How to Fix Leaking Windows During Heavy Rain [2024 Guide]

Table Of Contents

Have you ever noticed your windows leaking during heavy rain, leaving puddles on the floor or window sills? It’s frustrating when water drips inside your building, peeling paint off walls and damaging floors and furnishings. But don’t fret… you’re one step away from fixing those pesky leaks; you only need the right guidance, which we’re here to offer!

Read on as we discuss some easy DIY solutions to stop rain from sneaking in through your windows. With the right materials and techniques, you can seal up those leaks and bring an end to leaky windows during heavy rain!

Why Do Windows Leak During Heavy Rain?

We can’t discuss how to stop window leaks without the causes.

Here are the major reasons you are experiencing leaks in your building windows:

  1. A damaged sealant
  2. Faulty window installation
  3. Window frame or sash damage
  4. Building structure issues

1. A Damaged Sealant

One of the most common reasons for leaking windows during heavy rain is damaged or missing sealant, like caulk around the edges or seams of the window. The sealant is designed to fill in small gaps and cracks to prevent air and water from getting in, but over time, it can break down due to sun exposure, temperature changes, and normal wear and tear. Once the sealant starts to deteriorate, leaks are inevitable.

Damaged Sealant

Tip: Learn how to reseal windows in our step-by-step guide.

2. Faulty Window Installation

Leaks can also occur if contractors improperly installed windows during the building’s initial construction. A window or house wrap that is not securely fastened or is unevenly spaced can allow rain and moisture to seep in. Fixing installation issues typically requires removing and re-installing the windows to correct the problems.

3. Window Frame or Sash Damage

In some cases, the window frames, sashes, or glass panes themselves may be damaged or warped, creating openings for water to get through. Repairing or replacing damaged window components is often necessary to remedy these types of leaks.

4. Building Structure Issues

Leaks in high-rise office buildings can sometimes be traced to problems with the structure itself, such as cracks in walls or rooftops that allow water to penetrate window openings. These types of leaks require professional building repairs to fix structural damage and seal up any entry points for moisture.

By identifying the cause of your window leaks, you can determine how to stop rain from coming through windows and prevent future leaks. However, you must also understand the source of the leak to determine where to start fixing it.

Tips for Identifying the Source of the Leak

Knowing where your windows are leaking is essential to pinpointing areas where repairs are needed.

Here are some tips for locating the source:

  1. Check the details.
  2. Inspect the exterior.
  3. Explore other potential causes.

1. Check the details.

Inspect the gasket or seal between the glass and the frame for any damage or tears that could let water in. Also, check the weep holes in the bottom of metal or vinyl frames — these small openings are designed to let moisture out, but they can get clogged with dirt or debris and back up, allowing water to leak in.

2. Inspect the exterior.

Go outside and examine the caulking around the edge of the window. Over time, caulk can dry out, crack, and peel away from the siding or brick, creating gaps for water to seep through. If the caulk looks damaged or is pulling away from the wall, it can result in a wind-driven rain window leak. In this case, you’ll need to remove the old caulk and reapply a fresh bead to seal up any holes or cracks.

Inspect the exterior

3. Explore other potential causes.

Warped or damaged frames can also lead to windows leaking water. If your windows are older, the wood frames may have rotted or warped, or the sills could be damaged. In some cases, you may need to replace window parts to fully fix the leak.

It’s also possible that leaks are caused by issues with your roof, siding, or flashing above the window, allowing water to drip down onto the window. Be sure to check above the window for any potential sources of water entry.

By thoroughly examining the window panes and sealants, identifying any worn or damaged parts, and checking potential entry points above the window, you can pinpoint the leak source and take appropriate steps to fix it. So, how do you go about fixing window leaks during rain? Find out below!

Quick Fixes for Leaking Windows During Heavy Rain

While permanent solutions are often recommended, the following DIY fixes can help you gain some comfort within your office space during a heavy rainstorm. After that, you can schedule an inspection with a professional for a more permanent solution.

  1. Re-caulk any damaged exterior caulking.
  2. Ensure window sills are pitched downwards.
  3. Apply clear silicone caulk around glass panels.

1. Re-caulk any damaged exterior caulking.

The caulk sealing your window frames and sills to the exterior of your building is the first line of defence against leaks. Over time, caulk can crack or peel away, allowing water to seep in. Grab a caulk gun and apply a fresh bead of waterproof silicone or latex caulk over any damaged areas, pressing firmly to seal as you proceed. This should stop minor leaks and cracks.

2. Ensure window sills are pitched downwards.

For larger leaks around the window frame, the issue could be that your window sills aren’t properly pitched to allow water to run off. Window sills should be sloped downwards at about a 15-degree angle, so water flows away from the window, not into your building. You may need to apply a sealant or caulk to create this pitch or, in severe cases, install an angled sill extender. This will direct rainwater away from the vulnerable window edges, preventing windows from leaking from the top.

3. Apply clear silicone caulk around glass panels.

If you experience leaks in the glass panes of your window, the seal may have failed or broken. Apply a thin bead of clear silicone caulk around the edges of the glass where it meets the window frame to re-seal, pressing firmly as you go along to ensure good adhesion. The silicone will seal and waterproof the glass without being visible. This is a quick fix, but for large leaks, the glass may need to be re-sealed by a professional.

Following these steps can help eliminate the most common window leaks that occur during heavy rain. However, for chronic or severe leaks, it’s best to have a professional evaluate your windows to determine if re-glazing or full replacement is needed. Keep reading to learn about permanent fixes to bring rain-induced window leaks to an end once and for all!

Long-Term Solutions to Stop Rain From Coming Through Windows

If you’ve tried weatherstripping and caulking around leaky windows during heavy rains but have not had any success, it may be time to consider more permanent solutions to fix window leaks. These range from window replacement to installing new roof awnings.

1. Window Replacement

Replacing old, draughty windows is one of the most effective ways to stop window seals from leaking permanently, especially if the window units have exceeded their life span. New, energy-efficient windows provide an airtight seal and prevent water from seeping in. While window replacement can be pricey, the investment often pays off through lower energy bills and reduced maintenance costs. You can learn about the cost of replacing windows in this guide.

2. Installing Storm Windows

For a more budget-friendly option, you can install storm windows over your existing windows. Storm windows create an extra barrier against the elements while still allowing some light to pass through. They can reduce drafts and leaks by over 85% when installed properly. Storm windows also don’t require the removal or destruction of your current windows.

Installing Storm Windows

3. Roof Overhangs and Awnings

If the leaks are coming from water running down the side of the building during heavy rains, installing roof overhangs or awnings may help. These fixtures redirect rainwater away from the sides of windows to prevent it from ever reaching the window. They also provide shade, which can lower cooling costs in the summer.

Water leaking under window sill can be frustrating, but the good news is that there are several solutions, both temporary and permanent, to resolve the issue. By sealing, covering, or replacing draughty windows, you can say goodbye to leaks and enjoy peace of mind, even during the heaviest of storms. At GLRE, we can help with a more permanent solution for your industrial windows — contact us now to discuss your glazing needs!

Frequently Asked Questions

How do you stop a leaking window while it’s raining?

To stop a leaking window while it’s raining, consider the following:

  • Inspect the gasket between the window frame and the glass.
  • Re-seal any gaps with clear silicone caulk.
  • Ensure the window sill is slanted downward to guide water away.
  • Clean out any debris or insects from the frame’s weep holes to maintain proper drainage and prevent water buildup.

Why does my UPVC window leak when it rains?

Your UPVC window may leak when it rains primarily due to failing sealant. The chemical components within window sealants deteriorate over time, losing their effectiveness. This breakdown can lead to gaps and cracks where water can seep through. Additionally, improper installation, blocked drainage channels, or warped frames can contribute to leaks when it rains. It’s essential to regularly check and maintain these seals and components to prevent water from entering your building.

How do I stop water coming out of my windows?

To prevent water from coming out of your windows, start by inspecting the caulking for any damage. If you find compromised areas, thoroughly clean the window frame first. Then, apply clear silicone caulk to reseal the glass to the gasket, ensuring a watertight bond. Regular maintenance and timely repairs of the seals will keep the water contained and protect your interior from moisture damage.

Why does water come in my window when it rains?

Water can come in your window during a rainstorm for various reasons, but the culprit is often compromised sealant. Over time, the chemical makeup of window sealants can degrade, leading to gaps and cracks that allow water to seep through. In addition, issues like improper window installation, worn-out weatherstripping, or clogged weep holes can result in a leaking window frame. Regular inspection and maintenance are essential to prevent such water intrusion.


There are various easy fixes to stop annoying leaking windows during heavy rain, as outlined in this guide. Don’t let a little water ruin your day — roll up your sleeves, grab some caulk, and get to sealing those windows. In no time, you’ll be able to restore your building to its old self!

And if quick fixes don’t do the trick, call in a glazing expert for professional inspections. They can assess whether you need new weatherstripping, window repairs, or even full window replacements.

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