Addroom® — Attached Garden Rooms from Dunster House
Published: 1 June 2026
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If you've been searching for a conservatory alternative that you can comfortably use all year round, the Addroom® from Dunster House is worth exploring. It's a modular, self-build garden room designed to be attached directly to the back of your house — built around insulated panels, with skylights in the roof to keep the space bright and light throughout the year.
Sizes and Configurations
The Addroom® is available in three widths — 3m, 4m, and 5m — each offered in either a 3m or 2.5m depth, giving six size options in total. Each will create a good-sized extra room that could be used as a sitting room, playroom, or office area.
The front elevation is largely glazed, with uPVC frames and multi-point locking systems throughout. Wall configurations can be customised across solid panels, glazed sections, or door-and-window combinations depending on how you want to use the space and which direction it faces.
Roof and Natural Light
The Addroom® has a solid, insulated roof with built-in skylights. Each skylight measures 480mm wide by 1,590mm tall, with laminated and toughened glass, and they do a good job of keeping the interior feeling open and airy without relying solely on the front glazing.
The choice of skylights rather than a fully glazed roof strikes a good balance — you get the benefit of light from above, but combined with the insulation in the roof, walls, and floor, the space regulates temperature throughout the year far better than a conservatory does.
Insulation and Year-Round Use
The structure uses sandwich panel construction throughout: 140mm walls, 140mm roof, and 40mm floor. The result is a space designed for year-round use — not just the six months when the weather cooperates. It behaves more like a proper room extension than a seasonal space.
Finishes and Materials
The external walls use composite panels — a material that offers durability and is resistant to water and rot. Dunster House recommend painting the exterior using a multi-surface paint, which gives you flexibility over the final colour and ensures an even finish across all panels.
The roof is finished with felt shingles as standard. If you'd prefer to use a different roof covering, you can specify the building without shingles. Either way, flashings are not included as these are site-specific and will need to be ordered and fitted separately.
Internally, the walls use Fermacell boards: a fireproof composite material that can be painted or wallpapered. The floor frame is pressure-treated timber with a ten-year warranty. Windows and doors are 28mm double-glazed toughened uPVC, available in white or grey frames.
DIY Assembly
The Addroom® is delivered as a flat-pack of pre-made insulated panels. Two competent DIYers can put together a 3m x 3m unit in two to three days. The larger 5m x 3m will take longer, but the system is designed to be manageable without specialist building skills.
You'll need an existing solid base — a concrete slab or compacted paving stones will work. The kit comes with all fixings included, and delivery is free.
Pricing
The 5m x 3m Addroom® is priced at £12,654.93 (May 2026). Dunster House regularly runs promotional offers that can bring this down considerably — worth checking their site for current offers.
