07834 989360 Mon–Fri, 8am–5pm - AboutServicesAreasOur WorkReviewsContact07834 989360Request an Estimate Home/ - Areas we cover/ - Builders in Sidcup Sidcup · Rated 5.0 on Google # Your local Sidcupextension andrefurbishment team Sidcup is home. Our office is on Main Road, and a good share of our work is within a few miles of it: extensions, lofts, refurbishments and structural alterations. Request an estimate07834 989360 Written, itemised estimate after a survey, no obligation to proceed. 30 yearsof construction experience across the team CABE membersprincipals are members of the Chartered Association of Building Engineers 5.0 starsrated 5.0 from 14 Google reviews One point of contactdesign coordination, planning, procurement, build and supervision under one contract Building in Sidcup ## We work in Sidcup, and we know its houses Sidcup is where we are based: Onega House, 112 Main Road, Sidcup, DA14 6NE. A good share of our projects are within a few miles of the office, and we are contactable Monday to Friday, 8am to 5pm. Being local is not a marketing line here: it means surveys happen quickly, the drawings get discussed in person, and the people accountable for your build are in the same town. It also means we stand behind our work in the area we live and work in. Word travels in Sidcup, Blackfen and Albany Park, and a good share of our enquiries come from people who have seen a job or been told about one. The housing stock runs from inter-war semis and detached houses through post-war estates to newer development, with older cottages and larger period properties in among them. Our brickwork, carpentry and roofing trades know this stock well: which brick matches which era, how the roofs are built, where the drains usually run. The work we are asked for most locally is rear and side extensions to open up kitchens, loft conversions for an extra bedroom, structural openings between reception rooms, garden rooms and home offices, and complete refurbishments after a purchase. We also take on smaller structural work, a single opening, a chimney breast removal, where the design and sign-off need doing properly. Being local means we can survey quickly, get to site when it matters and stand behind work in the area we live in. It also means our brickwork and roofing trades know the local housing stock well. Every Sidcup project runs through the same five stages: design, planning and preparation, procurement, construction and project supervision, all managed under one contract by a team with 30 years of experience, with principals who are members of the Chartered Association of Building Engineers. You can request an estimate or read more about how we work. ## Get an estimate in Sidcup Send us the details and we'll be in touch during working hours, Mon–Fri, 8am–5pm. Services in Sidcup ## What we build in Sidcup ### Home Extensions Single-storey, double-storey and wraparound extensions, design coordinated and built by one team. Home extensions in Sidcup ### Loft Conversions Turn unused roof space into a bedroom, en-suite or office, structurally sound and building-control signed off. Loft conversions in Sidcup ### New Build Homes Individual new build homes delivered from design package through to completion. New build homes in Sidcup ### Full Refurbishments & Renovations Whole-house refurbishment, kitchens, bathrooms and period property renovation, managed end to end. Refurbishments & renovations in Sidcup ### Internal Alterations Knock-throughs, new openings, reconfigured layouts and structural steels installed safely. Internal alterations in Sidcup ### Outbuildings & Garden Rooms Insulated garden rooms, home offices, gyms and garages built to last all year. Outbuildings in Sidcup ### Architectural Drawings & Design Coordination Survey, concept, planning and construction drawings coordinated with our recommended architects, ready to build from. Drawings & design in Sidcup ### Structural Works Steels, foundations, load-bearing alterations and structural repairs. Structural works in Sidcup ### Carpentry & Joinery First and second fix carpentry, roof structures, staircases and fitted joinery. Carpentry in Sidcup ### Brickwork Extensions, garden walls, repointing and matched brickwork on period properties. Brickwork in Sidcup ### Roofing Pitched and flat roofing, dormers, leadwork and roof coverings on new and existing homes. Roofing in Sidcup ### Electrical, Plumbing & Gas Coordinated through vetted, accredited subcontractors: NICEIC/NAPIT registered electricians and Gas Safe engineers. Electrical & plumbing in Sidcup Why Ashcroft ## Why homeowners in Sidcup choose us ### Our office is here We are based at Onega House, 112 Main Road, Sidcup, DA14 6NE: this is our home patch, not an outlying area. ### Surveys arranged quickly Being local means a survey and a face-to-face conversation over the drawings are simple to arrange within working hours. ### 30 years of experience 30 years of construction experience across the team, on residential work and some commercial projects. ### CABE-member principals Our principals are members of the Chartered Association of Building Engineers and follow its codes of practice. ### Rated 5.0 on Google 5.0 stars from 14 Google reviews from clients in and around Sidcup. ### Everything under one contract Design coordination, planning and preparation, procurement, construction and supervision are all managed under one contract. Local property issues ## What we typically find on Sidcup properties ### Inter-war roofs and loft head height Many local roofs have adequate but not generous head height, and were built with lighter timbers than current standards. Both need measuring and designing around before a loft layout is fixed. ### Trees, clay and foundation depth Mature trees in the long back gardens common around Sidcup and Blackfen affect foundation depth on shrinkable ground. That is a survey item with a real cost, not an afterthought. ### Blocked sub-floor ventilation Decades of raised patios, new paths and blocked air bricks stop suspended timber floors breathing. The result reads as damp indoors and eventually as rot in the joists. ### Earlier extensions built to old standards Where a house already has a 1970s or 80s addition, its foundations, roof falls and insulation rarely meet today's requirements. Building onto it means checking it first. None of this is unusual, and none of it is a reason not to build. It is the reason we survey before we design and design before we price, so what turns up in Sidcup is in the estimate rather than in a mid-build conversation about extra cost. How it works ## Five stages, all managed under one contract - 01 ### Design We take your brief, survey the property and coordinate the drawings and design package with our recommended architects and engineers, so you have no separate consultants to find or brief. - 02 ### Planning & preparation Applications, building control and the programme of works are prepared and coordinated before anyone lifts a tool. - 03 ### Procurement Materials and vetted trades are secured against a fixed scope, so the build starts with everything in place. - 04 ### Construction Your build is delivered by skilled tradesmen working to the agreed drawings, programme and standard. - 05 ### Project supervision A named point of contact supervises the site, handles building control and keeps you updated to completion. Sidcup questions ## Frequently asked questions Where in Sidcup are you based?+Onega House, 112 Main Road, Sidcup, DA14 6NE. We are open Monday to Friday, 8am to 5pm. How quickly can you come and look at my house?+Because we are based in Sidcup, local surveys are easy to arrange during working hours. Call us and we will agree a time. What does an extension or loft conversion cost in Sidcup?+It depends on size, ground conditions, the amount of structural work, glazing and internal specification. We survey and issue a written estimate with the scope broken down item by item. Do you take on smaller jobs locally?+Yes: single structural openings, chimney breast removals, kitchens and bathrooms, and internal alterations, alongside larger extension and refurbishment contracts. Do you handle the drawings too?+Yes, though we do not draw them ourselves: we coordinate them with our recommended architects and engineers, and we prepare and coordinate planning applications and building control. Can I see examples of your work nearby?+Our work page shows the type and standard of projects we deliver, and current work is posted on our Instagram. Get in touch and we can talk through comparable local projects. Do you offer emergency call-outs?+No. We are a design-and-build contractor delivering planned projects rather than an emergency repair service. Which areas around Sidcup do you cover?+Blackfen, Welling, Bexley, Bexleyheath, Crayford, Dartford and the wider South East London and Kent area. Rated 5.0 from 14 reviews ## What our clients say “Adam, Robbie and the team were fantastic delivering our kitchen extension and bathroom, great communication throughout and happy to adjust the design as we went.”Peter TingayKitchen extension & bathroom“Adam and Rob's team did an amazing job on our extension, from start to finish they made the process straightforward and painless.”Keith WeirHome extension“Professional, friendly and did a wonderful job creating a new opening between rooms in our Victorian home. Adam communicated clearly throughout. Highly recommend.”Holly MillsStructural opening Coverage ## Areas near Sidcup we also serve Builders in BexleyBuilders in WellingBuilders in CrayfordBuilders in BlackfenAll areas we cover Alongside Sidcup we work across Blackfen, Welling, Bexley, Crayford and the wider Kent and South East London area from our office at Onega House, 112 Main Road, Sidcup, Kent, DA14 6NE. If you are not sure whether your postcode is covered, contact our Sidcup builders and we will tell you straight away. You can also see examples of our work or start from our home page. ## Planning work in Sidcup? Tell us about the property and what you want to achieve, or call 07834 989360. Request an estimate07834 989360 Extension, loft conversion and refurbishment specialists based in Sidcup, working across London, Kent and the surrounding areas. 5.0 from 14 Google reviews Facebook - Instagram ## Services Home extensions - Loft conversions - New build homes - Refurbishments & renovations - Internal alterations - Outbuildings - Drawings & design - Structural works ## Areas we cover - Bexley - Kent - South East London - Welling - Sidcup - Bexleyheath - Dartford - Crayford - Blackfen ## Get in touch - 07834 989360 - info@ashcroftconstructiongroupltd.co.uk - Onega House, 112 Main Road, Sidcup, Kent, DA14 6NEMonday8am – 5pm Tuesday8am – 5pm Wednesday8am – 5pm Thursday8am – 5pm Friday8am – 5pm SaturdayClosed SundayClosed © 2026 Ashcroft Construction Group Ltd. All rights reserved. ReviewsCookie policyPrivacy policyTerms & conditionsPrincipals are members of the Chartered Association of Building Engineers (CABE). 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