How To Find A Rain Leak In Your Building

We are often approached by laymen who ask us about the ropes of the trade. The facade doctor wouldnt do anything different from what you would do as an DIY. As with all other tradesmen, the difference is mainly in having right tools and acquiring specialized knowledge and experience. What a pro can do in one hour, you can probably accomplish in ten hours, becoming a pro in the process.

A) The process starts with the diagnosis, and the diagnosis starts with observation and testing. The simplest test is a garden hose test, in which water is sprayed onto a wall wetted starting from the bottom up until the leak is replicated, then the suspect areas are masked(with a duct tape) and re-tested. If the leak stopped, then you are almost done.
You would need to access the entire facade, which typically means having or renting aerial platforms, and some fancy equipment extending your vision, such as boroscopes and binoculars.
Once you gained the access, you need to investigate the facade by testing assemblies and gradually eliminating those that do not leak. Testing equipment is typically composed of some plumbing delivering and spraying water, as well as an apparatus generating and measuring air pressure difference, and tools used to identify gaps in building enclosures, such as smoke and noise generators, thermal cameras, etc. How do you do them? There are standard procedures available from industry associations, such as AAMA and ASTM describing how these tests should be performed, but you would end up modifying them anyway to make them work on your case.
More difficult are the prolonged tests dedicated to test the assembly over time or under hydrostatic pressure. E.g. you may need to plug your drains and flood horizontal assemblies. Or spray water from a grid of small spray nozzles to load a high-water-storage capacity assembly over time.
If water didn't do the trick, you may want to use air instead. Installing a blower door on the building and pressurizing its interior would allow you to trace the air leaks with thermovision camera or a smoke generator. Another way is using a noise generator and receiver.
Air pressure may also help or hurt you during water tests. It pays to monitor the pressure differential accross the facade with a manometer.
The results you would be getting may be quite confusing for someone unfamiliar with the design and construction of a high-rise buildings. Unlike small residential houses, large buildings are seldom alike, therefore their illnesses can be inferred only by a person familiar with both general construction and having extensive experience in high-rises.
Very often you may need to make exploratory openings in your building in order to get closer to some areas while testing. Needless to say, these openings would need to be temporarily secured once you are done.

B) The second part of the process is the remedial design. You need to direct your contractor what, where and how. The set of drawings and specifications should be based on a detailed survey, and contain a sufficient detail to confer the general intent. It typically requires making exploratory openings in your building to verify how it was built; if this step was not performed while testing. Remember that once you accept this set, you would become responsible to the contractor for its accuracy. A good practice is to have a second pair of eyes review the set. Just like you would do in the medical world, you want another doctor to give a second opinion. There are numerous issues which may arise, such as material compatibility, and some of them may require dedicated testing. This is why this part is best left to a building enclosure consultant (facade doctor). This is similar to hiring an architect or engineer, except you need this person to be knowledgeable and experienced in the building enclosure rehab and in the specific assembly identified as deficient. The average architect and engineer may not be fit for the challenge.

C) The repair, replacement, or alteration. This is the time to get some anesthesia to numb the shock of the incoming invoices. You will hire a general contractor and relevant subcontractors to perform the work, using the documentation from the facade doctor. How do you know if they dont discover some new conditions after the demolition begins? How do you know whether they actually properly prepare the substrate before squeezing the sealant in joints? You dont. This is why you need a facade doctor to occasionally watch over the contractors shoulder, help him clarify the situation, and report to you any discrepancies between the contractors obligations and the actual work. Remember that everything on a construction site is an experiment, and you dont want such a risk. Therefore, whenever an assembly installation begins, you need the contractor to build a mockup exemplifying the intended procedures, materials, and effect, and you may want the facade doctor to test this mockup to avoid surprises. Such a test is also advisable periodically as the construction progresses.