It appeared in the corner of the window, thin, almost invisible. The painter applied filler, sanded, painted, and it looked perfect. Six months later, the crack came back, in the same place, a little bigger.
This happens because filler and paint treat the symptom, not the cause. A crack is a message from the building, and each shape means something. Here you will learn to recognize the most common signs, know when to worry and understand how the reports that investigate, prevent and record these problems work.
What the crack is telling you
First of all, some relief: not every crack is serious. Many are superficial, linked to the shrinkage of the plaster or to temperature changes, and do not affect safety. But some indicate serious problems. And the engineer learns to tell them apart by observing three things: the shape, the direction and whether it is growing.
- Diagonal, starting from the corners of doors and windows: these usually indicate missing or deficient lintels and sills, the small beams that distribute stresses around openings.
- Stepped, following the block joints, or inclined from a corner of the house: these may indicate settlement, which is when one part of the foundation sinks more than another.
- Horizontal, just below the roof slab, especially on top-floor walls: these are usually linked to the slab expanding in the heat.
- Fine, forming a network like a map: these are generally mortar shrinkage, more aesthetic than structural.
Now, the signs that call for immediate attention: a crack that widens over time, doors and windows that start to stick, a floor that goes out of level, creaking in the structure, and cracks in beams, columns or slabs. In these cases, do not wait: call an engineer.
Leaks, exposed rebar and mould
The second family of problems is water. A leak can come from above, through roofs, gutters and poorly waterproofed slabs; from inside, through leaking pipes; or from below, when moisture in the soil rises through the walls. The last one is called rising damp, and it is typical of buildings whose foundations were not waterproofed. The sign is a band of staining, blistering paint and crumbling plaster along the bottom of the walls.
Water is also the main ally of a more serious problem: corrosion of the reinforcement. When the concrete protecting the steel is too thin or cracked, moisture reaches the reinforcement, the steel rusts and expands, and this pushes and breaks the concrete. This is the well-known "exposed rebar". It reduces the cross-section of the steel and, therefore, the capacity of the element. It is not an aesthetic issue.
And there are the more visible signs: mould, dark stains and efflorescence, those white marks that appear on the surface. They all point to water where it should not be.
Diagnosis: cause before solution
Faced with a problem, the most common mistake is to go straight to the solution: reinforce, waterproof, redo. But if the cause is not identified, the problem comes back, and the money goes.
Diagnosing building pathologies follows a method:
- Inspection: the engineer maps each symptom, measures the crack widths, photographs them and records their location.
- History: they investigate when the problem appeared, and whether there was a renovation, neighbouring construction, a leak or a change of use.
- Tests, when necessary: measuring moisture in the walls, locating the reinforcement and measuring the cover, assessing the strength of the concrete and checking how deep the concrete has lost its protection against corrosion. On active cracks, tell-tales can be installed to monitor whether they are moving.
With all of this, the engineer arrives at the probable cause and proposes the appropriate solution, with the urgency of each intervention. The result is a technical report, with an ART, which serves both to guide the repair and to document the situation, including in a dispute with the builder or the insurer.
Building inspection
So far, we have talked about investigating a problem that has already appeared. Building inspection is the way to find problems before they grow.
It is especially important in condominiums, commercial buildings and older buildings. The reference standard is ABNT NBR 16747. Under it, the engineer assesses the state of conservation of the building's systems: structure, façades, roof, waterproofing, plumbing and electrical installations, fire protection and lightning protection systems, lifts, common areas and accessibility.
Each anomaly found is classified by degree of risk and receives a recommendation, organized by priority. This turns a list of problems into an action plan that the condominium manager or building manager can carry out and present at a meeting.
The inspection also checks maintenance: whether there is a plan, whether it is being followed and whether the records are up to date. A well-maintained building lasts longer, spends less on repairs and gains value.
And this is the place to mention a document many people receive and leave in a drawer: the use, operation and maintenance manual, also called the owner's manual, whose content is guided by ABNT NBR 14037. It is delivered with the new property and says how to use each system, what can and cannot be done, which maintenance is needed and how often. The maintenance management standard, ABNT NBR 5674, organizes this work over the life of the building. Following the manual is not just good practice: many warranties depend on maintenance having been carried out correctly.
Handover inspection of a new property
Now, a moment when many people regret not having called an engineer: receiving the keys. A new property can also have defects, and the best time to point them out is before signing the acceptance form.
In a handover inspection, the engineer checks the property against the design and the specification report in the contract: the dimensions, the specified finishes, the fall of floors towards the drains, the operation of doors and windows, the electrical and plumbing installations, hollow tiles, cracks and leaks.
The result is a report with photos and a list of pending items, which you hand to the builder for correction. And keep this document: it is also important if a defect appears during the warranty periods.
Pre-construction neighbour survey report
And if the construction is yours, or your neighbour's? Excavation, piled foundations, demolition and lowering of the water table can cause vibration and movement in surrounding properties. If, after the work, a crack appears in the house next door, how can anyone know whether it was already there?
The pre-construction neighbour survey report answers exactly that. Before work begins, the engineer inspects the neighbouring properties and records the condition of each one, with photos, a description and measurements of existing cracks. It protects both sides: the neighbour is assured that any new damage will be identified, and the builder has proof of what already existed.
What a good report needs
Whatever its type, a good report has:
- the identification of the property and the objective;
- the methodology used;
- the description of the inspection, with photos;
- the technical analysis;
- the conclusions;
- the recommendations, with priorities;
- and, of course, the ART.
And it must be clear enough for you to understand what was found and what to do.
Common mistakes
- Hiding the crack with filler and paint.
- Waterproofing without finding out where the water comes from.
- Receiving the keys without an inspection.
- Starting construction right next to a neighbour without a pre-construction survey report.
Frequently asked questions
Is a crack in the wall dangerous?
Not always. Superficial and map-pattern cracks are usually shrinkage. These deserve immediate assessment: cracks that grow, cracks in beams, columns or slabs, doors and windows that stick, uneven floors and creaking.
What causes a diagonal crack at a window?
Often, missing or deficient lintels and sills, which distribute the stresses at the corners of openings.
How do you find the cause of a leak?
With a technical inspection and, if necessary, tests (moisture measurement, pipe tests), identifying whether the water comes from above, from inside or from below (rising damp).
Is exposed rebar serious?
Yes. Corrosion reduces the cross-section of the steel and the capacity of the element. It must be assessed and treated by a professional.
What is a building inspection?
It is the assessment of the state of conservation and maintenance of a building's systems, classifying anomalies by risk and priority (ABNT NBR 16747).
Is it worth having an inspection before receiving the keys?
Yes. It is the best time to record defects and ask the builder to correct them.
What is a pre-construction neighbour survey report?
It is the technical record of the condition of neighbouring properties before construction, which protects both the builder and the neighbours.
Are condominiums required to have a building inspection?
It depends on municipal legislation, but inspection is the condominium manager's best management tool.
Who asks for the pre-construction neighbour survey report?
Generally, whoever is going to carry out the work, to protect themselves and the neighbours.