Rear, side return, wrap-around and double-storey extensions, built by the team that also runs the structure, the heating and the electrics. One programme, one account, one set of certificates at the end.
Most homeowners arrive with a type in mind. It is worth testing it against the plan you actually have, because the cheapest extension is rarely the one that adds the most usable room.
Not every extension needs planning permission. Many single-storey rear extensions fall under permitted development, and where they do we'll apply for a Lawful Development Certificate so you have written confirmation on file for when you sell.
Permitted development rights are removed in some places — conservation areas, flats, and anywhere the council has made an Article 4 Direction. Several of the areas we work in are affected, so this is worth establishing before you settle on a design.
If your extension sits on or near a boundary, the Party Wall etc. Act 1996 applies. Notices have to be served on the neighbours, and where they dissent, surveyors are appointed and an award agreed before work can start. It is a common cause of delay and an avoidable one — we raise it at quote stage, not at mobilisation.
Groundworks are the least visible and least predictable part of an extension. Trees, made ground, a high water table or a neighbouring foundation deeper than yours can all add depth — and depth is concrete, labour and time before anything above ground begins.
Above ground, glazing usually carries the biggest single spec decision. A structural glazed corner or a sliding door run at three metres wide is a different proposition to a standard set of bifolds, both to buy and to install.
The third driver is what the extension does to the rest of the house. Opening the back of a property into a new space often means relocating the kitchen, extending the heating circuit, adding a zone of underfloor, and re-running power and lighting across the whole ground floor. That work is part of the project whether or not it appears in the extension drawing.
Often not. Many single-storey rear extensions on a house fall within permitted development, subject to depth, height and boundary limits. But permitted development rights don't apply to flats, are restricted in conservation areas, and can be withdrawn entirely by an Article 4 Direction. We check your specific address rather than assume, and we recommend a Lawful Development Certificate even where permission isn't needed.
A single-storey rear extension is typically 10–16 weeks on site. A wrap-around or double-storey is usually 16–26 weeks. Add lead time in front of that for design, structural calculations, planning determination where required, and party wall awards — that front end is frequently longer than the build itself.
If you're building on the boundary, cutting into a shared wall, or excavating within three metres of a neighbour's foundation at a lower depth, then yes. Notices need serving two months before work starts for party wall work, one month for excavation. We flag this at quote stage so it doesn't become the thing that delays your start date.
Yes, and we'd rather see them early. Reviewing a set before it goes to tender usually surfaces two or three details that are expensive to build as drawn and cheap to resolve on paper.
Yes — foundations, drainage, temporary support and steelwork are all in-house rather than subcontracted out. It's the phase where coordination matters most and where a split programme causes the most delay.
What it costs, what consent you need, and what to check before taking a quote.
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