Anyone else running a small woodburner in a timber cabin — how are you handling the hearth and clearances?

Just finished putting up a 4x3m larch-clad cabin on our smallholding in mid-Wales and I'm at the stage of sorting the heating. I've gone with a Hobbit stove (5kW nominal, though in a space this small I'll barely be touching it) and I'm trying to work out the hearth situation without massively overbuilding it. The floor is 18mm OSB over timber joists, so obviously needs proper protection underneath, but I don't want to pour a full concrete slab if I can avoid it.

At the moment I'm thinking 125mm solid dense concrete block, topped with 20mm vitrified porcelain tiles, sitting on a layer of 6mm Vitcas fire board. That should comfortably exceed the 12mm non-combustible requirement for a raised hearth, but I keep second-guessing myself. The stove is going against a studwork wall with a Selkirk twin-wall flue going straight up through the roof, and I've got 200mm of Rockwool between the flue and the nearest timber at the ceiling penetration.

Wall clearances are what's really nagging at me. The Hobbit spec says 150mm to a non-combustible wall and 300mm to a combustible one. My studwork is lined with two layers of 12.5mm Fireline plasterboard on the stove side — does that count as non-combustible for the purpose of those clearances, or am I still treating it as combustible because there's timber framing behind it?

Would genuinely appreciate hearing what others have done, especially in similar small timber builds. Photos welcome if you've got them.

@Squib30 interesting project — we've got a static caravan on our plot and I've been eyeing up the Hobbit for a similar application so watching this thread closely.

Quick question that might be relevant for your situation too — did you have to get any kind of sign-off or building notice for the installation, even in a timber outbuilding? I've seen conflicting advice about whether Permitted Development covers this or whether HETAS registration of the installer becomes mandatory regardless.

Also curious about your flue route — are you going straight up through the roof or out through a wall first? With a larch-clad structure I'd be nervous about the horizontal section and heat buildup near the boarding.

What's your floor construction — concrete slab or timber joists? That seems to dictate a lot of the hearth solution options.

Really nice project @Squib30! One thing worth flagging — in a timber-framed cabin the non-combustible hearth needs to extend at least 225mm in front of the stove door and 150mm either side as a minimum, but honestly I'd go bigger. I used 600x900mm of 20mm slate on a cement board substrate in mine and it's given me proper peace of mind.

For wall clearances, the Hobbit manual specifies distances but you can reduce them significantly with an air-gapped heat shield — basically a non-combustible board held 25-50mm proud of the wall on ceramic standoffs. Makes a real difference in tight spaces.

Worth getting a HETAS installer to sign it off too, especially if you're ever thinking of insurance on the cabin. Some insurers are awkward about self-installed stoves in timber buildings.

Really useful thread this. @Squib30 one thing I'd add on top of what @Curly66 is saying — don't overlook the wall clearances behind and to the sides of the stove itself. With the Hobbit being quite compact it's tempting to tuck it closer to a timber wall than you should. The manufacturer specifies minimum clearances but I'd honestly treat those as absolute minimums rather than targets, especially in a larch-clad build where the wall construction behind any board-and-batten might be drier than you'd expect.

We used a combination of Vitcas board and a small air gap behind it on ours, which keeps things well within safe margins without eating too much floor space. Worth having a read through HETAS guidance if you haven't already — it's freely available online and covers timber frame scenarios specifically.

Great project @Squib30, that Hobbit is a cracking little stove for a space that size.

One thing nobody's mentioned yet — thermal mass under and around the installation is your friend in a small cabin. A lot of people go minimal with the hearth just to meet the 125mm non-combustible requirement, but in a tight timber build I'd seriously consider going thicker with the hearth slab. It stores heat and releases it slowly, which evens out the temperature swings you'd otherwise get with a 5kW output in such a compact volume. We used a 75mm slate hearth on a concrete backer in our cabin and the difference compared to a thinner setup is noticeable.

Also worth thinking about ventilation — tiny cabins can depressurise surprisingly quickly once you've got a stove drawing, especially if you've gone airtight with your build. A dedicated air brick near the stove sorted ours.

Got a Hobbit in my tiny house too — brilliant little stove for the size.

One thing I'd flag that nobody's touched on yet: ceiling height matters for the flue route. In a low cabin, getting the required straight section above the stove before any bends can be trickier than expected. Twin-wall insulated flue is worth the extra spend here — keeps the surface temps down where it passes close to timber and maintains better draw.

Also worth checking the Hobbit's specific clearances on their HETAS docs rather than going off generic figures. The nominal clearances can sometimes be reduced if you fit a proper heat shield, which in a 4x3m space might save you some useful room.