Swap a Summerhouse for a Garden Room You Can Use Every Day of the Year
Published: 3 April 2026
Reading Time: 3 minutes 30 seconds
This 4.88m × 2.62m PRIMO 26.50 in West Sussex by A Room in the Garden is a great example of what changes when owners trade a seasonal summerhouse for a garden room built for everyday use. The old building was a small hexagonal structure; the brief was for something larger, properly insulated, and more practical, that would sit well in the established garden.
The answer was a model from the PRIMO range — A Room in the Garden’s pre-designed garden room range, developed from the same architect-led thinking that runs through their bespoke work, but with fixed sizes and a palette of options to personalise the layout and finishes. At 2.47m high, the finished room also sits in the size band that offers maximum positioning flexibility under the Permitted Development rules.
Contemporary Cube Styling
The PRIMO is confidently designed as a clean-lined cubist shape. A stylish detail is the anthracite fascia: it frames the Redwood-clad front wall like a deliberate picture border, and it is colour-matched to the doors and windows for a unified palette.
Glazing is configured as a three-panel run in the centre of the front wall — outward-opening French doors alongside a tall window — which opens the room straight onto the garden and keeps the indoor–outdoor connection strong throughout the year.
Sightline Through the Room
On both side walls the owners opted for full-height glazing. The windows are set slightly forward towards the front elevation.
Seen in side view, the glass lines up so you read a clear sightline through the room to the garden beyond, with light pulled in from two directions. It is exactly the sort of quiet design decision that signals architect-drawn work rather than cookie-cutter openings.
Narrow Redwood Cladding Detail
The detailing of the Redwood cladding is worth a closer look. The tongue-and-groove boards are narrower than the wide profiles that dominate much of the market, so the v-grooves sit closer together and the walls pick up a finer, more tailored rhythm as your eye moves across them.
On a standard PRIMO, mixed external cladding is specified — treated Redwood to the front and corrugated anthracite to the sides and rear. This is a stylish, low-maintenance combination, but A Room in the Garden offer options to personalise the exterior. Here, the owners upgraded both side walls so they are finished in Redwood to match the front, which gives three faces a continuous timber character.
SIP Shell, House-Quality Glazing, and a Turnkey Interior
Structurally, the room is a SIP (Structural Insulated Panel) build through walls, floor, and roof — the kind of continuous insulated envelope that separates a well-specified garden room from draughty summerhouse construction. Published U-values for the PRIMO shell (0.3 W/m²K on walls and floor, 0.22 W/m²K on the roof) demonstrate how well insulated the range is.
Double-glazed doors and windows sit inside that shell, with the internal and external build-ups completing the separation from the weather. Electric underfloor heating was specified for the colder days of the year, avoiding radiators on the walls.
Inside, the finish is like a new build house: white plastered walls and ceilings, a warm wood-effect laminate floor that echoes the exterior timber, and the usual PRIMO electrical package carried through as part of the turnkey handover — LED lighting, power points, internet routing, smart switching, and a dedicated consumer unit with certification.
The owners note that the room has quickly become the go-to spot for reading, relaxing, and having friends round — the outcome you can expect when choosing an insulated garden room designed for comfortable year-round use rather than a summerhouse.
PRIMO Garden Room Prices
On price, the PRIMO 26.50 is listed from £26,849 including VAT at the time of writing. A Room in the Garden clearly show prices and option costs on their site; the PRIMO page is the place to compare sizes and options for a pre-designed garden room.
Learn More
A Room in the Garden design and build pre-designed and bespoke garden rooms from their base in Sussex, working across England. To explore the PRIMO range, case studies, and specification detail, visit aroominthegarden.co.uk, call 01273 80 70 77, or email hello@aroominthegarden.co.uk
