The do it yourself resource for homeowners from home improvement professionals.

How to Repair a Leaking Roof

Realizing that your roof has a leak is a distressing discovery. You must make sure you take care of the problem quickly to avoid serious damage. Every drop of moisture entering your home sets the stage for structural rot and mold growth. Learning how to repair a leaking roof depends on the source of the problem. The problem could be damaged decking or a failure of the seal around a vent. Whatever the cause, plan on having another person assist you with the fix. A helper is important for safety and getting the job done in a timely manner.

Roof Repair Safety Tips

A roof is not a safe place to work. You must take precautions, such as:

  • Choose a dry day to work on the roof
  • Wear soft-soled shoes
  • Use a fall-prevention safety harness
  • Work with a partner

How to Repair a Leaking Roof Step by Step

  1. Enter your attic to pinpoint exactly where water is coming from. Stains on a ceiling or wall are often down slope from where water is actually penetrating.
  2. Once you find the leaking area, measure its distance from the roof ridge or eave. This can be an approximate figure. It is meant to help you find the right location once you get outside on top of the roof.
  3. If the leak appears to be at a roof vent, follow the directions for fixing a leaking vent.
  4. If broken or rotted decking is letting water in, follow the directions for fixing roof decking.

How to repair damaged roof decking:

  1. Acquire some new 3-tab shingles that match your roof’s color.
  2. Place your ladder on stable ground.
  3. Set up your fall-arrest system.
  4. Using your measurements, find the area of the roof which is damaged.
  5. Two rows of shingles above the damaged area, begin prying up shingles.
  6. Remove the nails and lift shingles off.
  7. Working downward, remove shingles until you have exposed all of the bad decking.
  8. Take the utility knife and slice through the roofing paper.
  9. Cut around the damage but leave the roofing paper over good decking in place.
  10. Locate the roof rafters on each side of the damage. The decking nails will reveal where the rafters are.
  11. Use the chalk line to snap a mark down the centers of the rafters on the right and left of the damage.
  12. Mark the top and bottom of the bad decking by snapping the chalk line at a 90-degree angle across the rafter lines.
  13. Now it is time to cut out the damaged decking.
  14. Measure the thickness of the roof decking and add 1/16 inch to that figure.
  15. Use that figure to adjust the depth of the blade on your circular saw.
  16. Do not put your weight on the decking that you are cutting free.
  17. After cutting, pry out the damaged decking.
  18. Measure the dimensions of the hole that you’ve cut into the decking.
  19. Working on the ground, cut a new piece of plywood to those dimensions.
  20. Nail the decking patch to the rafters with 8d common nails.
  21. Cut underlayment roofing paper to the cover the patch.
  22. Start at the bottom and attach paper with roofing nails. Set top pieces of underlayment so that they overlap bottom layers.
  23. Working upward from the bottom, nail on your first row of new shingles on their top edges.
  24. Integrate the new shingles with existing shingles on the left and right of the patch area.
  25. Secure the bottom flaps of the new shingles with roofing cement.
  26. Tuck the top edge of the final row of new shingles beneath the existing shingles.
  27. Nail the top edge and then stick down the overlapping shingles with a bit of roofing cement.

How to repair a leaking roof vent:

  1. When you locate a leak by a roof vent, you’ll likely need to buy a new housing or boot for the vent.
  2. Climb onto the roof while using your fall-prevention harness.
  3. Inspect the vent to identify what has gone wrong. You might see cracked housing or deteriorated caulk.
  4. Learning how to repair a leaking roof at the vent requires you to pry out the nails holding the shingles around the vent.
  5. Lift aside the shingles around the vent without removing them completely.
  6. Pry out the nails securing the vent housing to the roof.
  7. Take your new vent housing and run a generous bead of roofing cement on the bottom of its base.
  8. Your partner can hold back the shingles while you press the new vent housing into place.
  9. Nail the vent housing around the edges every 4 inches.
  10. Push the shingles back in place around the vent.
  11. Flash the vent so that the flashing covers the shingles.

Tools & Materials

  • Extension ladder
  • Flat pry bar
  • Flashlight
  • Tape measure
  • Pencil
  • Chalk line
  • Hammer
  • Utility knife
  • Circular saw
  • Caulk gun
  • Personal fall arrest system
  • Hook blade shingle cutter

When to Hire a Professional Roofer

Your DIY spirit is commendable, but some roof problems call for help from professional roofers. If you can’t find the source of the leak, then an inspection from a pro is needed. If you discover extensive damage, then you’ll want a full tear off and shingle replacement. A new roof will preserve the integrity of your home. If you live in the Mid-Atlantic, the team at PJ Fitzpatrick can put an end to roof leaks. Ask us for a roof repair estimate today.

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