Garden Room or Garage Conversion?

A garage conversion is often the cheaper option if you have an integral garage you no longer use, while a garden room is the better choice if you want to keep your garage, avoid building work inside the house, or have a room that sits apart from home life. MyJobQuote puts the average garage conversion at around £14,500, with single garages typically £10,000 to £20,000 and doubles £20,000 to £40,000. Our insulated composite garden rooms start from around £12,096 fully installed.

Both routes can give you an excellent extra room, so the decision usually comes down to what you would be giving up and how you want the space to feel. From working with homeowners across St Albans and Hertfordshire, we’ve found the deciding question is simple. Do you still use the garage? This guide compares cost, regulations, disruption and day to day use so you can weigh it up properly.

How do the costs compare?

An integral garage is usually the cheapest kind to convert, because it already shares walls, a roof and services with the house. MyJobQuote notes that detached and double garages tend to cost £20,000 or more, because of the larger floor area, extra insulation and additional service connections they need.

On top of the build, a garage conversion carries professional and approval costs. Trade pricing guide Trade2Base puts building control fees for a typical conversion at £300 to £700, and drawings or structural input can add more where the garage door opening is filled in or walls are altered.

Our garden rooms start from around £9,714 supply only or £12,096 fully installed for a 3.3m x 2.3m room, rising to roughly £29,845 installed for our largest standard size at 8m x 4.5m. That price includes insulated walls, an insulated roof, double glazing, an insulated floor and an electrical package, with the ground screw base quoted separately.

Building regulations and planning

A garage conversion into a habitable room normally needs building regulations approval. Garage walls, floors and roofs are rarely insulated, so they must be brought up to current standards, along with fire safety, ventilation, damp proofing and electrics. The Federation of Master Builders advises factoring the cost of approvals into your budget from the start.

Planning permission is not usually needed when the work is internal and the outside of the house is not significantly altered. However, some homes, particularly on newer estates, have planning conditions requiring the garage to be kept for parking, so it is worth checking your original planning documents. Changes to the front of a house in a conservation area can also need permission, and St Albans has several.

A garden room is an outbuilding, so it usually falls within permitted development, provided it meets the rules on height, size and position set out in the Planning Portal guidance on outbuildings.

What you give up

A garage conversion uses space you already have, which is its great advantage, but it also takes that space away. Bikes, tools, garden equipment and anything else stored in the garage need a new home, and if you park in it, the car moves to the drive or the street. Filling in the garage door also changes the front of the house, so the new window and wall need to look right alongside the rest of the property.

A garden room uses part of the garden instead. It leaves the garage untouched, and on most plots a well placed room still leaves plenty of lawn and patio around it.

How each space feels to use

A converted garage becomes part of the house. That makes it a strong choice for a bedroom, a playroom or a utility space you want to reach without going outside. It usually has windows on one side only, where the garage door used to be, so natural light can be limited.

A garden room is a separate building with glazing where you want it, often looking straight back over the garden. For a home office, the walk across the garden creates a clear line between work and home that a converted garage next to the hallway rarely does. For a garden gym, it keeps noise and dropped weights well away from the house.

In our experience, a garden room works better than a garage conversion when you want to keep the garage for storage or parking, because you gain a fully insulated room without losing the space you rely on, whereas a conversion trades one useful space for another. A garage conversion still makes more sense when the garage sits empty and you want the new room inside the house.

Disruption and timescales

A garage conversion is building work at your house, with trades coming and going, building control inspections at set stages and some noise and dust in the home. Depending on the scope, it typically takes several weeks.

A garden room is built away from the house. Our rooms sit on a no dig base using ground screws, and once delivered, most are installed in just three to four days. Delivery is typically four to six weeks from order and free within a 70 mile radius of our EN2 0QX base.

Long term upkeep

Both options give you a permanent room, but the outside of a garden room is the part that weathers. Ours is clad in composite that needs no painting, staining or sealing, with an EPDM rubber coated 100mm insulated roof and anthracite grey PVCu windows and doors, so it stays smart with an occasional wash down. Every room is backed by our guarantee.

Which should you choose?

Choose a garage conversion if you have an unused integral garage, want the new room inside the house and are comfortable with building regulations work and losing the garage. Choose a garden room if you still use the garage, want a room separate from the house, or would rather have the work done in a few days at the bottom of the garden.

Talk to us about your options

If you are weighing up the garage against the garden, a short conversation about how you will use the room usually makes the answer clear. Modern Composite Garden Rooms can advise on size, layout and position for your plot. Contact us, request a callback at a time that suits you, or call us on 07816 898512. You can also explore our full range.

To see finished rooms and installations, visit our Facebook page and YouTube channel.