House Extensions in Cornwall
An extension should feel like part of your home from day one. Edge Construction Cornwall designs and builds high-quality extensions across Cornwall that add space, comfort and long-term value. From contemporary open-plan kitchen diners to double storey additions that replan an entire home, we manage every stage with care and technical precision. Our team understands Cornish properties, coastal conditions and local planning expectations, so your project progresses smoothly, stays compliant and delivers the look and performance you expect.
We combine practical building experience with a clear, collaborative process. You will know what is happening, when it will happen and how decisions affect time and cost. Whether you bring your own architect or want us to work with you from concept, our focus is the same — a beautifully built, safe and durable extension that enhances daily life.
Design-led extensions for modern living
Well-planned extensions are about more than extra square metres. The best results re-balance a home so that circulation, daylight and sightlines feel natural. We look at how you live now and how you want to live next, then shape the extension around those needs. This might mean relocating the kitchen to the heart of the plan, adding a utility to keep clutter out of living areas or creating a stronger connection to the garden with wide openings and low-threshold access.
Natural light drives many extension projects. Rooflights, slimline glazing, clerestory windows and corner frames can transform north-facing rooms and long plans. We coordinate structure and services early, so steelwork, lintels and drainage routes support the design rather than compromise it. Thermal performance is equally important. We specify robust insulation, careful airtightness details and cold bridge control so the new envelope performs in winter without overheating in summer.
External appearance matters in Cornwall’s varied streets and rural settings. We can match existing stone, slate and render for a seamless look or create a considered contrast with timber cladding, zinc, aluminium or brick slips. Either way, we pay attention to junctions, trims and weathering details, because these are the parts that decide how well a building ages.
Single storey, double storey and wraparound solutions
Different homes need different extension types. A single storey rear extension is ideal for larger kitchen diners, snug spaces or home offices that open to the garden. Side return extensions unlock narrow Victorian and Edwardian plans, turning long galley kitchens into bright spaces with improved storage. Wraparound extensions combine rear and side volumes to reshape the ground floor entirely, often adding a utility, boot room and better access.
Double storey extensions deliver transformative change. They can create an extra bedroom with an en-suite, replan a cramped landing or add a study with quiet separation from family areas. Where rooflines meet, we plan the structure carefully so loads transfer cleanly and eaves details remain crisp. We use tried and tested approaches for foundations, steel design and floor build-ups, which helps avoid delays once work begins.
Whatever the form, the build should support day-to-day life. We plan temporary protection, clear access routes and phased works that keep neighbours and site teams safe. Waste management, deliveries and material storage are scheduled to suit tight plots, narrow lanes and coastal weather. The result is a tidy site and steady progress from groundworks to final finishes.
Planning permission and building regulations in Cornwall
Some extensions fall within permitted development, others require full planning. We help you understand the route that fits your home, location and goals. Height, depth and boundary distances all matter, as do roof forms and materials. In Cornwall, conservation areas, Areas of Outstanding Natural Beauty and coastal settings can add extra considerations. Early advice can save redesigns later, so we flag risks and opportunities before drawings are fixed.
Whatever the planning route, building regulations apply. Structure, fire safety, ventilation, drainage, energy performance and glazing all need to meet current standards. We coordinate with designers and building control from the outset, so details such as cavity closers, DPC levels, insulation thicknesses and escape windows are resolved early. Certification and sign-off are part of our agreed handover, giving you clear records for insurers, surveyors and future buyers.
Party Wall matters can arise where work is close to boundaries or shared walls. We can coordinate with surveyors and neighbours so notices, access and protections are in place. This keeps relations positive and avoids avoidable delays once excavation and structural phases begin.
Structure, foundations and envelope performance
Every successful extension starts below ground. We assess soil conditions, drainage paths and existing foundations, then select the right solution for your plot. Options include trench fill footings, deep strip foundations and reinforced slabs. On sloping or made ground, we may use ground improvement or engineered solutions that control settlement and protect the main structure. Accurate setting out and careful excavation are essential, so we invest time here to avoid later problems.
Above ground, structural steelwork often unlocks open-plan layouts. We coordinate beam sizes, padstones and connection details with your engineer, then install steel to tight tolerances so ceilings stay flat and lines stay true. Lintels, timber I-joists and composite beams are used where they add value or save headroom. We plan service routes through the structure so pipes, ducts and cables do not compromise fire stopping or acoustic performance.
The new envelope must be warm, dry and quiet. We detail insulation at junctions, use high-performance membranes where needed and specify windows and doors that balance U-values with daylight. Thresholds, cills and flashing details are set out to shed water cleanly. Where new meets old, we treat damp proofing, cavities and ventilation with care so the whole building works as one.
Kitchens, utilities and services integration
Most extensions change how services run through a home. We plan electrical layouts for working kitchens, home offices and media walls, with thought for task lighting, island sockets and smart control. Plumbing routes consider hot water recovery, efficient radiator placement or underfloor heating, plus sensible locations for manifolds and valves. Extract ventilation is sized for real-world use so moisture leaves quickly and quietly.
Kitchens and utilities benefit from early coordination. Appliance sizes, worktop runs and storage heights influence window positions, steel drops and MVHR routes. We build in zones for recycling, cleaning and pantry storage so daily life feels ordered. Where extensions open to gardens, we allow for boot storage, durable floor finishes and easy-clean details that make busy homes easier to manage.
Acoustics matter in open plans. We use discreet measures such as acoustic plasterboard, resilient bars and soft finishes to control sound between rooms and floors. The result is a calm space that works for meals, homework and entertaining without echo or noise transfer becoming a frustration.
Materials, detailing and finishes that last
Cornwall’s weather demands robust materials and careful detailing. We choose products that handle wind, rain and salt air well, then install them to the manufacturer’s guidance. Render systems receive proper beads, mesh and movement joints. Timber cladding is detailed with ventilation gaps and durable species. Aluminium frames are set with correct packers, sealants and end caps so edges stay tight and clean.
Inside, durable finishes keep maintenance down. Moisture-resistant boards in wet zones, washable paints and properly primed joinery help surfaces stand up to daily use. We recommend flooring that balances comfort with resilience, whether engineered timber, porcelain or LVT. Where natural stone is used, we pay attention to bedding, sealing and movement so floors and terraces remain level and stain resistant.
Small choices add up. Flush thresholds, tidy trims and neat service plates make spaces feel considered. We finish with careful snagging and a documented handover so you know how to look after each element across seasons.
Programme, communication and cost confidence
Clear programming keeps projects on track. We map the build into phases — groundworks, structure, shell, first fix, finishes and commissioning — then update you as each phase completes. Weather windows are planned into external works, long-lead items are ordered early and trades are sequenced so tasks do not clash.
Cost control is practical and transparent. We price clearly, agree change procedures and highlight choices that affect budget, for example roof lights, large spans or premium cladding. Regular site meetings and simple reporting give you confidence about progress and spend. If an unforeseen issue appears, we explain options and act quickly to protect time and quality.
Health and safety is integrated into daily routines. Sites are kept tidy, access is controlled and risk assessments guide how tasks are done. Neighbours are treated with respect and informed about key stages such as deliveries or steel installation. The aim is a steady, low-stress build that finishes well and stands the test of time.
How does this affect you?
A thoughtful extension can change how a home works day to day. More space is only part of the story. Better light, improved storage and easier movement often matter more over time. By focusing on structure, performance and the details you touch, Edge Construction Cornwall builds extensions that feel integrated from the first week and continue to repay the investment year after year.
If you are weighing up single storey, double storey, side return or wraparound options, the principles above will help you judge what will serve you best. Look for a plan that improves flow, a structure that feels solid underfoot and an envelope that is warm in winter yet bright in summer. When these elements come together, the result is a home that supports life as you live it in Cornwall’s unique settings.
