The Mystery of a Roof Leak

We can all agree that the roof on your building is there to keep water out. Pretty straight forward right? So when you have water coming into the building from somewhere above your head, it’s certainly annoying. I won’t argue that at all.

What’s even more annoying is when your roofing contractor makes 2, 3, 4, or even 5 trips out to repair the roof leak and that water is still coming in.

I mean come on, how hard can it be to find a roof leak?

Well sometimes it can be more difficult than you may think. Ongoing persistent leaks are incredibly annoying for roofers as well. They want it fixed the first time even more than you do.

Roof Leak Source
Small hole in roof surface allowing water infiltration

The problem is that water travel can be rather tricky to locate. It follows the path of least resistance which can take twists and turns that are unpredictable.

Throw in multiple roof systems, deck flutes and rooftop penetrations and the problem multiplies rather quickly. The point of a roof leak can be several feet away from the actual point of entry into the structure.

Typical Roof Leak Analysis Process

So let’s walk through a typical roof leak call.

A roof service technician is dispatched and will ask to see the leak area inside.

The leak is then measured (usually from two walls or by using window locations, etc.) to locate a starting point once on the roof.

If the underside of the decking is open, the roof technician will note the direction the flutes are running and if there are any penetrations in the area.

If ceiling tiles are installed, the tech will need to remove one or two for this process.

Metal decks have high and low flutes. The low flutes can collect water and may allow it to travel as little as 10 feet or as far as 100 feet before showing up inside as a leak. This can certainly add time to finding the source.

Wood, tectum, concrete and gypsum decks don’t usually allow water to travel as far once water reaches them.

Open Roof Seam
Open roof seam

After accessing the roof and mapping out the leak location, the technician can now start investigating. Starting with the obvious items in the area like curbs, pipes, drains etc and moving to seams and finally the field membrane itself. Water can enter the roof at deteriorated flashings (which tend to be a little more obvious) or tiny pinholes or slices (which can be much more difficult to find).

Aged membranes and years of dirt can also slow down the investigation process as these issues become hidden. If there aren’t any penetrations in the area the investigation process can literally turn into the technician crawling on his hands and knees looking for the proverbial needle in a haystack.

Once the immediate area is cleared, the search area is expanded using educated guesses. Conditions like roof slope (water doesn’t tend to run uphill) and deck type or direction the flutes run all come in to play here.

Problem with Multiple Roof Systems

One of the biggest causes for the ongoing headache is multiple roof systems. Water can travel a surprisingly long distance when there are two or more roof systems in place. The problem is that the underlying roof may not have any openings to allow water through for a couple hundred feet. This makes pinpointing the entry point extremely difficult.

We’ve actually had a couple of ongoing leaks where the hole causing it was up to 200 feet away. Frustrating doesn’t even begin to cover it! For this reason, when we recover a single-ply membrane (EPDM, TPO, PVC) the existing roof membrane is perforated in a grid so if any water enters the new system it can’t travel too far. This helps cut down on investigation time.

Open Roof Penetration Flashing
Open roof penetration flashing

Other Roof Leak Investigation Methods

If all else fails, there are a few tools that can be used to help narrow the search.

Spray Rack – Spray rack testing uses a controlled spray of water that can be isolated to certain areas (curbs, ducts etc). The process starts at the lowest point and slowly moves up until the leak is found. This can eliminate certain areas like the roof surface, the curb or ducting.

Infrared (IR) Roof Moisture Scans – An infrared roof scan can pin-point trapped moisture contained within a roof system. When the sun heats the roof up all day and then sets, the moisture rich areas hold that heat longer. This heat shows up as “hot spots” in the thermal imaging and can eliminate large areas of the roof.

Moisture Meter – Moisture meters detect moisture within roof systems either through pins that penetrate the roof surface or non-penetrating meters that contain sensors.

Roof Spray Rack Test

Prevent Roof Leaks Before They Start

Roof leak diagnosis is truly more of an art than a science. Unfortunately they can sometimes take time to locate. That is also why regular roof maintenance is so important.

With regular roof maintenance your chance of developing a roof leak can decrease. Annual roof maintenance is a great preventative measure that is relatively inexpensive and can eliminate most of these headaches altogether.

Vendors can also play a big part in creating roof leaks. If your rooftop is regularly accessed by HVAC or other contractors we recommend the installation of walkpads or a walkway on your roof system, especially on ballast roof systems.

Roof Walkway Systems

Final Thoughts

As you can see, fixing a roof leak is the easy part. Finding the roof leak can be a long process of elimination. I definitely recommend reporting the leak as soon as possible so that a technician can try to be on site while the leak is active. Being able to see exactly where water is dripping from can be a huge help.

Looking for help diagnosing an ongoing roof leak issue?

Jurin Roofing Services’ technicians are highly skilled in the art of solving difficult roof leaks

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