The short answer
A well-built, insulated garden room usually makes a house more appealing and can add value, especially now so many people work from home. Figures of 5% to 15% are often quoted, but they come from estate agents and suppliers rather than hard data. Quality, size and how much garden is left matter more than the room itself.
A garden room costs a lot of money, so it is fair to ask how much of it you get back when you sell. The honest answer is that it depends, and the figures you see online are less solid than they look.
What the figures say
Several numbers come up again and again:
- 7.5%. Research by the estate agent Barrows and Forrester, quoted by Legal & General in 2023, suggested a garden office could add an average of 7.5% to a home’s value.
- 5% to 10%. Unbiased, the financial advice site, gives this range in its guide.
- 5% to 15%. Some garden room suppliers quote this, citing estate agents and property experts.
None of these comes with a published sample or method we could check. They are useful as a sign that buyers like garden rooms, not as a promise of what yours will add. If you want a figure for your house, ask a local estate agent who sells homes like yours.
Why a garden room can add value
Working from home is here to stay
A separate office is now on many buyers’ wish lists. A garden room that already has power, internet and heating saves a buyer the cost and hassle of building one.
It adds usable space without an extension
A garden room gives a house an extra room without changing the house itself. For buyers who need an office, studio or gym, that can tip a decision.
It can help a house stand out
In a street of similar houses, a good garden room is a feature that photographs well and gives an estate agent something to talk about.
When a garden room might not add value
Poor quality
A cold, damp room with no insulation looks like a project, not a feature. Buyers may even see it as something to pull down.
Too much garden lost
In a small garden, a big room can leave too little outdoor space. Families with children or pets may value the lawn more.
Rules not followed
If the room breaks planning rules, or is used as a bedroom without permission, a buyer’s solicitor will ask questions. That can slow a sale or knock the price.
Very personal designs
A recording studio, sauna or bar suits some buyers and not others. A flexible room that could be an office, gym or playroom appeals more widely.
How to build a garden room that helps a sale
Build it properly
Insulation in the floor, walls and roof, double glazing, proper electrics and a solid base. Read what to ask for on our insulated garden rooms page.
Keep the paperwork
Hold on to the electrical certificate, any building regulations completion certificate and anything that shows the room meets permitted development. A Lawful Development Certificate from the council is optional, but it gives a buyer confidence.
Choose a sensible size
A room that leaves a usable garden is easier to sell. For many homes, 10 to 15 m² is enough for an office or gym without dominating the garden.
Make it flexible
Plain walls, good light and plenty of sockets let a buyer picture their own use.
Other costs to think about
Insurance
Tell your home insurer about the room and what is kept in it. Some policies cover outbuildings and their contents only up to a limit, and a garden office full of computers can go over it.
Council tax
A garden room used as an office, gym or hobby room alongside the house does not normally change your council tax. If it becomes a self-contained place to live, the Valuation Office Agency can band it separately, and it would also need planning permission.
Business rates
Working from home in a garden office is normally fine. If part of the room is used only for business, with customers visiting or staff working there, business rates can apply. Check with the Valuation Office Agency if that sounds like you.
Value isn’t the only reason to build
Most people build a garden room for the years they will use it, not for the sale. A home office you use every day saves commuting time and costs. A gym can replace a membership. Those benefits are easier to measure than a few percent on a future sale price.
Weigh the cost against how much you will use the room. Our cost calculator gives a typical price for your size, and our garden offices page covers what a good working room needs.
The short version
A good garden room is more likely to help a sale than hurt it. A poor one can do the opposite. Build it well, keep it within the rules, keep the certificates, and leave enough garden around it. Then treat any added value as a bonus.
If you’re thinking about a garden room in Sheffield, the quote form takes two minutes and the builder gives you a fixed price after a visit.