Why does my roof only leak in heavy rain or wind?

A roof that only leaks in heavy or wind-driven rain usually has a weak spot that light rain never reaches: worn flashing, a crowded valley, lifted shingle edges, a cracked vent boot, or the roof edge behind an overflowing gutter. Wind pushes water sideways and up, so the leak is usually on the side the storm came from.

If you want me to take a look, text a picture to 443-900-4815 or call the same number. I'm James. I've worked on roofs around Baltimore City and Baltimore County for 24+ years, and I'm licensed and insured, MHIC #154344.

Where does heavy rain get in?

• Flashing. The metal around chimneys, walls, skylights, and dormers. When it loosens or was short to begin with, a hard rain backs water up behind it. See roof flashing repair.
• Valleys. Where two roof slopes meet, a lot of water runs through one narrow channel. In a downpour it can rise over worn or badly cut shingles at the valley.
• Lifted shingle edges. Shingles that lost their seal still look fine from the ground, but wind lifts them and drives rain underneath.
• Vent pipe boots. The rubber collar around a plumbing vent cracks with age. Light rain runs past it, but heavy rain finds the crack. See vent pipe leaks.
• The roof edge. When the gutters overflow, water can back up under the first row of shingles and into the fascia. See why gutters overflow.

Why does wind make it worse?

Rain normally runs straight down the roof, and every layer of a roof is lapped to shed water that way. Wind changes the direction. It pushes water sideways under flashing, up under shingle edges, and into gaps that only face one way. That's why a roof can stay dry for months and then leak in one storm from one direction.

How can I narrow it down?

The next time it leaks, write down a few things. They help me find it faster:

• Which way the wind was blowing and how hard it was raining.
• How soon the drip started after the rain began. Right away often means an opening close by. A long delay often means water traveling a long way first.
• Where it shows up inside, and what's on the roof above that spot, like a chimney, a vent, or a valley.
• Pictures of the stain or drip, and a short video if it's actively dripping.

Water can run along a rafter or the roof deck before it drips, so the stain on the ceiling isn't always right under the opening. For what to do while it's dripping, see roof leaking, what to do.

What we do

1. Look at the roof from the outside, starting on the side the wind came from. On a steep roof I can use the drone. I'm an FAA-licensed drone pilot.
2. Check the usual spots: flashing, valleys, shingle edges, vent boots, and the gutters.
3. Find where the water is really getting in, not just where it drips inside.
4. Send you pictures of what we found, with a price before any work starts.
5. Fix the source, whether that's reflashing, resealing or replacing shingles, or a new vent boot.

See roof leak detection and repair for more on how we track down leaks.

You can text me at 443-900-4815 with a picture of the stain and which way the wind was blowing, or call the same number.

Heavy rain leak questions

Why does my roof leak only when it rains hard?

A hard rain puts more water on the roof than the weak spot can shed. Water backs up behind loose flashing, rises over worn valley shingles, or overflows the gutter onto the roof edge. In a light rain the water runs off before it reaches the opening.

Can wind-driven rain get under shingles?

Yes. Shingles that have lost their seal can lift in the wind, and the rain blows right under them. Edges, corners, and ridges get it first.

Why does the leak show up far from where the water gets in?

Water often runs along the roof deck, a rafter, or the upper side of the ceiling before it drips. The stain inside can be several feet from the opening on the roof.

Should I wait for it to rain again before calling?

No. Text a picture of the stain and what you noticed about the weather. Most leaks can be found on a dry day by looking at the roof above where the water showed up.

How much does it cost to fix a leak that only shows up in heavy rain?

It depends on what's causing it and how hard the spot is to reach. A loose piece of flashing is a different job from a worn valley. You get a price before any work starts.