How to Repair a Leaky Asphalt Roof – DIY Guide

In this guide, you’ll learn the basics of asphalt shingle roof repair:

  • Finding the leak
  • Repairing damaged shingles when possible
  • Removing and replacing damaged asphalt shingles
  • When it makes sense to replace the entire roof or section
  • The cost of asphalt shingle replacement
  • Have you had that “uh oh” moment when you look up at the ceiling and are hit with the tell-tale signs of a leaky roof? The drywall is wet, maybe stained too. Or water is making its way through a light fixture, and drip, drip, dripping onto whatever lies beneath. That’s definitely a problem, but we’ve got the solutions right here.

    Visually inspecting your roof from the ground using binoculars is something you should do after every high-wind event, and that’s often all it takes to discover the mauled or missing shingles, hopefully before a leak develops.

    via A Step in Time Roofing

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    Either way, your roof is the home’s most important defense against the elements, and leaks must be stopped immediately. If they’re allowed to continue, extensive water damage, rotting wood and mold that is difficult and costly to remove will result.

    Finding a Roof Leak

    The location the water enters your home is rarely the spot where the roof is damaged. One thing you can be sure of: The leak is level with or above the entry point. Water finds an opening such as a cracked or missing shingle, displaced flashing or a broken vent pipe boot, gets under the roofing materials and runs downhill. When the water hits a seam in the roof sheathing, it seeps through it. Once on top of the ceiling drywall, it soaks the drywall or puddles until it expands to a seam or to a light fixture cut-out, and there you have it. That’s the anatomy of a roof leak.

    Here are the steps to take to locate a roof leak in a sloped roof:

    • From inside, measure from the water’s entry point into your home to the two nearest outside walls.
    • Take those measurements to the roof to determine the starting point for your search. It’s possible that the damaged shingle or shingles might be immediately evident above that point.
    • If not, carefully work your way toward the slope, examining each shingle for cracks, tears and signs of being displaced. Check vent pipe boots for cracks and tears. If you get to the peak without locating damage, check the ridge shingles for issues. In most cases, you’ll pinpoint the damage.
    • If you can’t find the leak, you might have to call in a professional roofer or be prepared to re-roof that section from the leak point to the ridge.

    Caution: Ladders and roofs pose the danger of falling with serious consequences. If you aren’t experienced on ladders and roofs, or don’t have a quality ladder and a strong adult to hold it steady for you, grab your binoculars and look at the roof from terra firma or call a roofing contractor.

    Also, it makes sense to go onto a roof when the shingles are warm and dry, though not hot, rather than when they’re wet or icy.

    Repairing a Shingle without Replacing It

    via FloridaDisaster.org

    The most common scenario for this is something like a tree branch or baseball striking the roof and cracking a shingle or two.

    You’ll need a tube of roofing sealant like that made by Dap or Henry, plus a caulk gun and a narrow putty knife.

    Together, the cost of the above items will be $18-$35 depending on the quality of the caulking gun. Ahead of time, scoop shingle granules out of the gutter, rinse them in a sieve, and allow them to dry, and then:

    • Gently lift the broken shingle, and apply a thick bead of sealant to the underside of the crack
    • Press the shingle gently against the roof
    • Apply a bead to the crack from the top side
    • Tool the sealant with the knife, gently pressing it into the crack without scraping it off
    • Sprinkle the granules onto the sealant, and you’ve hidden your roof repair

    Repairing Cupped Shingles

    Older shingles cup at the edges, and this leaves your roof poorly protected against rain, especially wind-driven rain hitting the roof at an angle. This is a simple repair. However, once one shingle cups, the rest of the shingles are well on their way to imitating that one. Cupped shingles are a sure sign that the entire field of them should soon be replaced. 😉

    • Apply a quarter-sized dab of roofing sealant on the curled corners and a line of it on edges
    • Firmly press the shingle against the roof
    • If the roof pitch is 6/12 or less, hold down the curled areas with a brick, and leave the brick in place for a couple days
    • On roofs steeper than 6/12, strong tape might hold the shingle down, but you run the risk of pulling the shingle back off the roof when removing the tape or removing the protective granules

    The bottom line is that cupped shingles are better replaced than repaired.

    Replacing Damaged Asphalt Shingles

    The best long-term asphalt roof repair is always to replace rather than repair damaged shingles. Here’s what you’ll need and how to do it. Hopefully you’ve got a bundle of leftover shingles from when the roof was installed. If not, take a piece of a damaged one with you to the home improvement or builder supply store to match as closely as possible. Some lines of shingles from Owens-Corning, CertainTeed and other top brands are sold for a decade or more, so you might locate your shingles.

    • Shingles are sold in bundles of approximately 33 square feet of coverage and about 28 shingles; A bundle costs as little as $20-$25 for cheap 3-tab shingles, and $35-$75 per bundle or more for quality architectural shingles
    • Roofing nails, 1.25” long, cost $4-$7 for a box with enough nails to replace a bundle of shingles
    • A flat prybar costs $5-$10 depending on quality
    • Roofing hammer cost starts at about $7, and costs go to about $40 as quality improves

    With your tools gathered, here is how to replace asphalt shingles and stop that pesky leak:

    • Slide the flat end of the prybar beneath the shingle immediately above the damaged shingle and lift it until its sealer strip comes free
    • This will expose a row of top nails on the damaged shingle, and they can be removed by raising them with the prybar and pulling them with the claw on the hammer
    • You’ve now exposed the damaged shingle, so it will be easy to pull the remaining with the prybar and hammer and remove the shingle
    • Pull the backing from the sealer strip of the replacement shingle, and slip the shingle into place
    • Align it with the shingles around it before securing it with four nails through its nailing tab

    Replacing Asphalt Shingles: A Few vs. Many

    When there are more than a few damaged shingles in a roof section – for example, if a hail storm devastates the west side of your roof or a large tree limb crashes down on it – you might be better off replacing the entire section, and this calculator will help you determine how much material you’ll need.

    And here is how to measure the roof, in case you have multiple sections requiring a complete replacement: https://www.roofingcalc.com/how-to-measure-and-estimate-a-roof-like-a-pro/

    Here are a couple guidelines:

    • If the shingles are more than 15 years old, they’ll need replacing in the next five years anyway.
    • If more than 25% to 40% of the shingles are damaged, depending on how they are grouped, replacing an entire section will probably take less time than replacing individual shingles.

    Let’s talk about hiring a roofing contractor for the repairs. There is a tipping point when replacing an entire section is the cost-effective choice over replacing just the damaged shingles.

    The cost of asphalt shingle repair is $7.00 to $15.00 per square foot when just damaged shingles are replaced. Plus, the roofing contractor will have a minimum service fee of at least $100, and a fee of $250 isn’t out of the question.

    The exact cost of asphalt shingle replacement depends on the pattern of the damage:

    via Pioneer Roofers

    • When the damaged shingles are closely bunched, as when a tree limb falls on them, then tipping point is when 50% to 70% of the shingles are damaged
    • When random shingles are damaged like in a hail storm, then the point when you’ll save money replacing the section might be as low as 35% of damaged shingles.

    Another factor to consider is that an entire roof section installed at the same time will likely protect better than a section of the roof with a blend of old and new shingles.

    Our thoroughly researched and updated 2017 roof installation cost guide puts the cost of replacing an entire roof or section at $2.75 to $7.50 per square foot, depending on the roof difficulty, accessibility, height, number of existing layers, and your location. Check it out for all the details here: https://www.roofingcalc.com/roof-replacement-cost/. There’s also a spirited debate about pricing in the Replies section that is interesting and enlightening, and it shows we’re right on the money! 😉

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    What are your thoughts? Share them below, and if this information has been of help, pass it on to your friends and followers, because they’ve probably got some roofing issues to consider, too!


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