Original post: Summer 2025. Updated 14 November 2025.

How Much Should My Flat Roof Cost in 2026?

At Frampton Roofing, based in Broadstairs and serving homes across Margate, Ramsgate, and the wider Thanet area, one of the most common questions we get is:

“How much is it going to cost to do my flat roof this year?”

If you're planning a flat roof replacement or a new flat roof extension in 2026, let’s break it down so you know what to expect—and what to look out for.

Understanding Flat Roof Costs

Flat roofs are popular across Kent—especially for extensions, garages, and garden rooms. But prices vary depending on whether:

• You’re replacing an old roof, or
• You’re installing a roof on a new extension.

Here are the two main types of flat roofing jobs:

• Replacement – Remove the old roof covering and boards before the new roof goes on.
• New build – The roof frame and boards are already in place; we just apply the waterproof system.

Replacing an Old Flat Roof: What’s Included?

A replacement involves removing everything—old felt, damaged timber—and installing a new waterproof system. We usually recommend fibreglass, which lasts for decades and comes with a 20-year Lloyd’s-backed guarantee.

💷 Cost in 2026: Approx £100 per m²

This includes:

• Removing all old materials.
• Clearing and disposing of all waste.
• Reboarding with OSB.
• Full fibreglass system with neat edges and detailing.

This leaves you with a flat roof that looks smart and won’t need worrying about for decades.

New Flat Roof Extension: What to Expect

If you’re adding an extension or garden room and the builder has already laid boards, the price is lower. We just apply the fibreglass system on top.

💷 Cost in 2026: Approx £65 per m²

This includes:

• Fibreglass system applied to new boards
• Trims for upstands, outlets or skylights (if needed)
• Fully waterproofed, neat finish

Why Flat Roof Prices Vary

Here’s what can affect your quote:

• 🧱 Size – More area = more materials + labour
• 🧩 Complexity – Extra skylights or angles add time and cost
• 🪜 Access – Hard-to-reach roofs (e.g. over conservatories) cost a bit more
• 🪵 Condition – If we find rot or damage in the boards, we’ll replace them—but we’ll always explain before doing the work

Avoiding Common Roofing Pitfalls

Sadly, we see a lot of poor workmanship across Thanet. Watch out for:

• ❌ Cash jobs with no paperwork – No contract = no comeback if things go wrong
• ❌ Waste left on-site – We remove all rubbish as standard
• ❌ No insurance – Always ask for written proof of guarantee
• ❌ Vague quotes – Always get a detailed, written breakdown

Money-Saving Tips

• 💡 If building an extension, ask your builder to stop at bare boards. Let us handle the waterproofing for best value.
• 💡 For older roofs, book a site visit. We’ll check for hidden issues before quoting—no nasty surprises.

How Long Will It Last?

Our fibreglass systems typically last 20–30 years with a bit of care. It’s low maintenance, clean looking, and comes with a company guarantee from Frampton Roofing, to repair any defect beyond wear-and-tear or missuse.

Real-World Examples

• ✅ Garage roof in Broadstairs – Full rip-off and rebuild
• 18 m²
• Completed in 2 days
• Waste removed
• Company 20 year Guarantee
• Cost: under £100 per m² / £1,800 total.

• ✅ Garden office in Ramsgate – New extension roof
• 12 m²
• Fibreglass only
• Done in 1 day
• Cost: under £65 per m² / £780 total

What Should You Pay in 2026?