How to Repair Roof Leak

Check out these recommendations—some may be just what you need.

01.Inspect the roof from above

02.Go up to the attic

This is a must. Climb into the attic and inspect the space from the inside. You may notice water stains or marks on the underlayment. If the insulation is wet, that’s a sign of a leak. Water often enters at the joints of vapor or waterproofing membranes.

If no visible leak is found, check under the roof for nails that missed the framing. Moisture in the attic condenses on these exposed nails. It freezes overnight and melts during the day. At night, they may appear white due to frost.

What to do: Drive the nails tight against the decking and apply sealant to the nail heads.

03.Spray the roof with a garden hose

If the leak is hard to locate, test the roof with water. Climb up with a garden hose and begin spraying, starting from the bottom—right above the suspected leak location.

Soak the roof section by section. For example, near the chimney or skylight. Spray each area for a few minutes before moving on.

Have a second person stay in the attic and watch for leaks. This is the easiest way to locate the source. The process usually takes about an hour or more.

If you locate the general area but not the specific cause, remove some shingles. Look for signs of water, faded felt, or rotted wood.

04.Replace vent boots

Vent boots for chimneys come in plastic, metal, or a combination. Check plastic for cracks and metal for failed seams. Also inspect the rubber boot that wraps around the pipe—it may be rotted or cracked.

If damaged, replace the boot. Sometimes the issue is just loose nails. Swap them out with screws and rubber washers.

To replace nails, loosen shingles on both sides. Use a flat bar to break the sealant between the layers and remove the nails.

05.Install new vent pipes

Plastic roof vents may crack over time. If so, it’s better to replace them—sealing with caulk is a temporary fix.

If the vent pipe is intact, check the nails holding it down. They might be loose or missing. Replace them with screws and rubber washers.

You can replace the nails without removing shingles. Once the new vent is installed, reattach surrounding shingles with roofing sealant.

06.Check skylights and walls

Sometimes the water doesn’t come through the roof but through skylights or siding joints. Moisture may also get in through cracked joints between corner boards and siding, or through damaged siding itself.

If the sealant around the window frame is cracked, water can seep inside. Even intact sealant can occasionally allow leaks.

Remove faulty sealant with a putty knife and replace it with high-quality caulk. Also check the siding just above the wall flashing. Replace any cracked, rotten, or missing siding panels.

Still leaking? Then remove the corner boards and check the waterproofing at the joints. Often, you’ll find old, worn-out sealant that needs to be replaced.

07.Check Roof Joints

Complex roof structures require extra attention—especially where one slope meets another. These areas are more likely to leak during winter snowfalls or summer storms. The most common cause: poor waterproofing.

The soffit is one of the most challenging areas to waterproof, particularly when ice dams form. Issues are often caused by improper ventilation, insulation, or clogged gutters. As a result, water seeps through the roof joint into the soffit.

Solution:

• Remove shingles down to the roof deck.
• Apply a self-adhesive waterproofing strip under the joint between the flashing and roof. Each layer of material should overlap the previous one to ensure protection.
• Slide a metal flashing strip behind the siding (just behind the gutter), making sure it covers the joint by at least 2 inches (5 cm).
• Cover the area with roofing material.

Proper insulation and ventilation are the best ways to prevent ice dams. If that’s not enough, install heating cables in the most vulnerable areas.

08.Replace Old Flashing Tape

Step flashing helps prevent leaks where the wall intersects with the roofline. It directs water safely downward. If the flashing layer comes loose, water may flow into the home.

Over time, flashing tape around gutters or wall joints can degrade. To replace it, remove the shingles and lift the siding. Install new tape beneath the siding and fasten it to the wall.

09.Inspect Around Chimneys

Metal flashing around chimneys can rust—especially at 90-degree bends. Once compromised, water may seep into the roofing layers and damage the decking.

Quick fix: Slide a new piece of flashing under the old one. Any water that gets in will be directed away. However, replacing the entire flashing is the best solution.

10.Seal Holes in the Roof

Small cracks in shingles may go unnoticed but can lead to rot, leaks, and roof deterioration. Some holes remain from satellite dishes, mounting brackets, or hardware. Nails may also work loose over time and need to be replaced with screws and rubber washers.

You can use roofing sealant to plug small holes—but liquid waterproofing products are often more effective.

11.Seal Roof Holes Properly

Caulk and roofing cement are rarely the best way to fix leaks. Mechanical repairs—like replacing shingles or flashing—are more reliable.

Use sealant only for very small holes or in situations where full waterproofing replacement isn’t possible.

12.Clean the Gutters

Clogged gutters are a leading cause of ice dams. Ice buildup along the eaves allows water to seep under the decking and into the home as temperatures rise—causing drywall stains, mold, and structural damage.

Regular gutter cleaning is a key part of roof leak prevention—and home maintenance in general.