19 December, 2025

How Much Does It Cost to Build An Outbuilding?

Building an outbuilding is one of the best features that you can add to your property. You can turn it into a guest room, home office, hobby room, or even just a place to unwind! It’s a practical and cost-effective way to expand your home without the disruption of a full extension.

But before starting any build, one key question always comes first:

How much does it cost to build an outbuilding?

At JML Garden Rooms, we design and build high-quality, fully insulated outbuildings across Scotland, and we’re here to help you understand the cost that comes with this building.

In this guide, we’ll discuss what an outbuilding is, why it’s worth investing in, the factors that influence cost, and what you can expect when choosing JML Garden Rooms as your provider.

Let’s dive into it!

What Is an Outbuilding?

An outbuilding is essentially a garden room, which is a standalone structure built separately from your main home. Unlike basic sheds, an outbuilding is fully insulated, powered, and designed for comfortable everyday use.

Homeowners choose outbuildings for many different purposes, including:

TV or cinema room for family entertainment

Home gym or yoga studio for personal wellness

Art or craft studio with plenty of natural light

Library or reading retreat

Home office for quiet, productive work

Hobby room or multi-purpose creative space

If you’re looking to create a peaceful sanctuary or a practical workspace, an outbuilding gives you the flexibility to design a space that suits your lifestyle while incorporating the beauty of the outdoors into it.

Do You Need Planning Permission?

One of the advantages of building an outbuilding is that many can be constructed without planning permission. If your structure meets the required size and height limitations, it can typically be built without formal approval.

For example, if you’re creating a garden studio for art, music practice, a games room, or general recreational space, you’re unlikely to need planning permission.

However, in some cases formal approval will be required, either through planning permission or a Building Warrant, depending on the nature of the work.

Planning permission is required if:

The property is within a conservation area

The property is a listed building

The garden room or outbuilding is built less than one metre from the boundary

The roof height exceeds Permitted Development Regulations:

Flat roof: maximum height of 3 metres

Pitched roof: eaves must not exceed 3 metres

The internal floor area exceeds 30m²

The garden room is built in the rear garden only under Permitted Development Rights and not within the front garden or curtilage

This includes:

Adding a toilet, shower, or other facilities connected to the main house.
Any plumbing or drainage requires a Building Warrant, not planning permission.

If your outbuilding will function as guest accommodation or any form of self-contained living space, especially for rental purposes.
Any space used as a dwelling, including sleeping accommodation with fixed heating such as underfloor heating or a log-burning stove, must meet current Building Regulations, including enhanced insulation requirements.

Because regulations vary by location and by project, it’s always best to consult with your local authority Planning Department and Building Control Department. Experts in garden room design and construction can advise whether your project needs planning permission or not to avoid delays.

Benefits of Building an Outbuilding

Adding an outbuilding to your property is more than just an extra space. It provides a dedicated, purpose-built space that improves your daily living.

Here are some of the key benefits of building an outbuilding:

Extra living space just outside your home: Perfect for having a space to separate work and life without moving or extending your house.

Multi-use functionality: From a gym to a studio, office, cinema room, or workshop, an outbuilding adapts to whatever you need.

Can increase property value: High-quality, insulated outbuildings are an attractive feature for potential buyers.

Ideal for hobbies, work, or relaxation: Enjoy a dedicated space designed for focus, creativity, or calm.

Faster and more cost-effective than a home extension: Build times are shorter, disruptions are minimal, and costs are typically lower than traditional home renovations.

How Much Does It Cost to Build an Outbuilding?

The cost of building an outbuilding varies on many factors. At JML Garden Rooms, our outbuildings start from £33,500 (including VAT), with a selection of high-quality designs to suit different needs and lifestyles.

You can choose from our modern flat-roof Lowlander and the traditional pitched-roof Highlander.

Lowlander

The Lowlander is ideal for homeowners looking for a contemporary, practical space. Its flat-roof design offers flexibility, making it a perfect choice for creative studios, workspaces, and hobby rooms.

Case study: Art Studio, Edinburgh

An Edinburgh-based professional artist chose the Lowlander after realising she needed a dedicated studio that was both functional and quick to build. The design’s simplicity and versatility allowed her to create a spacious, well-lit environment tailored to her creative process.

By opting for the Lowlander, she benefited from:

A full turnkey solution: We managed everything from site clearance to installation, handing over her completed studio within two months.

A personalised interior: She chose to keep the chipboard walls and ceiling exposed, creating a practical space where she didn’t have to worry about paint spills.

A dedicated creative environment: Separate from the main home, the studio gave her room to focus, display her work, and expand her practice professionally.

Highlander

The Highlander displays craftsmanship and character with its pitched, slated roof and natural finishes. It’s a good choice for those wanting a timeless outbuilding that feels like an extension of the landscape.

Case study: Art Studio, Auchterarder

A client in Perthshire selected the Highlander to maximise their garden’s stunning hillside views and create a peaceful, multi-purpose retreat. The traditional design, with its warm materials and generous natural light, helped transform their outdoor space into a beautiful, functional part of their home.

The Highlander enabled them to enjoy:

A serene creative and wellness space: Perfect for painting, yoga, and quiet moments of relaxation.

A multifunctional family hub: The studio became a place for movie nights, social gatherings, and peaceful studying.

Premium, durable finishes: From reclaimed Scottish slate and cast iron downpipes to triple-glazed Aluclad doors and Siberian larch cladding, the structure was built to last.

Seamless indoor–outdoor living: The bespoke curved deck created a natural flow to the garden, ideal for entertaining.

What’s Included in a JML Garden Room?

We’re proud to build and design garden rooms to the highest standards using premium materials and industry-leading construction methods.

Whether you choose our Lowlander or Highlander range, you’ll receive a ready-to-use building designed for year-round comfort, relaxation, and productivity.

Let’s check out what’s included as a standard below:

Ground screw foundation system

Highly insulated SIP panel wall, floor, and roof structure

Factory-finished double-glazed timber door system with fixed sidelights and a top swing window

Engineered oak flooring for a warm, durable finish

MDF painted skirting for clean, modern detailing

Fully plastered walls, decorated in the colour of your choice

Internal and external LED lighting

RCD breaker for safe, compliant electrical installation

Full erection and installation works

Roofing and cladding options included:

Lowlander:

Firestone single-ply flat roofing membrane (20-year guarantee; ~50-year expected lifespan)

Cedar external cladding

PVC gutters and downpipes positioned at the rear

Highlander:

Traditional Spanish slate roofing for a timeless finish

Larch external cladding

Cast iron–effect gutter and downpipe for enhanced character

Transform Your Outdoors with a Trusted Scottish Garden Room Specialist

At JML Garden Rooms, every outbuilding is built with precision, care, and a clear understanding of how people want to use their homes today. From modern studios to traditional pitched-roof builds, we deliver spaces that are functional, beautiful, and built to last.

If you’re considering adding an outbuilding to your property, our experts are here to help you understand your options, budget, and the best design for your needs.