliant and properly documented.
What's Included in Every Groundworks Project
- Free site survey and ground assessment
- Structural engineering design for foundations
- Building control liaison and inspections
- Site clearance and demolition
- Excavation and spoil removal
- Foundation construction to engineer's specification
- Below-ground drainage installation
- Service connections and diversions
- Backfilling and compaction
- CCTV drain surveys (where required)
- As-built drainage drawings
- Full project management throughout
Groundworks Cost Guide - London 2026
| Service Type | Price Range | Duration |
|---|---|---|
| Foundations | £10,000 - £30,000 | 2-4 weeks |
| Drainage | £5,000 - £20,000 | 1-3 weeks |
| Site clearance | £3,000 - £10,000 | 1-2 weeks |
Prices are indicative for London in 2026 and vary based on ground conditions, depth, site access and project complexity. Contact us for an accurate quote for your project.
Frequently Asked Questions
How much do groundworks cost in London in 2026?
Groundworks costs in London vary by scope. Foundation work typically costs £10,000-£30,000, drainage installation £5,000-£20,000, and site clearance £3,000-£10,000. The final cost depends on ground conditions, depth requirements, site access and project complexity. Contact Alstruct for a quote.
Do groundworks require building regulations approval?
Yes, foundation work and drainage installations must comply with Building Regulations. Foundations must be designed by a structural engineer and inspected at key stages. Drainage connections to the public sewer require approval from the local water authority. Alstruct manages all approvals and inspections.
How long do groundworks take?
Foundation work typically takes 2-4 weeks, drainage installation 1-3 weeks, and site clearance 1-2 weeks. Timescales depend on ground conditions, weather, and project scale. Alstruct provides a detailed programme before work begins.
What type of foundations does my extension need?
The foundation type depends on ground conditions, the weight of the structure, and proximity to trees. Common options include strip foundations, trench-fill foundations, and piled foundations. Alstruct's structural engineers assess your site and specify the most appropriate and cost-effective foundation solution.
Can you work on sites with difficult access?
Yes, Alstruct has extensive experience working on London sites with restricted access, narrow side returns, and limited space for machinery. We use mini excavators, conveyor systems for spoil removal, and carefully planned logistics to deliver groundworks in even the most constrained locations.