Construction defects in roofs

What is important to check on the roof of a shared building? These are the main issues.

Roof waterproofing

The roof has to be completely watertight so that water does not get into the building, as required by the Israeli Standard and by the Planning and Building Regulations that bind the contractor. That requires correct waterproofing details made with the correct materials.

For example, this is what a proper waterproofing detail looks like where a pipe comes out of the roof (a "grandpa's cane" gooseneck, makel saba): the pipe is installed inside a bent sleeve that keeps water out.

In many cases, faulty waterproofing around a pipe on the roof, which is quick and simple to repair, causes serious dampness problems. Two such examples from buildings we inspected appear on the page Defects we found in buildings.

Safety and maintenance on roofs

No less important is safety and the ability to maintain the roof properly. For example: a standard, safe ladder to the upper roof, standard railings 1.05 meters high, and access routes between the installations on the roof (water heaters, the solar system, air-conditioner units and more).

We have come across several cases where a row of solar collectors was installed so that the part of the roof behind it could not be reached. More on railings and safety on the page Safety.

Electricity on roofs

Electricity and water do not mix, so the electrical system on the roof has to be safe and watertight. For example, electrical conduits have to be raised above the roof floor and led correctly into watertight boxes.

Roof slopes

The roof slopes have to be such that no puddles form on it. Puddles increase the risk of water getting into the building, and can also create a sanitary hazard (mosquitoes, odors). That is why a lightweight concrete fill (betkal) has to be laid for the slopes first, and only then are the bituminous membranes installed, so that a slope of 1.5% is created.

Solar system

You need to check whether the solar collectors are positioned to make the best use of the sun's energy, or whether there is shading of more than 10%, beyond what Standard 579 allows.

When there is shading like this, the efficiency of the system suffers. In that situation the collectors have to be reinstalled, raised, so that the shading does not exceed what the standard allows, and you need to check whether the collector output has to be increased according to the factor obtained at the new location.

Roof coping

The coping (the horizontal stone slabs installed on top of the roof parapet) has to be anchored to the parapet with a screw in every slab, with expansion joints as required by Israeli Standard 2378. Otherwise there is a real danger of stone slabs falling onto the balconies and into the building's yard.