We use essential cookies to run this site, and optional cookies only with your consent. Cookie policy AcceptReject Open 7 days · Hours vary by day · 25 years' experience Office: 01279 216 215 | Mobile: 07932 442502 Services Areas About Our Work Blog Reviews Contact 01279 216 215 Free Quote - Home - Roofing - Flat Roofing - How Much Does a Flat Roof Cost in 2026? Guide · Flat Roofing # How Much Does a Flat Roof Cost in 2026? Flat roof prices vary widely by system, size, deck condition and access. Here are the honest 2026 figures we quote on real Hertfordshire and Essex jobs — including what's normally hidden in cheap quotes. Last updated: May 2026 · By Jamie Pocock Quick Answer For a typical garage or extension flat roof in 2026, expect £85–£150 per m² supplied and fitted — EPDM at the lower end, GRP at the higher. A complete 25m² garage re-roof normally lands between £2,200 and £3,800. A 50m² extension roof typically runs £4,500–£7,500. Add £25–£40 per m² if the deck needs replacing and £20–£35 per m² for upgraded insulation. ## Cost per square metre by system (2026) - Felt (3-layer torch-on): £55–£85/m² — cheapest, shortest life (10–15 yrs typical). - EPDM rubber: £85–£130/m² — best value mid-range, 40–50 year service life. - GRP fibreglass: £100–£150/m² — premium domestic, walk-on rated, 25–35 year service life. - Single-ply (TPO/PVC): £110–£170/m² — typically commercial, occasionally domestic. Compare systems directly in our EPDM vs GRP guide. ## Total cost by roof size ### Small garage (15m²) EPDM: £1,400–£2,000. GRP: £1,650–£2,400. Includes deck inspection, new firrings, drip trims and gutter outlet. One-day install for EPDM, two days for GRP. ### Standard double garage or single-storey extension (25–35m²) EPDM: £2,200–£4,500. GRP: £2,800–£5,300. The most common flat roof job we quote. ### Larger rear extension (50–70m²) EPDM: £4,500–£9,100. GRP: £5,500–£11,000. Larger jobs typically have better £/m² rates because mobilisation cost is fixed. ### Full first-floor flat (90m²+) EPDM: £8,000–£14,000+. GRP: £10,000–£17,000+. Usually involves access scaffold (£800–£2,500 added). ## What pushes the price up - Deck replacement: +£25–£40/m² if existing OSB/ply is soft, sagging or wet. - Firrings (new falls): +£15–£25/m² where the existing roof was flat or poorly drained. - Insulation upgrade: +£20–£35/m² for 100–150mm PIR. Often required by Building Control on full replacements. - Access scaffolding: £800–£2,500 typical hire on first-floor and second-floor jobs. - New rooflights or skylights: £400–£1,200 each fitted into the new membrane. - Lead flashing renewal at upstands: £35–£70 per linear metre. - Asbestos-containing existing roof: +£600–£2,500 for licensed removal and disposal. ## What you actually get for the money Spec level£/m² rangeTypical inclusions Budget felt£55–£85Strip, new felt, basic trims. No insulation upgrade. No firrings. 10–15 yr life. Standard EPDM£85–£130Strip, deck check, new firrings, EPDM membrane, GRP edge trims. Premium EPDM / GRP£130–£170All above + insulation upgrade to current Part L, new lead flashings, integrated outlets, full BR sign-off. The cheapest quote almost always becomes the most expensive over 10 years. Flat roofs that fail early cause internal damage that costs multiples of the original install to put right. ## Things that catch people out on price Deck condition is unknowable until the strip. Honest quotes will give you a fixed price for the membrane work and a clearly-stated rate for any deck replacement found on strip. Quotes that promise a fixed all-in price without a deck check are either over-priced (carrying the risk silently) or about to come back with a "we found rot" change-order. Building Regulations approval. Any flat roof replacement covering more than 50% of the roof area triggers Approved Document L compliance — meaning insulation has to meet current standards. Budget for it. Reputable contractors include the BR notice and sign-off in the quote. VAT. Standard rate (20%) applies on most domestic flat roof work. Reduced rate (5%) sometimes applies on properties unoccupied for 2+ years or being converted. Discuss with your contractor early — it's a meaningful number. Guarantee paperwork. An "completion sign-off" means a third-party insurer covers the workmanship if the contractor goes bust. Ask to see the certificate and the insurer name before signing. Without it, a 25-year guarantee is only as good as the contractor still trading in 2050. About the Author ## Jamie Pocock — Owner & Lead Contractor Jamie has 25 years' hands-on experience in roofing and building across Hertfordshire and Essex. He runs every J&Co Contractors project personally — from quote to completion — and writes these guides from real on-the-tools knowledge of what works, what doesn't, and what costs what in 2026. - 25 years' hands-on roofing and building experience - CRC Certified Roofer — self-certifies under Building Regs - SafeContractor approved - Written completion sign-off on every job FAQs ## Frequently asked questions ### svg]:rotate-180 text-left font-bold text-base hover:no-underline py-5" data-radix-collection-item=""> Why is my quote so much higher than another I've had? ### svg]:rotate-180 text-left font-bold text-base hover:no-underline py-5" data-radix-collection-item=""> How long does a flat roof installation take? ### svg]:rotate-180 text-left font-bold text-base hover:no-underline py-5" data-radix-collection-item=""> Do I need scaffolding for a flat roof? ### svg]:rotate-180 text-left font-bold text-base hover:no-underline py-5" data-radix-collection-item=""> Can a flat roof be repaired instead of replaced? ### svg]:rotate-180 text-left font-bold text-base hover:no-underline py-5" data-radix-collection-item=""> Will a new flat roof add value to my property? ### svg]:rotate-180 text-left font-bold text-base hover:no-underline py-5" data-radix-collection-item=""> Do you offer free quotes for flat roofs in Hertfordshire? Related Guides EPDM vs GRP comparison Roof repair vs replacement Back to Flat Roofing ## Get an honest, itemised flat roof quote We survey the deck, recommend the right system for your scope, and quote line by line — no hidden extras, no day-rate drift. Workmanship guarantee on every install. See our flat roofing service 01279 216 215 Page last updated: May 2026 · J&Co Builders Ltd · 1 Ugley Hall Cottages, Bishop's Stortford CM22 6JB Owner-led roofing and building contractors covering Bishop's Stortford, Hertfordshire and Essex. 25 years of hands-on trade experience. Open seven days. 01279 216 215 (office) 07932 442502 (mobile) info@jandco-contractorsltd.co.uk 1 Ugley Hall Cottages, Bishop's Stortford CM22 6JB Open 7 days a week - Sun 07:00–17:30 - Mon 07:00–17:00 - Tue 07:30–17:00 - Wed 07:00–17:30 - Thu 07:00–17:30 - Fri 06:00–18:00 - Sat 09:00–17:00 We accept VISAAMEX PayG Pay ### Roofing - All roofing services - Flat Roofing - Roof Repairs & Maintenance - Emergency Roof Repairs - Guttering, Fascias & Soffits - Chimney Repairs & Repointing ### Building & Construction - All building services - Building & Extensions - Loft Conversions - Renovations & Refurbishments - Brickwork & Masonry - Damp Proofing & Waterproofing - Plastering & Rendering - Patio & Driveway Installations - Fencing & Garden Walls - Property Maintenance ### Areas We Cover - Bishop's Stortford - Stansted Mountfitchet - Sawbridgeworth - Great Dunmow - Harlow - Saffron Walden - Epping - Ware - Hoddesdon - Broxbourne - Cheshunt - Welwyn Garden City - Stevenage ### Company - About J&Co - Our Recent Work - Blog - Customer Reviews - Contact Us © 2026 J&Co Builders Ltd · Trading as J&Co Contractors · All rights reserved. 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