High-tech house in Batumi: steel, glass and precise geometry

A high-tech house in Batumi relies on a frame that allows large spans and cantilevers, and on a facade of glass and flat planes with crisp joints. It looks simple, but that simplicity demands precision: the joints between cladding panels line up with the edges of the windows, there are no downpipes on the facade, and the exposed steel doesn't rust by the sea. We design interiors in this style separately, as described on the page about high-tech interior design; this page is about structure and materials.

The frame: concrete, steel or a combination

For a house like this we more often suggest a cast-in-place concrete frame. It copes with damp without trouble and immediately provides a level slab for a usable roof. A frame of hot-rolled steel sections is chosen when you need column-free spans or slender supports on show. How each of them behaves in an earthquake and by the sea is covered in the comparison of concrete vs steel frame.

The result is often a hybrid: a concrete lower floor partly set into the slope, and a steel or concrete upper part with cantilevers. The structural engineer designs the joint where the steel bears on the concrete, and we set the cast-in plates for the steel columns before the pour using a template, so that each column stands exactly on its grid line. On a high-tech facade an error of a couple of centimetres can be seen from the road.

Cantilevers and overhanging volumes

A signature move of the style is an upper floor that overhangs the entrance or a terrace by several metres. Such a volume can be carried by a thick slab with beams, by a steel truss hidden in the wall, or by the concrete walls of the floor itself acting as a deep beam. In the last case the whole wall is load-bearing, and the windows in it are limited: every opening cuts into the beam. We draw the windows of the cantilevered volume together with the structural engineer, who sets the reach and the member sizes by calculation, taking seismic loads into account.

The underside of a cantilever is exposed to the outside, and without insulation the floor of the room above is cold in winter. We cover the insulation underneath with the same cladding as the facade or with exterior soffit panels over a ventilated gap, and fit a drip along the edge so that water from the facade doesn't run back onto the soffit of the cantilever.

Exposed steel by the sea

The metals and fixings we use for any house near the shore are listed on the page about houses by the sea. In a high-tech house the steel is on show: columns, canopy beams, external stairs. Any orange rust streak on it becomes part of the facade, so we think through the protection on the detail drawing, before the part ever reaches the paint shop.

We round off the edges before painting: on a sharp edge the paint goes on thin and wears off first. We try to avoid welding after hot-dip galvanising, because it burns off the zinc, so the joints are bolted. Stainless steel bolts go in with isolating washers, so that the zinc around the hole isn't eaten away. Hollow sections are capped at the ends or given drainage holes at the bottom, and beam flanges are turned so that puddles and leaves don't collect in them. We record the paint code in the handover file, so that a chip can be touched up in the same shade.

The facade: planes and joints

The flat facade of a high-tech house is usually a ventilated one: large-format porcelain tiles, fibre cement boards or aluminium composite cassettes on an aluminium or stainless steel subframe. Why by the sea we prefer a ventilated facade to render, and how heavy cladding is fixed for seismic loads, is covered in the comparison of ventilated facades and ETICS.

Cast-in-place concrete is never perfectly flat, and high-tech cladding doesn't forgive deviations. We use a subframe with adjustable brackets and set out the plane with a laser, not by following the wall. We draw a panel layout for each wall so that the joints line up with the edges of the windows, the corners and the floor slabs, and cut panels don't end up as a narrow sliver next to an opening.

Drainage you can't see

A high-tech facade usually has neither gutters nor downpipes. Water from the flat roof goes into internal outlets, and the risers run inside the house in ducts with access on every floor. We don't bury a riser in masonry or concrete: otherwise, if it leaks ten years later, finding the leak will mean taking the wall apart.

Without visible drainage the water has fewer backup routes, so an emergency overflow in the parapet is essential here. We draw its spout on the facade as a neat detail, in line with the cladding joints. Canopies and cantilevers collect water too: we give them a fall towards a concealed gutter or towards an edge with a drip. Falls, parapets and roof access are described in detail on the page about a usable flat roof.

Full-height glass

In a high-tech house the glazing often runs floor to ceiling across the whole wall. We build such walls with mullion and transom curtain wall systems, and the exits to the terrace with thermally broken aluminium lift-and-slide doors. The glass is set in the frame with the clearance the system specifies: in a tremor the frame shifts, and glass without clearance cracks. The mullions are fixed to the slabs on adjustable brackets, because a facade system needs millimetre accuracy.

On a smooth facade, external louvres and sun blinds are hidden in cassettes flush with the cladding. We build space for them into the facade detail before the curtain wall system is ordered: if they are remembered only after installation, the box will stick out of the plane. Which glass to use on the west side and how to make a threshold-free exit to the terrace is covered on the page about a house with a panoramic terrace.

The cost of a high-tech house in Batumi

A turnkey high-tech house costs from 2,520 to 3,120 ₾ per m² of total floor area. The price covers a usable flat roof, panoramic glazing in thermally broken aluminium, a ventilated facade, all the building services and the final finishes. The house design is priced separately.

Within this price, the glass and the facade move the estimate most. A turnkey ventilated facade with porcelain tiles or composite panels costs from 420 to 540 ₾ per m² of wall, and lift-and-slide doors from 1,800 ₾ per m² of opening. A complex shape with cantilevers and bay windows adds 18–24% to the price of the house. A compact volume without cantilevers, where the panoramic glazing is concentrated on one wall facing the sea and the other windows are of ordinary size, comes out cheaper. The final cost is set on the basis of the design, after a visit to the plot and once the estimate is agreed.