Ventilated facade vs ETICS: which withstands Batumi's climate

By the sea, the real test of a ventilated facade vs ETICS comes in the very first winter of wind-driven rain. In a ventilated facade, the cladding hangs on a subframe, with an air gap and insulation behind it. In ETICS (an external thermal insulation composite system, often simply called insulated render), the insulation is glued to the wall and covered with reinforced render, so the render coat itself takes the rain.

Wind-driven rain and moisture in the wall

In a storm, water hits the wall almost horizontally. The cladding of a ventilated facade takes it and sheds it downwards, and any drops that get through a joint dry out in the air gap. The insulation behind the cladding is covered with a breather membrane and stays dry.

ETICS keeps water out only as long as the render coat is intact. While there are no cracks, all is well, but a hairline crack at a window reveal lets water straight into the insulation, and the insulation is slow to dry out. That is why we add extra reinforcing mesh at the corners of openings.

We also look at what the wall is made of. Aerated concrete and other porous blocks need to release moisture outwards, and we advise against covering them with expanded polystyrene: the vapour meets a dense layer and the moisture stays in the wall. For walls like these we use mineral wool with a vapour-permeable render, or a ventilated facade.

Ventilated facade vs ETICS by the sea: salt and fixings

A ventilated facade contains a lot of metal, and by the sea that metal sits in salt air. We use an aluminium or stainless steel subframe with stainless fixings, and we separate different metals with isolating pads so that they do not corrode each other. We don't use galvanised steel for a ventilated facade subframe by the sea, because cut edges and drilled holes are the first to rust.

The brackets are held by anchors, and the wall has to be able to take them. In aerated concrete we use anchors designed for porous blocks, and before installation starts we pull-test several of them on site. ETICS has almost no metal, but in a humid climate green patches of algae appear on shaded walls over time, so we use a paint that resists them.

Seismic load and heavy cladding

Porcelain stoneware and fibre cement panels are heavy, and a panel falling from height in an earthquake is dangerous. So we fix the cladding according to a calculation that covers bracket spacing, anchors, clips and the gaps between panels. In a tremor the subframe moves with the wall, and each panel stays on its own fixings.

ETICS is light, but it cracks where the wall is not uniform. Usually that is where a concrete column or floor slab meets the blockwork: the materials expand differently and move differently in a tremor. We cover these joints with mesh that extends well to both sides.

Weather on site

ETICS needs dry weather. The adhesive, render, primer and paint all have to dry, and rain washes off a fresh coat. In Batumi we plan this work for dry weeks and hang protective mesh on the scaffolding against wind and direct sun. A ventilated facade depends less on the weather, although we still cover the insulation against rain while it is being installed.

The timing differs too. ETICS goes on in layers, and each one needs to dry, so a rainy week pushes back the whole sequence. A ventilated facade is installed section by section: subframe, insulation and cladding on one wall, then on to the next.

Insulation and fire safety

For both types of facade we prefer mineral wool. It lets vapour through, is not affected by heat and does not burn, which matters in a house where guests sleep. Expanded polystyrene is cheaper and lighter, but on a porous wall in a humid climate it carries more risk.

In ETICS, the insulation boards are glued around the edges and in dabs across the middle, then held with insulation fixings as well. In a ventilated facade the mineral wool is held by the fixings alone, and the membrane protects it from wind. We record the make of the wool, adhesive and fixings in the handover file, together with photos of the insulation before it is covered.

Repairs and cost

A damaged panel on a ventilated facade is replaced on its own, and the rest of the wall stays as it was. On ETICS a patch shows, and after a repair the whole wall is often repainted. In a rental house the plinth and the walls by the entrance get knocked by suitcases and bicycles, and cladding lasts longer there than render.

ETICS is cheaper in both materials and labour. A ventilated facade costs more because of the subframe and the cladding, but the wall behind it needs repairs less often. If the wall allows both options, we price both, and you see the difference in the figures.