House shell construction in Batumi: frame, slabs, walls and stairs

What the house shell includes

The shell is the structural part of the house without the roof, windows, services and finishes: the foundation, the cast-in-place concrete frame or load-bearing walls, floor slabs, external walls, the staircase between floors and seismic ring beams. In the stage table on the construction hub, the shell together with windows, the entrance door and service connections makes up the black frame. When the shell is finished the house has its form and all its floors, but rain still gets in, and the next step is the roof and windows.

The shell can be ordered on its own, for example if you will do the finishing with your own crew, or as part of a turnkey build. Either way it is built to a design with a structural section calculated to the Georgian seismic code. The foundation is usually part of the shell estimate, and how it is chosen is described on the Foundations page.

House shell construction in Batumi: frame or load-bearing walls

For a private house of two or three storeys in Batumi we most often build a cast-in-place concrete frame: columns, beams and floor slabs of reinforced concrete, with the walls between the columns built of aerated concrete, clay block or brick. The frame takes the seismic load, and the masonry fills the openings and keeps the heat in. The second option is load-bearing walls of block or brick with seismic ring beams and vertical concrete cores. It is cheaper for a small single-storey house, but limits the size of openings and the freedom of the layout.

How the shell rises floor by floor

Every floor of a concrete-frame house is built to the same rhythm. First the columns: reinforcement cage, formwork, concrete. Then the slab formwork on props, two layers of reinforcement mesh, sleeves for soil stacks and ventilation, concrete in one shift. While the slab gains strength, the walls between the columns are built below and the columns of the next floor are prepared above. The stair flight is concreted together with the slab or straight after it.

More on the individual parts: floor slabs, load-bearing walls and partitions, reinforcement and seismic ring beams, staircases.

What we check before the concrete

In a shell almost everything that matters ends up hidden in concrete. So before every pour the site foreman checks the reinforcement against the drawings: bar diameter and spacing, laps, stirrups at the column and beam joints, the cover on spacers. Separately we check the sleeves for soil stacks, ventilation and wiring: a finished slab cannot be cut through later without the engineer's consent. All of this is photographed, and you get the photos before the concrete arrives. You can send your own engineer to sign off the reinforcement.

Weather and protecting the shell

We do not pour concrete in a downpour: water washes cement out of the top layer. In heat the slab is watered and covered so the surface does not crack. Blocks and cement are kept under cover, and fresh masonry is sheeted over at night. We try to close the finished shell with a roof quickly: open slabs soak up water in the rainy season, and screed and plaster then take weeks to dry.

Mistakes that are expensive to put right

• Columns poured without checking plumb: the walls are then built with cut blocks, and the facade has to be trued up with several coats of render.
• A slab without sleeves for soil stacks: the sewer then runs through holes broken out next to the reinforcement or in boxing round the rooms.
• Masonry not anchored to the columns: in an earthquake the whole wall falls out of the frame.
• Lintels over openings made of whatever steel was to hand instead of concrete to the calculation: cracks appear over the windows.
• A slab loaded with pallets of blocks on the third day after the pour.

If another contractor started the shell, we first take over what has been built against a signed report with photos and only then carry on.

Timing

A two-storey 150 m² house shell on a concrete frame usually takes 3–5 months after the foundation. Time is driven most by the weather in the rainy season, the complexity of the frame and access for concrete. Each stage closes with a signed acceptance report with photos, and you pay for the next stage after signing.

How much house shell construction in Batumi costs

The shell of a masonry house costs from 690 ₾ per m² of total floor area: foundation, concrete frame, floor slabs, external walls, staircase and seismic ring beams. Individual items: a concrete frame without walls from 650 ₾ per m², a 200 mm cast-in-place floor slab from 305 ₾ per m², 30 cm aerated concrete walls from 145 ₾ per m², a seismic ring beam from 100 ₾ per linear metre, a cast-in-place stair flight from 3,900 ₾. The roof, windows, services and finishes are not part of the shell. We send a preliminary estimate from the house plan within 24 hours on working days; the final cost is set from the design, after a site visit and agreement on the estimate.