How We Find Roof Leaks, Even the Complicated Ones

April 4, 2022 Laura MacCormac




As a Property Manager, you know how careful you need to be when managing expectations.  On one hand you want the board to know you’re getting things done quickly, and on the other hand, you want them to understand that it needs to be done right. Residents want to know why the roof is leaking, why the roofing technicians are on a different part of the roof, why it leaked again, etc.


In this post we’ll show you the steps that we, at Detail Roofing, go through for a leak inspection, why some investigations get complicated, and why some roofs leak after a repair is made.


What is a Roof Leak Investigation?

A roof leak investigation is the process of locating the deficiency on the roof that has caused water ingress and how the water got to the leak point. When a resident calls in a leak and we attend, it’s usually coming from the ceiling. Figuring out how it got there is the investigation.


Sometimes we are able to pinpoint the problem right away. Other times it’s not that simple.There could be no signs of any defects in the area above the leak, or maybe there are multiple defects, and we have to figure out which one is causing the problem.

Our Nine-Step Process

1. Interior Inspection

We use a measuring tape, when inside the building, to trace out where the reported leak is in relation to the window or the wall so we have a point of reference on the roof.

2. Cut Drywall

We will cut the drywall or lift a ceiling tile if possible, because there can be helpful signs there. We’re able to see any additional staining behind the ceiling  and get an idea of what’s happening. If there are any penetrations or piping where the water might be coming from, this might be our first clue.

3. Inspect Between Roof and Ceiling

We always want to access any sort of attic space, crawlspace, mechanical room, or really anything between the leak area and the roof. For example, there may be additional staining in the attic that can help us trace the issue. If there is anything that looks like mold it is helpful to relay that back to the Property Manager so that they can have the appropriate remediation specialists look into it.

4. Trace Out Investigation Area

The first attempt to find the area where this leak has started is done directly above where it was found inside. We use the measurements from our interior inspection and trace out an area to check for deficiencies.

5. Inspect Membrane and surrounding areas

We move top layers so we can check the roof membrane.  We also look at penetrations to see if there is worn caulking or rusted out spots.  We survey this area carefully.

6. Cut Tests

We perform cut tests to determine the makeup of the roof system. This way we can see if there is any water or moisture beneath the roof membrane.  It’s also important to note whether or not there’s a vapour barrier under the membrane because that can contribute to traveling water.

7. Temporary or small repairs

In the time allotted we apply compatible temporary or small repairs.

8. Reassemble

After moving layers and making cuts we replace everything, sealing layers on properly.

9. Provide Project Summery Report

While all of this is going on our technicians are taking detailed photos of all of these steps so that we can provide you with the project summary report outlining all of our findings with any additional corrective repair recommendations.



Why does the Roof Continue to Leak After Being Repaired?

Multiple contributing defects can be a result of traveling water, poor failing membrane systems, or damage that is present in multiple areas. Once water gets under the roof membrane and travels, it can could go to several places, not just one.  If a leak shows up in the same spot inside, it could be that the membrane is failing in several places and the water is taking the same path to the original spot inside. This is a sign that it’s time for a roof replacement. It could also mean the roof was damaged, like in a big storm with flying debris or a falling tree, and it affected more than just one spot on the roof.

Traveling Water

Sometimes we do a cut test right above where we found staining on the ceiling and we cannot find any defects in the roof system in that area. When this happens we have to check and find out if water has been traveling under the roof membrane. Water can travel a long way between the entry point in the membrane to the spot where it’s noticed inside. Sometimes it’s a few feet away, sometimes 50 or even 100 feet. Common causes of water traveling are if the roof deck is steel or concrete, a vapour barrier under the membrane, a green roof, and internal piping.This is a more elaborate test and it involves actually re-creating the leak. This is called a controlled water test.

Green roofs can be extra complicated because the actual membrane  is several layers below where you’re actually standing on the roof. So, in order to properly investigate, you can’t just do a visual inspection. You have to actually dig up these areas and take out all the layers to be able to look at the membrane below.


Obstructions on the roof surface can also complicate the process. defects could be somewhere we can’t reach, like in behind stairs. If the stairs are welded in place and there is no other access point, it’s impossible to know what the problem is and what repair is needed. Welded-in stairs is an extreme example though and usually we can have something moved. Fencing or railings, are a common obstruction that can be moved or removed.

Three “Don’ts” for When Roof Leaks Happen

1. Don’t Hold off on Reporting the Leak

A lot of interior damage happens over time which leads to health and safety risks. If the issue on the roof is not addressed it could spread and become a bigger issue that will take longer to solve.


2. Don’t Get A Superintendent or General Contractor Address a Roof Leak

Sometimes the supers that we deal with have been working at a building since it was built. They know it very well are very familiar with everything going on. The thing is, they’re not trained on everything that could be happening to a particular roof membrane. They might not recognize exactly why there’s a failure so will not be able to fix the real problem.


3. Don’t Do Interior Repairs Before a Confirmed Resolution of Leak

Oftentimes managers want to have the interior repairs completed either before we’ve been on site for the corrective repairs or on the same day. We always recommend that after the repairs are completed the area be monitored for a period of time. Ideally you want the same weather conditions present as when the original leak occurred. So, for example, if it only happened during wind driven rain, wait for that to happen after the repair has been done. Confirm that the issue has been resolved before spending money on the interior repairs.

Finding the Roof Leak Source

Leak Investigations can be straight-forward or extremely complicated.  It depends on roof material, age or condition of the roof , type of roof and of course the deficiency itself.

Minimizing and Preventing Roof Leaks

We recommend getting a roof inspection done at least once a year. We look for anything that is subject to wear and tear or that gets worse over time: Renewing sealants on penetrations, removing any debris or vegetation that disrupts the flow of water to the drains, checking the metal flashing to make sure it’s secure. Even if you’re concerned that the board doesn’t have much money right now, getting an assessment will tell you if you have a critical item. Maybe you can find some money somewhere because it will cost more to not deal with it. If you have a major issue, just being aware of what’s happening will help plan.  If the roof is large, it might make sense to do small repairs over time.  For example, if there are 300 vents, maybe we caulk 50 or 100 vents each year.

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