Self-contained annexes for the people you love — independent living for a parent or adult child, with their own bedroom, bathroom, kitchen and entrance, close to the main house but private. Garden annexes, attached extensions and conversions, designed for accessibility and built by one team under one fixed-price contract, with the planning handled.
A granny annexe answers one of the hardest questions a family faces: how to keep a parent close as they age — or give an adult child a foothold — without anyone losing their independence or privacy. The answer is self-contained accommodation on your own property: a place with its own front door, bedroom, bathroom, living space and kitchen, where a relative lives their own life, a few steps from yours.
This page is for the granny annexe, the granny flat, the self-contained annexe — designed for genuine independent living and built to last. As a design-and-build contractor, we deliver the whole thing under one fixed-price contract: the feasibility and planning, the structure, the accessible kitchen and bathroom, the services and metering, and the finish — whether the annexe is a new garden building, an attached extension or a conversion of existing space.
Annexes are different from a garden office in one crucial respect: they are living accommodation, which almost always requires planning permission and is assessed by the council as ancillary to the main house. Getting that planning approach right at the outset is the single most important decision, because it shapes everything — what you can build, where, and on what conditions. We have a strong track record securing annexe consents across London and will advise you honestly on what is achievable on your plot before you spend on detailed design.
The best annexes are designed for how needs change. We build in step-free access, an accessible bathroom and reachable controls from the start, and provide for future adaptations — rails, a hoist, a wet room — so the space works comfortably for an active parent today and adapts gracefully as they age. The aim is an annexe that feels like a welcoming home, not a medical facility, while quietly being ready for whatever comes.
We have designed and built annexes and self-contained accommodation across NW3, NW8, NW11, N6 and SW London — garden annexes in longer plots, side and rear extensions with their own entrances, and conversions of garages and lower-ground floors. Each is designed around the relative who will live in it and the family around them.
The right approach depends on your plot, your budget, the level of accessibility and the planning context. These are the six we build most.
A purpose-built, fully self-contained building in the garden — the most private and independent option, with its own everything. Single-storey and step-free for accessibility, designed to sit comfortably in the garden.
A single or two-storey extension with its own entrance, attached to the house but self-contained — close and weather-protected, ideal where the garden is small or a relative wants to be under the same roof.
An attached or detached garage converted into self-contained accommodation — one of the most cost-effective routes, reusing an existing structure and footprint while adding insulation, services and an accessible layout.
Part of the house — a lower-ground floor, a wing, or a self-contained level — converted into an annexe with its own access. Keeps everyone under one roof while giving real independence.
Where the plot and planning allow, a two-storey annexe gives a separate bedroom floor and more generous living space — suited to a couple or longer-term independent living, with a lift or stair as needed.
A single-storey annexe designed around accessibility from the ground up — level access, wide doors, a wet room, reachable controls and provision for hoists and rails. Comfortable now, ready for changing needs.
A self-contained annexe is a complete small home. Every element below is delivered and warranted under one fixed-price agreement.
Architectural design of the annexe around the relative who will live in it, the planning strategy to keep it ancillary to the house, and the full application managed in-house — the critical first step that shapes everything.
For a new annexe, engineered foundations and a fully insulated structure; for a conversion, upgrading the existing shell — all built to be warm, dry and comfortable as a year-round home, not an outbuilding.
A full kitchen or a kitchenette to suit how independent the annexe needs to be — with accessible-height units and pull-out storage where required, so daily life is genuinely self-sufficient.
A level-access wet room or accessible bathroom — walk-in shower, grab rails, comfort-height fittings and a layout that works with a wheelchair or frame — designed to luxury standard, not a clinical one. See our accessible bathrooms page.
A comfortable bedroom and a living area sized for real life, with good daylight and storage — the heart of an annexe that feels like a home rather than a single room with facilities.
Level thresholds, gentle ramps where ground levels differ, wide doorways and circulation that works with a frame or wheelchair — designed in from the start, not retro-fitted as an afterthought.
Efficient heating and a well-insulated envelope sized for an occupant who may be home all day and feel the cold — warmth and low running costs are a genuine welfare consideration, not just a spec line.
Power, water, drainage and data run to the annexe, with the option of separate or sub-metering — and accessible, reachable switches, sockets and controls throughout.
Where the annexe is attached to or part of the house, proper fire separation, detection and escape designed to Building Regulations — keeping both the annexe and the main house safe.
Structural provision for grab rails and ceiling hoists, blocking behind walls, and a layout that can adapt — so the annexe meets needs that may grow over the years without another building project.
A warm, homely finish to the standard of the main house — this is somebody's home, and it should feel like one, not like a unit.
A two-stage snag, commissioning, a 12-month defects period, a 10-year workmanship warranty and a six-month service visit.
An annexe has to serve the relative who lives in it and the family around it. These are the six things we resolve at design stage.
The balance between privacy and closeness — a separate entrance and full facilities for autonomy, positioned so family is a knock away. We design the relationship between annexe and house deliberately.
Step-free access, wide doors, a wet room and reachable controls designed in — far better, and cheaper, than adapting later. Comfortable now and ready for changing needs.
Good daylight, generous-feeling space, real storage and a warm finish, so the annexe is somewhere a relative is genuinely happy to live — not a box that feels like a compromise.
Getting the planning strategy right first — ancillary use, conditions, what the council will accept on your plot. The decision that determines whether the project is straightforward or stuck.
An occupant home all day, possibly on a fixed income, needs a warm, cheap-to-run home. Insulation and efficient heating are a welfare decision as much as a technical one.
An annexe that can later become a home office, guest suite or teenager's space — designed so it adds lasting, adaptable value to the property whatever the family needs next.
An annexe is a sensitive project — for a family member — and it rewards a careful, well-planned process.
We discuss who the annexe is for, the level of independence and accessibility needed, and your budget — at your home so we can assess the options. No charge, no obligation.
A survey of the plot or space, and a feasibility report on the best route — garden, attached or conversion — with the planning strategy and an outline cost band.
The annexe designed around independence and accessibility, presented with a 3D view and refined with you and the relative who will live in it.
We prepare and submit the planning application — usually required for an annexe — manage consultees and respond to conditions, alongside the Building Regulations submission.
Full structural, services and accessibility detailing, fire strategy where attached, and a written specification — everything fixed before build.
Foundations or conversion shell, structure, envelope, then first fix, kitchen and bathroom, services, second fix and decoration. Weekly updates throughout.
Commissioning, a joint snagging walk, the certification pack and handover of a finished, ready-to-live-in annexe.
A 12-month defects period, a six-month service visit and a 10-year workmanship warranty.
What an annexe costs depends on whether you build new or convert, the size, and the level of accessibility and finish. Here is how our four tiers differ.
For a representative detached garden annexe at around £100,000, here is the honest breakdown of where every pound is spent.
A self-contained annexe is built to the standards of a home. Here is what is designed and installed.
An annexe is living accommodation, so the planning approach is different from an outbuilding — and getting it right first is everything.
Because a granny annexe is self-contained living accommodation, it almost always requires planning permission — it is not an incidental outbuilding like a garden office, and the council assesses it as ancillary to the main house. Permission is typically granted with a condition that the annexe is not sold or let as a separate dwelling and remains tied to the main home. Some modest internal conversions or attached annexes may be possible under Permitted Development, but for most new annexes a full application is the right and necessary route.
This is the single most important thing to get right at the outset, because the planning position shapes what you can build, where, at what size, and on what conditions. We have a strong record securing annexe consents across London boroughs, and we lead with the planning strategy — advising honestly on what is achievable on your plot before you commit to detailed design, so you do not spend on a scheme that will not be approved.
On council tax, annexes used by a dependent relative may qualify for an exemption or discount, and family-occupied annexes are often banded at a reduced rate — but this depends on your local authority and the Valuation Office's assessment, so we design to the planning conditions and recommend you confirm the position with the council and a tax adviser. For an early budget, use the cost calculator; for the office-not-living-space alternative, see our garden office page.
A representative programme for a detached, accessible garden annexe. Yours will differ by type, but this is what a properly run build looks like.
An annexe is for someone you love. Here is why ours is worth doing properly.
We lead with the planning strategy and have a strong record securing annexe consents — the part that most often stops an annexe before it starts.
Step-free access, wet rooms and reachable controls built in from the start — and provision for changing needs — not bolted on later.
Design, planning, structure, kitchen, bathroom, services and finish under one fixed-price contract.
Insulated, warm and finished to the standard of the main house — somewhere a relative is genuinely happy to live.
Our core trades are PAYE staff — continuity and care on a sensitive family project.
Professional indemnity and public liability at £10M, well above industry standard.
Designed to adapt — and to become a home office or guest suite later — for lasting, flexible value.
An insurance-backed workmanship warranty protecting the annexe long after completion.
A granny annexe is one way to create accommodation. Start here, or speak to us about the alternatives.
Self-contained accommodation for staff or family within larger homes and estates.
An attached annexe is an extension with its own entrance — our full extensions service.
Converting a garage into an annexe — the most economical route to self-contained space.
The level-access wet rooms and mobility bathrooms at the heart of an accessible annexe.
If you need a workspace rather than living space — the office, not the annexe.
A lower-ground annexe — converting or excavating basement space for self-contained living.
Creating an annexe as part of a wider whole-house renovation.
The wider range of garden buildings we design and build.
Comparable projects and finishing standards across our work. Browse the case-study hub and the wider portfolio, and to talk through the right option for your family, contact us.
Self-contained accommodation within larger homes — the same disciplines as a granny annexe.
Explore →Five-storey period house with self-contained lower-ground accommodation as part of the works.
View case study →Real projects with real budgets, planning context and finishing standards.
View hub →Browse the full portfolio of buildings, extensions and renovations across London.
View portfolio →“I would like to thank Ross and his team for their consistent commitment to quality and their unerring reliability. They delivered our property to specification and on time, proving to be an extremely effective, experienced, and proactive contractor.”
“We have worked with Ross and his company many times. They are extremely professional and hardworking individuals who can work under any circumstances. There was no variation to the works.”
Book a no-obligation consultation at our Finchley Road design studio or in your home. The first meeting is free, lasts 60–90 minutes, and concludes with an honest indication of feasibility, programme and budget band. No salespeople. No pressure.
Site visit · feasibility assessment · outline cost estimate · programme indication. No obligation. Saturday appointments available.