Wood-chip concrete house in Batumi: what to know before ordering blocks

A wood-chip concrete house is built from large blocks made of wood chips and cement; the material is also sold under the name arbolite. The chips are treated with mineralising agents so that the sugars in the wood don't stop the cement from setting, and in the finished block every chip is coated in cement stone. The wall is warm and light, holds nails and screws and is good at stopping sound. It has two weak points: wood-chip concrete absorbs a lot of water, and it is almost impossible to find in Georgia. In Adjara both of them matter.

Wood-chip concrete in Georgia: delivery and batch checks

We haven't found any wood-chip concrete production in Georgia, and the big builders' merchant chains don't stock it either. Blocks for a house are brought in from abroad to order, and delivery takes weeks. This affects both the price of the shell and the schedule: we build the foundations while the blocks are on their way, and start laying only once the whole quantity is on the plot. Quickly buying the missing pallets won't be possible.

The quality of wood-chip concrete depends heavily on the plant, so before ordering we ask for test reports on strength, density and water absorption, plus a few samples. We look at the chips: they should be needle-shaped and roughly the same size, without sawdust or shavings, which weaken the block. At a broken edge every chip should be wrapped in cement, with no voids or loose spots, and the corners of the block shouldn't crumble in your hands. We check the batch again on unloading.

Where wood-chip concrete fits in Adjara and where it doesn't

Wood-chip concrete makes sense for a one- or two-storey house on a dry plot, where the owner wants a warm wall with a wood aggregate and is prepared to budget for a protective facade. It suits a house you also visit in winter, because the wall warms up quickly. For a mountain house in Adjara, where winters are colder, this is especially noticeable, but getting imported blocks there is even harder, and this has to be taken into account from the start.

We don't use wood-chip concrete in a plinth or basement, in walls that stand in the ground, or in damp lowlands where water lies for weeks after a downpour. On the seafront it needs cladding with a ventilated air gap, because render there gets soaked too often. If delivery doesn't fit the budget, we suggest a replacement made from local materials.

Water: the main weakness of wood-chip concrete

Wood-chip concrete absorbs noticeably more water than aerated concrete and takes a long time to dry. A wet block loses strength, and if it stays damp for months, mould appears on it. So a wood-chip concrete house starts with a high concrete plinth: the blocks must sit on a damp-proof course above the splash zone of heavy rain, and in the mountains above the snow that lies by the walls as well. We make the roof overhangs wide, gutters are a must, and the paved apron slopes away from the house.

On site we keep the blocks on pallets under a shelter, not under plastic sheeting on the ground. Overnight and before rain, the laid masonry is covered on top and on the windward side. In bathrooms and the kitchen, the walls under tiles are protected with waterproofing over the full height of the wet zone, behind the sink as well.

Ring beams, floors and seismic loads

Wood-chip concrete is not very strong, and it handles point loads poorly. So beams and slabs never bear directly on the masonry: we pour a reinforced concrete ring beam along the top of the walls, and the lintels over windows are concrete too. Wood-chip concrete works best with a timber floor on joists resting on the ring beam. A heavy cast-in-place concrete slab goes only on a cast-in-place concrete frame.

For seismic design, the low weight of the walls helps: a lighter house takes less force in a tremor. But weak masonry without ties fails more easily, so the ring beam, the cores at the corners and by openings and the anchoring to the foundations are calculated by the structural engineer. We offer a two-storey wood-chip concrete house only with a concrete frame, using the blocks to fill the walls.

Facade and finishing

The open structure of wood-chip concrete lets air through, so the masonry is plastered on both sides, otherwise the wind blows through the wall. Plaster grips the coarse, porous surface well, and we lay mesh over the whole surface. Outside we use lime-cement render and vapour-permeable paint, inside gypsum or lime plaster. We don't put polystyrene or dense membranes on wood-chip concrete.

For walls exposed to wind-driven rain, a ventilated facade is more reliable: fibre cement or timber board cladding on a subframe, with a gap behind it where the masonry can dry out. How it differs from render over insulation is shown in our look at the two facade types. In our experience a 30 cm wood-chip concrete wall in Batumi usually doesn't need insulation, but the thermal calculation makes the final decision.

Fixings and wiring

This is where wood-chip concrete is more convenient than other blocks. It holds nails and screws without wall plugs, shelves and kitchen cabinets hang on ordinary fixings, and window frames are secured reliably. For the water heater and heavy appliances we still use long anchors or embedded fixings, because the block's strength is low.

In a wood-chip concrete wall we run the wiring in non-combustible corrugated conduit or metal pipe. Factory-made wood-chip concrete burns poorly, since the chips are coated in cement, but the wood aggregate is still there, and we don't want to take risks. Photos of the runs before plastering go into the handover file.

What can replace wood-chip concrete

If delivery doesn't fit the timeline or the budget, we price a replacement. Aerated concrete in a cast-in-place concrete frame gives similar warmth and is made in Georgia itself, but it doesn't hold nails. A timber frame with mineral wool goes up faster and also holds fixings; there is more on the page about timber frame houses. Closest to wood-chip concrete in composition is permanent formwork made of wood-cement blocks that are filled with concrete, but these blocks are also rare in Georgia, and we check supply before the design.

How much a wood-chip concrete house costs

The shell of a wood-chip concrete house costs from 860 ₾ per m²: foundations with a high plinth, walls of imported blocks with ring beams, floors and roof. The protective facade, windows, building services and finishing are priced separately. A turnkey wood-chip concrete house starts from 1,860 ₾ per m².

Wood-chip concrete costs more than other blocks because of delivery: a 30 cm wall laid with materials costs from 230 ₾ per m². For comparison, an aerated concrete shell and a timber frame house shell both start from 750 ₾ per m². A turnkey ETICS facade costs from 205 ₾ per m² of wall, and a seismic ring beam from 100 ₾ per linear metre.

The price moves with the cost of transport and the exchange rate on the order date, the height of the plinth, and the type of facade and floors. We send a preliminary estimate from the house plan within 24 hours on business days. The final cost is set on the basis of the design, after a visit to the plot and once the estimate is agreed.