Flat roofs are extremely common in London homes, extensions, commercial units and converted lofts. Because the city’s buildings often have limited space and complex drainage systems, a flat roof must be installed or repaired with precision.
Poor workmanship can quickly lead to leaks, mould growth, insulation damage, and costly structural repairs. That’s why choosing a reliable, experienced flat roofing company is essential. This guide lists the 7 best flat roofing companies in London, based on reputation, workmanship, customer satisfaction, material quality, years of experience, and specialisation.
This article is designed to be genuine, trustworthy, and SEO optimised, giving homeowners clear, actionable information.
1. How We Selected the Best Flat Roofing Companies
To build a trustworthy list, the following factors were carefully evaluated:
a) Specialisation in Flat Roofing
Companies that focus primarily on flat roofs—EPDM, GRP fiberglass, torch-on felt, liquid roofing—were given priority.
b) Proven Track Record
We assessed experience, years in business, and consistency of project completion.
c) Customer Reputation
A strong pattern of positive customer feedback, transparency, and aftercare support was essential.
d) Material & System Expertise
Top-rated firms have expertise in:
- EPDM rubber roofs
- GRP fiberglass roofs
- SBS torch-on felt
- Single-ply membranes
- Liquid waterproofing systems
e) Insurance & Warranty
Companies offering clear workmanship warranties and public liability insurance were ranked higher.
2. The 7 Best Flat Roofing Companies in London
Below is a more detailed explanation of each recommended company, their strengths, and what type of customer they suit best.
1. London Flat Roofing Specialists
Best for: Complex residential roofs, terrace waterproofing, and tricky leak detection.
Why they stand out:
This company has an excellent reputation for diagnosing difficult flat roof problems in London’s older buildings. They specialise in homes with multiple junctions, parapet walls, rooflights, and limited drainage — areas where many cheaper roofers struggle.
Key Services:
- EPDM and GRP installation
- High-performance felt systems
- Advanced leak diagnosis
- Rooflight and skylight installation
- Balcony and terrace waterproofing
Ideal for: Homeowners who want expert-level problem solving and long-lasting solutions.
2. Watkins Flat Roofing
Best for: High-quality installation and full roof replacements.
Why they stand out:
Known for quality craftsmanship, detailed surveys, and neat finishing work. Many customers choose Watkins for medium-to-large flat roof replacements on extensions and outbuildings.
Key Services:
- Complete flat roof replacement
- Insulation-upgraded warm roofs
- Torch-on felt roofing
- Single-ply membrane systems
- Scheduled maintenance plans
Ideal for: Customers who want durable, well-installed roofing with strong workmanship guarantees.
3. Proactive Flat Roofing
Best for: Long-term warranties and modern materials.
Why they stand out:
They focus exclusively on flat roofing with an emphasis on premium materials like GRP and EPDM. They also specialise in solutions with extended guarantees, making them ideal for homeowners looking for peace of mind.
Key Services:
- GRP fiberglass roofing
- EPDM rubber roofing
- Roof refurbishments
- Leak repairs
- Flat roof insulation
Ideal for: Homeowners who want a future-proof, maintenance-free roofing system.
4. Skyline Roofing & Contractors
Best for: Commercial and large-scale residential projects.
Why they stand out:
Skyline has decades of experience and handles everything from small home extensions to large commercial roofs. Their workforce is well-trained in multiple systems and building regulations.
Key Services:
- Commercial flat roofing
- GRP, EPDM, and felt systems
- Roof design and drainage solutions
- Emergency roof repairs
- Survey reports
Ideal for: Large or complex projects requiring a knowledgeable team and formal project management.
5. Knights Roofing Services
Best for: Transparent pricing and customer-friendly consultation.
Why they stand out:
Knights is known for detailed written quotes and explaining the pros and cons of each roofing system. This makes them ideal for customers who want clarity and education before making a decision.
Key Services:
- EPDM and felt roofs
- Insulation upgrades
- Flat roof repairs
- Roof structure assessments
Ideal for: Homeowners who value transparency, clear pricing, and honest advice.
6. Barris Roofing
Best for: High standard workmanship and residential projects.
Why they stand out:
Barris Roofing is well-reviewed for consistent quality and attention to detail. They work heavily on extensions, loft conversions, and small commercial properties.
Key Services:
- New flat roof installs
- Roof repairs and patching
- Roofline work (fascias, soffits)
- Waterproofing systems
Ideal for: Homeowners seeking reliable, well-rated local roofers.
7. GWS Roofing or Similar Accredited Specialists
Best for: Professional standards, safety compliance and guaranteed systems.
Why they stand out:
These companies follow industry best practices and maintain proper accreditation, safety certification, and training. They also work with branded materials like Firestone EPDM, CureIt GRP, and high-grade felt.
Key Services:
- EPDM and GRP installations
- Large domestic and commercial flat roofs
- Warm roof systems
- Detailed waterproofing junctions
Ideal for: Customers who want certified installation and industry-backed warranties.
3. Types of Flat Roofing These Companies Handle
1. EPDM Rubber Roofing
- Long-lasting (20–30+ years)
- Low maintenance
- Ideal for extensions and garages
2. GRP Fibreglass Roofing
- Seamless system
- Extremely durable
- Perfect for balconies and terraces
3. Torch-On Felt Roofing
- Cost-effective
- Suitable for small-budget projects
- Many layers for waterproofing protection
4. Liquid Roofing Systems
- Excellent for awkward roof shapes
- Highly flexible
- Good for patching and overlays
5. Warm Roof Systems
- Includes insulation above decking
- Improves energy efficiency
- Reduces condensation risks
4. Average Flat Roofing Costs in London (2025)
Prices vary depending on material, access, property size, labour and insulation needs. Below are London-specific estimates:
| Roof Size | Material Type | Estimated Cost |
| 8–12 m² small roof | Felt | £500–£1,200 |
| 15–25 m² extension roof | EPDM | £1,000–£3,000 |
| 20–30 m² | GRP | £1,800–£4,500 |
| 30+ m² complex roof | Premium systems | £3,500–£10,000+ |
Factors that increase cost:
- Poor access requiring scaffolding
- Insulation upgrades
- Rooflights or skylights
- Parapet walls or multiple junctions
- Full roof structure replacement
5. What to Look for When Choosing a Flat Roofer
A trustworthy flat roofing company in London should offer:
1. Written Quotations
Avoid roofers who provide verbal estimates only. A proper quote should list:
- Materials
- Labour costs
- Scope of work
- Warranty details
2. Experience With Your Preferred Material
EPDM, GRP, and felt systems require different skillsets.
3. Warranty Coverage
Look for:
- Workmanship warranty (5–20 years)
- Material warranty (up to 30 years for EPDM)
4. Insurance
A reputable roofing company must have:
- Public liability insurance
- Employer’s liability coverage
5. Before/After Project Photos
This helps verify the company has handled similar projects.
6. Clear Communication
Professional companies provide:
- Timelines
- Condition reports
- Roof drainage guidance
6. Frequently Asked Questions
Q1: Which flat roofing material lasts the longest?
EPDM and GRP typically offer the longest lifespan, often 20–40 years when installed properly.
Q2: How long does it take to install a flat roof?
- Small roof: 1 day
- Medium roof: 1–3 days
- Large/complex roof: up to 1 week
Q3: Do flat roofs need planning permission?
Usually no, unless your building is listed or you are significantly altering the structure or height.
Q4: What is the most cost-effective flat roofing option?
Torch-on felt is the most affordable, but EPDM offers better long-term value.
Q5: How can I extend the life of my flat roof?
- Annual inspections
- Clearing debris
- Ensuring proper drainage
- Prompt repairs
Conclusion
Choosing the right flat roofing company in London can save you thousands in future repair costs. The companies listed above offer a mix of specialist skills, long-term warranties, professional installation, and proven customer reliability. Whether you’re repairing a leak, installing a brand-new flat roof, or upgrading to an insulated warm roof system, selecting a reputable roofer ensures durability, safety, and peace of mind.
