Granny Annexe Ideas and Layouts: Studio vs One-Bed

Most granny annexe regrets are not about money. They are about layout. A family spends carefully, then finds the bathroom is too small to help someone wash, or there is nowhere to sit that isn't the bed, or a wheelchair can't turn in the hallway.

This guide is for anyone designing an annexe a relative will actually live in, not just visit. You'll get a straight comparison of studio versus one-bed, a room-by-room walk through what works, and the accessibility decisions that matter most while they cost the least.

Studio vs one-bed: the decision that shapes everything

Almost every other choice flows from this one. Get it right and the rest of the design falls into place.

The studio annexe

A studio is open-plan. Sleeping, living and kitchen share one space, with the bathroom or wet room partitioned off. Think roughly 20–30 sqm of internal floor area.

What a studio does well:

• Costs less to build, heat and maintain
• Sits more easily within planning limits on scale and garden coverage
• Simpler to make fully accessible, because there are fewer walls and doors to work around
• Feels bright and spacious when the ceiling height and glazing are generous

The catch is the lack of separation. There is no closing a bedroom door on an unmade bed when a grandchild visits, and no getting away from the sound of the television if two people share the space. For one active, independent person, that trade is usually fine. For a couple, or for anyone who spends a lot of the day at home, it wears thin.

A studio suits a single parent who is still out and about, values simplicity, and wants the cheapest route to a comfortable, private space of their own.

The one-bed annexe

A one-bed gives you a separate bedroom, a distinct living area, and a kitchen you don't sleep next to. Expect roughly 30–45+ sqm, so it is a meaningfully bigger building.

What the extra space buys you:

• Genuine separation of sleeping and living, which matters more the more time someone spends indoors
• Room for a couple, or for a live-in carer to have a proper sleeping space
• A layout that copes with declining mobility, where a bed might need clear space on both sides
• Stronger resale appeal, because "self-contained one-bed" reads as a real dwelling to a future buyer

The one-bed costs more and takes up more garden, which pulls it further into planning scrutiny. But for long-term living, or where care is likely down the line, it is almost always the better home.

A one-bed suits a couple, a parent who is home most of the day, or any family planning for care needs that could grow rather than shrink.

A quick way to choose

Ask one question: is this space for someone who is mostly out, or mostly in? Mostly out, and independent, points to a studio. Mostly in, or a couple, or care on the horizon, points to a one-bed. If you can stretch the budget and the garden allows it, the one-bed rarely disappoints.

Scale is not just a comfort question. The bigger the footprint, the more of the garden it covers, and garden coverage is one of the things councils weigh when they decide an application. Our annexe planning permission guide covers how that judgement works before you commit to a size.

Accessibility is the backbone, not an add-on

Here is the single most useful thing in this guide. The accessibility features you build in at the start cost very little. The same features retrofitted later, after a fall or a diagnosis, cost a fortune and arrive under stress.

So design the annexe for independence now and possible care later, even if the person moving in is fit and mobile today. None of this makes a home look like a hospital when it's done well. It just makes it work.

The features worth building in from day one:

• A level, threshold-free entrance. No step, no lip at the door. This is the difference between a wheelchair or walking frame rolling in and someone being trapped indoors.
• A wet room, not a shower tray. A floor-level, fully tanked wet room means no stepping over anything, room for a seat, and space for a carer to help. It is the room families most often wish they had done properly.
• Wide doorways. Aim for around 900mm clear width on internal doors, which comfortably clears a wheelchair. Standard doors are often too narrow once you account for the door itself.
• Turning space. A wheelchair needs roughly a 1,500mm turning circle. Check it in the bathroom, the bedroom and the kitchen, not just the hallway.
• Lever taps and lever handles. Kind to arthritic hands, and no harder to fit than the alternative.
• Grab-rail-ready walls. You don't have to fit rails now, but put timber noggins behind the plasterboard by the toilet, in the wet room and along key routes. Then rails go up in an afternoon whenever they're needed, screwed into solid backing.
• Low-maintenance finishes. Slip-resistant flooring, wipe-clean surfaces and easy-reach storage all reduce the daily effort of living there.

Two things worth knowing on cost. First, accessibility works done at build stage may attract a Disabled Facilities Grant from the local council, which can help fund adaptations like a level-access wet room where there's an assessed need. Second, the broader case for designing homes this way is well made by the Centre for Ageing Better, whose work on age-friendly housing is a good primer if you want to understand what changes as people age.

Room by room: what actually works

Space is tight in an annexe, so every square metre has to earn its place. These are the layout decisions that make a small home feel generous.

The kitchenette

You are not fitting a family kitchen, and you shouldn't try. A compact galley or single run with a full-size fridge, a two-ring hob, a combination microwave oven, a sink and a decent stretch of worktop covers real daily cooking for one or two people.

Set worktops and appliances at heights that suit the person moving in, and leave clear knee space under the sink or a section of counter if seated use is likely. A pull-out larder makes far better use of a narrow gap than a deep cupboard nobody can reach the back of.

The bathroom or wet room

Go bigger here than instinct suggests. This is the room where help is given and independence is kept, so it earns floor space more than anywhere else. A wet room with a fold-down seat, a wall-hung basin you can approach seated, and clear space beside the toilet will serve for decades.

Fit an extractor that actually clears the moisture, and choose slip-resistant flooring that runs up the walls where it needs to.

The bedroom or sleeping space

In a one-bed, size the bedroom so a bed can be reached from both sides. That single decision transforms how easily someone can be helped in and out, or nursed if it comes to that.

In a studio, zone the sleeping area with a change in flooring, a half-height storage unit or a shift in ceiling detail rather than a full wall. You keep the open feel and the accessibility, while giving the bed a sense of being its own corner.

Storage, light and outlook

Storage is where small annexes fail quietly. Build it in: full-height wardrobes, under-bed drawers, a utility cupboard for a slim washer-dryer, hooks and shelves at reachable heights. Retrofitted freestanding furniture eats the floor space you designed so carefully.

Natural light does more for wellbeing than any single feature. Aim for windows on more than one aspect so the space is never gloomy, and think about the outlook. A relative who is home a lot will look out of these windows every day, so point the main ones at the garden or the sky rather than a fence two metres away.

The link to the main house

Decide early how connected the annexe should feel. A connecting internal door, or a covered link, keeps a frail relative out of the rain and within easy reach, and it can help an application by showing the annexe functions as part of the household rather than a separate house.

That said, a fully self-contained annexe with its own everything has council tax implications worth understanding before you finalise the design, which we cover in annexe council tax rules. Independence and connection are a spectrum, and you get to choose where on it you sit.

Private outdoor space

Give the annexe a small patch of its own. A level patio by the door, a raised bed at working height, a bench in the sun. A few square metres of private outside space does an enormous amount for someone's sense of having their own home rather than living in the corner of someone else's garden.

Designing for the budget you have

None of this is free, and the specification you choose drives the cost. A modest studio and a fully accessible one-bed sit at very different ends of the range. Before you fall for a layout, sanity-check what it costs to build in our granny annexe costs guide.

Two more practical notes. Anything with sleeping accommodation has to meet building regulations approval, which covers structure, insulation, ventilation, fire safety and drainage, so budget for that alongside the build. And the accessibility features above are the cheapest insurance a family buys. Spend there before you spend on finishes.

When you're weighing up which layout fits your plot and your relative, the garden annexes route is the usual starting point for a standalone build, while an annexe extension may suit families who want the space attached to the main house.

Turning an idea into a plan

The best annexes are designed backwards from the life inside them. Picture the actual person, on an ordinary Tuesday and on a harder day five years from now, and let that shape the walls before anyone talks about cladding.

When you've got a layout in mind and want to know what it would take to build, tell us about your project and we'll match you with suppliers who design for real living, not just a photo. No pressure, and an honest steer on what your plot and budget will actually allow.

This guide offers general design and accessibility principles, not a substitute for advice from an architect, occupational therapist or building control officer. Grant eligibility, building regulations and planning rules vary by council and by nation - always confirm your specifics locally before committing to a design.