Exposed Fastener Metal Roof Problems: Leaks, Repairs & Solutions

Metal roofs have a reputation for lasting a long time. And they can.

But if your commercial building has an exposed fastener metal roof, the metal panels themselves may not be the first thing to give you trouble.

The screws are.

An exposed fastener system uses screws installed directly through the metal panels to secure them to the building. Each of those screws creates a penetration through the roof and relies on a small sealing washer to keep water out.

One screw isn’t much of a concern. Hundreds or thousands of them across a commercial roof are a different story.

As the roof ages, screws can loosen, washers can deteriorate, holes can enlarge, seams can open, and flashing can fail. Add Michigan’s temperature swings, snow, ice, and freeze-thaw cycles, and an older metal roof can quickly turn into a frustrating game of “where is that leak coming from now?“

Springfield Roofing has worked on commercial roofs throughout Northern and Central Michigan for more than 40 years. Here’s what building owners should know about exposed fastener metal roofs, why they leak, and what can be done about them.

What Is an Exposed Fastener Metal Roof?

An exposed fastener metal roof uses metal panels that are attached directly to the building’s roof structure with screws driven through the face of the panels.

You’ll commonly find these systems on:

• Warehouses
• Manufacturing facilities
• Agricultural buildings
• Storage buildings
• Shops
• Pre-engineered metal buildings
• Older commercial and industrial facilities

Look at the roof and you’ll usually see rows of screw heads running across the metal panels. That’s where the name comes from. The fasteners are literally exposed to the elements.

Each roofing screw typically includes a rubber sealing washer beneath the head. When properly installed, that washer compresses against the metal panel to create a watertight seal around the penetration.

It’s a simple and effective design.

It also means the roof has a lot of potential maintenance points.

Why Do Exposed Fastener Metal Roofs Leak?

One of the most common problems with exposed fastener roofs is also the most obvious:

Every screw penetrates the waterproofing surface.

The fastener and washer have to remain properly seated and sealed while the roof is exposed to years of sunlight, rain, snow, wind, temperature changes, and movement.

Meanwhile, the metal panels themselves are expanding and contracting as temperatures change.

Over time, that combination can cause fasteners to back out, washers to deteriorate, and fastener holes to become enlarged.

Once the seal around a screw fails, water has a direct path through the roof.

And remember, we’re not talking about one screw.

We’re talking about an entire roof full of them.

Common Exposed Fastener Metal Roof Problems

Leaks around screws are certainly common, but they aren’t the only problems we look for when inspecting an aging metal roof.

Loose or Backed-Out Screws

Metal expands when it gets hot and contracts when it gets cold.

On an exposed fastener roof, the panels are secured directly through their surface. Years of expansion, contraction, building movement, vibration, and wind can place stress on those attachment points.

Eventually, some screws may begin backing out.

Even a slightly raised screw can reduce the compression of the sealing washer underneath it.

Once that seal is compromised, water may begin entering around the fastener.

A handful of loose screws may be a relatively straightforward maintenance issue.

Loose fasteners throughout an entire roof are a sign that the overall fastening system needs closer attention.

Deteriorated Fastener Washers

The washer underneath a roofing screw has a pretty important job for such a small piece of material.

It’s the primary seal around the hole created by the fastener.

Those washers spend their entire lives exposed to weather, UV radiation, heat, cold, and movement. Over time, the sealing material can harden, crack, shrink, deform, or lose the compression needed to maintain a watertight seal.

The screw may still appear to be in place while the washer beneath it is no longer doing its job.

This is one reason a metal roof can begin developing seemingly random leaks even though the panels themselves still look relatively good.

Overdriven or Underdriven Fasteners

Sometimes the problem starts during installation.

A roofing screw needs to be driven correctly for the sealing washer to work as intended.

An overdriven fastener can crush or distort the washer, potentially damaging the seal.

An underdriven fastener may not compress the washer enough to create an adequate seal.

Fasteners installed at an angle can create another problem because the washer may not sit evenly against the metal panel.

Multiply an installation problem by hundreds or thousands of fasteners and what seems like a small detail can become a much larger roofing problem.

Enlarged Fastener Holes

The screw isn’t the only thing that can move.

As metal panels repeatedly expand and contract, movement around a fastener can gradually affect the hole through the panel.

In some situations, the original hole may become elongated or enlarged.

Now simply tightening the existing screw may not solve the problem. The fastener may no longer have the holding power or sealing surface it originally had.

This is why “just tighten the screws” isn’t always a complete metal roof repair strategy.

Rust and Corrosion

Metal roofing is designed with protective finishes to resist corrosion, but damage, age, standing moisture, incompatible materials, and deterioration of those protective surfaces can eventually allow corrosion to develop.

We pay particular attention to rust around:

• Fasteners
• Panel edges
• Scratches or damaged coatings
• End laps
• Roof penetrations
• Areas that hold moisture
• Previous repairs

Surface rust and a panel that has rusted through are two very different problems.

The extent of corrosion matters when determining whether the roof can be repaired, restored, or needs more extensive work.

Open Seams and Panel Laps

Exposed fasteners aren’t the only place water can enter a metal roof.

Metal panels overlap at seams and end laps, and those areas also have to remain watertight.

As the roof moves and ages, sealants can deteriorate and laps can become vulnerable to water intrusion.

Wind-driven rain can make these conditions even more problematic.

If a metal roof is leaking, we don’t just look at the nearest screw. We look at the complete roof assembly.

Flashing Around HVAC Units and Penetrations

HVAC equipment, pipes, vents, curbs, walls, and other penetrations are common trouble spots on almost any commercial roof.

Metal roofs are no exception.

These areas combine different materials, angles, fasteners, sealants, and components that may move differently as temperatures change.

Over time, flashing can separate, sealants can deteriorate, and previous repairs can begin failing.

Repeatedly adding another layer of caulk or roofing mastic over a failing detail isn’t necessarily fixing the underlying problem.

Eventually, you’re just putting a new repair on top of the old repair.

And then another one on top of that.

Failed Sealants

Sealant is an important part of many metal roofing details, but it shouldn’t be expected to compensate indefinitely for movement, poor flashing, loose fasteners, or deteriorated roofing components.

We often find older roofs where a problem area has been coated with layer after layer of sealant.

That may stop a leak temporarily.

But if the metal underneath continues moving or the original detail is failing, the problem often comes back.

A good metal roof repair should address why the area is leaking, not simply cover the evidence.

Damage From Snow and Ice

Northern and Central Michigan aren’t exactly known for gentle winters.

Snow accumulation and ice can place additional stress on an aging metal roofing system.

Problems can become especially noticeable around:

• Eaves
• Gutters
• Valleys
• Roof transitions
• Snow retention systems
• Areas where heat loss contributes to melting and refreezing

Ice buildup can damage roof edges, gutters, fasteners, and other components.

Attempts to physically remove heavy ice can cause even more damage if the roofing panels or protective coatings are struck or scraped in the process.

Condensation That Looks Like a Roof Leak

Not every drip inside a metal building is coming through a hole in the roof.

Sometimes the problem is condensation.

Warm, moisture-containing indoor air can come into contact with colder metal surfaces. Under the right conditions, moisture condenses on the underside of the metal roof and can drip into the building.

That can look a lot like a roof leak.

Insulation, ventilation, air sealing, indoor humidity, and the building’s use can all influence condensation.

This is why identifying the actual source of water matters before making repairs.

Otherwise, you can spend a lot of money fixing a “roof leak” that wasn’t actually coming through the roof.

Why Insulation Matters on a Metal Building

Insulation can affect more than your heating bill.

Inadequate insulation and air leakage can contribute to uneven roof temperatures during winter. Heat escaping through the roof can melt accumulated snow.

That water then travels toward colder areas of the roof, where it can refreeze.

Repeated melting and freezing can contribute to ice buildup around eaves and drainage areas.

Improving the roofing system during a major retrofit can provide an opportunity to evaluate insulation and thermal performance at the same time.

For many commercial building owners, that means a roof project can address more than just leaks.

Can an Exposed Fastener Metal Roof Be Repaired?

Yes.

An exposed fastener roof does not automatically need replacement because a few screws are leaking.

Localized problems can often be repaired.

Depending on the condition of the roof, repairs may include:

• Replacing failed fasteners
• Replacing damaged sealing washers
• Addressing oversized fastener holes
• Repairing localized corrosion
• Resealing panel laps
• Repairing flashing
• Replacing damaged panels
• Correcting isolated penetration problems

The important question is whether the problems are isolated or widespread.

If you have several failed screws on an otherwise serviceable roof, repair may make perfect sense.

If fasteners are failing throughout the entire roof, seams are opening, panels are corroding, flashing is deteriorated, and leaks keep appearing in new places, individual repairs may be buying less and less time.

Should You Replace All the Screws on an Older Metal Roof?

Sometimes widespread fastener replacement is appropriate.

But replacing every screw isn’t automatically the answer to every aging exposed fastener roof.

Before recommending it, we want to know:

• Are the existing fasteners actually failing?
• Are the fastener holes still usable?
• What condition are the metal panels in?
• Is corrosion present?
• Are seams and laps failing too?
• What condition is the flashing in?
• Are leaks isolated or widespread?
• Is the roof experiencing excessive movement?
• Are there insulation or condensation problems?
• How much useful service life is left in the rest of the roof?

Replacing thousands of screws doesn’t make much sense if the rest of the roofing system is approaching the end of its serviceable life.

That’s why the roof should be evaluated as a complete system.

Repair, Restore, or Retrofit an Exposed Fastener Metal Roof?

There are several potential approaches to an aging metal roof.

The right one depends on its condition.

There isn’t one solution that makes sense for every building.

And there shouldn’t be.

What Is a Metal Roof Retrofit?

A metal roof retrofit installs a new roofing system over an existing metal roof rather than simply replacing failed screws or continually repairing individual leaks.

For commercial buildings with aging exposed fastener roofs, a retrofit can provide an opportunity to address several problems at once.

Depending on the building and roof design, a retrofit may:

• Eliminate reliance on thousands of aging exposed fasteners as the primary waterproofing
• Cover existing seams and panel laps
• Address recurring leak areas
• Improve insulation
• Create a new continuous waterproofing surface
• Reduce the need for extensive tear-off
• Extend the useful life of the building’s roofing assembly

Springfield Roofing specializes in commercial metal roof retrofit systems using Duro-Last PVC roofing.

Instead of continually chasing individual leak points across an aging metal roof, the retrofit creates a new waterproof roofing system over the existing roof.

How Does a PVC Metal Roof Retrofit Work?

Every building is different, so the exact roof assembly depends on the existing metal roof and building conditions.

Generally, the existing roof is first evaluated to identify damaged panels, structural concerns, wet areas, penetrations, drainage issues, and other conditions that need to be addressed.

Insulation or other materials can then be incorporated into the new roof assembly as appropriate.

A Duro-Last PVC membrane is installed over the prepared roof to create a continuous waterproof surface.

Because PVC seams are heat-welded, the finished membrane no longer depends on thousands of exposed screw washers to serve as the primary waterproofing layer.

For an aging commercial metal roof with widespread fastener problems, that is a major difference.

Can You Put PVC Roofing Over an Existing Metal Roof?

In many cases, yes.

Metal roof retrofit systems are specifically designed to allow an existing metal roof to remain in place when conditions are appropriate.

But that doesn’t mean every metal roof should simply be covered.

Before recommending a retrofit, Springfield Roofing evaluates factors such as:

• Existing metal panel condition
• Structural condition
• Corrosion
• Existing leaks
• Wet insulation or other moisture concerns
• Roof penetrations
• Drainage
• Building use
• Existing insulation
• Attachment requirements
• Applicable building codes
• Manufacturer requirements

Any necessary repairs or preparation should be completed before the new roofing system is installed.

The goal isn’t to hide the old roof.

It’s to use the existing roof as part of a properly designed new roofing assembly when it makes sense to do so.

Metal Roof Problems and Michigan Weather

An exposed fastener roof in Michigan has a lot working against it.

Summer heat causes metal panels to expand.

Winter cold causes them to contract.

Then we add snow, ice, wind, spring rain, freeze-thaw cycles, and the occasional Michigan week where the weather seems to cycle through all four seasons.

That repeated movement matters on a roof where screws penetrate directly through the panels.

Regular inspections can help identify backed-out fasteners, deteriorated washers, failing sealants, damaged flashing, corrosion, and other problems before they become larger leaks.

This is particularly important after winter and severe weather.

Exposed Fastener Metal Roof Repair and Retrofit in Michigan

Springfield Roofing has been working on commercial roofs since 1985.

With locations in Kingsley and Big Rapids, we inspect, repair, maintain, and retrofit commercial metal roofing systems throughout Northern and Central Michigan.

If your exposed fastener metal roof is leaking, we’re not automatically going to tell you to cover the entire thing.

Sometimes a repair is exactly what the roof needs.

But when fasteners are failing throughout the roof, leaks keep returning, and maintenance has turned into an annual game of finding the next problem, it may be time to look at the bigger picture.

We’ll inspect the existing roof and help determine whether repair, restoration, or a complete metal roof retrofit makes the most sense for your building.