Window leaks
It can be challenging to know why your window leaks. For the last 20 years, I have been looking at window leaks all over the country and figuring out what the problem is and if you need window replacement or if it can be repaired. Below are the five reasons why window leaks. I can guarantee one of them is your issue.
Why you have a window leak
These are the five main reasons you are experiencing a window leak or leaks at your building, property, or facility.
- Failed sealant or caulking around the perimeter of the window
- Failed silicone or glazing of the window
- The window system itself is not functioning properly
- The weep system of the window is clogged or has bugs
- The window itself may not be the problem; the leak could be coming from another area
Specific information on window leaks
The above-listed factors are the most common reasons why you are experiencing a leaky window. To deal with or further identify the issue precisely, testing would be needed to truly identify the root cause of the leak. I will publish an article and video covering that exact topic in another post. But I will provide more information and context that hopefully helps and points you in the right direction below.
Failed sealant or caulking around the perimeter of the window
This is a reasonably standard issue. Over time, the sealant that bridges the gap between the window’s metal frame to the facade or exterior wall will break down and fail.
Time, sunlight, heat, and cold will eventually cause the sealant around the window frame to lose its ability to be elastic and cause the loss of adhesion, come loose, and pull away from the window frame or the substrate.
Once this happens, it can allow water to get into the building and works its way into the interior space. If this happens, you will most likely notice the leak in more wind-driven rain. Rain, along with the window, will push more directly onto the wall and thus the window.
The fix here for the leaky window is to remove and replace the caulking or sealant. For most applications, you would utilize a urethane sealant. So, break out the old caulking gun and get to work.
Failed silicone or glazing of the window
When silicone gaskets fail, they can become rigid and not bond to the metal or the glass; this can create a path for water to get into the window and leak, as shown in the above photo.
Like the window perimeter sealant that bridges the gap between the window’s frame and the wall, your window glazing bridges the gap from the glass to the window frame.
Now the exterior “glazing” will also break down over time and with expansion and contraction. One of the signs of this type of leak is when the water emanates from the sill of the window. The water has gotten through the unsealed gap and comes from the metal frame at the base of the window. Also, an indicator that the glazing or gasket has failed is with double pane glass. You will notice moisture or condensation in the glass, even when it is not raining outside.
This exterior glazing of the window is silicone; it provides the best adhesion to the glass and the metal. It is not typically recommended to utilize urethane in this instance. Part of the problem is that the urethane will not properly adhere to the previously installed silicone, and silicone will perform better over time. The solution here is to again break out the caulking gun and install new silicone caulking.
The Window system itself is not functioning properly
So, you inspect the window, and the sealant looks good, and it has been replaced, and still, there is a leaky window.
In some cases, it can be the window systems themselves that are the problem.
- For apartment buildings with operable windows. Sometimes these windows can be installed incorrectly. Meaning that the installer put the wrong size window in place. Or the installation itself needed to be put in correctly. This can be due to incorrect sizing of the window opening or the wrong window for the building.
- Operable windows can move or rack if not done correctly, thus creating issues with the window, making a watertight seal when closed.
- For older metal window systems, the weep system itself may have rusted and failed; this will be very difficult to observe since it is in the window itself. This would lead to occasional leaks, usually when there is a driving rain that overwhelms the weep system and has enough water that it flows back into the interior space and create a noticeable leak.
The weep system of the window is clogged or has bugs
Most commercial-grade windows have a weep system built into them, allowing water that got into the window to weep or direct itself out of the window frame and not let it back into the interior of the building. Most masonry buildings also have these systems; they have either weep tubes or weep vents. They allow water that infiltrated the wall to exit and not get into the interior of the building. Now over time, weep tubes can solidify. They have a rope in the tube to prevent bugs and dirt from entering the cavity, but they need to be checked periodically over the years to ensure that the material has not broken down and clogged the tube.
Weep vents typically have a vent material; that material can shrink or break down over time and naturally come loose, leaving an exposed hole, as shown in the picture below.
When you have holes, minor bugs, and dirt can sometimes affect how the weep system works.
A more significant issue is when a person that does not entirely understand the window system sees these holes and thinks, a hole…. that is how the water is getting into the window!! Aha
But in their efforts, they make the issue worse by closing off the weeps of the windows; they trap the water trying to get out. I have seen this numerous times by maintenance staff and even contractors who should know better.
The weeps of windows are always at the base of the window and can be had to detect; manufacturers try and hide and disguise this part of the window for aesthetics.
The window itself may not be the problem, the leak could be coming from another area
Here is an example of deteriorated brickwork on the corner of this building. This can be a direct contributing problem to this window leaking.
Water is tricky, and when you see water coming from or around a window, the natural thought is that the window is the problem. This may be right in most cases, but in my experience, other factors or issues can be at play.
Depending on where the window is, here are a few other things that may be the culprit of the leaking window.
1. The facade or exterior wall itself. Depending on the exterior of your building, there may be a crack or deterioration of the wall system that allows water to find its way to the window.
2. For masonry brick-type buildings, masonry times there is something called Thru-Wall flashing that can be installed at floor line relief angles, but also about window heads, there is Thru wall flashing that allows water to escape the brick facade. A membrane is adhered to the block back up and then turns down and out like an L to direct water from getting into the window head.
3. If it is near the roof, a leak from the roof could work its way to the window area with pipes, HVAC ducts, and the metal of the building. Water can travel a distance before it is noticed or seen on the interior.
4. Vents or PTAC units can allow water to get into the wall, and the water could work its way to the window below.
5. Plumbing again leaks are tricky. Sometimes roof drains that run through the building could have a crack or a clog that backs up at specific areas that, when overwhelmed, cause a leak and go back to number 2. Pipes, HVAC ducts, and building metal parts can give water a path to the window area.
6. Air pressure, this is a rare detail, but it has been observed. More significant high-rise buildings with non-operable windows with controlled air can be an issue if not configured correctly. If the negative air pressure is not correct, it can cause a situation where the air pulls on the window, and when water is introduced, it pulls it in through the window.
7. For exteriors with siding, the flashing may have been installed incorrectly or had a tear or rips that, on heavy rains, will allow water to infiltrate.
What do to if you have a leak
Ok, great, we know we have a leak, but what next?
Now you have some information that may help you or give you an idea of the problem; what do I do now with my leaking window?
Options, you can:
- Test if the window is in a suitable location that you can access SAFELY! Then a water test would be a great place to start. Simply get a hose and spray the area, replicating a driving rain. Start low and work your way up till you reach the window. You will need a person on the inside to monitor the leak; once they see water coming in, make sure they can call or radio you to let you know to stop before you do damage.
2. If the testing went well and you think it is the sealant or caulking, you should take the next step and resolve the leak yourself. If you suspect that the sealant or caulk is the problem, you may feel up to the task and try and caulk yourself. We will publish an article about caulking a window perimeter joint and glazing or sealing the exterior gasket.
3. Another option is to call a reputable waterproofing contractor and get their expert opinion. A word of advice, refrain from steering the contractor; let them tell you what they see and explain their thought process. If you tell them off the bat your diagnosis is, and they do what you tell them, there is no responsibility on their part. They are just doing what you have told them to perform. Once they have a diagnosis and explain their thoughts on the repair, engage them on what ifs and next steps.
- If you have widespread issues, consider engaging an engineer to evaluate and diagnose the problem. They can go through the process, create specifications, and bid out the project once the root cause has been determined. In some cases, the best solution is window replacement, depending on the age and conditions of the windows.
In this process, leaks can come from multiple points, so the fix may be more than one thing, depending on the condition of your building.
For example, if you have an older masonry building in rough shape, the sealants may fail and deteriorate, but the masonry facade also has issues. So, keep in mind that it may be multiple problems vs. one or the other.
Water leak plan
The info-graphic may help you in the process of eliminating leaks or leaks for your building.
Following the flow chart of decisions can be a great guide in solving your leaking windows.
Depending on your situation, the final result is that you may need window replacement, I know most building owners want me to be the one to fix the problem with a caulking gun, but sometimes that is not the case.
If you have any questions about window leaks and how to best solve the issue, please feel free to reach out and email me with anything.
If you have specifics, please include them; here is a list of helpful information:
1. Pictures of the areas close up and far back for context
2. Age of the building
3. Any information about the history of work performed on the exterior or lack thereof
4. How long has the leak been ongoing
5. Have any steps been taken to try and remediate the leaks within the last year or two
6. When does the window leak? Is it every time or close to every time it rains, or is it periodically and when the wind is driving the rain?
7. How much water is being observed? Is it just towels on the sill, drywall bubbling, or delamination, or do you need buckets when it rains?
It is good to have that information just so you are prepared if and when reaching out to a professional trying to troubleshoot the leak.
Also, if you need information or have questions about the parts or components, check out this article by Pella, The parts of a window. Or check out this article by Marvin WINDOW PARTS: LEARN ABOUT THE ANATOMY OF A WINDOW
In doing additional research, I reached out to Pella windows, Anderson Windows, and Marvin Windows to see if they had any other good information about window leaks. The only company to get back to me was Marvin and their PR rep recommended me to this link on their site Window and Door Maintenance: Cleaning, Care, Painting and More | Marvin for additional information
Thanks for taking the time!!!
jay@leakfixes.com
