Engineer Ron Arad
Arad Bedek Bayit
Stone cladding has been the subject of many articles, covering just about every way it can fail. There are, indeed, several failure modes that show up during a home inspection (bedek bayit). This article covers the most dangerous one: missing anchors.
There are two main ways to install stone cladding. One uses anchors that tie the stone to the iron mesh behind the cladding system; the other relies on adhesive. Adhesive bonding is a dangerous method with no Israeli standard behind it: it borrows practices from certain countries abroad without the knowledge or regulation those countries actually apply. The anchor method is the safe, correct approach, especially for thick stone (over 2 cm).
The real danger appears when workers use the anchor method but, out of ignorance or negligence, skip anchors or install too few, creating construction defects that later surface during an engineering home inspection.
Another important detail is the metal angle bracket installed under the bottom row of stone. It gives that row extra support if the anchors fail. The bottom row needs this support because, unlike the rows above it that rest on one another, it sits "in the air", often above openings or alongside balconies.
Here is an example from a recent project where a home inspection was carried out to find construction defects.
No anchors or bottom angle brackets were found. This was the bottom row of stone cladding on a wall, using stone 4.5 cm thick: very heavy stone.
This violates Israeli Standard 2378 for natural stone cladding and Mafmakh 378, section 106.3.2(b):
b) Determining the static scheme of the stone and its attachment points:
- for horizontal loads: by the attachment points;
- for vertical loads: by the location of the floor-level support bracket.
And section 201.5:
201.5 Angle brackets
Horizontal angle brackets that support the panels above them must be attached to the wall at ceiling level, or at vertical intervals no greater than 3.5 m.
The fix in these cases is to install angle brackets along every bottom row and anchor all the tiles in the building with bolts into the concrete walls. To limit the visual impact, the bolt head is sunk slightly below the surface and sealed with marble adhesive, then the stone is polished. It is expensive, thorough work, but necessary: without the repair, the danger is a genuine risk to life.
The engineers of Arad Bedek Bayit, led by building engineer Ron Arad, whom courts appoint as their own expert on construction defects. The company has been inspecting apartments and buildings since 2001. Engineer Ron Arad · More about the company