CLT house in Batumi and Georgia: what is possible and what to choose instead

CLT, or cross-laminated timber, is a panel made of several layers of boards, with each layer laid across the one before it. Once glued under a press, it works as a slab: it carries loads in both directions and, within its own plane, hardly changes size with moisture. Abroad, these panels are used for private houses and multi-storey buildings alike. In Batumi a CLT panel house is still a rarity, and we start any conversation about one with where to get the material.

How a CLT house is assembled

The factory cuts the panels on a CNC machine to the design of the house: it cuts out the windows and doors, the rebates for the joints, the holes for pipes and the channels for cables. The panels arrive on site numbered, and a crane sets them on the foundations according to the assembly diagram. The walls are connected to each other and to the floors with steel angle brackets and long screws, and fixed to the foundations with anchors that hold the wall against sliding and uplift.

A CLT wall in a private house is usually 100–140 mm thick. It carries the load, keeps the house rigid in a tremor and in wind, and can stay as bare wood on the inside. It doesn't hold heat well, so insulation and a facade go on the outside. CLT has almost none of the settling you get with solid timber, and finishing starts straight after installation.

CLT in Georgia: where to get the panels

We haven't found any CLT production in Georgia, and we haven't seen ready-made CLT houses offered on the local market either. That means the panels will have to be ordered from a factory abroad, and we name the factory and the country of supply in the estimate once the choice is made. For a single private house this means a design for a particular factory, a place in its production queue, delivery by lorry or by sea in containers, and customs clearance. Panel size is limited by transport, so long walls and floors are cut into sections, and every extra joint adds work during installation.

We don't suggest ordering CLT straight away. When we get such a request, we price the same layout in two other methods as well and show how much time and money the delivery will take, and you make the decision on the figures. Delivery to Batumi and customs are usually handled by the supplier, and sometimes by a broker you hire. On our side are the factory's lead times before the contract, the site, the crane and accepting the panels against the schedule.

Seismic design: what the factory does and what our structural engineer does

The factory designs the panels and connections to the codes of its own country. For Georgia this isn't enough, and our structural engineer recalculates the house to the Georgian seismic code and the ground conditions of the plot. A CLT house is light and rigid, and in an earthquake everything comes down to the connections: hold-down anchors against uplift at the ends of the walls, angle brackets against sliding, and the connection between the floors and the walls. The structural engineer checks these first, and after the check the connections may change, and a large window may need a solid section of wall next to it.

Our structural engineer's comments go to the factory, and the factory revises the cutting plan. Until the connections are agreed on both sides, the panels don't go into production. What else helps a house withstand a tremor is covered on the page about earthquake-resistant construction.

Crane installation and protection from rain

A CLT shell goes up quickly: the walls and floors of a small house are installed in a few days. For those days you need access for a lorry and a mobile crane, a crane pad on firm, level ground, and space for unloading if the installation can't keep pace with the deliveries. On a slope or a narrow street, preparing the access can cost more than the installation itself.

The panels must not get wet during the build. Water that gets into the edges and joints takes a long time to come out and leaves stains on the visible surface. So we try not to schedule installation in the rainy season, from September to January, and pick dry weeks. We cover the edges and tops of the walls with a membrane straight after installation, tape plastic sheeting over the floors, and put the roof on right after the last panel.

Insulation, facade and vapour

The insulation goes on the outside of the panel: mineral wool as calculated, a breather membrane and a ventilated facade with an air gap. On the inside the wood stays solid, and a vapour barrier membrane like the one in a timber frame house usually isn't needed: the panel itself holds back vapour, and if moisture gets into the wall, it lets it out through the mineral wool and the air gap. The engineer still checks the wall build-up with a moisture calculation, because in Batumi in summer vapour moves from the street into the cool room.

The cladding can be timber boards, fibre cement or porcelain tiles on a subframe. For CLT we recommend a ventilated facade rather than render over insulation: if water ever gets behind the cladding, it has somewhere to go. How else these two solutions differ is explained in our comparison ventilated facade vs ETICS.

Fire and noise between floors

The fire resistance of CLT walls and floors is calculated from the thickness of the panel and the number of layers, and where there isn't enough margin, the panel is covered with plasterboard. The flue of a fireplace goes through the floor in a non-combustible firestop.

Noise is harder to deal with. A CLT floor is light, and footsteps from above can be heard if the floor finish sits directly on the panel. So on top we lay a floating screed or a dry floor on a sound-insulating layer, and underneath, if needed, a suspended ceiling. In a house for rent this is a must, and how to lay out the rooms so that bathrooms, not just a single wall, sit between neighbouring beds is shown on the page about guest houses.

CLT panel house or another method

People choose CLT for the wood in the interior and a fast, precise shell. In Batumi a similar result can be achieved another way, usually for less and with a material that is easier to get:

• glulam gives the same timber wall on the inside and hardly settles, and its shell costs less;
• a timber frame house of kiln-dried timber, lined inside with tongue-and-groove boards or veneer, costs several times less, and the timber for it is sold in Georgia;
• a cast-in-place concrete frame house with wood in the finishes copes better with damp and needs less upkeep;
• a mixed scheme: masonry walls, with CLT only for the floors or the roof, where the wood is visible on the ceiling; far fewer panels are needed then, and the bearing on the masonry is calculated by the structural engineer.

We compare by estimate: the same layout in two or three methods, with the shell price, timeline and upkeep. If CLT still comes out on top after that, we start corresponding with the factory.

How much a CLT panel house costs

The shell of a CLT panel house costs from 2,220 to 2,760 ₾ per m² of floor area, and this covers the foundations, the walls, floors and roof made of factory-cut panels, crane installation, the roof covering and the windows. Unlike our timber and log shells, windows are already included here. Utilities, finishing and the design are priced separately, and a turnkey house starts from 3,420 ₾ per m².

The biggest line in the estimate is the panels: from 570 ₾ per m² of wall or floor, including cutting, delivery and installation. A foundation slab costs from 390 ₾ per square metre of footprint. Insulation and the ventilated facade are not included in the shell: a turnkey ventilated facade with materials starts from 420 ₾ per m² of facade. For comparison, glulam costs from 1,980 ₾ per m² for the shell and from 3,000 ₾ for a turnkey house.

Costs go up with delivery from abroad and the exchange rate, long panels that travel as an oversize load, difficult crane access and a visual-grade surface in every room. They come down with a simple plan and industrial-grade panels wherever the finishes will cover them. We send a preliminary estimate from a sketch within 24 hours on business days, and the final cost is set on the basis of the design and the factory's calculation, after a visit to the plot and once the estimate is agreed.