Your New Roof Is Leaking — Now What?

You paid for a full roof replacement. The crew showed up, worked for a few days, and called the job done. Then, four days later, water started dripping through your ceiling.

You called your contractor. Instead of an apology, you got a bill and a brush-off: “Sometimes on older homes, the details take a couple of tries.”

That’s not how a legitimate roof job works. If your new roof is leaking, something went wrong — and in many cases, it comes down to one of the most overlooked parts of the entire system: roof flashing.

This guide explains what flashing is, why it fails, and what signs of bad roof installation California homeowners should never ignore after a roof replacement.

What Is Roof Flashing — and Why Does It Matter So Much?

Flashing is thin metal sheeting installed at every vulnerable joint on your roof — around chimneys, skylights, vents, walls, and valleys. Its job is simple: redirect water away from gaps where two surfaces meet.

When it’s installed correctly, you never think about it. When it’s done wrong, water finds its way in every single time it rains.

Why Old Flashing Gets Reused (and Why That’s a Problem)

On a full roof replacement, many homeowners assume everything is new. In reality, some contractors leave old flashing in place to cut time and labor costs. This isn’t always wrong — if existing flashing is in solid condition and properly integrated, it can sometimes remain.

But reusing flashing that is visibly damaged, corroded, or full of holes is a different story entirely. Holes mean water entry points. Old sealant around fasteners means failed waterproofing. And if those flaws are now buried under new shingles, you won’t see the damage until it shows up inside your home.

The Flashing-Warranty Connection

Many manufacturer warranties — including GAF’s Silver Pledge — cover the full roofing system, not just individual materials. If your flashing is compromised and causes a leak, the manufacturer may deny your warranty claim because the failure didn’t originate with their product.

That means a homeowner can have a brand-new roof, a warranty certificate, and zero coverage — all because of old, reused metal that cost a few hundred dollars to replace.

What Happens When Roof Flashing Fails

Bad flashing doesn’t announce itself loudly. It starts small — a faint water stain on the ceiling, a musty smell in the attic, a damp spot on an interior wall after rain. By the time visible damage appears, water has likely been sitting inside your home for weeks.

Water Damage Behind Your Walls

When water enters through failed roof-to-wall flashing, it travels down the wall cavity before it ever shows up as a visible stain. By then, the insulation is wet, the drywall is compromised, and the framing may already be showing early signs of rot.

For more on what can happen when a new roof starts leaking right after installation, the damage timeline moves faster than most homeowners expect.

Mold Growth in the Attic

Trapped moisture and California’s warm temperatures create ideal conditions for mold. Attic mold from a roof leak is particularly dangerous because it’s invisible from inside the home and can spread to structural wood before anyone notices.

The Costs Add Up Fast

A failed flashing job that costs a few hundred dollars to fix properly can turn into a mold remediation bill, drywall replacement, and structural repairs costing $5,000 to $20,000 or more. The irony? A contractor who cut corners on flashing to save time created a much bigger problem for you down the road.

How to Tell If Your Roofer Cut Corners

Most homeowners have no idea what to look for after a roof replacement. Contractors count on that. Here are the most common signs that a roofing job was done improperly — and what you can do about it.

Visible Holes, Rust, or Damage on Flashing

Walk around your home after the job is done. If you can see flashing from ground level, look for rust streaks, visible holes, patched areas, or flashing that simply looks old next to everything else that’s new. New shingles combined with visibly aged or damaged metal is a red flag.

Exposed Underlayment After Completion

The underlayment is a secondary water barrier installed beneath your shingles. It should never be visible after a job is complete. If you can see black underlayment peeking out from the edges or along wall transitions, the job was left unfinished.

Unsealed Fasteners and Gaps

Screws or nails driven through flashing without sealant are open water entry points. Any fastener that penetrates a roof surface needs to be properly sealed. If yours aren’t, you have a leak waiting to happen.

For a full breakdown of roofing contractor red flags and what a finished job should actually look like, California homeowners are often surprised by how many shortcuts are standard practice among lower-quality crews.

Learning the most common roof replacement mistakes California homeowners face can help you ask better questions before you sign anything — and verify the job before you hand over a check.

What a Properly Installed Roof Should Look Like

A quality roof replacement in California isn’t just about shingles. It’s a complete system — and every component needs to be installed correctly for the whole thing to perform.

New Flashing at Every Transition Point

On a legitimate full replacement, all flashing should be new at roof-to-wall transitions, around chimneys, at valleys, and around any roof penetrations. Step flashing — the individual interlocking pieces that run along a wall — should be woven with each shingle course, not just slid behind existing siding as an afterthought.

Properly Integrated Underlayment

Underlayment should run beneath flashing, not on top of it. Water always needs to be directed away from the structure. When underlayment and flashing aren’t layered in the right order, water can get behind the system instead of running off it.

Use this roof installation quality checklist to review the key things to verify on your own home before making your final payment.

Your Warranty May Not Cover What You Think

One of the most painful discoveries a homeowner can make is that their brand-new roof warranty is essentially useless. This happens more often than it should — and it’s almost always tied to improper installation.

How Manufacturer Warranties Get Voided

GAF, Owens Corning, and other major manufacturers require licensed installation and full system compliance to honor their warranties. If a contractor reuses damaged components, skips step flashing, or fails to follow installation specifications, the manufacturer has grounds to deny any future claim.

Contractor Warranties vs. Manufacturer Warranties

Your contractor may offer their own workmanship warranty, but if they go out of business or simply stop answering calls, that warranty is worthless. Understanding exactly what roofing warranty coverage in California actually means — and what can void it — is critical before you choose a contractor.

What to Do If Your Roof Was Done Wrong

If you’re reading this because your new roof is already leaking, here’s what to do right now.

Document Everything

Take photos and video of every issue you can see — flashing, exposed underlayment, unsealed fasteners, water stains inside. Date your documentation. This protects you legally if you need to dispute the work or file a complaint.

Don’t Make Final Payment Until It’s Verified

California law gives homeowners legal standing to withhold final payment for incomplete or defective work. If a contractor pressures you to pay before defects are resolved, that is itself a red flag.

Get a Second Opinion from a Licensed Contractor

A CSLB-licensed contractor can perform an independent inspection of the work and provide a written assessment of what was done incorrectly. This documentation is invaluable if you need to pursue a dispute or file a complaint with the Contractors State License Board.

Understanding what to do when your new roof fails gives California homeowners a clear path forward — one that protects both their home and their investment.

Why US Power Does It Differently

At US Power, every roof replacement is treated as a complete system installation — because that’s the only way a warranty means anything.

CSLB-Licensed Contractors and Proper Installation

Our crews are CSLB-licensed and trained to install every component of the roofing system to manufacturer specifications. That includes new flashing at every transition point, properly integrated underlayment, and sealed fasteners throughout.

Limited Lifetime Warranty on Materials and Workmanship

We back every installation with a Limited Lifetime Warranty covering materials, workmanship, and performance. That warranty is only as good as the installation — which is why we don’t cut corners to save an afternoon of labor.

Transparent Pricing and No Pressure

We offer free roof inspections (virtual or on-site), transparent pricing with no hidden fees, and a 3 to 6 week installation timeline after approval. Our 180+ five-star Google reviews reflect what happens when a contractor actually finishes the job they were hired to do.

Solar-Ready Roofing: Plan for the Future While You Fix the Present

If your roof needs to be replaced — whether it was done wrong the first time or it’s simply reached end of life — this is the best moment to also plan for solar.

Why Roof Condition Matters for Solar

Solar panels are mounted directly to your roof structure. If your roof needs to be replaced within the next five to ten years, you’ll have to remove and reinstall the panels to do it — which adds significant cost. Installing a new, solar-ready roof now eliminates that problem entirely.

One Investment, Maximum Long-Term Value

A solar-ready roof installation pairs the structural upgrade of a new roof with the infrastructure needed for solar panels. For California homeowners facing high utility costs, this combination offers some of the strongest long-term ROI available in home improvement.

Protect Your Home — Before the Next Rain Hits

A bad roof flashing job isn’t just a cosmetic problem. It’s an open invitation for water, mold, and structural damage that gets more expensive the longer it sits.

If your new roof is already leaking — or you’re not confident the job was done right — don’t wait for the damage to show up on your ceiling. Get a second opinion from a licensed, accountable contractor who will tell you exactly what was done wrong and what it takes to fix it properly.

US Power serves California homeowners with CSLB-licensed crews, premium materials, and a Limited Lifetime Warranty. We offer free inspections with no obligation, transparent pricing, and a process built around accountability — not excuses.

Your roof is your home’s first line of defense. Make sure someone actually treated it that way.

Frequently Asked Questions About Roof Flashing and Bad Installations

Can a roofer reuse old flashing on a new roof?

In some cases, yes — if the existing flashing is in genuinely good condition and properly integrated with the new system. However, reusing flashing that is visibly damaged, corroded, or full of holes is never acceptable on a full replacement. Always ask your contractor in writing what flashing will and won’t be replaced.

What should I do if my brand-new roof is already leaking?

Document everything immediately with photos and dates. Do not make your final payment if the defects haven’t been corrected. Contact a CSLB-licensed contractor for an independent inspection and consult the Contractors State License Board if the original contractor refuses to address the issue.

Does bad flashing void my roofing warranty?

It can. Manufacturer warranties like GAF’s require that the full roofing system be installed to their specifications. If old, damaged, or improperly installed flashing causes a leak, the manufacturer may deny the claim on the basis that the system wasn’t compliant.

How long does a properly installed roof last in California?

A quality asphalt shingle roof installed correctly in California typically lasts 25 to 30 years. California’s UV exposure and heat accelerate wear, which is why proper underlayment, ventilation, and flashing installation matter even more here than in cooler climates.

How do I find a licensed roofing contractor in California?

You can verify any contractor’s license status through the CSLB (Contractors State License Board) at cslb.ca.gov. Always ask for proof of licensing and insurance before signing a contract, and get at least two to three written estimates before making a decision.