Basement Tanking Solutions for Greenwich SE10 Homes

Dealing with damp or active water ingress in a Greenwich SE10 basement can feel overwhelming. Basements in this area — especially those in Victorian or Edwardian properties — often suffer from poor drainage, high groundwater levels, and ageing brickwork. This guide breaks down realistic tanking options, timelines, and key considerations based on real London projects we encounter across SE10.

Types & Options

Cementitious Tanking

A traditional damp-proofing method applied directly to masonry. It forms a barrier to stop moisture penetration. Works well on structurally sound walls, but is less effective on basements with high hydrostatic pressure. Proper preparation and multiple coats are crucial for long-term success.

Cavity Drain Membrane Systems (CDM)

Modern, reliable, and widely used in London. Plastic studded membranes are fitted to walls and floors, allowing moisture to travel behind them into a drainage channel, then pumped out via a sump pump. CDM is ideal for Greenwich basements with irregular walls or heavy groundwater pressure.

Sump Pumps & Drainage Channels

If your property suffers from rising water levels — common in SE10 areas near the Thames — a sump pump system is essential. It redirects water away from the property and prevents long-term pressure on the basement structure.

External Waterproofing

In some cases, external excavation allows for the installation of drainage membranes and waterproof coatings. This is highly effective but disruptive and costly. Limited access around London terraced houses makes this option difficult, but where possible, it provides long-term protection.

Costs & Timeline

• Survey & Waterproofing Design: £500–£1500 (1–2 weeks)
• Cementitious Tanking (small basement): £5,000–£12,000 (6–10 weeks)
• Cavity Drain Membrane System (small basement): £8,000–£20,000 (8–12 weeks)
• Larger basements / excavated areas: £15,000–£40,000+ (12–20 weeks)
• Drainage & sump pump installation: £2,000–£10,000+ (4–8 weeks)
• Internal finishes (plastering, rendering, stud walls): £2,000–£8,000 (2–6 weeks)

Prices for basement tanking in Greenwich SE10 vary dramatically due to property age, construction type, and underlying ground conditions. Many Greenwich homes sit on clay-heavy soil, which increases hydrostatic pressure. Narrow access points, shared walls with neighbours, or sloping gardens can extend timelines. Period properties may require specialist breathable materials or lime-based plaster.

Safety & Common Mistakes

• Failing to remove loose plaster, paint, or render before applying membranes.
• Ignoring cracks or structural weaknesses that allow water to bypass the tanking system.
• Using the wrong materials — especially non-breathable products on older brickwork.
• Installing membranes without appropriate drainage channels or a sump pump.
• Poor ventilation after tanking — leading to condensation and mould growth.
• Check electrical requirements and Part P guidance via NICEIC: https://www.niceic.com/

Local Advice (London / UK)

• Many Greenwich basements were never originally designed as living spaces; waterproofing must consider long-term pressure and soil movement.
• High rainfall and Thames proximity increase risk of water ingress — robust systems are essential.
• Party wall agreements may be required for drainage, excavation, or structural works.
• Access can be tight around SE10 terraces — factor in parking suspensions for material deliveries.
• Properties with bay windows or lower-ground entrances may need scaffolding and extra bracing.
• Historic homes may require lime-based repairs instead of modern cement to avoid trapping moisture.

Next Steps

1. Book a specialist damp survey with a contractor experienced in London basements.
2. Discuss suitable waterproofing systems and compare long-term maintenance requirements.
3. Request a detailed scope of work, drawings, and a fixed or staged cost breakdown.
4. Secure any required permissions, including party wall notices and building regulations approval.
5. Monitor progress and ensure membranes, drainage channels, and pumps are installed correctly.
6. Complete the project with appropriate finishes and obtain final warranties or certificates.

FAQ

How long does basement tanking typically take?

Timeframes depend on the chosen system, property condition, and access. Expect 8–20 weeks for full waterproofing, with longer timelines for large or complex basements.

What is the average cost of basement tanking in Greenwich, SE10?

Most projects fall between £5,000 and £40,000+, depending on size, chosen membrane or tanking system, structural repairs, and drainage requirements.

Can I tackle basement damp myself?

Minor issues like condensation can be DIY-managed, but genuine water ingress requires professional installation. Incorrect DIY tanking often fails within months and can increase long-term damage.