A garden room can be a great way to expand your living space without building an extension on your home. For example, you might want more space for an office, a gym, or even a bedroom for one of your kids – but don’t want to extend the kitchen or block light to it.
A garden room with a bathroom allows you to build a completely new room, separate from your home but connected to the central heating, so you get the best of both worlds. And, you can often build connected pathways between the garden door and your garden room to create a beautiful and dry approach.
The average cost of a garden room with a bathroom is £1,400-£2,400 per square foot. This includes materials, labour, and the costs of necessary permits, structural planning, and excavation. However, depending on the materials you use, costs could be as much as triple. This means that for a 4 x 3 garden room, you’ll pay £21,600-£28,800 and for an 8 x 6, you’ll pay £86,400-£115,200.
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How Much Does A Garden Room With Bathroom Cost?*
The cost of a garden room heavily depends on factors like what you choose to build, how big you build it, and what kinds of fixtures you use. For example, even a bathroom and shower can range from about £2,400 to over £30,000.
The following cost estimates include pricing for a 4 x 6 x 3.5 metre garden room with a toilet and shower using basic fixtures, 3 brick walls, and 1 glass wall.
| Costs | Hours | Total | ||
| Hourly Rate | £10- £60 | £1,150 – £4,100 | ||
| Pouring Slab | 4-6 | £40-£200 | ||
| Bricklaying | 32 | £600- £1,000 | ||
| Roofing | 4-8 | £40- £350 | ||
| Electric Work | 2-8 | £50- £150 | ||
| Plumbing | 4-8 | £200- £480 | ||
| Glazing | 4-8 | £100- £480 | ||
| Heating | 4-8 | £40- £480 | ||
| Drywall | 4+ | £40- £180+ | ||
| Insulation | 4-8 | £40- £720 | ||
| Building Regulation Approval for Notifiable Work | £170- £690 | |||
| Structural Engineering | 2-6 | £250- £2,600 | ||
| Materials & Fittings | £9,690- £21,801 | |||
| Brick | £2,520- £4,500 | |||
| Cement | £120- £396 | |||
| Roofing | £2,880 – £4,620 | |||
| Shower Cabin | £300+ | |||
| Glazing | £4,500- £7,200 | |||
| Toilet Units | £500+ | |||
| Insulation | £415- £2,075 | |||
| Heating | £800+ | |||
| Drywall | £100- £500 | |||
| Light Fixtures | £50+ | |||
| Electrical | £145- £860 | |||
| £10,840 – £25,901 | ||||
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*Please note, these costs were based on price averages at the time of writing in April 2023. Actual rates are subject to change and may be different at the time of reading.
8 Price Factors Which Influence Your Quote
Garden rooms can cost a widely different amount depending on what you build with, how you build, and even what you’re building on. This means that you can’t get an accurate quote without showing the builder the lot and having them do an inspection. You’ll also have to pick materials before you can get an accurate quote.
1. Materials
Materials can impact the final quote by tens of thousands of pounds. For example, building in natural stone costs something like £60-£130 per metre for basalt and up to £270 for nicer stone. If you’re building with concrete bricks, that could fall as low as £40-£60 per square metre.
Materials will be a factor in every stage of the building.
- What kind of foundation?
- Which kind of materials for the walls?
- What about roofing materials
- Insulation?
- Drywall? Wood panelling?
- Paint?
- Glazing? Double or triple? Aluminium, uPVC, or wood sashes?
- Shower cabin?
- Flooring?
The difference in cost between different materials can be ten thousand pounds or more at every step. For example, the difference between the cheapest shower cabin and the highest end option at even a hardware store is usually about £8,000. And, the difference between the cheapest flooring and the most expensive will usually be about £450 – per square metre.
In general, your building can be as expensive as you want it to be. Therefore, this guide sets the baseline for minimum costs, and you can always spend more if you have it or want to.
2. Labour
Labour is the second largest cost in building a garden room. Here, you’ll have to calculate an average of £300 in labour, per day – based on the average day rate of £150 per person. However, those rates can vary significantly depending on what kind of materials you’re using. For example, bricklayers may actually charge a flat rate, such as £1,000 or £1,500 per 1,000 bricks including bricks and labour – which is a full day of work for one person.
In addition, labour rates may not include extras like travel, equipment, and specialty drivers for equipment. This means you may pay a higher rate for the first hour of work. It’s not uncommon to pay an initial fee of £100-£150 for the first hour of work followed by a £30-£60 per hour tariff.
And, different materials take different amounts of time to fit. For example, if you want to use cinder blocks to build the inner walls of your garden room, you can expect materials to cost slightly less than bricks. However, cinder blocks are larger and fit together faster, meaning you might save 50% of the labour.
Finally, you’ll need a range of different specialists for installing a garden room.
- General Contractors – £150 per day
- Bricklayers – £150- £200 per day
- Electrician – £150 for the first hour, £60 per hour following
- Plumber – £150 for the first hour, £50- £60 per hour following
- Tile layers – £50 per hour
If you need insulation specialists, they’ll usually give you a flat rate, including the cost of material and installation. That’s especially true if you’re using a loose fill insulation that can be blown in. However, chances are high that you can have most insulation installed by your general contractors, which will save you money.
In addition, surveyors and inspectors will cost extra money if you need them. For example, if you hire Registered Competent Persons to do the work, they can self-inspect and issue the Part P Certification you need for Building Control. If you don’t, you’ll have to pay separately for an inspector, which can cost £ 200+ per inspection for electric, water works, structural support, sewage, roofing, etc.
3. Fittings and Fixtures
Fittings basically cost as much as you want them to. The most basic toilet units start at around £100 each. It’s usually hard to get to an upper limit. Therefore, you’ll want to shop around for fixtures and fittings and set a budget that allows you to buy the kind of fixtures you want.
This should include a toilet, sink, shower cabin or bath, and any other extras you want. Prices range from about £2,000 for everything to well over £10,000.
4. Size
The larger your garden room, the more you’ll pay in flat-rate pricing. However, it’s not a direct price increase. In addition, if you’re installing a bathroom, you’re actually going to need planning permission, which means spending the extra money on requesting planning permission, submitting documentation, and having a structural engineer design the project. Therefore, there are no impediments to making your garden room as large as you want.
For example, you can usually expect to pay £96-£462 in application fees, unless the development is intended to enable someone with disabilities better access to facilities.
If you’re building without a bathroom, you can normally build up to 4 x 3 metres before having to apply for planning permission. However, the installation of facilities means it’s not incidental development and you’ll always have to apply for planning permission.
This means that you can plan to have it as large as you want – although keep in mind that planning permission may be denied if the building takes up more than half of the garden space.
Size also affects the direct cost of building. However, costs are not directly proportional to volume of the build, except with relatively flat-rate things like insulation, roofing, and bricks. For example, foundations and pipework will only increase a small amount in rate based on the size of your home. Larger glass windows are usually comparable in price to medium-sized ones, and so on.
Therefore, you’ll always pay more if you build larger. However, the price increase is not proportional and you may find it only costs about 20% more to build 40% larger. On the other hand, it could cost much more if that increase in size means getting unusual spans of wood or expensive materials.
In addition, it almost always costs more to build more than one storey. However, costs won’t be proportional. For example, it typically costs twice as much labour to build a second story of brick, simply because the structure requires scaffolding and additional safety requirements.
5. Local Cost of Permits
The cost of planning permission is the same across the country. However, building control is handled by the city council. This means that the cost of notifying building control can vary significantly from city to city.
In fact, building control notifications cost £170- £690 depending on where you’re at in the UK. While that’s likely to be a small overall percentage of your total project, it’s important to check if you’re spending £600 on notifications when planning your budget.
6. Ease of Access
If your garden is accessible, you can skip this section. However, it’s often the case that you may have to remove fences, remove turf, and move everything out of your garden during construction. Worst case, you’ll spend a significant amount of time removing fencing and you may even inconvenience your neighbours.
7. Time of Year
In general, you want to plan construction projects in the fall and winter – because fewer people are doing them. This will mean more availability from your contractor and therefore cheaper prices. However, that won’t always be the case.
8. Current Setup
Your current utilities and electrical setup will heavily impact the cost of running electric, sewage, and water to your new garden room. For example, if the soil pipe is in the back of the house and runs roughly to where you want the new garden room anyway – you might find that costs to install drainage in your new garden room are very low.
On the other hand, if the same soil pipe is at the front of your house and has to be run through the house, costs could extend into the thousands.
Benefits Of Garden Rooms
Garden rooms allow you to expand home spaces without extending the back wall of your current home. This is ideal for anyone who needs more space but with no ideal home layout for an extension.
Doesn’t Block Light or Windows
Building an extension from the back wall of your current home can block all of the light going into that room. In most home layouts, that means blocking light to the kitchen or to the living area. Both cases aren’t ideal.
Or, for example, if you extend the back wall of the kitchen, you could shift the kitchen back against the new wall, and then put your new space in between. That new space wouldn’t have any natural light.
Garden rooms mean you can build a separate room from your house, complete with its own windows and even glass walls – without blocking any light or access to your current home.
Easy Way to Add Extra Space
Garden rooms allow you to quickly build new living space into your home without disrupting your actual living space. Of course, it will disrupt your garden. There will also be several weeks of noise. However, putting in a garden room doesn’t require ripping out the back wall of your house and having it open for several weeks at a time.
That means you won’t have to find a new place to live for the duration. In addition, you won’t have to restrict construction to the warmer months for heating purposes. Instead, you can just build your new space whenever you want – without impacting your sleep schedule other than based on when construction starts in your garden.
Connects to Home Heating
Conservatories and glass home extensions cannot connect to the home’s heating because they don’t meet environmental regulations. Garden rooms are fully insulated according to building control regulations. This means they can be connected to your existing boiler system – providing it is rated for the extra space.
It also means you can relatively cheaply install heat and hot water to the shower or bath in the new space – without installing a full new boiler system. That can save you considerable time and hassle, because you’ll simply have to extend the insulated piping.
However, it won’t always be a good idea to connect your garden room to your home heating. For example, if the garden room is too far from the main home, your plumber may recommend that you install a new boiler, rather than reducing the efficiency of your heating system.
Hiring A Builder Checklist
Hiring a builder always means checking their qualifications, reviews, and prices.
- Are they a Registered Competent Person?
- Do they have relevant qualifications for other work such as plumbing work and electricians work?
- Is one contractor completing the full job or are they subcontracting to electricians and plumbers? Do you have to do any work to find/hire these people as needed?
- Do they have good reviews?
- What about references? Can you call them?
- Do they offer detailed quotes that compare favourably to the competition?
- Is the contractor insured?
- Do they provide worker’s compensation?
In most cases, if the contractor is able to show proof of past work, has relevant qualifications, is part of the Competent Person’s Register, and has good reviews, the only other thing you have to worry about is the quote.
Building Regs & Planning Permission
A garden room with a toilet always requires planning permission. You’ll also have to contact building control.
Your Building Control Notification also means you’ll need a Part P Certificate, which your contractors can provide for you if they are on the Competent Person’s Register. If they are not on the Competent Person’s Register, you’ll have to pay for an inspection of the heating, structure, and electrical work, which can cost £2,000 or more.
- Planning permission
- Part P Certification
- Building Control Notification
Your Planning Permission Application should be submitted 6-8 weeks before you intend to start building.
In addition, it will cost £96-£462 depending on the scope of the building project and whether the authority deems it an extension to your existing home or a new build, which will depend on several factors in your structural designs. You’ll also have to work with your structural engineer to get the full plans before submitting this application.
In most cases, the cost of building control notification will be included in the rate offered by your contractor. However, you may have to pay it separately. In addition, if your contractor is not on the Competent Person’s Register, you’ll have to notify them on your own. This will mean paying £170- £690 in notification fees and filing the notification yourself.
Will This Add Value to My House?
A garden room may add value to your home. However, if your prospective buyers don’t need the space and prefer to have extra garden space instead, it may detract from the appeal of your home.
Garden rooms can be great spaces for offices, gyms, bedrooms, and even guest rooms. However, not everyone likes them. This means you’ll add to the value of your home, but you may narrow the audience of people interested in purchasing the home.
Summary
A garden room is an easy way to extend the amount of living space in your home. If you add a bathroom, it becomes a self-contained living area, where you can sleep or work without having to go back to the main house. That can be ideal and much more practical and affordable than extending the back wall of your home. However, it can be quite costly, with most garden rooms costing £1,400- £2,400 per square metre. Of course, there are no real upper limits on how much you can spend on materials and fittings, so that can always go higher.
If you’re ready to install a garden room, asking around for quotes is the best way to save money. Use the form at the top of the page to request quotes from local builders so you can get the best rates.