★ 4.9/5 · GRP & EPDM Specialists · 10-Year Guarantee

Flat RoofingSouthampton

Southampton's maritime humidity puts flat roofs under constant stress. The damp, salt-laden air that comes off the Solent accelerates failures in ageing felt and exposes poorly sealed joints in membranes. We install GRP fibreglass and EPDM rubber flat roofs that perform in these conditions — and last 25 years or more.

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Flat Roofing

Flat Roofing in Southampton

Flat-roofed rear extensions are extremely common across Southampton — particularly on the Victorian and Edwardian terraces in Portswood, Bevois Valley and St Denys, where single-storey kitchen extensions were added throughout the 20th century. The 1960s council-built properties in Thornhill and Lordshill also feature large areas of flat roof on single-storey outbuildings and side extensions.

GRP Fibreglass Flat Roofing

GRP (glass reinforced polyester) is a seamless, fully waterproof system that is ideal for Southampton's damp maritime climate. There are no joints or seams for water to penetrate. Once laid, it is virtually maintenance-free and carries a manufacturer-backed guarantee. It handles the UV exposure Southampton roofs receive in summer and the wet conditions in winter equally well.

EPDM Rubber Roofing

EPDM single-ply rubber membrane is our preferred choice for larger flat roof areas — particularly on extensions over 30 square metres. It is flexible, highly resistant to UV and moisture, and performs exceptionally in the temperature range Southampton experiences throughout the year. A professionally installed EPDM roof will outlast the building it sits on.

Flat Roof Replacement on Southampton's 1960s Stock

The post-war and 1960s estates in Thornhill, Lordshill and Weston have a significant volume of felt flat roofs that have been repaired and patched over decades. At this point, replacement with a modern system is substantially cheaper over a 10-year period than ongoing felt repairs. We assess, advise and quote honestly.

Flat Roofing Costs

Small extension (under 15m²): £900–£1,800 · Medium extension (15–30m²): £1,800–£3,500 · Large garage or extension (30m²+): £3,500–£6,000. Costs depend on area, material, access and condition of existing deck.

What Do Our Customers Say?

What Do Southampton Homeowners Say?

★★★★★

"Rear extension in Portswood had a felt flat roof that leaked every winter. Replaced with GRP — the difference is immediate. Fully waterproof, no maintenance needed. They explained the options clearly and delivered exactly what was promised."

Liz K. · Portswood, Southampton

★★★★★

"Had our garage flat roof replaced after 20 years of patch repairs. EPDM installation in one day. Two years on and not a single issue. Should have done it years ago instead of spending on patches."

Graham F. · Weston, Southampton

★★★★★

"The flat roof on our Thornhill extension was the original 1967 felt — we knew it needed replacing. These guys stripped it back, replaced some rotten deck boards and laid a new GRP system. Very clean job."

Sandra L. · Thornhill, Southampton

By Area

Flat Roofing Near Southampton

We cover Southampton and the surrounding towns. Select your area for local pricing, specific advice and availability.

Flat Roofing Eastleigh → Flat Roofing Hedge End → Flat Roofing Totton → Flat Roofing Chandler's Ford → Flat Roofing Romsey →

Honest advice

Do You Actually Need Flat Roofing?

Not every tired flat roof needs replacing, but felt in Southampton’s damp coastal air rarely lasts. Here is how to tell whether yours has reached the end.

Ponding water that still sits on the roof a day after rain
Blistering, cracking or splitting in an old felt covering
A persistent leak into the room or garage below
Felt that is over 10–15 years old on a Southampton extension
Sagging or soft spots underfoot indicating a failing deck

When it is not the answer: If the covering is sound and only a seam or upstand has failed, a targeted repair beats a full re-cover — we will tell you honestly which you need Read the full guide.

Warm deck versus cold deck flat roof build-ups compared layer by layer — Warm-deck construction puts insulation above the deck, removing the condensation risk that plagues cold-deck extensions.

The process

From First Call to Sign-Off

1. Free survey

We measure the roof, check the deck and the fall, and confirm whether GRP or EPDM suits your Southampton roof and how the drainage should run.

2. Written itemised quote

You get a clear quote covering the covering, any deck repairs, correcting the fall, insulation and skylights if wanted — no hidden extras.

3. Scheduling

We book the work, usually within the week for a standard extension or garage roof across Southampton.

4. The work

We strip the old covering, repair or renew the deck, correct the fall, then lay GRP or EPDM with properly detailed upstands and drip edges.

5. Cleanup & sign-off

We clear the old material, confirm the roof drains cleanly, and hand over the guarantee.

Timescales

Job Durations at a Glance

Job	Typical duration
Small garage or porch roof — GRP	Half to 1 day
Single-storey extension — GRP or EPDM	1–2 days
Large extension + new insulation	2–3 days
Flat roof + integrated skylight	2–3 days

GRP needs dry conditions to cure, so we watch the forecast; EPDM is more forgiving in Southampton’s damp spells.

Access

Getting Safely onto Southampton Roofs

Most single-storey flat roofs are reached from towers or a modest scaffold; larger or higher roofs are quoted with full scaffold, always itemised. Scaffold is specified for: first-floor and higher flat roofs, and any roof where edge protection is needed for safe working - always itemised in your written quote, never a hidden extra, and we arrange it.

Southampton’s Victorian terraces off Portswood and in Bevois Valley often have no side access, so repairs there need pavement scaffold and a council permit rather than a ladder. Pavement scaffold and skip permits go through Southampton City Council; allow a few working days on streets like Bevois Valley Road, Portswood Road, the terraced streets off Northam Road where space is tight.

Pricing

Flat Roofing Prices in Southampton

Job	Typical range	Notes
Garage / porch roof — GRP	£800–£1,600	Small area
Single-storey extension — EPDM	£1,500–£3,000	Typical rear extension
Single-storey extension — GRP	£1,800–£3,500	Typical rear extension
Large extension + insulation	£3,500–£6,000	Warm-deck build-up
Flat roof + integrated skylight	£2,500–£5,000	Incl. rooflight

What moves the price

Covering system — GRP or EPDM
Roof area and any deck repairs needed
Whether the fall must be corrected
Insulation to meet warm-deck standard
Skylights or access hatches added

Worked example: An EPDM re-cover on a single-storey rear extension in Shirley: around £2,100 including a corrected fall and new trims.

No large deposit; a materials stage then balance on completion. Written itemised quote with the system warranty stated. VAT included where applicable.

Guarantee

The Guarantee in Plain Terms

The new flat roof carries a 10-year workmanship guarantee; GRP and EPDM systems carry manufacturer material warranties of 20 years or more on top.

Covered: workmanship for 10 years, in writing, transferable if you sell.
On top: manufacturer warranties on materials (terms vary by product).
Not covered: storm or impact damage - that is an insurance matter, and we will document it for your claim.

If a fault appears in covered work, we come back and put it right. No quibbling, no re-charge.

“BS 6229, the code of practice for flat roofs, requires that surface water drains freely with no ponding after prolonged dry weather — the single most important factor in flat-roof longevity.”— British Standard BS 6229

Good to know

Disruption, Mess & Weather

Flat-roof work is quieter than a re-roof — some stripping noise and old-felt waste in a skip — and rarely disrupts the rooms below. You do not need to stay home for external work - we just need power and access agreed in advance.

EPDM lays year-round; GRP needs a dry, mild window to cure, which we schedule around Southampton’s weather. Southampton’s position at the head of Southampton Water brings humid, salt-influenced air and south-westerly Solent gales that drive weather onto exposed roofs.

FAQ

Frequently Asked Questions

A well-installed GRP fibreglass flat roof will last 25 years or more in Southampton conditions. EPDM rubber is similarly durable. Cheaper felt flat roofs typically last 10 to 15 years. The maritime humidity and UV exposure in Southampton mean material choice and quality of installation matter more than in drier inland areas.

GRP fibreglass is our recommendation for most Southampton properties. It is seamless, highly resistant to the damp maritime conditions around the Solent, and requires no maintenance for 25-plus years. EPDM rubber is an excellent alternative, particularly for larger roof areas where the single-ply membrane suits the geometry better.

It depends on the material and condition. Felt flat roofs that are split or have significant blistering are usually better replaced than patched — especially after 12 to 15 years. GRP and EPDM roofs can often be repaired effectively if the problem is localised. We inspect and advise before quoting.

Yes, this is one of our most common jobs. The large 1960s estates in Thornhill, Lordshill and Weston have many properties with flat-roofed rear extensions that were built using materials now well past their service life. We replace with GRP or EPDM and provide a full written guarantee.

NFRC Registered

We are registered with the National Federation of Roofing Contractors. Membership requires proof of public liability insurance, a company check and a commitment to industry standards. Check our membership at nfrc.co.uk.

Fully Insured

We carry full public liability insurance. You are completely protected on every job. We provide insurance certificate details on request before any work begins.

10-Year Guarantee

All roofing work carries a written 10-year workmanship guarantee. If a problem arises from our workmanship within 10 years, we return and fix it at no charge. The guarantee is provided in writing on completion.

No Hidden Costs

We quote clearly before starting any work. No call-out fees. No surprise extras on the invoice. If additional work is found during a job, we explain and agree a price before proceeding — never after.

How We Work

How Does Our Roofing Process Work?

Free Survey

We inspect the roof thoroughly — ridge, flashings, valleys, tile condition, guttering. We look at the whole picture, not just the reported problem. No charge, no obligation.

Written Quote

You receive a written, itemised quote specifying exactly what will be done, the materials to be used, the timeline and the total cost. No verbal-only quotes. No surprises on the invoice.

Work Carried Out

Our team carries out the agreed work. Clean site throughout. Property secured at the end of each day. If anything unexpected is found, we discuss and agree before proceeding — never after.

Guarantee Issued

A written 10-year workmanship guarantee is provided on completion of all roofing work. NFRC registration and insurance details provided on request.

Flat RoofingSouthampton

Flat Roofing in Southampton

GRP Fibreglass Flat Roofing

EPDM Rubber Roofing

Flat Roof Replacement on Southampton's 1960s Stock

Flat Roofing Costs

Get a Free Quote

What Do Southampton Homeowners Say?

Flat Roofing Near Southampton

Do You Actually Need Flat Roofing?

From First Call to Sign-Off

1. Free survey

2. Written itemised quote

3. Scheduling

4. The work

5. Cleanup & sign-off

Job Durations at a Glance

Getting Safely onto Southampton Roofs

Flat Roofing Prices in Southampton

What moves the price

The Guarantee in Plain Terms

Disruption, Mess & Weather

Frequently Asked Questions

NFRC Registered

Fully Insured

10-Year Guarantee

No Hidden Costs

We Cover All of Southampton and Hampshire

How Does Our Roofing Process Work?

Free Survey

Written Quote

Work Carried Out

Guarantee Issued

Get Your Free Roofing Quote