Construction defects: cracks in walls and what lies between them

You do not need to be a building inspection expert to notice cracks in walls. They are one of the most common construction defects, and one of the main reasons people call in a home inspection (bedek bayit) expert.

Whenever you find defects in a structure, whether a house, an apartment or a business, do not ignore them. Address the cracks, work out how they formed, and decide whether urgent repairs are needed so you can keep using the structure safely.

What causes cracks in walls?

There are many possible reasons cracks like these appear (see also our guide to home inspection of plumbing):

• Soil moisture changing with the climate can cause the structure to swell and its foundations to expand, producing construction defects such as bulging exterior walls and cracks, mainly around openings. The fix is to separate the ground from the concrete floor.
• Tree roots growing under the foundations can shift them over time. Planting a tree close to a building may look harmless at first, but combined with moisture, the roots can expand the ground beneath the foundations and require extensive repair work.
• Heavy sun exposure is another natural cause: it makes walls expand over time and cracks appear.
• Human error plays a role too, such as poor foundation planning or asymmetrical construction. If one foundation settles more than another, it pulls the whole structure toward it, creating diagonal cracks that plaster cannot fix and that call for professional treatment, such as reinforcing the foundations.
• The quality of the concrete itself can also cause defects to appear as it sets.
• Missing reinforcement mesh between different elements, installed before plastering, can also cause cracks. Another cause is expansion and contraction between the wall and the ceiling; this usually produces only minor cracks, whose effect on the structure is mainly cosmetic.

Found cracks? Here's what to do

For more on cost, see how much a home inspection costs.

If you find cracks during a pre-purchase inspection, raise the issue with the contractor and back it up with the technical specification, which is legally binding on him. Have a home inspection expert review that specification professionally so the contractor cannot talk his way around it. The same applies to a resale apartment: an inspection gives you grounds to ask the sellers to fix the issues or lower the price.

You will not always spot cracks in a resale apartment. A crack hidden behind a decorative cornice along the wall, for example, may only surface once the sellers move out and the cornice comes down, or once the crack spreads beyond the cornice's edge.

The contractor's warranty on structural cracks

If you discover defects after buying, check whether the contractor's warranty still applies. By law, when cracks stem from structural elements, the contractor's warranty runs for eight years, and in some cases it can extend further depending on how promptly the cracks were reported.

Either way, once you spot cracks in a structure, a full engineering diagnosis by a home inspection engineer is essential: it identifies the source of the problem, speeds up the fix, and allows proper waterproofing that keeps water from getting in through the cracks and causing further damage.

So how do you deal with cracks in a new house? Left alone, they can lead to safety hazards and to sealing and dampness problems down the road. A thorough inspection catches shortcomings that are not always obvious to the eye: a professional company knows how to act and where to look, so nothing gets missed and there are no unpleasant "surprises" later.

When you hire a company that specializes in finding defects, make sure it is established and experienced enough to see you through the whole process, from the first inspection to getting what you are legally entitled to.