When it's time to replace a commercial roof, property owners often begin by asking which roofing material is best.

Should we install TPO? EPDM? PVC? Modified Bitumen?

Those are important questions, but choosing a commercial roof involves more than choosing a membrane.

The existing roof, roof deck, insulation requirements, attachment method, building use, rooftop conditions, drainage, and budget can all influence which roofing system makes sense.

In fact, more than one roofing system may perform well on the same building. The real decision is often finding the right balance between building conditions, performance, and what the property owner is prepared to invest.

Here's what commercial property owners should understand about the most common options.

TPO Roofing

TPO, or thermoplastic polyolefin, is one of the most commonly installed single-ply commercial roofing membranes today.

TPO membranes are reinforced, and adjoining sheets are joined using hot-air welded seams. White TPO also provides a highly reflective roof surface, although the actual energy performance of a building depends on the complete roof assembly, insulation, building construction, and operating conditions.

One reason TPO has become so common is versatility. Depending on the roof design and building conditions, TPO systems can be mechanically attached or fully adhered.

In today's market, mechanically attached TPO is often one of the more economical single-ply options B&D encounters, making it attractive to property owners trying to balance performance with initial project cost.



TPO can be used for new construction, reroofing, and specialized applications such as single-ply retrofits over qualifying commercial metal roofs.

But even when TPO is the preferred membrane, that doesn't automatically tell us how it should be installed.

EPDM Roofing

EPDM is a synthetic rubber roofing membrane with a long history in commercial roofing.

Unlike TPO and PVC, EPDM seams aren't heat-welded. They are joined using adhesives, tapes, primers, and other components specified for the roofing system.

EPDM can be installed in several ways, including fully adhered, mechanically attached, and ballasted assemblies.

A fully adhered EPDM system can be considerably more expensive than some mechanically attached alternatives, but initial price isn't the only consideration when choosing a roofing assembly.

The existing building may make one attachment method more appropriate than another.



And sometimes an existing EPDM roof is already giving the owner a clue about what may work well on that building.

Don't Overlook a Good Ballasted Roof

Ballasted EPDM roofs are common on many older commercial buildings in our area.

In a ballasted system, the membrane is covered with stone ballast that helps hold the roofing system in place. The simplicity of the concept is one of its strengths, and properly designed ballasted EPDM systems can provide excellent service.

They do have their quirks. The stone can make locating and accessing the source of a leak more challenging when repairs are necessary.

But an aging ballasted roof shouldn't automatically be converted to a completely different roofing system simply because another membrane is more familiar today.

If the existing roof assembly remains suitable, replacement may involve temporarily moving the ballast, replacing the membrane and other components as required, and reinstalling the ballast.



Sometimes the building already has a roofing system worth keeping.

PVC Roofing

PVC, or polyvinyl chloride, is another thermoplastic single-ply roofing membrane.

Like TPO, PVC membrane sheets have heat-welded seams. One of PVC's distinguishing characteristics is its resistance to certain chemicals, oils, and grease, which can make it particularly useful for buildings where the roof may be exposed to those materials.

Commercial kitchens and some industrial facilities are examples where those conditions may influence the roofing decision.

That doesn't mean every restaurant or industrial building automatically needs PVC. The type and amount of exposure, existing roof construction, attachment requirements, and other project conditions still need to be considered.



PVC can be an excellent solution when its particular characteristics solve a problem the building actually has.

Modified Bitumen Roofing

Modified Bitumen, often shortened to Mod Bit, is an asphalt-based commercial roofing material reinforced and modified to improve performance.

Unlike single-ply TPO, EPDM, and PVC systems, Modified Bitumen systems may incorporate multiple layers and are available with different application methods depending on the specified system.

Mod Bit can be particularly useful on certain existing asphalt-based roofs, roofs with numerous details, and projects where the characteristics of a multi-layer asphalt-based system make sense.



As with the other systems, the decision shouldn't be based solely on the name of the material. The existing roof and the way the new system will be constructed matter just as much.

The Membrane Is Only Part of the Roof

This is where commercial roofing can become confusing for property owners.

Two contractors may both propose a TPO roof, but that doesn't necessarily mean they're proposing the same roofing assembly.

The roof may include:

• Existing or new insulation
• Additional insulation to achieve a specified R-value
• Cover board
• Vapor or air-control components where required
• The roofing membrane
• Flashings and penetration details
• Perimeter and edge components
• A specific attachment method

Even the same membrane can be installed differently depending on the building.



That's why comparing commercial roofing proposals based only on price per square foot or membrane type can be misleading.

Mechanically Attached, Fully Adhered or Ballasted?

How a commercial roof is secured to the building can be just as important as the membrane selected.

Mechanically Attached

A mechanically attached roofing system uses specified fasteners and plates to secure components of the roofing assembly to the roof deck or supporting structure.

These systems can provide an economical and effective solution for many commercial buildings.

But mechanically attached doesn't work everywhere.

For example, some buildings have electrical conduit or other sensitive components located directly beneath the roof deck. Driving roofing fasteners through the deck in those conditions can create unnecessary risk.



That may take an otherwise attractive mechanically attached option off the table.

Fully Adhered

In a fully adhered system, the membrane is bonded to an approved substrate rather than relying on rows of field fasteners through the membrane to secure it.



A fully adhered assembly may cost more, but it can make sense when the building's construction or other project requirements make mechanical attachment undesirable.

Ballasted

On suitable buildings, a ballasted roofing system provides another approach.

Instead of relying on field fasteners or adhering the entire membrane, ballast helps secure the roofing system in place.



The building must be suitable for the system, including the additional weight involved. Ballasted roofs aren't appropriate for every structure, but where they make sense, they shouldn't be dismissed simply because they're an older or less frequently discussed approach.

Why Can Commercial Roofing Prices Vary So Much?

The membrane is only one part of the price.

Commercial roof costs can vary substantially depending on:

• Existing roof conditions
• Tear-off requirements
• Type and amount of insulation
• Cover board requirements
• Membrane selected
• Mechanically attached, adhered, or ballasted construction
• Roof size and configuration
• Penetrations and rooftop equipment
• Perimeter and flashing requirements
• Manufacturer specifications and warranty requirements
• Labor required to install the complete assembly

This is also where budget becomes part of the conversation.

There may be several technically appropriate ways to reroof a building, but they may not cost the same.

A property owner may decide that a more economical roofing assembly better fits the property's needs and budget.

Another owner may decide that spending more for a different assembly makes sense for the way the building will be used or how long they expect to own it.

Neither decision is automatically wrong.

Is the Most Expensive Roof Always the Best Roof?

No.



A more expensive roofing system may provide characteristics or construction that are valuable for a particular building, but paying more doesn't automatically make it the right choice.

Is the Cheapest Roof Always the Best Value?

Also no.

A lower initial price doesn't necessarily mean two roofing systems provide the same assembly, attachment method, insulation, performance characteristics, or long-term value.

That's why B&D doesn't believe commercial roofing decisions should begin and end with the lowest number on a proposal.



The goal is to understand what you're buying and why that particular roofing assembly is being recommended for your building.

So Which Commercial Roofing System Is Right for Your Building?

There isn't one answer that applies to every commercial property.

TPO may provide an excellent balance of performance and cost for one building. EPDM may make sense for another.

PVC may solve a particular exposure problem. Modified Bitumen may be appropriate for an existing roof or building configuration where its characteristics are beneficial.

And sometimes the membrane the building already has is worth keeping when it's time to reroof.

The decision should consider the existing roof, roof deck, what's beneath the deck, insulation, attachment options, drainage, building use, budget, and the owner's long-term plans for the property.



Choosing the right commercial roof isn't about finding the roofing material with the best marketing claims. It's about designing the appropriate roofing assembly for the building—and for the owner who has to pay for it.

The B&D Promise

We believe commercial property owners deserve honest recommendations—not sales pressure.

Our job is to evaluate the existing roof and building conditions, explain the available roofing systems and how they differ, and help the property owner understand the tradeoffs between performance, construction, and cost.

Sometimes the appropriate solution is mechanically attached TPO. Sometimes a fully adhered or ballasted system makes more sense. And sometimes the roof already on the building tells us a great deal about what should replace it.



Whatever the recommendation, we'll explain the reasons behind it and tell you what we would recommend if it were our own building.