Description

The Mercia Harlow 5m x 3m Premium Insulated Garden Room is a contemporary extension to your home, offering a versatile living space that blends style and practicality. The sharp geometric lines and architectural wing design make this garden room stand out, while the recessed front provides shelter and a welcoming porch area. It’s a perfect choice if you’re looking for a home office, gym, or additional guest space that feels like a natural part of your property.

Premium insulation sets this garden room apart. The walls, roof, and floor are fitted with Eco-quilt multi-foil insulation, equivalent to 100mm of glass wool, keeping the interior warm in winter and cool in summer. Double-glazed French doors and interchangeable fixed and opening windows allow light to flood in while ensuring excellent thermal performance. The 100mm double-skinned walls also feature removable inner panels, allowing you to run and conceal electrics for a neat and modern finish. A long-lasting EPDM rubber roof membrane, with a 50-year life expectancy, adds superior durability against the elements.

Handmade to order in the UK by skilled craftsmen using sustainably sourced timber, the Harlow combines modern design with trusted quality. With flexible options to adjust door and window placements, this garden room can be customised to suit your space and needs. Whether for work, relaxation, or entertaining, it’s a stylish investment lasting decades.

The high-quality materials and modern design of the Mercia Harlow make this one of the best insulated garden rooms available. Come to our Nottingham showroom, where you will be able to take a closer look and have a walk around one of these top-spec garden rooms from Mercia.

Professional Home Installation – Included as Standard

From start to finish, we make the process effortless. Our expert installation service is included in the price of your building, so you can simply sit back and watch your new retreat take shape.

On the day, our skilled installers will arrive ready to build your garden room with precision and care. Once complete, they’ll leave everything spotless – so all that’s left for you to do is step inside and enjoy your beautiful new space.

Customisable to Suit Your Style

The Mercia garden room range is versatile and customisable. The garden room range is available in a range of sizes and styles, that can be tailored to suit your exact needs. Prefer extra windows for more natural light? Need an extra single or double door? No problem. Speak to our friendly team, we’ll work with you to create a layout that’s just right for you. Your perfect garden room, your way, call us, and we can discuss the options.

Optional UPVC Windows and Doors

Mercia's Insulated Garden Rooms with UPVC windows and doors are an excellent choice. Choose from anthracite, oak, or white to personalise your garden building effortlessly. UPVC provides enhanced security with its lightweight yet strong frame, advanced locking systems, and double-glazed panels that deter break-ins. Considering energy efficiency, these UPVC frames with double-glazing, ensuring a warm, quiet, and efficient space suitable for year-round enjoyment.

Durable 50 Year EPDM Rubber Roof - Included as Standard

Enhance the durability and weather resistance of your Mercia garden room with our high-quality EPDM roofing solutions. The building comes with EPDM roof covering as standard. Designed to provide superior protection, EPDM is a versatile and long-lasting material that ensures your timber structures remain secure against the elements. Its strong waterproof properties, combined with resistance to UV rays and temperature fluctuations, make it an ideal choice for outdoor use.

Fully Insulated Design for all Seasons

This Insulated Garden Room is built with fully insulated walls, roof, and floor to ensure year-round comfort keeping the space warm in winter and cool in summer.  The Merica Insulated Garden Room Range features 100mm thick walls which are double skinned with EcoQuilt insulation layered between the timber cladding. The same high-performance EcoQuilt insulation is also used in the roof. Made in the UK, EcoQuilt is a multi-foil insulation that incorporates an effective vapour control layer, protecting your garden room from damp and moisture.

For the floor, we use AirTec insulation, designed with a bubble structure that traps air, reducing heat loss.

Available sizes:
Mercia Harlow Insulated Garden Room is available in sizes: 3m x 4, 4m x 3m, 4m x 4m, 5m x 3m, 5m x 4m, 6m x 3m, 4m x 4m

Features:

Installation - Included in the price

Guarantee - 10-year anti-rot

Walls - 100mm double skinned walls insulated with (internal 12mm tongue and groove + 72mm framing + external 16mm Shiplap+ and EcoQuilt Insulation)

Floor - high quality 16mm tongue and groove floor with Air Tec Insulation between the bearers

Roof - pent tongue and groove roof with EcoQuilt Insulation and a rubber roof membrane provided

Windows - 4 double glazed windows

Doors - double glazed french doors 

Lock - mortise lock and key (keys provided)

Treatment - untreated (application of preservative and waterproof coat required)

Make the Most of Your Garden Room

The Harlow Premium Insulated Garden Room can be tailored to fit seamlessly into your lifestyle. As a garden office, it offers a professional, light-filled workspace free from distractions, with discreet cabling hidden behind wall panels. It has the space and year-round insulation for fitness enthusiasts to house gym equipment, creating a private training space steps from your home.

Alternatively, it can be styled as a cosy guest suite or an inviting hub for family and friends. The open-plan interior and contemporary porch make it equally suited to hosting gatherings, creating a quiet hobby studio, or enjoying relaxed evenings overlooking your garden. However you choose to use it, the Harlow enhances your home with comfort, style, and flexibility.

About Your Order

The Mercia Harlow Garden Room is a UK-made insulated garden room that features sustainably sourced timber. You get a top-quality garden room with a low carbon footprint. High-quality timbers are used throughout the construction of the garden building. Mercia garden rooms are installed by a team of professional installers. The garden room is supplied untreated and will need an application of wood preservative immediately after installation. 

Please note: Images may show the garden room painted and may depict furnishings and accessories; these are for illustration purposes only and are not included with your order.  Top-opening and fixed windows can be swapped to suit preference and do not need to be in the same positions as shown.

Delivery And Installation Information?

Since this building includes free professional installation, there’s hardly any effort required on your part!

You will need to ensure there is a 24” clearance all the way around the building and have the area cleared and ready on the day.  This will allow for the building to be assembled and for you to be able to treat the building.

Once your order is placed, the manufacturer’s installation team will be in touch with a short pre-installation questionnaire. This helps us confirm that the site for your new Insulated Garden Room is ready, making sure everything runs smoothly on installation day. 

After the foundation is set and access to your garden is clear, our installers will take care of the rest!

Note: The installation team will not dismantle or remove any old buildings.

Aftercare & Guarantee:

The garden room is supplied untreated. You must apply a preservative and waterproofing topcoat immediately after installation. Using the treatment after installation, followed by consistent annual treatment of the garden room, will maintain the high-quality finish and is a requirement of the 10-year anti-rot guarantee. A 1-year manufacturer's warranty is included as standard.

To treat the garden room, elbec recommends Protek wood treatment. Browse our Protek Royal Exterior Wood Finish Paint range to find the best paint colour to add your own personalised finish.  We’ve also included in the options section some popular colours and a Wood Preserver+ to be used underneath the colour of your choice.

Planning Permission - Do You Need It?

The garden building designs have been created to adhere to planning permission guidelines. However, we cannot guarantee that you will not need planning permission for a garden building.  We advise checking with your local authorities before constructing your garden room. 

Garden Room Base Requirements?

A flat, level base is required for the installation of your Insulated Garden Room. You can purchase the Mercia Elite Timber Base with Ground Screws.  When constructing your own base, solid concrete or concrete slabs are what is recommended. For more information on how to build a garden room base, you can contact us.

Prior to the Garden Room installation, be sure to check the base is level in all directions. If the base is not level, it will cause the building to twist and warp with the natural movement of the timber. It’s essential to adjust your base accordingly to achieve this before the installation process begins.

About Mercia - Quality You Can Trust

Mercia is one of the best UK garden building manufacturers. They have over 140 years of experience, so you get a summerhouse of the highest quality when choosing Mercia. Mercia combines the latest manufacturing techniques with the best hardwearing materials to produce British-made sheds and summerhouses built to the highest standards.

Every product Mercia produces is made with safety and exceeding your expectations in mind. When you receive your order, you will immediately see why this is one of the best summerhouse and shed manufacturers. All products are made from ethically sourced materials. 

View other products in Mercia Summerhouses »

Delivery

Since installation is included at no extra cost, setting up your new garden room couldn’t be simpler.

After placing your order, you will be contacted and supplied with a short pre-installation form. This quick check helps us confirm that the location you’ve chosen is suitable, ensuring everything runs smoothly when our fitters arrive to assemble your Insulated Garden Room.

A solid, level foundation is essential. You can either prepare your own base, concrete or paving slabs are ideal, or choose the Elite Timber Base upgrade for a hassle-free solution.

For installation to run smoothly, please ensure there is at least 24 inches of clear space around the entire building. This clearance not only allows our team to complete the setup safely and efficiently, but also makes it easier for you to treat and maintain the exterior of your Garden Room once installation is complete.

Once we’ve confirmed that the groundwork and access to your garden are ready, we’ll be in touch to arrange a delivery and installation date that works around your schedule.

Before Delivery
On the morning of your scheduled delivery, you’ll receive a text message with a 2-hour estimated arrival window. (This service is available only if a mobile number was provided at checkout).

On the Day
Your Garden Room will arrive on a 3.5T, 7.5T, or 18T lorry, depending on the size of your order. For safety and insurance reasons, our installation team is unable to carry the building through your property. This avoids any risk of accidental damage to your home.

Specification

Quickview

The 5m x 3m Mercia Harlow Premium Insulated Garden Room features a striking winged design with a sheltered front porch. It's built for year-round comfort with 100mm insulated double-skinned walls and double glazing. The key features include: 

• Free Home Installation
• 2 fixed and 2 top-opening 14 mm double-glazed windows
• Ultra modern wing design
• EcoQuilt insulated walls and roof
• Air Tec Insulated floor
• Customisable design
• 10-year anti-rot guarantee