Exterior stone cladding: a life-threatening hazard

Written in collaboration with engineer Ron Arad

Arad Bedek Bayit

What exterior cladding caught your eye on a friend's building? Marble, or are you more the slate type? Whichever you prefer, cladding is a matter of taste, but one thing gets forgotten just as often: safety. Cladding needs a building inspection too, and here is why.

Raining stones

Everyone remembers the marble cladding that fell 13 floors from a new building in Ashdod. Miraculously, no one was hurt: the lobby glass was damaged, the city engineer was called in, and the danger zone was taped off to keep people away.

Hod HaSharon was less fortunate. A tile that came loose from the wall seriously injured a child playing beneath the building.

These are not isolated cases. A quick search online turns up plenty of modern buildings whose marble cladding has, mysteriously, come loose.

Why tiles fall off

As with every other part of construction, there is a standard for exterior cladding: Israeli Standard 2378 and its parts, and Specification 378 of the Standards Institution. Most contractors follow it and take it seriously, but not all.

Serious defects still turn up every year: marble panels falling from the walls of modern buildings is not rare. Why? Over the decades, building facades in Israel have gone through plaster, textured spray coating, granolithic coating, mosaic and ceramic tile.

For the last twenty years the most popular finish has been marble and stone tile, which gives a plain concrete building the look of solid stone. A whole industry has grown up around it, offering tiles in every size and thickness, from beige marble to Jerusalem stone.

This kind of cladding depends on getting the fixing right. There are two methods, dry and wet (wet is more common), and contractors looking to cut costs are often careless about using galvanized metal for the anchors.

The result: after a few winters, the anchors corrode and the tiles start to fall. A second common problem is too few anchors per tile: with thousands of tiles on a building, each needing several anchors, some inevitably end up with fewer than required, or none.

A third is the stone itself: some grades are not strong enough for the standard and crack under structural movement and temperature change. A fourth is workmanship: cladding needs expansion joints every few meters, and without them the tiles crack.

Missing anchors at the bottom of a row, from carelessness or from not knowing the standard, is a serious defect that can bring tiles down over doors and windows. There are many more ways tiles get damaged and fall; these are only the most common.

And needless to say, cladding fixed with adhesive alone, with no anchors at all, has no Israeli standard behind it and alarms building inspection engineers whenever they see it.

Take responsibility

The lesson is twofold: even in construction, where safety is supposed to matter most, not every contractor meets the standard, and you may be exposed to real danger on your own property. If there is a problem, you will never know about it without a building inspection, and no one wants to find out after paying for an apartment that the building is unsafe.

What to do: get a building inspection

Whether you are buying a new apartment from a contractor or a resale apartment, have a specialist engineer carry out a full building inspection before you commit. It should be part of your purchase costs. No inspection catches every defect, but it will turn up far more than an untrained eye ever could.

You may already be looking for an engineer who can tell you whether the structure is sound, the walls are free of hidden dampness, and the floor tiles are laid straight and even. Now you know one more thing to ask for: a building inspection should not stop at the inside of the building. Checking the exterior cladding matters just as much.