How to Fix a Leaking Roof from the Outside

Roof leaks can quickly escalate into serious problems if not addressed in time. Even a small leak can cause water damage, mold growth, and structural deterioration. Knowing how to fix a leaking roof from the outside gives you a critical advantage in minimizing damage and protecting your home.

Whether you’re dealing with a minor shingle issue or a more complex breach in flashing or underlayment, this guide walks you through step-by-step repair strategies. B&M Roofing has been serving Colorado homeowners for over 75 years, and our team knows what it takes to restore a roof safely and effectively.

Signs of a Roof Leak You Can Spot from the Outside

Before attempting any repairs, it’s essential to correctly identify that your roof is leaking and where the issue is originating. Common visual clues from the exterior include:

Missing or Curled Shingles: Wind, hail, and UV exposure can cause shingles to warp or detach entirely.
Cracked Flashing or Vent Boots: Flashing protects vulnerable areas like chimneys, valleys, and vents. When flashing fails, water often seeps in.
Water Stains on Fascia Boards: Look for discoloration beneath the eaves or behind the gutters.
Pooling Water or Sagging Gutters: Clogged or misaligned gutters can redirect water into the roof structure.
Moss or Algae Buildup: These growths trap moisture and accelerate roof deterioration.

Regularly inspecting your roof, especially after major storms, is a key step in preventive maintenance.

How to Fix a Leaking Roof from the Outside: Step-by-Step

Once you’ve spotted exterior signs of a leak, it’s time to act. Below is a practical sequence to help you address minor leaks or apply temporary fixes until professional repairs can be made.

Step 1: Locate the Source of the Leak

Start by inspecting the suspected area. Use binoculars from the ground if your roof is steep or inaccessible. Look for:

Shingles that appear darker, discolored, or warped
Gaps around chimneys, skylights, and roof vents
Cracks in flashing or ridges
Wet spots under eaves or at the roofline

Pro Tip: You can also run a hose over different roof sections while a second person watches inside the attic for drips or moisture.

Step 2: Apply a Temporary Fix

If rain is in the forecast or you can’t complete a full repair immediately, apply a short-term solution to prevent further water intrusion.

Use a Tarp: Cover the affected roof section with a durable plastic tarp, extending it past the ridge to ensure proper runoff. Secure it with wood strips and nails.
Apply Roofing Tape or Cement: For small punctures or cracks, roofing tape or a generous application of roofing cement can temporarily seal leaks.

Safety tip: Never attempt roof work in wet, icy, or windy conditions. Always use fall protection and a stable ladder.

Step 3: Replace Damaged Shingles or Flashing

Start replacing the damaged materials once the weather is dry and you can work safely.

How To Replace a Shingle:

Carefully lift the shingle above the damaged one to expose the nails.
Remove the nails using a flat pry bar.
Slide out the damaged shingle.
Slide in a new shingle of the same type and color.
Nail it in place and seal with roofing cement.

How To Repair Roof Flashing:

Remove any cracked or rusted flashing sections.
Apply roofing cement under the new flashing.
Secure it with nails and apply an additional bead of sealant along the edges.

Step 4: Clean and Realign Gutters

Clogged gutters can force water to back up under shingles or rot the fascia.

Remove all debris from gutters and downspouts.
Ensure that gutters are sloped correctly (typically 1/4 inch per 10 feet toward the downspout).
Check for leaks at seams and seal them with gutter caulk or sealant.

Step 5: Seal Exposed Fasteners and Roof Penetrations

Roof leaks often originate around exposed nails, vents, and joints.

Apply roofing sealant or cement to any exposed or corroded fasteners.
Re-caulk around chimneys, skylights, and vent boots as needed.
Use a patching kit to cover small holes in shingles or metal panels.

Materials and Tools You’ll Need

To properly fix a leaking roof from the outside, gather the following supplies:

Replacement shingles
Roofing nails and hammer
Roofing cement or sealant
Flat pry bar and utility knife
Ladder and safety harness
Tarp and wood strips (for temporary repairs)
Caulking gun and roofing caulk
Gutter scoop or garden trowel

Having the right tools on hand reduces the risk of errors and helps ensure your repair lasts.

When to Call a Professional Roofer

While a handy homeowner can manage some minor leaks, there are several situations where calling a professional like B&M Roofing is strongly recommended:

You cannot safely access the roof or identify the leak source.
The leak involves large sections of roofing or structural damage.
Water is entering your attic or living space.
There are signs of mold, insulation damage, or ceiling discoloration.
Your roof is under warranty, and you want to avoid voiding it.

A licensed roofer can provide a thorough inspection and professional-grade repairs and help with insurance documentation if needed.

Why Choose B&M Roofing for Roof Leak Repair

B&M Roofing has built a reputation as one of Colorado’s most trusted roofing contractors by offering reliable solutions backed by expert craftsmanship. When you choose us for your roof repair, you get:

Experienced roofers trained to detect hidden damage.
Emergency response for active leaks or storm damage
High-quality materials and attention to detail
Long-term protection, not just a quick fix
Honest guidance about whether to repair or replace

We’ve helped thousands of homeowners across the Front Range secure their homes against hail, snow, and wind. You can count on us to do the job right the first time.

Fix Roof Leaks Fast—Start with a Trusted Roofing Partner

Learning how to fix a leaking roof from the outside empowers homeowners to take quick action, but not all leaks should be handled alone. When safety, quality, and long-term performance matter, trust the professionals at B&M Roofing.

Contact B&M Roofing today for a professional roof inspection or emergency repair assessment. Our expert team will identify the source of the leak, provide transparent recommendations, and get your roof back to peak condition—fast.