Bespoke Garden Rooms Across Hertfordshire, Buckinghamshire, Essex & North London
Premium Bespoke SIP Garden Rooms for Offices, Studios & Year-Round Living
We design and build high-performance garden rooms across Hertfordshire, Buckinghamshire, Essex and North London. Using advanced SIP construction, our buildings deliver superior insulation, structural strength and true year-round comfort — ideal for offices, gyms, studios and more.
Why Our Garden Rooms Are Built Differently
Not all garden rooms are the same. At TRJ Construction, we build engineered garden rooms using Structural Insulated Panels (SIPs), designed for long-term performance — not just appearance.
Superior Insulation That Actually Works
Our SIP panels provide continuous insulation throughout the structure, eliminating cold spots and maintaining a stable internal temperature all year round.
Airtight & Energy Efficient
Our system creates an airtight envelope, reducing heat loss, eliminating draughts and improving energy efficiency — ideal for daily use as a real living space.
Built for Year-Round Use
Warm in winter, cool in summer — our garden rooms are not seasonal buildings. They are designed to be used every day, just like a room inside your home.
Thicker, Stronger Construction
- 125mm SIP walls (most competitors use 100mm)
- 150mm roof and floor
- High structural rigidity with fewer internal supports
Garden Rooms Designed Around Your Lifestyle
Every garden room we build is tailored to how you want to use the space. From home offices to gyms and creative studios, our SIP-built structures deliver comfort, performance and flexibility all year round.
Home Office Garden Rooms
Work from home in a quiet, fully insulated space designed for focus, productivity and comfort — with no distractions from the main house. A compact home office of around 10sqm typically starts from £14,000+
Garden Gym Rooms
Create your own private training space with a durable structure, proper insulation and ventilation — built to handle daily use all year round. A practical garden gym of around 15sqm typically starts from £21,000+.
Studios & Creative Spaces
Ideal for music, art or content creation, with excellent thermal performance and reduced external noise for a more controlled environment. Most creative studios of around 15sqm to 20sqm typically start from £21,000 to £28,000+.
Multi-Use Garden Rooms
Flexible spaces designed to adapt to your lifestyle — whether you need a guest room, relaxation area or additional living space. A well-balanced multi-use garden room of around 20sqm typically starts from £28,000+.
Garden Rooms with Bathrooms
Add extra convenience with integrated shower rooms or WC facilities, perfect for long stays or independent use. Garden rooms with bathrooms are usually around 20sqm+ and typically start from £30,000+, depending on drainage, plumbing and fit-out.
Business & Therapy Rooms
A professional space at home, ideal for beauty treatments, consultations or private client meetings in a calm and comfortable setting. A bespoke business or therapy room of around 15sqm typically starts from £21,000+.
Standard Features of Our Garden Rooms
FOUNDATION
We typically use engineered screw pile foundations to support our garden rooms. This system avoids the need for large concrete slabs and keeps ground disturbance to a minimum. It is a fast, clean and efficient solution that works particularly well where access is limited or where a lower-impact installation is preferred.
STRUCTURALLY INSULATED PANELS KIT
We build our garden rooms using high-performance Structural Insulated Panels (SIPs). Each panel is made from two layers of OSB bonded to a rigid insulating core, creating a strong, energy-efficient structure. SIP construction offers excellent thermal performance, improved airtightness and a more solid feel than many traditional timber-framed garden buildings, making the space comfortable to use all year round.
INTERNAL DECORATION
The interior is finished to a clean, modern standard, with plasterboard-lined walls ready for decoration and neatly finished joints for a smooth appearance. Walls are painted in a matt off-white emulsion, while skirting boards are finished in white gloss, creating a bright and fresh internal space that is ready to furnish and use.
INTERNAL LIGHTING
We provide a full electrical package designed for practical everyday use. This can include internal and external lighting, double sockets and the connections required to supply the building from the main house. From recessed downlights to decorative wall lighting, we can tailor the electrical layout to suit how you plan to use the space.
WINDOWS AND DOORS
Grey uPVC French doors come as standard, complete with secure, insurance-approved Euro cylinder locks. We also offer upgrade options including aluminium windows and doors for a more contemporary appearance, slimmer sightlines and a premium finish.
INTERNAL FLOORING
Our garden rooms are designed to accept a range of internal floor finishes to suit the intended use of the building. Whether you prefer laminate, engineered wood, vinyl or other practical flooring options, we can help create a finish that is durable, attractive and suitable for year-round use.
EXTERNAL CLADDING
We offer a choice of external finishes to match both the style of the building and the character of your property. Options can include modern composite cladding, natural timber finishes or rendered systems, depending on the design and location of the garden room. Our aim is to create an exterior that looks smart, durable and in keeping with its surroundings.
ROOF COVERING
Our garden rooms are finished with durable roof coverings designed for long-term weather protection and a clean modern appearance. Depending on the design, this may include high-quality EPDM rubber roofing for flat roof structures or other suitable coverings for pitched roof options. Each roof is selected to provide reliability, low maintenance and a neat finished look.
EXTRAS & UPGRADES
We offer a range of optional extras and upgrades to make your garden room even more comfortable, practical and personalised. Options can include air conditioning, integrated sound systems, CCTV, internet and network cabling, additional sockets, bespoke lighting, skylights, roof windows, and upgraded windows and doors. Whether you are creating a workspace, home gym, studio or relaxation area, these added features help tailor the building to your exact needs.
This allows us to create a garden room that is not only well built, but fully suited to how you want to live, work or relax.
Get a Garden Room Quote
Our bespoke SIP garden rooms start from £1,400 per sqm including VAT, with typical guide prices of:
- 10sqm garden room from £14,000+
- 15sqm garden room from £21,000+
- 20sqm garden room from £28,000+
- 25sqm garden room: from £35,000+
Every project is designed around your preferred size, layout and finish, whether you need a simple insulated home office, a garden gym, a creative studio or a fully fitted garden room with bathroom and premium upgrades. Because every garden room is bespoke, the most accurate way to price your project is with a tailored quote based on your exact requirements. We can help you choose the right size, specification and finish to suit how you want to live, work or relax — and give you a clear, realistic figure from the start.
Ready to get started? Contact TRJ Construction today for a free garden room quote and let us price a bespoke SIP garden room around your space, your needs and your budget.
Frequently Asked Questions About Garden Rooms
Everything you need to know about bespoke garden rooms, from costs and foundations to insulation and permitted development.
How much does a garden room cost?
Our bespoke SIP garden rooms start from £1,400 per sqm including VAT. The final cost depends on the size, layout, specification, glazing, foundations and any extras such as a bathroom, air conditioning or upgraded finishes.
Are your garden rooms suitable for year-round use?
Yes. Our garden rooms are designed for comfortable use in every season, with SIP construction that provides excellent insulation, improved airtightness and a more stable internal temperature throughout the year.
What can a garden room be used for?
Garden rooms can be designed for a wide range of uses, including home offices, gyms, creative studios, therapy rooms, guest spaces and flexible multi-use living areas. Your page already targets these uses directly.
Can you build a garden room with a bathroom?
Yes. We can create garden rooms with integrated WC or shower room facilities, making them ideal for longer daily use, guest accommodation, therapy rooms or more independent living space. Your current page already promotes garden rooms with bathrooms as one of the main use cases.
Why choose SIP construction for a garden room?
SIP construction gives you better insulation, stronger structural performance and a more solid, energy-efficient building than many lower-spec garden rooms. Your page also highlights thicker construction, including 125mm SIP walls and 150mm roof and floor systems.
Do garden rooms need planning permission?
Many garden rooms can be built under permitted development, but it depends on the size, height, location and intended use of the building. We can guide you on the likely route for your project and advise whether planning permission may be needed.
What foundations do you use?
We typically use engineered screw pile foundations. These are fast, clean and efficient, reduce ground disturbance and are especially useful where access is limited or a lower-impact installation is preferred.
What is included in a typical garden room build?
A typical build includes foundations, the structure, SIP panels, plasterboard-lined interiors, electrics, lighting, doors, windows, roof covering and your chosen external finish. Optional upgrades can include air conditioning, CCTV, sound systems, network cabling, skylights, and upgraded windows and doors.
How long does it take to build a garden room?
Build times depend on size, specification and site conditions, but garden rooms are usually much quicker to complete than a traditional extension. We provide a clear build plan and quotation based on your project.
Which areas do you cover?
We build garden rooms across Hertfordshire, Buckinghamshire, Essex and North London,but we can cover more than that .
