How to Fix a Leaky Roof – Forbes Advisor

Working hours: 2 to 6 hours
Total time: 1 to 2 days
Skill level: Advanced
Project costs: $ 100- $ 300

A leaky roof is a major problem that can cause a number of rapidly cascading problems inside residential buildings, from damp loft insulation to broken floors. Repairing a leaky roof is important to the maintenance of your home.

Repairing leaky roofs is a labor-intensive project that is not for everyone. But when you are up to the task, it is relatively inexpensive and pays off significantly when it comes to maintaining the value of your home.

When to roof a house

Roofers can repair a house roof almost any time of the year as they have enough manpower and experience to adapt to the weather. As a DIY enthusiast, choose the driest and warmest time of the year as the rooftop terrace can be exposed for a day or two.

In most areas, this means repairing your leaky roof from late spring to mid or late summer and even well into fall. Check the instant weather forecast before you start sealing your leaky roof.

Security aspects

Repairing a leaky roof can be dangerous. However, with proper working practice, roof repairs can be a safe project. Always work with an assistant.

Avoid falls by never working on a wet, snowy, or icy roof. Remove debris such as twigs, pine cones, leaves, and moss. Wear boots with soft soles.

Use a Personal Fall Protection System (PFAS) to slow and stop your fall from the side of the house. Or use a fixed fall arrest system to keep you from reaching the unprotected edge of the roof.

In the comprehensive OSHA publication “Protecting Roofing Workers” you will find all the safety recommendations to protect you when sealing your leaky roof. Also use all other personal protective devices such as hearing and eye protection, gloves and a breathing mask.


  • Flat chisels
  • hammer
  • Hook knife shingle cutter
  • Utility knife
  • ladder
  • flashlight
  • Cartridge gun
  • Chalk line
  • circular saw
  • Tape measure
  • pencil
  • Personal protective devices


  • Composite shingles with three flaps
  • Roofing paper or synthetic underlay
  • Roof nails
  • 8d ordinary nails
  • Roof cement or exterior sealant
  • Roof vent (if a damaged vent is replaced)
  • 7/16 inch plywood or OSB board for outdoor use (when repairing a damaged roof terrace)


1. Find the roof leak

Start at the lowest point of the roof leak, e.g. B. on a ceiling stain, and work your way up. Access the attic with a ladder and flashlight and visually follow a vertical line to the roof. The leak can start a few feet higher on the roof line towards the ridge of the roof. The location of the leak on the underside of the roof terrace may be black or white, or it may have mold or mildew.

Roof vents are a major cause of roof leaks. Roof vents can include roof fans, turbines, plumbing for piping, and any metal-faced elements that extend across the roofline. Or the source of the roof leak could be a damaged plywood roof deck (also known as a cladding).

2. Examine the roof vents

If the leak is from roof vents, return to the top of the roof and check the condition of the vents. The cases or boots may have cracked. The vents themselves may have come loose. Check for nails that are missing or loose and that the vents are holding on to the roof.

3. Remove the damaged roof vent

Remove the damaged roof vent from the top of the roof. First, using the lever bar, pull out the nails that secure the shingles to the vent. Then use the lever bar to pull back the shingles covering the bottom of the vent. It helps to have an assistant hold the shingles. Do not remove the shingles. Remove the nails holding the vent to the roof deck. Finally, remove the vent.

4. Replace roof vent

Apply a thick bead of roof cement or exterior sealant to the bottom of the vent. Gently let the wizard roll back and separate the shingles as you slide into the vent.

The bottom of the vent should go over the shingles to prevent leakage. Nail the opening at all corners and every 4 inches. Cover the nails with cement or sealant.

5. Tear off old shingles

If the leak is from damage to the roof deck, you will need to remove the shingles to gain access to the damaged section.

Push the lever bar from the bottom up (towards the roof ridge) under the shingles. Start about two rows of clapboard above the intended repair point. Then work your way down through the rows, gradually loosening the nails and pulling the shingles away.

6. Remove the old roofing paper

Roofing paper or synthetic underlay separate the shingles from the roof terrace. Cut the paper or backing with the utility knife. Keep as much intact as possible.

7. Highlight the top cut area

Snap a chalk line across the rafters on the left and right sides of the damaged section of the roof deck. Make sure the line in the middle of the rafters clicks into place. Follow the existing nails as a guide for the center of the rafter.

Then snap a chalk line across or 90 degrees to the rafters above and below the damaged section.

8. Cut away the damaged roof terrace

Adjust the depth of the circular saw blade to the thickness of the roof deck plus another 1/16-inch. Follow the chalk lines to cut off the damaged section of the roof terrace. When cutting, be sure to kneel outside of the marked section.

9. Remove the roof terrace

Use the pry bar to pull nails out of the roof deck cutout. Then pry off the damaged plywood, but do not discard it yet.

10. Cut off the new roof patch

Use the damaged section of the rooftop as a template to mark the dimensions of the new rooftop field. Cut this patch on the floor for safety.

11. Apply the roof patch

On the roof, put the roof terrace and nail it to the rafters with 8d common nails.

12. Place paper or pad

Nail the roofing paper or underlay with roofing nails from bottom to top. Overlap each row by at least 4 inches.

13. Complete the first row of clapboards

Starting in the bottom row, lay the first row of new clapboards. Maintain the established rows by scrolling the new clapboard into the existing clapboard from left to right.

Apply a bead of roofing cement to the underside of the shingles. Nail the shingles in place along the top of the shingles.

14. Complete the shingles

Work upwards until you reach the top row of clapboards. Mesh the new shingles with the existing shingles by sliding the new shingles under the top row.

When to call a professional

Stopping roof leaks can be complex and labor intensive. The interwoven components of the roofs must be precisely coordinated to avoid leaks. The job involves a lot of climbing and pulling.

If you are concerned about whether you can fix the leaky roof in a timely manner, contact a roofing company or general contractor. If you feel unsafe working on a roof, consult a professional.

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