The Hearth
- Office
- Studio
- Lounge
- Retreat
- SIP Construction
- 216mm Wall System
- Ground Screw Foundations
- 10 Year Structural Warranty
Design Your Hearth.
Choose your size, doors, cladding, interior and extras. The price updates instantly — no commitment until you're ready.
- Building Size
- External Cladding
- Door Style
- Window Layout
- Interior Finish
- Flooring
- Heating
- Lighting
- Decking
- Pergola Options
Built like a home. Not a shed.
SIP panels — engineered to outperform stick-frame sheds.
216 mm insulation envelope rivals new-build homes.
Heat retention up to 7× better than typical garden rooms.
No concrete. Faster install, kinder to the garden.
2–5 days on site once your build is delivered.
Structural guarantee on every Arden & Oak build.
See what makes an Arden & Oak different.
Every layer serves a purpose — strength, insulation, ventilation and durability.
- Structural SIP construction
- 90 mm PIR insulated core
- Ventilated rainscreen cavity
- Service void for electrics
- Year-round use
- Basic timber stud
- 50 mm rockwool insulation
- No service void
- Minimal thermal performance
- Seasonal use only
Over twice the wall thickness of most garden rooms.
The numbers behind why an Arden & Oak feels — and performs — like a home.
The headline numbers.
- 216 mm SIP wall panels
- Insulated roof & floor cassette
- Structural Insulated Panel system
- PIR core throughout
- U-value: 0.18 W/m²K
- Triple-layer thermal envelope
- 9 mm birch ply standard
- Optional plaster & paint
- Engineered oak flooring available
- uPVC windows & doors as standard
- Choice of 4 colour finishes
- Argon-filled double glazing
- Full first-fix wiring
- Consumer unit & RCD
- LED downlights & sockets
- Wall-mounted panel heater
- Optional air conditioning
- Underfloor heating available
More ways to fund a garden room than you might think.
Most customers are surprised by the number of ways a garden room can be funded — from savings and personal loans to home equity and business funding. There may be options that suit your circumstances.
Explore funding options →- Savings
- Home equity
- Business funding
- Personal loans
One room. Endless lives.
The same building, configured for the way you want to use it.
Built to last. Loved by owners.
“Better insulated than our extension. Use it year-round as a working office and weekend bar.”
“Quality is night-and-day above the brochure-built sheds we looked at. Arden's team had it weather-tight in 3 days.”
“Genuinely premium feel inside. Walls feel solid, finish is impeccable. Worth every penny.”
From first call to finished room.
Site assessment, lifestyle brief, model selection.
Itemised pricing, structural drawings and timeline.
Panels machined in the UK; ground screws set on site.
2–5 days on site, full clean-up and warranty pack.
Everything else. On-demand.
Open any section to dive deeper — construction, energy efficiency, payment schedule, FAQs and more.
Structural Insulated Panels (SIPs) sandwich a high-density PIR core between two engineered timber skins. The result is a wall system that's stronger, straighter and dramatically better insulated than traditional stud frames. Every Arden & Oak panel is precision-cut in the UK and delivered ready to assemble.
From outside in: ventilated cedar / larch rainscreen → breather membrane → 18mm OSB → 142mm PIR core → 18mm OSB → service void → 9mm birch ply (or plastered finish). Total wall thickness 216mm. U-value 0.18 W/m²K — beating current Part L building regs for new homes.
Independent thermal modelling shows our envelope retains heat up to 7× longer than a 70mm stud frame shed. A 1.5kW panel heater is typically enough for a 15m² office in mid-winter. Annual running cost for a year-round home office: ~£140 at 2026 electricity rates.
Standard finish is 9mm A-grade birch ply with a clear matt lacquer. Upgrades include plastered & painted walls (any Farrow & Ball or Little Greene shade), oak veneer panels, slatted acoustic walls and integrated joinery.
Survey & ground assessment (week 1) → ground screw foundations laid in a single day → panels arrive flat-packed → typical 4×3m build installed and weather-tight in 3 days → second-fix electrics, glazing and finishing over a further 2–4 days. No mess, no concrete, no skip.
10% deposit on order. 40% on factory production start. 40% on delivery to site. Final 10% on completion and snag sign-off. We don't broker finance — most customers fund their build through savings, a personal loan, home equity or business funding. See our funding guide at /funding-your-garden-room for a plain-English breakdown of each route.
Used wholly for business? Limited companies can claim Capital Allowances on the contents and services (electrics, heating, glazing) — typically 35–55% of the build cost. VAT is reclaimable. The structure itself remains personal asset, so no Capital Gains issue on house sale.
Do I need planning permission? — Most builds fall under Permitted Development (under 2.5m eaves, no closer than 2m to a boundary at full height). Can it run plumbing? — Yes, with mains feed from the house. Lead time? — 6–8 weeks from deposit to install.
We install across England and Wales. Standard delivery covers everywhere within 250 miles of our Devon workshop; further north (above Manchester) carries a £450 logistics supplement. Scotland and Northern Ireland by quotation.
Ready to create your space?
Whether it’s a home office, gym, studio or retreat, we’ll help design the perfect garden room for your lifestyle.
- SIP Construction
- 216mm Wall System
- Ground Screw Foundations
- 10 Year Structural Warranty