Frequently asked questions

Modern basements are dry, warm, comfortable spaces. We use waterproofing systems designed to BS 8102 (the UK’s governing code of practice for waterproofing below-ground structures), which is typically a cavity drainage membrane with a sump and pump, sometimes combined with tanking, giving two independent forms of protection. Properly installed systems come with long-term guarantees – and ours do, of course.

Converting an existing cellar into living space usually doesn’t, as it’s a change of use of existing space within the home. Excavating a new basement or enlarging one, adding lightwells, or altering the external appearance generally does require permission, and some London boroughs have specific basement policies. We’ll confirm the position for your property before any work begins.

Through lightwells, glazed pavement lights, sunken courtyards and carefully positioned internal glazing. Good lighting design, layering natural and artificial light, is a core part of our basement schemes, so the finished space feels like a natural extension of your home rather than a cellar.

In areas where space is at a premium and moving costs are high, basements are often the most valuable square footage you can add, commonly used for gyms, cinema rooms, home offices, utility rooms or self-contained guest suites. Whether the numbers stack up depends on local property values, and we’re always honest with clients about whether a basement makes financial sense for their street.

There are three main types: a half basement, which converts or extends a partially below-ground space such as an existing cellar; a garden basement, built out beneath the garden with lightwells or a sunken courtyard; and a full basement, excavated beneath the entire footprint of the house. The right option depends on your property, how much space you need and your budget. Our basement conversion process guide covers each in detail.

Schemes come and go. At various points these have included the Boiler Upgrade Scheme (for heat pumps) and ECO funding for insulation, with eligibility rules that change regularly. We’d recommend checking the current position on GOV.UK or with your energy supplier before your project starts, and we’re happy to design the work so it qualifies where possible.

Absolutely. New work must meet current Building Regulations (Part L), which demand far better insulation and airtightness than most existing housing stock. A well-built extension or loft conversion is typically the warmest, most efficient part of the house, and the project is a great opportunity to upgrade insulation, glazing and heating in adjoining areas at the same time.

A lot. Around a quarter of a typical home’s heat is lost through the roof alone, so insulating properly during a loft conversion often reduces bills for the whole house. Upgrading glazing, insulating solid walls during an extension and improving airtightness all compound the savings, and they make the home noticeably more comfortable year-round.

A build project is the cheapest time to add them, because scaffolding is already up, floors are already open – or yet to exist in entirety – and electrics are being rewired anyway. Underfloor heating pairs particularly well with heat pumps and works brilliantly in extensions and basements. We can incorporate any of these into your design and connect you with accredited installers. It’s also worth thinking about air conditioning options as British summers get hotter.

Where the budget and design allow, we use responsibly sourced (FSC-certified) timber, high-performance insulation, low-VOC paints and finishes, and locally sourced materials to cut transport miles. We also segregate and recycle site waste wherever possible rather than sending everything to landfill.

Yes. We carry full public liability and employer’s liability insurance, and our work is guaranteed for 10 years. Structural work and waterproofing systems carry their own long-term warranties, and you’ll receive all certificates, including electrical, gas and building control, on completion.

Look for a written contract, a detailed itemised quote rather than a single line saying “extension: £80,000”, staged payments rather than large sums up front, proof of insurance, and, most importantly, recent references and completed projects you can actually see. We’ll happily provide all of the above, and you can read more about how we work on our Why Choose Us page.

Get in touch for a free, no-obligation consultation. We’ll visit your property, talk through what you want to achieve, give you an honest view on feasibility and budget, and follow up with a written proposal. From there, you decide the pace.

It can happen, especially in older properties. If we uncover something such as rot, poor foundations or hidden pipework, we stop, show you the issue, explain the options and agree any cost or programme change in writing before proceeding. No work is ever added to your bill without your sign-off.

We offer a full design-and-build service, meaning drawings, structural engineering, planning, building control and construction are all managed under one roof with a single point of contact, in the form of your own dedicated project manager. If you already have an architect, that’s fine too: we’re equally happy working to your existing drawings.

Yes, and most of our clients do. We section off the work area, maintain access to kitchens and bathrooms for as long as possible, and keep the site clean and secure at the end of every day. For kitchen extensions, we can often set up a temporary kitchen area to keep disruption manageable.

If your extension involves excavating within 3m of a neighbour’s structure, or building on or near the boundary, the Party Wall etc. Act 1996 applies and you’ll need to serve notice on your neighbours. It’s a routine process. Our party wall guide explains it step by step, and we have experienced party wall surveyors where needed.

Not always. Single-storey rear extensions of up to 6m (semi-detached and terraced) or 8m (detached) can often be built under Permitted Development via the prior approval process. Side extensions, two-storey extensions and anything beyond these limits usually need full planning permission. We have a more in depth article on planning permission here.

We manage the whole process on your behalf, including drawings and submissions. And a word of caution: since April 2024, unauthorised building work can face enforcement action for up to 10 years, so it’s never worth skipping the proper route.

A typical single-storey rear extension takes 10 to 14 weeks on site, and a two-storey or wraparound extension 14 to 20 weeks. Before that, you’ll also need to allow time for design, planning approval and structural calculations. We’ll give you a realistic programme at the outset and keep you updated weekly. Our house extension process guide explains more.

As a general guide, single-storey extensions in and around London typically start from £2,500 to £3,000 per square metre for a good-quality build, but this is excluding the costs of kitchens, bathrooms and the ever-dreadedVAT.
Two-storey extensions tend to offer better value per square metre because you’re doubling the space over one set of foundations and under one roof. We provide itemised, fixed-price free quotations so there are no surprises.

In most cases, no. The majority of loft conversions fall under Permitted Development rights, provided the new space doesn’t exceed 40 cubic metres for terraced houses or 50 cubic metres for detached and semi-detached homes, and any dormers sit below the existing ridge line.

Exceptions will apply if you live in a conservation area, a listed building, or a flat or maisonette. We check all of this as part of every initial survey and handle the application for you. For the full picture, see our planning permission guide here.

Typically 8 to 12 weeks, but this is depending on the type. A simple rooflight (Velux) conversion sits at the shorter end, while a dormer or hip-to-gable conversion takes longer. Most of the work happens from the outside via scaffolding, so disruption inside your home is kept to a minimum until the final stages. Check out our loft conversion process guide to go through every stage from survey to sign-off.

The key measurement is head height: you generally need at least 2.2m from the top of the ceiling joists to the underside of the ridge, but there can be some flexibility there in some instances. Roof structure matters too. Traditional cut roofs are usually straightforward, while modern trussed roofs need structural alterations, which is still very doable and simply factored into the design. We will check the feasibility before you commit to anything.

The main options are rooflight (often called by the brand name of skylight Velux), dormer, hip-to-gable and mansard. Dormers are the most popular because they add significant floor space and headroom at a sensible cost. Mansards create the most space but involve the biggest structural changes. A well-designed loft conversion with an en-suite could add 15 to 20% to a property’s value. If you’re weighing up a loft conversion against an extension, our guide on what build project is best for your house compares the two.

Yes. All our conversions are designed and built to comply with Building Regulations, covering structural stability, fire safety (including escape routes and fire doors), insulation and staircase design. You’ll receive a completion certificate at the end, which you’ll need when you come to sell or remortgage.

All our quotations state clearly whether figures include VAT, which is charged at the standard 20% on most residential building work. We itemise what’s included and, just as importantly, what’s excluded, such as planning fees, party wall surveyor costs or client-supplied fixtures, so you can budget for the full picture from day one.

Usually, yes, particularly loft conversions and kitchen extensions in high-demand areas, where added value commonly exceeds build cost. That said, every street has a ceiling price. If we think a proposed project won’t make financial sense for your property, we’ll tell you before you spend money on design fees.

We work to a transparent staged payment schedule tied to milestones, for example: deposit, completion of foundations and structure, watertight stage, first fix, second fix and final completion. You only pay for work as it’s completed, and the schedule is set out clearly in your contract before we start.

Common routes include remortgaging or a further advance from your existing lender, a secured homeowner loan, savings, or specialist renovation finance. We’re builders rather than financial advisers, so we can’t recommend specific products, but we can provide the detailed, staged cost breakdowns that lenders typically ask for, and we’d always suggest speaking to an independent mortgage broker or financial adviser before committing.

Yes. We recommend all clients keep a contingency of around 10 to 15% of the build cost. Older properties in particular can hide surprises such as unrecorded drains, historic alterations or poor previous work. Our detailed surveys minimise unknowns, but a contingency means an unexpected discovery is an inconvenience rather than a crisis.