When a building needs a pathology study

The damp in the living room was patched three times and came back three times. The crack in the courtyard wall was sealed last year and is longer today. The management council is about to vote an extraordinary levy to waterproof the whole roof, and nobody has said where the water gets in.

At some point in that story the problem stopped being one of maintenance. This article is about where that point lies.

The question that separates the two

It is not how much it costs, nor how large the damage is. It is a single one: does anybody know why it happened?

Maintenance repairs a deterioration whose cause is known and foreseeable: paint that has run its course, a seal that aged, a tile shifted by the wind. You know what produced it, you know it will happen again and you know how often. That is programmed and carried out.

Diagnosis comes in when the cause is not known, when the repair did not correct it, or when what you can see may be the symptom of something you cannot. At that point, repairing without studying is not saving money: it is paying twice.

Six signs that it has stopped being maintenance

1. 1It comes back. The same defect, in the same place, after being repaired. Once may be poor workmanship; twice is a wrong diagnosis.
2. 2It progresses. The crack is longer, wider or more branched than it was six months ago. Stabilised damage and active damage are treated differently, and they are told apart only by measuring with a date attached.
3. 3It spreads. It appeared at one point and today there are similar defects elsewhere. When the pattern repeats across several elements, the cause is usually common to them and lies beneath all of them.
4. 4It appeared suddenly. Damage that was not there and shows up within days, with no work nearby to explain it, is a change of conditions. It may be water, it may be ground, it may be load.
5. 5The water cannot be located. You know where it comes out, not where it goes in. It is the situation in which most money is spent blindly, because the stain is hardly ever below the point of entry.
6. 6There is steel in view, rust or spalling. Concrete that opens and shows the reinforcement has stopped being a matter of finishes. Corrosion does not stop by itself and it grows in volume, so the damage feeds on itself.

None of the six is, on its own, an emergency. All of them are reason enough to find out the cause before signing a repair contract.

The four cases where the code requires it

Up to here it is professional judgement. From here on it is an obligation, and it is written in a single place: Chapter A.10 of NSR-10, the Colombian seismic building code, under the heading "Assessment and intervention of buildings constructed before the entry into force of the present version of the Regulation".

That chapter sets the criteria and procedures for assessing the seismic vulnerability of an existing building and for designing its intervention. Its scope expressly names four situations:

And the case where the code says it is not needed

It is worth saying with the same clarity, because nobody says it: there are works that call for no study, and anyone selling you one is selling you something you do not need.

With one exception, and it is in the next numeral: if there is also a change of use, the exemption falls away. It is the only door the code deliberately leaves open.

What a pathology study is, and what it is not

Here something uncomfortable has to be said: "estudio patológico" is not a Colombian regulatory term. NSR-10 does not define it, Decreto 1077 does not define it, no statute defines it. It is a name from the trade — English practice would call the same work a building condition survey or a structural appraisal — and that is why things bearing no resemblance to one another are sold under the label: from a forty-minute visit with photographs to six weeks of work with testing and modelling.

What is regulated, and is the yardstick worth measuring any offer against, is the assessment procedure of A.10. Its first three stages describe the work of diagnosis exactly:

1. 1Verify that the case is covered by the scope of the chapter. That is: first you settle whether this is or is not an A.10 problem.
2. 2Collect and study the existing information on the geotechnical design, the structural design and the construction process of the original building and of its later alterations, and carry out investigations in the building itself.
3. 3Rate the condition of the structural system, on two axes: the quality of the original design and construction, and the state of maintenance and conservation.

That second stage is what separates a serious report from a decorative one. The code lists what has to be investigated: whether the design documents match what is built today — checked on site, with investigations at representative places and a record of their extent —, the quality of the original construction, the state of conservation, evidence of local failures, excessive deflections and corrosion of the reinforcement, the occurrence of settlement of the foundations, and the past occurrence of extraordinary events: explosion, fire, earthquake, previous remodelling, finishes that added load.

From that you can deduce, by elimination, what a pathology study is not:

• —It is not a repair quotation. The quotation comes afterwards and only makes sense once the diagnosis exists.
• —It is not a visual inspection on its own. The code asks for investigations, not only observation, and asks for a record of the extent of those investigations.
• —It is not a single test. A rebound hammer on one column is not a diagnosis; it is one piece of data inside one.
• —It is not a post-earthquake assessment. The rapid inspection made after a tremor serves to decide whether the building can be occupied. It is another tool, with another scope and another signatory, and it does not replace the study.

Who signs it

This is the part where the market is most misrepresented, and the code leaves no margin. The memorandum justifying the assessment and the intervention, says A.10.1.5.1, must be signed by a duly registered civil engineer meeting the conditions of articles 26 and 27 of Ley 400 de 1997.

It is worth saying as well what an architect does do in work of this kind, because it is half the commission and it is underrated: surveying what is built where there are no drawings — which is nearly always —, reconstructing the history of the interventions, diagnosing the defects of envelope, roof, damp and finishes, coordinating the structural engineer and the geotechnical engineer, and writing the report so that a management council can decide with it in hand.

One more detail, for anyone who has already decided to intervene: the construction of a structural intervention must be subject in all cases to technical supervision, with no area threshold and no exceptions. That is a line in the budget, not a formality.

When it is worth doing even where nobody requires it

Four moments at which the study pays for itself, and not one of them appears in the code:

1. 1Before buying. It is the only moment at which the result of the diagnosis can still change the price, or the decision. After signing, the finding is yours.
2. 2Before remodelling. A refurbishment budget drawn up for a building nobody knows gets revised upwards on site, always. And if the work turns out to touch the structure, the study has gone from advisable to compulsory.
3. 3Before the ten-year cover runs out. Ley 1796 de 2016 obliges the builder or the seller of a new dwelling to cover financial loss arising within the ten years following the technical certificate of occupancy. Damage found and documented inside that window has somebody to claim against; the same damage found afterwards does not.
4. 4Before the general meeting votes a levy. A council approving a major intervention with no diagnosis is deciding on the information of the party selling the repair. The study costs a fraction of the works and is the only thing that makes comparable offers that today are not.

What to ask before commissioning it

1. 1Who signs, with what registration, and what do they prove? If there is going to be a structural conclusion, there has to be a civil engineer with the experience of article 27.
2. 2What investigations does it include, and how many? Trial pits, openings, opening-up, testing. Without those it is a visual inspection under another name.
3. 3What previous documentation are they going to look for? The drawings filed with the permit, the design memoranda, the original ground investigation, the propiedad horizontal by-laws. Stage 2 of A.10 begins there.
4. 4Will the report state the cause, or only the solution? It is the question that causes the most discomfort and the one that filters best.
5. 5Who carries out the repair? If it is the same party that diagnoses, the diagnosis has an interest attached. It is not always a problem, but you should know beforehand.

What the document handed to you should contain — section by section, and how to recognise one that is of no use — is a separate subject and deserves an article of its own.

Everything above is transcribed from the articles in force. What is not in the code — the six signs, the four moments — is said as what it is: trade judgement.