07447 188036info@gnbroofing.co.uk Serving East AngliaMon–Sat 7am–6pm HomeAboutServicesFlat Roof InstallationFlat Roof ReplacementFlat Roof RepairsEPDM Rubber RoofingSingle-Ply Membrane (SFlex · Sika Plan · Resitrix)Commercial Flat RoofingFascias & Soffits (UPVC)Guttering & BargeboardsCladding — UPVC, Timber-Effect & Composite AreasNorfolk NorwichThorpe St Andrew & SprowstonHellesdonCostesseyTaverhamDraytonCringlefordWymondhamDerehamGreat YarmouthThetfordKing's Lynn County overview Norfolk (county overview)Suffolk (county overview)Cambridgeshire (county overview) Our WorkReviewsContact07447 188036Get Free Quote - Home - Services - Flat Roof Installation Flat Roof Installation # Flat Roof Installationin Norwich &East Anglia A properly specified, single-ply or EPDM flat roof — installed by a Sika Plan Approved Installer, guaranteed 20 years on materials and 10 years on workmanship, for a fixed written price with zero call-out fees. Get my free fixed-price quote 07447 188036 Free survey · No call-out fees · Written quote in 3–4 days · You deal with Neil directly Flat-roofing specialist Sika Plan Approved Installer 20-yr product / 10-yr workmanship PL & EL fully insured Free fixed-price quotes Service overview ## What we do, who it's for, and when to book it. ### What it is Full flat roof installation on new extensions, garages, dormers, outbuildings and warm-roof upgrades. We fit modern single-ply membranes (SFlex, Sika Plan, Resitrix) and EPDM rubber — the specialist systems we're trained and approved to install. ### Who it's for Homeowners building an extension or garage conversion, landlords refurbishing tired flat-roofed properties, and commercial clients who need a warrantied, long-life covering rather than a patched surface. ### When it's needed At new-build stage, when replacing a failed roof, or when upgrading a cold-deck build-up to a compliant warm roof. If you're already re-decking or extending, that's the right moment to specify a proper system rather than repeat the old one. ### Why it matters A flat roof only works if the falls, upstands, drainage detailing and membrane specification are right on day one. Wrong falls or a poor upstand will leak within a season — no membrane, however premium, will save a bad detail. That's why the installer matters more than the brand. The cost of leaving it ## What actually happens when this is put off. ### If it's ignored - Ponding water on incorrect falls accelerates UV and biological breakdown, halving the useful life of any membrane. - Poor upstand and termination details let wind-driven rain track under the covering, rotting the deck from below with no visible surface leak. - A cold-deck build-up without a vapour control layer traps interstitial condensation, causing joists to soften and blacken over years. ### Common mistakes we clean up after - Choosing the cheapest quote without checking the installer is manufacturer-approved for the system being fitted — voiding any warranty from day one. - Reusing an old timber deck that's already saturated. The membrane is only as good as what it's bonded to. - Skipping insulation upgrades during install, then paying twice when Building Control require it later. Our process ## A predictable path from first call to guaranteed sign-off. - 01 Free survey Neil visits, measures, checks the deck and existing falls, and talks through your options in plain English. - 02 Fixed written quote in 3–4 days You get a written specification naming the exact membrane, insulation, upstand and drainage detail — plus a fixed price. - 03 Strip and deck prep Old covering removed, deck inspected, rotten boards replaced, falls corrected where needed, vapour control layer laid. - 04 Insulation & membrane install PIR insulation to current U-value, then SFlex / Sika Plan / Resitrix / EPDM installed to manufacturer spec by an approved installer. - 05 Detailing & sign-off Upstands, drips, outlets and flashings finished. Site left clean, photos taken, guarantee paperwork issued. What you actually get ## The outcomes — not the sales talk. 20-year product guarantee Backed by Sika / SFlex / Resitrix / EPDM manufacturer warranty when installed by an approved contractor — us. 10-year workmanship guarantee Written, in your name, from GNB Roofing directly. Fixed price, no call-out fees The quote you sign is the price you pay. No day-rate creep. One installer, one crew Neil quotes it and Neil installs it. No handoffs, no subcontractors on your roof. PL & EL fully insured Public Liability and Employers Liability cover in place for every job. Long life, low maintenance A correctly specified single-ply or EPDM roof should give 25–30+ years with minimal upkeep. Specification detail ## The technical honest version. Flat roofing isn't one product — it's a build-up. The right specification depends on the deck, the falls, the insulation strategy, the perimeter details and the exposure. Here's what we actually install, and when each system is the right call. ### SFlex single-ply membrane A mechanically fixed or adhered PVC single-ply membrane suited to larger domestic and commercial roofs. Excellent for cost-effective long-life coverings on garages, extensions and outbuildings where a clean, uniform finish is wanted. ### Sika Plan (Sika Sarnafil family) Premium PVC single-ply with a proven 30+ year service history. We're a Sika Plan Approved Installer, which means the manufacturer stands behind our workmanship with an extended system warranty. ### Resitrix EPDM A high-performance self-adhesive EPDM sheet with a bitumen backing — ideal for complex detailing, refurbishments over existing bitumen, and roofs with lots of upstands, pipes or rooflights. ### EPDM rubber (Firestone / Classic Bond) One-piece EPDM rubber for small-to-medium roofs — garages, porches, dormers. Fast, seamless, cost-effective, and typically 25+ year lifespan on a properly prepared deck. ### Warm roof vs cold roof Almost every new install we do is a warm-roof build-up: insulation over the deck, membrane over the insulation. It eliminates the condensation risk of an old cold-deck and meets current Building Regulations for U-value. ### Our specialism Flat roofing is what we lead with — single-ply membranes and EPDM systems installed to manufacturer spec. Staying in our lane is how the workmanship stays sharp. Frequently asked ## Questions we answer at almost every survey. How much does a new flat roof cost?+Every roof is priced individually because deck condition, insulation upgrade, size and system all change the number. What we can promise: a free survey, a fixed written quote in 3–4 days, and no call-out fee whether or not you go ahead. How long does installation take?+A typical single-garage or extension roof is 1–3 working days. Larger commercial jobs are scheduled and staged so you're weather-tight each evening. Which system is best for my roof?+For most domestic extensions and garages, EPDM or SFlex is the right balance of cost and life. For premium spec, complex detailing, or commercial, we'll usually recommend Sika Plan or Resitrix. Neil talks you through the trade-offs at survey. What guarantee do I get?+20-year manufacturer product guarantee on the membrane system, plus a 10-year workmanship guarantee from GNB Roofing in writing. Do you handle Building Regulations?+Yes — the build-up we quote will meet current U-value and condensation requirements. For notifiable work you can use a competent-person scheme or Building Control; we'll advise which fits your job. Will you remove the old roof?+Yes. Strip-out, disposal, deck repair and any tip fees are included in the fixed quote. You don't get a separate bill on completion day. Do you cover the whole of Norfolk, Suffolk & Cambridgeshire?+Yes. We're based in Norwich (NR5) and work across Norfolk, Suffolk and Cambridgeshire — including all the Norwich suburbs (Thorpe St Andrew, Sprowston, Hellesdon, Costessey, Taverham, Drayton, Cringleford), Wymondham, Dereham, Thetford, Great Yarmouth and King's Lynn. If you're on the edge of that area, phone and ask — we don't charge to travel to quote. Do you charge call-out fees?+No. Surveys and quotes are free, and there are no call-out fees. You get a fixed written price before any work starts — no day-rates, no hidden extras. Who will I actually deal with?+Neil, the owner, personally quotes and runs every job. You won't be handed to a call centre or a subcontracted crew. One point of contact from first call to final sign-off. Where we cover ## Flat Roof Installation across Norfolk, Suffolk & Cambridgeshire. NorwichThorpe St Andrew & SprowstonHellesdonCostesseyTaverhamDraytonCringlefordWymondhamDerehamGreat YarmouthThetfordKing's LynnNorfolk (county overview)Suffolk (county overview)Cambridgeshire (county overview) Related services ## Also worth looking at. Flat Roof Replacement Strip the failed covering, put the deck and falls right, upgrade the insulation, and re-cover in a manufacturer-warranted system — for a fixed price with a 20-year product guarantee and a 10-year workmanship guarantee. View service EPDM Rubber Roofing A one-piece EPDM rubber roof — seamless, low-maintenance, 25+ year design life — installed for a fixed written price by an owner-run, insured, Sika Plan Approved installer. View service Single-Ply Membrane (SFlex · Sika Plan · Resitrix) Premium single-ply membrane systems — SFlex, Sika Plan and Resitrix — installed by a Sika Plan Approved contractor with the extended manufacturer warranty that comes with it. View service One next step ## Get a fixed written quote for your flat roof installation — in 3–4 days. Free survey. No call-out fees. Sika Plan Approved. 20-year product / 10-year workmanship guarantee. Neil quotes it and Neil installs it. Book my free survey Call 07447 188036 Mon–Sat 7am–6pm Flat-roofing specialists serving homes and businesses across East Anglia. Sika Plan Approved. Fully insured. Owner-run by Neil Cockman. Sika Plan Approved Installer ### Services - Flat Roof Installation - Flat Roof Replacement - Flat Roof Repairs - EPDM Rubber Roofing - Single-Ply Membrane - Commercial Flat Roofing - Fascias & Soffits ### Service Areas - Norwich - Thorpe St Andrew & Sprowston - Hellesdon - Costessey - Taverham - Drayton - Cringleford - Wymondham - Dereham - Great Yarmouth - Thetford - King's Lynn - Norfolk (county overview) - Suffolk (county overview) - Cambridgeshire (county overview) ### Contact - 07447 188036 - info@gnbroofing.co.uk - 6 Gilbard RoadNorwich, NR5 8TR - Mon–Sat 7am–6pm · Closed Sun © 2026 GNB Roofing Services. All rights reserved.Privacy PolicyCookie PolicyTerms & Conditions Call NowGet Free Quote We use essential cookies to make this site work, and optional ones only if you accept. Cookie policy. AcceptReject