Commercial Roofing Questions in Florence

A commercial roof is the roof system on a business, industrial, institutional or farm building, and around Florence most fall into two families: low-slope membrane roofs and metal panel roofs. Low-slope roofs move water to interior drains, scuppers or gutters through a slight pitch. Metal roofs shed water down the panel ribs to an eave gutter.

Both families share the same layers in some form:

• Structural deck of steel, concrete or wood
• Insulation boards and, on many roofs, a cover board
• Waterproofing, either a membrane or metal panels
• Flashing at walls, curbs and penetrations
• Edge metal, gutters or parapet caps along the perimeter

TPO, EPDM and metal cover most commercial buildings around Boone County, with PVC and modified bitumen filling specific needs. Single-ply membranes such as TPO and EPDM fit flat and low-slope roofs on warehouses, retail and offices. Standing seam and R-panel metal fit pitched roofs on shops, barns and plants.

PVC shows up where grease or chemicals reach the roof, such as around restaurant exhaust fans. Modified bitumen appears on older low-slope roofs and small additions. The choice follows slope, drainage, rooftop traffic and what happens inside the building. A roof crowded with RTUs and service paths needs a membrane and walkway pads that handle boots and tools.

Replacement makes sense when the insulation underneath is wet across large areas, the membrane or panels are failing in many places at once, or repairs chase new leaks every season. One leak at a curb is a repair. Leaks at seams, drains, walls and penetrations all at once point to a worn-out system.

Signs that move a roof toward replacement:

• Soft, spongy spots underfoot from saturated insulation
• Shrinking membrane pulling flashing away from parapet walls
• Rust-through on metal panels along eaves and end laps
• Patches stacked over patches at the same seams

An infrared or core moisture survey shows how much wet insulation sits under the membrane.

Before any new roofing goes on, the inspection checks the deck, insulation, membrane or panels, and every detail where water can enter. Crews walk the field, take a few cores, and photograph drains, scuppers, curbs, parapet caps and edge metal.

Inside, they look at the underside of the deck for rust, rot or stains. They also measure slope toward drains, count RTUs, pipes and skylights, and note where hatches, ladders or a lift can reach the roof. Those notes set the roof assembly, the tear-off or recover decision, and the order of work.

TPO is a white single-ply thermoplastic membrane, rolled out in wide sheets and joined with hot-air welded seams, used on flat and low-slope commercial roofs. Installers lay insulation and often a cover board over the deck, then fasten or glue the sheets over it.

Each sheet overlaps the next, and a robotic welder fuses the lap into one piece. Hand welders finish corners, pipe boots and curb flashing around RTUs. The membrane turns up parapet walls and ends at a termination bar or edge metal, so the whole roof becomes one welded surface.

All three are single-ply membranes, and they differ mainly in seam method, color and resistance to grease and chemicals.

For a Florence warehouse with a clean roof and few exhaust fans, TPO is a common fit. Restaurants and plants with oily exhaust lean toward PVC around those curbs.

Attachment method follows the deck type, wind exposure and building height, and each method holds the TPO sheet down in a different way.

Ballast is rare on TPO. The roof's wind design, set by the building code and the manufacturer's tested system, decides fastener spacing at corners and the perimeter.

Tapered insulation builds slope into a flat roof so water runs to drains and scuppers instead of ponding in low spots. The boards come cut at a slight pitch and get laid in a pattern that steps up away from each drain.

Crickets, small sloped sections, push water around RTU curbs and away from parapet walls. A tapered layer also adds R-value, which counts when a replacement brings the roof up to current insulation levels. Under TPO, a cover board over the tapered layer adds puncture resistance for foot traffic.

Seams, flashing at curbs and walls, and the membrane around drains need the most attention on a TPO roof once it is in service. Walks in spring and fall catch problems early:

• Probe welded seams for open spots or fishmouths
• Clear drain baskets and scupper boxes of leaves
• Look for punctures along service paths to RTUs
• Check counterflashing and termination bar on parapet walls
• Watch for dirt rings that mark ponding

Walkway pads around equipment protect the white sheet from tools and boots. A log with photos after each storm builds a record for the building file.

EPDM is a synthetic rubber roofing membrane, usually black, sold in large sheets that cover flat and low-slope commercial roofs with few seams. Its stretch handles freeze-thaw movement and building settling well, which fits older masonry buildings, churches, schools and long warehouse roofs.

Sheets come in thicknesses such as 45, 60 and 90 mil, and in reinforced versions for mechanically attached systems. Owners who want a reflective surface can order white-on-black EPDM. Around RTUs and pipe penetrations, installers use pre-formed boots and flashing tape made for EPDM.

Modern EPDM seams use primer and seam tape pressed into the lap with a roller, and seam quality decides how well the roof keeps water out. Older EPDM roofs used liquid splice adhesive, which dries out and lets laps peel with age.

A lasting seam starts with a clean, primed lap and steady roller pressure along its full length. Cover strips go over field seams at edges and over termination bar. Inside and outside corners on curbs get pre-formed pieces instead of folded membrane, since folds leave small channels where water can travel.

Older EPDM pulls away from walls and curbs because the rubber shrinks slowly with age and heat, and that tension stretches the membrane where it turns up a parapet or RTU curb. Roofers call the result bridging, where the sheet spans the corner like a drumhead instead of lying flat.

Bridged flashing tears or pulls its termination bar loose, and water gets behind it. New EPDM installs use securement strips at the base of walls and curbs to anchor the sheet and take that load before it reaches the flashing.

Black EPDM absorbs more sunlight than a white membrane, so the roof surface runs hotter in summer, which matters most on buildings with thin insulation under the deck. In a climate with hot summers and cold winters like Northern Kentucky's, that summer heat gain trades against winter heat loss.

Owners who want a cooler surface choose white-on-black EPDM or a light-colored ballast stone. Insulation thickness under the membrane also shapes comfort and energy use. The Cool Roof Rating Council directory lists tested reflectance values for rated roof products, which helps compare membrane colors.

Tying new EPDM into an older section means cleaning the old rubber down to fresh membrane, priming it, and joining the sheets with seam tape. Weathered EPDM carries chalky oxidation that blocks adhesion until it is scrubbed off.

This comes up on building additions, RTU swaps and partial reroofs where one roof area gets new membrane and the next one stays. Crews set the tie-in high on the slope so water flows over the lap. Where the old section has wet insulation, the tie-in moves back to the nearest dry, solid area.

Industrial roofing covers plants, distribution centers and process buildings, where the roof faces heat, exhaust, chemical fallout, heavy equipment and constant service traffic. A roof over a production line carries fans, ductwork, hoods and pipe racks that a retail roof rarely sees.

The assembly has to match that load. Thicker membranes, high-density cover boards and walkway pads take foot traffic. Resistant membranes go near exhaust that carries oils or chemicals. Large curbs, expansion joints and equipment rails get custom flashing, and work runs in phases around production schedules.

Membranes rated for the specific exhaust hold up near fans and vents, so the first step is identifying what lands on the roof. Grease, oils, solvents and acid mist each attack membranes differently, and manufacturers publish chemical resistance charts for their sheets.

Plants often run one membrane across the field and a resistant membrane or protective pads around each discharge zone. Grease containment boxes at kitchen-style hoods catch drips before they reach the sheet. Exhaust stacks also get taller curbs so condensate drains away from the flashing.

An operating plant gets roofed in small sections that are opened, insulated and sealed before the crew leaves, so each night ends with a watertight roof. Crews plan with plant management around:

• Hot work rules near flammable processes and dust
• Fresh air intakes on RTUs that pull in fumes
• Crane picks timed outside shift changes
• Debris chutes and dumpster spots away from loading docks

Working in sections also limits debris falling through gaps into the space under the work. Temporary tie-ins at the end of each day seal the new roof to the old one at the edge of the work area.

Whether a deck carries new rooftop equipment is a structural question for an engineer, and roofers flag it before new curbs or rails go in. Steel decks on bar joists have set load capacities, and older plants added equipment over decades.

Signs of trouble on the roof surface include ponding around existing units, sagging between joists, and deck rust visible from inside.

Long industrial roofs need expansion joints and area dividers because the structure grows and shrinks with temperature, and a membrane stretched across that movement tears. Buildings hundreds of feet long often have a raised expansion joint curb where the structure is split.

The roof carries that joint with a flexible cover, bellows or a flashed curb high enough to keep water off it. Area dividers break large membrane fields into sections. Drains near joints get extra attention, because the joint can tilt the deck slightly and shift where water collects.

Commercial metal roofs use two main panel types, standing seam and exposed-fastener R-panel (also called PBR), and they differ in how the panels attach and seal.

Each manufacturer sets the slope limit for its panel and seam profile.

Most commercial metal roofs use 24-gauge or 26-gauge steel, with heavier 24-gauge common on standing seam and 26-gauge on many R-panel buildings. Finish matters as much as thickness. Galvalume steel carries an aluminum-zinc alloy layer that resists rust, and painted panels add a factory finish over it.

PVDF paints hold color longer than SMP paints, and SMP costs less. Barns and animal buildings with ammonia exposure need a finish the manufacturer approves for that use. Ridge cap, eave trim and gutters should match the panel finish so they age together.

Retrofit framing lets a new metal roof go over an existing flat roof by building light-gauge steel purlins and sub-framing that create slope above the old membrane. The framing bears on the existing structure at columns or bearing walls.

Panels then shed water to new gutters, which can retire interior drains that leaked for years. An engineer checks the added load first. Ventilation in the space between old and new roofs keeps moisture from condensing on the old deck. Existing RTUs get raised curbs or move to new curbs set through the metal.

Most leaks on an existing commercial metal roof are repaired by replacing the small parts that seal it, while the panels stay in place. The crew finds the failed detail, fixes it, and checks the matching details nearby.

On older Florence warehouses and shops, matching a discontinued panel profile can take a sample piece sent to the supplier.

A commercial metal roof stays watertight with a walk-through each spring and fall and after any hail or high wind. Each visit looks at the parts that move or wear.

• Fastener rows near the eave, ridge and end laps, checked for loose or rusted screws.
• Gutters, valleys and downspouts, cleared of leaves and grit that hold water against the steel.
• Curbs, pipe boots and vents, with cracked sealant renewed.
• Trim, closures and ridge cap, refastened where wind has lifted them.
• Panel surfaces, scanned for scratches and rust spots to touch up before they spread.

A dated photo log from each visit shows which spots keep needing work, which helps Boone County owners plan repairs before winter.