--- title: "Loft Conversion Cost UK 2026: Full Price Guide | J&Co" description: "Loft conversion cost guide for 2026. Velux, dormer, hip-to-gable and mansard prices, what's included and what drives the cost. Honest Hertfordshire builder." lang: en-GB json-ld: | [ { "@context": "https://schema.org", "@type": "Article", "headline": "Loft Conversion Cost UK 2026: Full Price Guide", "description": "Loft conversion cost guide for 2026. Velux, dormer, hip-to-gable and mansard prices, what's included and what drives the cost. Honest Hertfordshire builder.", "mainEntityOfPage": "https://jandco-contractorsltd.co.uk/guides/loft-conversion-cost-uk/", "datePublished": "2026-05-07", "dateModified": "2026-05-07", "author": { "@type": "Person", "name": "Jamie Pocock", "jobTitle": "Owner & Lead Contractor", "worksFor": { "@id": "https://jandco-contractorsltd.co.uk/#business" } }, "publisher": { "@type": "Organization", "name": "J&Co Contractors", "url": "https://jandco-contractorsltd.co.uk" }, "image": [ "https://jandco-contractorsltd.co.uk/assets/wa-435-79-Cfvt7K6N.jpeg" ] }, { "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "Do I need planning permission for a loft conversion?", "acceptedAnswer": { "@type": "Answer", "text": "Often no — Velux and rear dormer conversions on most semi-detached and detached houses fall under Permitted Development. Hip-to-gable and mansard usually need planning. Conservation areas, listed buildings and Article 4 zones always need planning. We confirm during the quote stage." } }, { "@type": "Question", "name": "How long does a loft conversion take?", "acceptedAnswer": { "@type": "Answer", "text": "Velux: 5–7 weeks build time. Dormer: 8–10 weeks. Hip-to-gable: 10–14 weeks. Mansard: 12–16 weeks. Add 8–14 weeks for design, planning and prep before site start. Total from first call to handover: typically 4–7 months." } }, { "@type": "Question", "name": "Do I need to move out during a loft conversion?", "acceptedAnswer": { "@type": "Answer", "text": "No — most loft conversions are done with the family in residence. The roof is opened in stages and made watertight overnight. Disruption is moderate (noise, dust, occasional water-off for plumbing) but liveable. Pets and very small children may benefit from short stays elsewhere during 1st-fix days." } }, { "@type": "Question", "name": "Is my loft tall enough?", "acceptedAnswer": { "@type": "Answer", "text": "Minimum 2.2m head height in the existing space gives the easiest conversion. 1.9–2.2m at the apex usually still works with a dormer or hip-to-gable to lift floor-to-ceiling height. Below 1.9m at the apex, conversion may need roof raising — significantly more expensive." } }, { "@type": "Question", "name": "What's the value uplift on a loft conversion?", "acceptedAnswer": { "@type": "Answer", "text": "In Hertfordshire and Essex, well-executed loft conversions typically add 15–20% to property value — frequently more than their cost. A £55,000 dormer on a £450,000 semi typically lifts value by £55,000–£90,000. Excellent investment in addition to the immediate space gain." } }, { "@type": "Question", "name": "Do you handle planning, Building Control and architects in-house?", "acceptedAnswer": { "@type": "Answer", "text": "We coordinate the whole project including architect, structural engineer, planning submission and Building Control sign-off — single point of contact, single owner-led project management. You don't have to chase three separate firms." } } ] }, { "@context": "https://schema.org", "@type": "BreadcrumbList", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "Home", "item": "https://jandco-contractorsltd.co.uk/" }, { "@type": "ListItem", "position": 2, "name": "Building & Construction", "item": "https://jandco-contractorsltd.co.uk/building-construction/" }, { "@type": "ListItem", "position": 3, "name": "Loft Conversions", "item": "https://jandco-contractorsltd.co.uk/loft-conversions/" }, { "@type": "ListItem", "position": 4, "name": "Loft Conversion Cost UK 2026: Full Price Guide", "item": "https://jandco-contractorsltd.co.uk/guides/loft-conversion-cost-uk/" } ] } ] --- We use essential cookies to run this site, and optional cookies only with your consent. [Cookie policy](/cookie-policy/) AcceptReject Open 7 days · Hours vary by day · 25 years' experience [Office: 01279 216 215](tel:01279216215) | [Mobile: 07379 964569](tel:07379964569) [![J&Co Contractors logo](/assets/jandco-logo-DkXiFtbE.png)](/) Services Areas [About](/about/) [Our Work](/our-work/) [Blog](/blog/) [Reviews](/reviews/) [Contact](/contact/) [01279 216 215](tel:01279216215) [Free Quote](/contact/) 1. [Home](/) 2. [Building & Construction](/building-construction/) 3. [Loft Conversions](/loft-conversions/) 4. Loft Conversion Cost UK 2026: Full Price Guide Guide · Loft Conversions # Loft Conversion Cost UK 2026: Full Price Guide Loft conversions have a wide price range — anywhere from £30,000 for a basic Velux up to £90,000+ for a mansard. Here's what each type actually costs in 2026 and what drives the variation on real Hertfordshire jobs. Last updated: May 2026 · By Jamie Pocock Quick Answer **2026 UK loft conversion costs: Velux £30,000–£45,000, dormer £45,000–£65,000, hip-to-gable £55,000–£80,000, mansard £65,000–£90,000+.** All figures include structure, insulation, plastering, electrics, plumbing, staircase, fire-rated doors and Building Regs sign-off. Bathroom adds £6,000–£12,000. London prices typically 20–30% higher; Hertfordshire and Essex broadly track the national figures above. ![Completed loft conversion with dormer and Velux skylights in a Hertfordshire family home](/assets/wa-435-79-Cfvt7K6N.jpeg) ## Cost by conversion type (2026) ### Velux loft conversion (£30,000–£45,000) Roof space converted with no change to roof shape — Velux skylight windows let light in and the existing roof line stays. Cheapest, simplest, fastest (typically 5–7 weeks). Suits roofs with adequate existing head height (1.9m+ at the apex). Often permitted development without planning permission. ### Dormer loft conversion (£45,000–£65,000) Box-shaped dormer added to the rear (or side) of the roof to create full standing height across more of the floor area. The most popular type by volume — adds significantly more usable space than a Velux for a moderate price uplift. 8–10 weeks typical. Permitted development in many cases (rear dormers under permitted size). ### Hip-to-gable loft conversion (£55,000–£80,000) The hipped end of the roof is rebuilt as a vertical gable wall, creating significantly more internal volume. Often combined with a rear dormer ("hip-to-gable plus rear dormer") for maximum space. Suits hipped semis and detached homes. 10–14 weeks typical. Usually requires planning permission. ### Mansard loft conversion (£65,000–£90,000+) Most expensive and most space-creating. The roof is essentially rebuilt with near-vertical sides and a flat top, creating a full additional storey. Common in London and conservation areas. Always requires planning permission. 12–16 weeks typical. ## What's normally included in those figures - Structural works (steel beams, new floor joists, dormer framing) - Insulation to current Part L (typically 100–150mm PIR plus 50mm internal) - Roof covering, lead flashings, weather detailing - New stairs (usually within existing landing footprint) - Plastering, decorating ready (mist coat included; final paint usually not) - Electrics (1st and 2nd fix), heating extension, smoke and heat detection - Fire-rated doors on landings (Part B compliance) - Velux skylights as designed (typically 2–4 included) - Building Control submission, inspections and final sign-off - Written completion sign-off See our [loft conversion service page](/loft-conversions/) for full scope detail and our [dormer vs Velux comparison](/guides/dormer-vs-velux-loft-conversions/) for choosing between the two simpler types. ## What pushes the price up - **Bathroom or en-suite:** +£6,000–£12,000 depending on spec. - **Architect and structural engineer:** £2,500–£5,500 typical (often paid separately upfront). - **Planning permission:** £258 application fee plus possible drawings revisions. - **Party Wall Act notices and surveyor:** £1,200–£3,500 if works affect a shared wall. - **Premium fittings:** oak doors, designer skylights, bespoke joinery — variable, easy to add £5,000–£15,000. - **Steel and timber prices:** have stabilised since 2023 but remain 20–30% above 2019 levels. ## What you get for each price band Type Cost (2026) Floor area added Time Planning Velux £30k–£45k 15–25 m² 5–7 wks Usually PD Rear dormer £45k–£65k 20–35 m² 8–10 wks Often PD Hip-to-gable + dormer £55k–£80k 30–45 m² 10–14 wks Planning Mansard £65k–£90k+ 35–50+ m² 12–16 wks Planning Direct cost-per-m² comparison: Velux £1,400–£2,000/m², dormer £1,600–£2,200/m², hip-to-gable £1,650–£2,200/m², mansard £1,800–£2,400/m². Mansards cost more per m² because the structural rebuild is significantly larger. ## Things people forget to budget for **Architect and engineer fees.** Often quoted separately to the build cost. Budget £2,500–£5,500 for typical residential drawings, structural calcs and planning submission. Reputable builders will recommend an architect early, not after they've quoted. **Decoration and flooring.** Most build quotes include plaster ready for paint, but not the final paint, flooring, curtains or furniture. Budget another £3,000–£8,000 for these — not insignificant on a £45,000 build. **Heating system upgrade.** Adding a bathroom and 2 radiators upstairs may push your existing boiler past its capacity. Boiler upgrade cost £2,000–£3,500 — worth assessing during design rather than discovering at second-fix. **Property value uplift.** A well-executed loft conversion typically adds 15–20% to property value in our area — frequently more than its cost. The investment case is good, but only if the work is done to a standard surveyors and buyers will accept. **VAT.** Standard rate (20%) applies on most loft conversions. Reduced rate (5%) sometimes available for properties unoccupied 2+ years or for certain conversions — confirm with your contractor early. We discuss VAT position openly during quoting. ![Recently completed roofing project by J&Co Contractors in Hertfordshire](/assets/wa-435-169-BMBPQKLs.jpeg) 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 ### Do I need planning permission for a loft conversion? ### How long does a loft conversion take? ### Do I need to move out during a loft conversion? ### Is my loft tall enough? ### What's the value uplift on a loft conversion? ### Do you handle planning, Building Control and architects in-house? Related Guides [Dormer vs Velux loft conversions](/guides/dormer-vs-velux-loft-conversions/) [How much does a house extension cost?](/guides/how-much-does-a-house-extension-cost/) [Back to Loft Conversions](/loft-conversions/) ## Planning a loft conversion in 2026? We deliver Velux, dormer, hip-to-gable and mansard conversions across Hertfordshire and Essex. Owner-led project management, single team, written fixed quote — no day-rate drift. [See our loft conversions service](/loft-conversions/) [01279 216 215](tel:01279216215) Page last updated: May 2026 · J&Co Builders Ltd · 1 Ugley Hall Cottages, Bishop's Stortford CM22 6JB ![J&Co Contractors](/assets/jandco-logo-DkXiFtbE.png) Owner-led roofing and building contractors covering Bishop's Stortford, Hertfordshire and Essex. 25 years of hands-on trade experience. Open seven days. 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