Can a metal roof be repaired, or does it need to be replaced?

Most metal roofs can be repaired because leaks usually come from fasteners, laps, trim or penetrations rather than the panels. Replacement becomes the better choice when panels are rusted through or have lost strength across large areas. In between, a restoration coating system can treat widespread fastener and seam problems and coat the whole field.

Why does my metal roof leak at the screws?

On exposed fastener roofs, screws pin each panel to the structure, so daily expansion and contraction works on the fastener. Over time washers degrade and holes can enlarge, especially on long panels. The usual repair is to remove the old fastener, seal the hole and install an oversize fastener with a new washer, as McElroy Metal describes.

Is caulking a metal roof leak a good repair?

Generally no. McElroy Metal warns against fixing leaks by applying caulk over joints because surface sealants lose adhesion, trap water and cause corrosion. A lasting repair opens the joint, cleans it, reinstalls the correct sealant and re-fastens it. Caulk may be a short-term emergency measure, not a permanent fix.

Does salt air from Galveston Bay affect metal roofs?

It can. Panel makers set separate guidance for marine environments. MBCI's bulletin, for example, lists Galvalume guideline distances such as 800 feet from the coastline of a large saltwater bay, and says site conditions vary. Buildings near the bay should be inspected for corrosion at laps, fasteners and panel undersides.

Can you coat a metal roof instead of replacing it?

Often, if the panels are structurally sound. GAF's metal restoration process cleans and tests the roof, primes rust, seals seams and fasteners, details penetrations and then coats the field. GAF lists limited warranty or guarantee terms of 10, 15 or 20 years depending on the specification, with eligibility set by GAF.

Do you repair metal roofs you did not install?

Yes. Mammoth Services repairs standing seam and exposed fastener metal roofs whether or not Mammoth installed them. Each visit ends with photos and written findings you can keep for your records. To schedule an assessment, use our contact page or call (832) 416-1566.

Metal Roof Repair · Houston, Texas

Metal Roof Repair in Houston

Most commercial metal roofs that leak can be repaired. The trick is finding the real failure point, fixing it with methods the panel maker supports, and knowing when a restoration coating makes more sense than chasing one more leak. This guide covers both standing seam and exposed fastener roofs across Houston and the Bay Area.

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The short answer

Metal Roof Repair: what Houston owners should know.

Yes, a metal roof can usually be repaired. Most leaks on commercial metal roofs come from a short list of details: loose or stripped fasteners and worn washers, open side and end laps, failed ridge, rake and trim flashing, penetrations and skylights, and rust where water sits or dissimilar metals drain onto the panels. Repairs replace or reseat the failed part rather than smearing sealant over it.

Mammoth Services repairs standing seam and exposed fastener metal roofs in Houston and the Bay Area, including roofs it did not install, and provides written findings with photos. When a roof has widespread fastener or rust problems, it can price a restoration coating as an option. Call (832) 416-1566.

Repair or not

Can a metal roof be repaired?

Usually, yes. Metal panels are durable; the details around them are what wear out.

A metal roof is a system of panels, fasteners, sealants, closures, trim and flashings. The panels themselves often outlast everything attached to them. That is why most metal roof leaks are repairable: the failure is a washer, a lap sealant, a trim piece or a curb, not the steel.

Repair stops making sense when the problem is the whole field rather than a few details. Widespread rust through the panel, panels that have lost structural strength, or hundreds of failing fasteners at once point toward restoration or replacement. GAF notes that some rust is acceptable for restoration as long as the panels remain strong and intact.

The method matters as much as the decision. Panel maker McElroy Metal warns owners never to let workers fix leaks by smearing caulk over them, because surface sealants lose adhesion, trap water and cause corrosion. A durable repair takes the joint apart or replaces the part, then reinstalls it with the right sealant and fasteners.

Sources: McElroy Metal O&M manual, GAF on roof restoration.

Two roof types

Standing seam vs exposed fastener metal roofs

The roof type changes where leaks start and how repairs are made.

	Standing seam	Exposed fastener (through-fastened)
Attachment	Concealed clips or fastening flange; fasteners do not pierce the panel	Screws with washers driven through the panel into purlins or deck
Thermal movement	Clips allow panels to expand and contract	Fasteners absorb movement; holes can enlarge over time, more often on long panels
Typical leak points	End laps, trim, ridge, penetrations, seam damage	Fasteners and washers, side and end laps, trim, penetrations
Common repair	Rework trim and flashings, re-seal laps, add proper curbs or boots	Replace with oversize fasteners and washers, re-seal laps, replace trim

Sources: McElroy Metal, S-5!.

Where they leak

Common metal roof leaks and how we repair them

These four areas account for most of the metal roof leak calls we investigate.

Fasteners and washers

On exposed fastener roofs, screws pin the panel to the structure. S-5! points out that this gives no thermal relief, so the fastener takes the movement. Washers age and holes can slot. McElroy's fix: remove the old fastener, fill the hole with butyl sealant and install an oversize, long-life fastener.

Check for loose, stripped or backed-out screws
Replace, do not overdrive
Address every fastener in the leak zone, not one

Side laps and end laps

Where panels overlap, sealant tape and stitch screws keep water out. Once the sealant fails, wind-driven rain gets in. The repair is to open the lap, clean it, reinstall sealant and re-fasten.

End laps on low slopes are high risk
Watch for rust lines below laps

Ridge, rake and trim

Trim and flashings are thin and exposed to uplift. McElroy specifically calls for checking flashings and trim for looseness, damage and punctures after high winds or hail. Loose trim is replaced or re-secured, and missing closures are reinstalled.

Ridge caps and closures
Eave and rake trim
Gutters and their attachment

Penetrations, curbs and skylights

Pipes, vents, units and skylights interrupt the panel's drainage path. Water builds up on the upslope side of curbs, and McElroy lists those areas for ponding checks. Repairs re-flash with boots, curbs or diverters suited to the panel profile.

Upslope side of every curb
Skylight frames and plastic panels
Abandoned penetrations

Sources: McElroy Metal O&M manual, S-5!.

Gulf climate

Heat, humidity and salt: why Houston metal roofs corrode

Houston's climate puts metal roofs through heat cycles and moisture year round. Near the bay, salt adds a third stress.

Heat and movement

NWS 1991-2020 normals put the August normal high at Houston Hobby at 93.5°F. Panels expand in afternoon sun and contract when a storm cools them, every day of the season. On through-fastened roofs that repeated movement works directly on fasteners and washers.

Salt exposure near the bay

Panel makers treat salt as a separate risk. MBCI's marine environment bulletin lists Galvalume guideline distances of 1,500 feet from coastline with surf, 800 feet from a large saltwater bay and 400 feet from saltwater marshes or canals, and says no single safe distance applies everywhere. Buildings on Clear Lake, Galveston Bay and the bayous should be checked for underside and lap corrosion, not just the top surface.

Corrosion you can prevent

McElroy lists causes that are often within the owner's control: copper or lead contacting or draining onto panels, AC condensate carrying copper ions, metal shavings and debris left by other trades, treated wood, and water trapped by ponding or failed surface repairs. Routing condensate lines and clearing debris costs far less than replacing panels. The Metal Construction Association also advises checking with the panel manufacturer before any new metal is added in contact with the roof.

Sources: NWS Houston, Hobby August normals, MBCI marine environment bulletin, McElroy Metal.

Restore

Restoration coatings for metal roofs

When fastener and lap problems are spread across the whole roof, a restoration coating system can address the details and the field in one project.

Qualify and prepare
The roof must be structurally sound, clean and tight. GAF's metal restoration steps call for an adhesion test, repairs and power washing first.
Prime rust
Rusted areas are treated with a rust-inhibiting primer, such as GAF Metal Roof Primer, after loose rust is removed.
Seal seams and fasteners
Ridges, rake edges, laps and fasteners are reinforced with brush-grade flashing and fabric, such as GAF Premium Brush-Grade Acrylic Flashing with GAF Premium Fabric.
Detail penetrations
Curbs, penetrations and drains get the same flashing and fabric treatment before the field is coated.
Coat the field
GAF's Premium HydroStop metal system applies two coats of GAF Premium Acrylic HydroStop Top Coat. GAF also lists a silicone over metal system. GAF states limited warranty or guarantee terms of 10, 15 or 20 years depending on specification; eligibility and coverage are set by GAF and depend on the system and project.

Source: GAF Premium Acrylic HydroStop over metal, 5 step info sheet. See also commercial roof coating in Houston.

The visit

What a metal roof repair visit includes

A repair is only as good as the diagnosis. Every visit follows the same order.

Leak history first

Where and when it leaks, during which rain and wind direction. Wind-driven leaks at laps behave differently from steady leaks at a curb.

Inside and outside

We trace stains and drips from below, then work upslope on the roof, because water often enters well above where it shows.

Source repair

Fix the failed component with compatible materials: fasteners, sealant tape, trim, closures or flashings, not surface caulk.

Surrounding check

Inspect fasteners, laps and trim near the repair, plus gutters and debris that could cause the next leak.

Written findings

You receive photos and written findings: what failed, what we did, and what still needs attention, ready for your records or capital plan.

Service area

Metal roof repair across Houston and the Bay Area

Metal roofs show up on warehouses, plants, churches and retail across the region. Exposure and use change what fails first.

Houston, TX

Pre-engineered metal buildings fill the city's warehouse and light industrial districts, and long through-fastened panels are where fastener slotting shows up first. Commercial roofing in Houston.

Webster, TX

Metal canopies, retail buildings and service shops along the I-45 and NASA Parkway corridor often leak at trim and penetrations added after the original build. Webster commercial roofing.

Clear Lake, Houston

Technical and office campuses near the NASA Johnson Space Center include metal roofs on support buildings, where rooftop equipment changes create new curbs and flashing points. Clear Lake commercial roofing.

Nassau Bay, TX

With Clear Lake on one side, metal roofs here sit close enough to brackish water that lap and fastener corrosion deserves a close look at every inspection. Nassau Bay commercial roofing.

Seabrook, TX

Marinas, boat storage and waterfront businesses on Galveston Bay put metal right in the salt air, so trim, fasteners and panel undersides need checking for corrosion. Seabrook commercial roofing.

League City, TX

Churches, schools and retail buildings with metal roofs face both bay storms and heavy afternoon rain, which expose open end laps and failing ridge closures. League City commercial roofing.

La Marque, TX

Industrial and agricultural metal buildings here tend to be through-fastened, so fastener replacement and lap resealing are the most common repairs. La Marque commercial roofing.

Dickinson, TX

Shops and storage buildings near Dickinson Bayou and Galveston Bay see moisture and salt together; condensate lines and debris should be cleared off panels to slow rust. Dickinson commercial roofing.

Santa Fe, TX

Metal barns, shops and church buildings are common, and many are older exposed fastener roofs that are good candidates for a metal restoration coating. Santa Fe commercial roofing.

Pasadena, TX

Plant buildings and warehouses near the Houston Ship Channel can face chemical exposure and heavy foot traffic from equipment crews, both of which damage panel finishes. Pasadena industrial roofing.

Questions

Metal Roof Repair: direct answers.

If your question is not here, call Mammoth Services at (832) 416-1566.

01
Can a metal roof be repaired, or does it need to be replaced?
Most metal roofs can be repaired because leaks usually come from fasteners, laps, trim or penetrations rather than the panels. Replacement becomes the better choice when panels are rusted through or have lost strength across large areas. In between, a restoration coating system can treat widespread fastener and seam problems and coat the whole field.
02
Why does my metal roof leak at the screws?
On exposed fastener roofs, screws pin each panel to the structure, so daily expansion and contraction works on the fastener. Over time washers degrade and holes can enlarge, especially on long panels. The usual repair is to remove the old fastener, seal the hole and install an oversize fastener with a new washer, as McElroy Metal describes.
03
Is caulking a metal roof leak a good repair?
Generally no. McElroy Metal warns against fixing leaks by applying caulk over joints because surface sealants lose adhesion, trap water and cause corrosion. A lasting repair opens the joint, cleans it, reinstalls the correct sealant and re-fastens it. Caulk may be a short-term emergency measure, not a permanent fix.
04
Does salt air from Galveston Bay affect metal roofs?
It can. Panel makers set separate guidance for marine environments. MBCI's bulletin, for example, lists Galvalume guideline distances such as 800 feet from the coastline of a large saltwater bay, and says site conditions vary. Buildings near the bay should be inspected for corrosion at laps, fasteners and panel undersides.
05
Can you coat a metal roof instead of replacing it?
Often, if the panels are structurally sound. GAF's metal restoration process cleans and tests the roof, primes rust, seals seams and fasteners, details penetrations and then coats the field. GAF lists limited warranty or guarantee terms of 10, 15 or 20 years depending on the specification, with eligibility set by GAF.
06
Do you repair metal roofs you did not install?
Yes. Mammoth Services repairs standing seam and exposed fastener metal roofs whether or not Mammoth installed them. Each visit ends with photos and written findings you can keep for your records. To schedule an assessment, use our contact page or call (832) 416-1566.

Sources

This page is general information for commercial property owners, not legal, insurance or engineering advice. Warranty eligibility and terms are set by the manufacturer.

Commercial Roof Coating Storm and Hail Damage Roof Asset Management Commercial roofing services Roof management with Roof React

Next step

Talk to Mammoth about your roof.

Call Mammoth Services at (832) 416-1566, or book a roof assessment and tell us about your building. For planned work, book a roof assessment call.