Often, but not always. Many rear extensions fall under permitted development, which means no application is needed — one of the projects on this site was built that way. But permitted development has strict limits and they are easy to trip over without realising: how far you can project, how high, how close to a boundary, and what has already been added to the house in the past. 

It is also restricted, or not available at all, in some situations. Flats and maisonettes do not have the same rights as houses. In conservation areas the rights are narrower, and in some places they have been removed by an Article 4 direction. Listed buildings need listed building consent for most changes, whatever the planning position. And extensions forward of the front of the house, other than a small porch, are not permitted development. 

We can usually tell you on the phone whether your project is likely to need permission. The Feasibility & Options Study gives you a clear written answer for your address. 

Every project is different, and anyone who gives you a single number without seeing the house is guessing. But the shape is usually similar. 

Feasibility & Options Study: about three weeks from the site visit. Design: four to eight weeks, depending on how many rounds of changes you want. Planning: a householder application is normally determined within eight weeks of validation, longer if it is unusual or goes to committee. Building Regulations: four to six weeks, including coordinating the structural engineer. 

So from the first conversation to a set of drawings a builder can price, six to nine months is realistic for most projects. The build itself is separate and depends on your builder. 

We are architects, not builders, so we do not price building work — and we would not trust an architect who claimed to. Costs vary enormously with the specification you choose, the condition of the existing house, ground conditions, access and how much of the house you are touching. 

What we do give you, in the Feasibility & Options Study, is an indicative range. That is enough to tell you early whether your ambition and your budget are in the same place, which is the question that actually matters at the start. 

A firm figure comes later, when builders price your actual drawings. 

Because a free visit is not really free. It is paid for by the clients who do go ahead, and it is designed to win you as a customer rather than to answer your question. 

What most people actually need at the start is not a sales visit. It is an answer: can this house do what we want, will the council allow it, and roughly what will it cost to build? That takes a site visit, a proper look at the planning position for your specific address, and several hours of an architect’s time. 

So we do that work properly and charge £625 + VAT for it, and we credit the whole amount against your design fee if you appoint us within six months. If you do not, the report is yours to keep and use however you wish. 

Once. Every other residential application we have submitted — 26 of them — has been approved, and the one refusal was later overturned on appeal. 

That record is not luck. It is what comes of testing the planning position before the design is fixed rather than after, which is exactly what the Feasibility & Options Study is for. 

If it did happen to you, we would tell you plainly why. A refusal notice sets out the officer’s reasons, and in most cases those reasons point at something that can be designed out. Amending the scheme and submitting a fresh application is usually the sensible route; the council charges a new application fee for it. 

Redesigning and resubmitting is charged as additional work, and we would agree the cost with you before starting. We do not handle planning appeals; if an appeal were the right answer rather than a resubmission, we would say so and help you find a planning consultant who specialises in them. 

No, and we say so clearly rather than letting it become a surprise later. Our appointment takes your project to Building Regulations approval — the drawings a builder needs to price and build from. We do not act as project manager or contract administrator on residential projects. 

Two optional services sit alongside the build. Tender support: we prepare a short tender package, issue it to up to three builders and give you a written comparison of what came back — where the prices differ, what each has included and excluded, and which is genuinely the better offer. Design visits: we visit at key moments to check that what is being built is the house we designed. Building Control checks compliance; nobody but us checks the design intent

For homes, we work across East and West Sussex, broadly from Brighton to Chichester. Being close enough to visit easily matters more on a house than people expect. 

For commercial, industrial and education projects we work across Sussex and Hampshire. If you are further afield, ask — depending on the project it may still make sense.