Have you noticed your roof leaking intermittently? One day it’s dry and the next, there’s water inside. At Thompson Home Improvement, we frequently hear from homeowners who experience leaks that only appear under specific conditions, such as after a storm or during high winds. It’s a common issue. One that can be hard to pinpoint without the right information.

That’s why we’ve created this checklist. It walks you through the most common reasons a roof may leak occasionally. The list is based on key factors like the age of your roof, the location of the leak, and recent weather or roof activity.

If any of these points uncover a concern, or if you still can’t figure it out, our team is ready to help.

The age of your roof plays a significant role in identifying the cause of a leak.

New roof: If your roof was installed recently, it should still be under warranty. Reach out to the original installer. They may inspect or fix the issue at no cost. Leaks in new roofs are often tied to incomplete sealing, especially if the roof was installed in cold or damp conditions. Some materials, such as asphalt shingles, may not fully seal until the warmer weather arrives. Until then, wind or rain can find their way underneath. It is also possible that an exposed nail is allowing water to enter when conditions are just right.

Old roof: Over time, shingles wear down, flashing deteriorates, and UV exposure weakens roofing materials. These issues can lead to leaks that only appear when rain hits from a certain direction or during high winds. In some cases, shingles may have blown off or been compromised, making it easier for water to enter under the right conditions.

Where you see the water inside can give valuable clues about what’s happening on the outside.

Try to match the indoor leak location with exterior roof features like:

• Bathroom or kitchen vents
• Chimneys or skylights
• Pipe boots or exhaust pipes

If the leak is near a vent pipe, it might be due to a failed or improperly installed flange. This can occur in older homes where the flange has deteriorated due to sun exposure, or in newer homes where another trade, such as a plumber, may have installed it incorrectly. Also, check the rubber gaskets on your pipe boots, which can wear down from UV exposure and create a leak if not regularly maintained.

If the leak has only happened once, it could be caused by unique weather conditions, such as wind-driven rain. In rare cases, wind and rain can strike at just the right angle and speed to push water under shingles, through roofing vents, or even past window sills. These types of leaks can be complicated to reproduce or spot.

If it has happened more than once, that usually indicates a more persistent or structural issue that will likely require professional attention.

Ask yourself the following:

• Has there been a recent storm?
• Have contractors, such as electricians, siding installers, or window crews, been on the roof?

Storm damage and foot traffic are both common causes of minor yet significant roof damage. A lifted shingle, an exposed nail, or damage from someone walking on the roof can allow water to enter when weather conditions are right.

Animals and debris can silently damage a roof. Birds, squirrels, or raccoons can pull up shingles or chew around vents. Meanwhile, leaves and branches can clog gutters and valleys. When water cannot drain properly, it backs up and flows under the roofing materials instead of off the roof like it should.

Ensure that you regularly clean out runoff areas and remove any tree debris from valleys, gutters, and roof crevices.

A poorly ventilated attic can accumulate moisture, especially during rapid temperature fluctuations. This can mimic a roof leak even when the roofing material is intact. If warm air inside the home condenses in the attic, it may drip down and appear as a leak. This issue can affect both new and older homes.

Flashing seals the areas where your roof connects with walls, chimneys, or skylights. If flashing is missing, damaged, or poorly installed, water can slip through very easily. This problem can happen in both new construction and aging homes. If flashing is not installed correctly or maintained regularly, it can become loose or break down.

Masonry chimneys are a very common but often overlooked source of roof leaks. If they are not properly maintained, they can allow water in even when the rest of the roof is in good condition. 

Look for:

• Cracked or broken chimney caps
• Failing mortar joints
• Deteriorated brick faces
• Loose or missing flashing

Any of these signs can lead to occasional leaks, especially when paired with wind or heavy rain.

Some leaks are easy to trace. Others appear only under the right combination of weather, roof condition, and location. If you are unable to identify the issue confidently or if the problem persists, calling a professional roofer is your best course of action.

At Thompson Home Improvement, we understand the many variables that can lead to occasional roof leaks. From aging shingles to loose flashing or poor attic ventilation, our team has the knowledge and experience to diagnose the cause accurately and provide the right solution.

We offer free, no-obligation roofing estimates. Whether your roof is brand new or several decades old, we will thoroughly inspect it, explain our findings, and recommend next steps without pressure.

If you’ve noticed a roof leak that comes and goes, schedule a free evaluation with Thompson Home Improvement today. We’re here to help you protect your home with confidence.