--- title: "Home Extensions Builder in King's Lynn | Humphries Construction" description: "Single and double-storey extensions across King's Lynn and West Norfolk. Fixed-price builds, 10-year structural warranty, owner-managed with 25+ years' experience." lang: en-GB json-ld: | [ { "@context": "https://schema.org", "@type": "GeneralContractor", "@id": "/#business", "name": "Humphries Construction", "image": "/favicon.png", "logo": "/favicon.png", "telephone": "+44 7460 036540", "email": "info@humphriesconstruction.co.uk", "url": "/", "address": { "@type": "PostalAddress", "streetAddress": "Station Cottage, Gayton Road", "addressLocality": "East Winch", "addressRegion": "Norfolk", "postalCode": "PE32", "addressCountry": "GB" }, "areaServed": [ "King's Lynn", "Norwich", "West Norfolk", "Downham Market", "Swaffham", "Fakenham", "Hunstanton", "Wisbech", "Dereham" ], "priceRange": "££", "openingHoursSpecification": [ { "@type": "OpeningHoursSpecification", "dayOfWeek": [ "Monday", "Tuesday", "Wednesday", "Thursday", "Friday" ], "opens": "07:00", "closes": "19:00" }, { "@type": "OpeningHoursSpecification", "dayOfWeek": "Saturday", "opens": "08:00", "closes": "17:00" }, { "@type": "OpeningHoursSpecification", "dayOfWeek": "Sunday", "opens": "10:00", "closes": "16:00" } ] }, { "@context": "https://schema.org", "@type": "Organization", "@id": "/#organization", "name": "Humphries Construction", "url": "/", "logo": "/favicon.png", "contactPoint": { "@type": "ContactPoint", "telephone": "+44 7460 036540", "contactType": "customer service", "areaServed": "GB", "availableLanguage": "en-GB" } }, { "@context": "https://schema.org", "@type": "WebSite", "@id": "/#website", "name": "Humphries Construction", "url": "/", "publisher": { "@id": "/#organization" }, "inLanguage": "en-GB" }, { "@context": "https://schema.org", "@type": "Service", "name": "Home Extensions Builder", "serviceType": "Home Extensions Builder", "description": "A well-built extension changes how a house feels every day and adds real value the day you sell. We take extensions ground-up: foundations, structural steels, brickwork, roof, plaster, second fix, all managed from one contract, with a fixed written price and a 10-year structural warranty in the paperwork.", "areaServed": [ "King's Lynn", "Norwich", "West Norfolk", "Downham Market", "Swaffham", "Fakenham", "Hunstanton", "Wisbech", "Dereham" ], "provider": { "@type": "GeneralContractor", "name": "Humphries Construction", "telephone": "+44 7460 036540", "email": "info@humphriesconstruction.co.uk", "areaServed": "West Norfolk", "address": { "@type": "PostalAddress", "streetAddress": "Station Cottage, Gayton Road", "addressLocality": "East Winch", "addressRegion": "Norfolk", "addressCountry": "GB" } }, "url": "/services/extensions" }, { "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "How much does an extension cost in King's Lynn?", "acceptedAnswer": { "@type": "Answer", "text": "A basic single-storey rear extension in West Norfolk typically starts around £2,000–£2,400 per square metre for a straightforward shell finish, rising with glazing spec, kitchen fit-out, structural complexity and finishes. we survey free and comes back with a written, itemised, fixed-price quote within 3 working days so you're not guessing." } }, { "@type": "Question", "name": "How long does an extension take to build?", "acceptedAnswer": { "@type": "Answer", "text": "A single-storey rear extension is typically 10–14 weeks on site. A double-storey extension is usually 14–20 weeks. Your fixed quote includes a target programme with stage dates." } }, { "@type": "Question", "name": "Do I need planning permission?", "acceptedAnswer": { "@type": "Answer", "text": "Sometimes. Many single-storey rear extensions fall under permitted development, but permitted development rights don't apply to every property (flats, listed buildings, some conservation areas, some previously extended houses). we will flag this at the survey stage before you spend on architect's fees." } }, { "@type": "Question", "name": "What does the 10-year structural warranty cover?", "acceptedAnswer": { "@type": "Answer", "text": "It covers the structural elements of the extension we've built, foundations, load-bearing walls, structural steels and roof structure, against defect for 10 years from completion. Full terms are issued with the completion paperwork." } }, { "@type": "Question", "name": "How do stage payments work?", "acceptedAnswer": { "@type": "Answer", "text": "You pay as visible progress happens on site, typically after foundations, after weathertight shell, after first fix, and on completion. No large upfront deposit before materials are delivered. The exact schedule is agreed in writing before contract signing." } }, { "@type": "Question", "name": "Do you handle building control?", "acceptedAnswer": { "@type": "Answer", "text": "Yes. We notify building control at each required stage, work to your approved plans, and don't cover foundations or drains until they've been inspected. You receive the completion certificate at handover." } }, { "@type": "Question", "name": "What about party wall issues?", "acceptedAnswer": { "@type": "Answer", "text": "If your extension is close to a neighbouring boundary or involves cutting into a shared wall, the Party Wall Act may apply. We'll flag it at the survey stage, the notice itself has to be served by you (or a party wall surveyor) rather than by the builder." } }, { "@type": "Question", "name": "Can you match the existing brick?", "acceptedAnswer": { "@type": "Answer", "text": "Almost always. We'll take a sample, price a match through local brick merchants, and show you before ordering. Slight variation is normal, a perfect match on a weathered wall is impossible, but a sympathetic match is standard." } }, { "@type": "Question", "name": "Do you offer design or work only to my architect's drawings?", "acceptedAnswer": { "@type": "Answer", "text": "We build to your architect's or designer's drawings. If you don't have one yet, we can recommend architects and structural engineers we've worked with locally who understand West Norfolk housing stock." } }, { "@type": "Question", "name": "What happens if I want to change something mid-build?", "acceptedAnswer": { "@type": "Answer", "text": "Variations are normal, but they're always agreed in writing before we do the work, with the cost impact stated up front. That way there are no surprise invoices at the end." } } ] }, { "@context": "https://schema.org", "@type": "BreadcrumbList", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "Home", "item": "/" }, { "@type": "ListItem", "position": 2, "name": "Services", "item": "/#services" }, { "@type": "ListItem", "position": 3, "name": "Home Extensions Builder", "item": "/services/extensions" } ] } ] --- [07460 036540 ](tel:+447460036540) [info@humphriesconstruction.co.uk](mailto:info@humphriesconstruction.co.uk) Tue–Mon · 7am–7pm [![Humphries Construction](/__l5e/assets-v1/2400a8ee-f8ea-4946-a84c-85d5685b2f83/humphries-logo.png)](/) [Home](/) Services Areas [Our Work](/our-work)[Reviews](/reviews)[About](/about)[Contact](/contact) [07460 036540](tel:+447460036540)[Request Free Quote](/contact) ![Completed brick garden room extension with bifold doors | home extensions in King's Lynn by Humphries Construction](/__l5e/assets-v1/2e9ca38e-0bb3-4423-9243-e10e034d941b/home-extension-finished-brick-garden-room-kingslynn.jpg) [Home](/)[Services](/services)Home Extensions Builder Extensions · King's Lynn & West Norfolk # Home Extensions Builder in King's Lynn Full builds, owner-led project management A well-built extension changes how a house feels every day and adds real value the day you sell. We take extensions ground-up: foundations, structural steels, brickwork, roof, plaster, second fix, all managed from one contract, with a fixed written price and a 10-year structural warranty in the paperwork. [Request Your Free Quote](/contact) [Call 07460 036540](tel:+447460036540) £1M public liability insured Free site survey within 7 days Owner-managed by Jason, 25+ years on the tools 10-year Structural warranty £1M Public liability 25+ Years experience 7 days To free survey Fixed Written pricing Recent home extensions builder work ## Real projects, photographed on site in Norfolk. ![Completed brick garden room extension with bifold doors | home extensions in King's Lynn by Humphries Construction](/__l5e/assets-v1/2e9ca38e-0bb3-4423-9243-e10e034d941b/home-extension-finished-brick-garden-room-kingslynn.jpg) ![Finished rear extension with full-width bifold doors opening to garden | home extensions in King's Lynn by Humphries Construction](/__l5e/assets-v1/bbcd26ee-810e-496c-9934-ad738d2bdf75/home-extension-finished-bifold-doors-kingslynn.jpg) ![New brick porch and frontage extension on a Norfolk home | home extensions in King's Lynn by Humphries Construction](/__l5e/assets-v1/c8aa9d04-fc02-45a7-a593-1d30ed9fc0d5/home-extension-finished-03-porch-frontage-kingslynn.jpg) ![Landscaped rear extension with rendered walls and patio | home extensions in King's Lynn by Humphries Construction](/__l5e/assets-v1/c85cfd2c-fb4f-435f-8d23-3e3be259df43/home-extension-finished-04-rear-extension-landscaped-kingslynn.jpg) ![Extension brickwork under construction around a new window opening | home extensions in King's Lynn by Humphries Construction](/__l5e/assets-v1/2dedcfea-a9c5-44ca-a2a4-c179c308768b/home-extension-in-progress-02-brickwork-window-kingslynn.jpg) ![Blockwork walls going up on a home extension in progress | home extensions in King's Lynn by Humphries Construction](/__l5e/assets-v1/02257d1f-8484-4320-83b9-af9aff0b6c7a/home-extension-in-progress-blockwork-kingslynn.jpg) Service overview ## What's involved, explained plainly. What it is A residential extension is a permanent addition to your home, usually a single or double-storey side, rear or wrap-around build tied structurally into the existing property. Every stage sits under Building Regulations and, in many cases, planning permission or permitted development. Who it's for Homeowners in and around King's Lynn who need more space and would rather build than move. Typical projects are kitchen-diner rear extensions, side infills, double-storey extensions above a garage, and wrap-around builds that redraw the whole ground floor. When you need it Once you have an idea of scope, it's worth booking a survey even before drawings. we can tell you what's realistically buildable, what triggers planning, and what a sensible budget looks like before you commit to fees. Why professional help matters Extensions touch structure, damp-proofing, insulation, fire separation, drainage and thermal performance. Get any of those wrong and you don't just get a poor room, you get a house that won't survey cleanly when you come to sell. A single accountable contractor is the difference between a build that lasts and one that costs twice. Ignore it and… ## The cost of getting it wrong. The horror stories are almost always the same shape: cheap price, missing detail on the quote, half-finished job, main contractor gone, homeowner chasing subcontractors who were never paid. It's avoidable, but only if you get the contract, insurance and warranty side right before day one. ### Cold, damp new rooms Missed cavity trays, weak insulation continuity, or bad detailing at the join between old and new walls means the new room is colder than the rest of the house from day one. ### Cracked walls and steels Under-specified structural steel, poor padstones, or steels installed without engineer sign-off cause visible cracking and eventually structural movement. ### Roof leaks at the junction The join between existing and new roof is where most leaks happen. Bad flashing, missed soakers or lazy lead work will drip within a couple of winters. ### Sale-blocking building control issues Regulations sign-off is what your solicitor asks for when you sell. No completion certificate means renegotiated price or a collapsed sale. Common mistakes we see - Signing a quote that lists 'extension' as one line item with no breakdown - Paying a large upfront deposit before materials are on site - Using a builder with no proof of public liability insurance - Skipping structural engineer's calculations to save fees - Not agreeing a written specification for kitchen and bathroom fit-out - Assuming permitted development applies without checking Our process ## A predictable path from enquiry to handover. [Talk to Jason](tel:+447460036540) 1. 01 ### Free site survey the owner visits, measures up, understands what you want and flags any planning, party wall or structural issues before you spend on drawings. 2. 02 ### Fixed written quote Itemised quote within 3 working days, foundations, structure, brickwork, roof, first fix, plaster, second fix, decoration. You see every line. 3. 03 ### Contract & pre-start Contract signed, stage-payment schedule agreed in writing, materials scheduled, building control notified, party wall notices served where required. 4. 04 ### On site build Groundworks, structure, roof, then weathertight before first fix. owner on site regularly, one trade lead at any one time, tidy compound. 5. 05 ### Sign-off & warranty Building control final inspection, snagging walked with you, completion certificate handed over, 10-year structural warranty issued. Benefits ## What you actually get for your money. ### One accountable builder the owner prices, manages and finishes the job personally. When something needs deciding, you talk to the man who signed the quote. ### 10-year structural warranty Every extension is covered by a 10-year structural warranty, the paperwork your solicitor will ask for when you sell. ### Fixed written price The number on your quote is the number on your invoice. Variations are only ever agreed in writing before work happens. ### Stage payments, not deposits You pay as visible progress is made on site, not a fat deposit before a spade goes in the ground. ### Thermally correct detailing Cavity trays, insulation continuity, cold-bridge breaks at slab and lintel, done properly so the new room isn't the coldest in the house. ### Tidy, respected site One clean compound, waste managed daily, neighbours respected. You still have to live there while we're building. In detail ## Materials, methods and the situations we cover. ### Types of extension we build We build the shapes that actually work on Norfolk housing stock. Some need planning, some are permitted development, we'll tell you which before you commission architect's drawings. - Single-storey rear extensions (kitchen-diner, open-plan living) - Double-storey rear and side extensions - Side infills and wrap-arounds - Two-storey extensions over an existing garage - Porches, utility rooms and boot rooms - Sunroom and orangery-style extensions with lantern rooflights ### Structural work we handle Most extensions need structural steels, either as a beam over a knocked-through wall or as a frame carrying an upper storey. We work to your engineer's calcs, install to spec with correct padstones and bearings, and coordinate the building control inspection. - RSJ and UB steel beams to engineer's specification - Correctly sized padstones and bearings - Steel encasement for fire protection where required - Coordination with structural engineer and building control ### Weathertight shell, brick, block, roof We build in traditional brick-and-block cavity construction with insulation to current Part L standard. Roofs are cut and pitched or trussed depending on span. Flat roof sections are warm-deck fibreglass or EPDM, detailed properly at the abutment. - Facing brick chosen to match existing - Full-fill or partial-fill cavity insulation to Part L - Pitched roofs, cut and pitched or truss, felt/batten/tile - Flat sections, GRP fibreglass or EPDM single-ply - Lead flashing and soakers at every roof junction ### First fix, plaster, second fix Once weathertight, we run first-fix electrics and plumbing to your spec, insulate, plaster and screed. Second fix takes it to finished: sockets, radiators, doors, skirting, tiling, coordinated so trades don't tread over each other's work. - First-fix electrics by a qualified, insured electrician - First-fix plumbing and heating by a qualified, insured plumber - Two-coat plaster and skim finish - Underfloor heating installation where specified FAQ ## The questions homeowners actually ask. Straight answers on cost, timelines, guarantees and how the job runs. If yours isn't here, call Jason on 07460 036540. How much does an extension cost in King's Lynn? A basic single-storey rear extension in West Norfolk typically starts around £2,000–£2,400 per square metre for a straightforward shell finish, rising with glazing spec, kitchen fit-out, structural complexity and finishes. we survey free and comes back with a written, itemised, fixed-price quote within 3 working days so you're not guessing. How long does an extension take to build? A single-storey rear extension is typically 10–14 weeks on site. A double-storey extension is usually 14–20 weeks. Your fixed quote includes a target programme with stage dates. Do I need planning permission? Sometimes. Many single-storey rear extensions fall under permitted development, but permitted development rights don't apply to every property (flats, listed buildings, some conservation areas, some previously extended houses). we will flag this at the survey stage before you spend on architect's fees. What does the 10-year structural warranty cover? It covers the structural elements of the extension we've built, foundations, load-bearing walls, structural steels and roof structure, against defect for 10 years from completion. Full terms are issued with the completion paperwork. How do stage payments work? You pay as visible progress happens on site, typically after foundations, after weathertight shell, after first fix, and on completion. No large upfront deposit before materials are delivered. The exact schedule is agreed in writing before contract signing. Do you handle building control? Yes. We notify building control at each required stage, work to your approved plans, and don't cover foundations or drains until they've been inspected. You receive the completion certificate at handover. What about party wall issues? If your extension is close to a neighbouring boundary or involves cutting into a shared wall, the Party Wall Act may apply. We'll flag it at the survey stage, the notice itself has to be served by you (or a party wall surveyor) rather than by the builder. Can you match the existing brick? Almost always. We'll take a sample, price a match through local brick merchants, and show you before ordering. Slight variation is normal, a perfect match on a weathered wall is impossible, but a sympathetic match is standard. Do you offer design or work only to my architect's drawings? We build to your architect's or designer's drawings. If you don't have one yet, we can recommend architects and structural engineers we've worked with locally who understand West Norfolk housing stock. What happens if I want to change something mid-build? Variations are normal, but they're always agreed in writing before we do the work, with the cost impact stated up front. That way there are no surprise invoices at the end. Next step ## Get your extension priced honestly, from a builder who'll still be here to guarantee it. Free site survey within 7 days. Written, itemised quote within 3 working days. Owner-managed by Jason personally, no call centre, no middlemen. [Request Your Free Quote](/contact) [Call 07460 036540](tel:+447460036540) What you're covered by - £1,000,000 public liability insurance - 10-year structural warranty on every extension - 2-year workmanship guarantee on garage conversions - Fixed written price, no mid-job surprises Related services ## Works well with [Groundworks ](/services/groundworks)[Foundations & Footings ](/services/foundations-footings)[Garage Conversions ](/services/garage-conversions)[Bricklaying ](/services/bricklaying)[Not sure which service you need? Ask Jason. ](/contact) ![Humphries Construction](/__l5e/assets-v1/2400a8ee-f8ea-4946-a84c-85d5685b2f83/humphries-logo.png) Groundworks and general building contractor serving King's Lynn, West Norfolk and beyond. Owner-managed by Jason Humphries with 25+ years on the tools. £1M Public Liability Insured #### Services - [Groundworks](/services/groundworks) - [Extensions](/services/extensions) - [Garage Conversions](/services/garage-conversions) - [New Build Groundworks](/services/new-build-groundworks) - [Driveways](/services/driveways) #### Areas Covered - King's Lynn - West Norfolk - Norwich · Downham Market - Swaffham · Fakenham - Hunstanton · Wisbech · Dereham #### Contact - [07460 036540](tel:+447460036540) - [info@humphriesconstruction.co.uk](mailto:info@humphriesconstruction.co.uk) - Station Cottage, Gayton Road, East Winch, Norfolk - Mon–Fri 7am–7pm Sat 8am–5pm · Sun 10am–4pm © 2026 Humphries Construction. All rights reserved. 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