Commercial Roofing Questions in Radcliff

From the deck up, a commercial roofing contractor builds the whole roof on buildings such as warehouses, offices, plants, churches, schools and farm buildings. On a flat or low-slope roof that means insulation, cover board, a single-ply membrane, flashing at every curb and wall, and edge metal. On a sloped metal building it means panels, trim, closures and gutters.

A new roof covers these pieces.

• Insulation boards and tapered insulation that carry water to drains and scuppers.
• Membrane or metal panels across the field.
• Flashing at parapets, rooftop unit (RTU) curbs, pipes and skylights.
• Edge metal, coping caps and gutters that finish the perimeter.

Each layer has a job, and leaks start most often where two of them meet.

TPO, EPDM and PVC single-ply membranes cover most flat and low-slope commercial roofs, and each handles heat, grease and seam work in its own way.

The roof walk settles the choice, based on what sits on the roof, what vents onto it, and how water leaves it through drains and scuppers.

A low-slope commercial roof is a stack of layers on a steel, wood or concrete deck, and each layer handles one threat. Water, heat and foot traffic attack different parts of the stack.

Vapor retarders matter most over cold-storage rooms, pools and humid plants. A soft spot in the membrane over wet insulation shows that water has been moving through the stack for a while.

Roof slope sets the first boundary, since single-ply membranes are made for flat and low-slope roofs and metal panels need enough pitch to shed water past their laps. Standing seam panels handle lower slopes than exposed-fastener R-panel, because their raised seams sit above the water running down the pan.

• Flat roofs with parapets and interior drains take TPO, EPDM or PVC.
• Pitched roofs on metal buildings, barns and churches take standing seam or R-panel.
• Retrofit framing can turn a flat roof with chronic ponding into a sloped metal roof.

Panel makers publish a minimum slope for each profile, and the installer checks that figure at every roof plane.

TPO fits warehouses, distribution buildings, retail strips, offices and schools with open roof areas and modest rooftop equipment. Its white surface reflects sunlight and keeps the membrane cooler in summer.

Restaurants and plants that vent grease through roof fans often get PVC or a protection layer around those curbs, since animal fats break down some membranes over time.

Mechanical fasteners, full adhesive, or induction-welded plates hold TPO to the deck, and the deck type, wind exposure and building use decide which one fits.

Wind pulls hardest at corners and perimeters, so fastener rows run closer together along parapets and edge metal than in the middle of the field.

Hot-air welders join TPO seams, with a walk-behind unit in the field and a hand welder at corners, curbs and flashing, and every seam gets probed along its full length.

1. Clean the lap with membrane cleaner so dust and film come off.
2. Run a test weld and pull it apart by hand to set heat and speed.
3. Weld the lap at the width the manufacturer specifies.
4. Probe the seam edge with a blunt pick to find gaps.
5. Cover each T-joint, where three sheets meet, with a patch.

When the sheet tears before the seam separates, the test weld passes. Crews repeat test welds as the membrane warms through the day, because surface temperature changes how the welder bonds.

TPO can go over one existing roof when the old membrane and insulation are dry and the deck still holds fasteners, a method called a recover. Wet insulation, a damaged deck, or two roofs already in place push the job to a full tear-off, and the local building official has the final word on code limits.

Recover work on a TPO job follows a set pattern.

• Core cuts or a moisture scan find wet insulation, which gets cut out and replaced.
• A cover board or recovery board goes over the old surface.
• Loose flashing at curbs and walls comes off before new TPO flashing goes up.
• Edge metal and scuppers rise to match the new roof height.

Flashings at curbs, walls, drains and pipes are where most TPO roofs leak, so they get pre-formed corners, welded flashing and termination bars. The open field of membrane is the easy part of the job.

Details to look for on a new TPO roof.

• RTU curbs wrapped with membrane welded to the field and capped with pre-formed corners.
• Parapet walls flashed up the face and finished under a coping cap or counterflashing.
• Drains with the sheet clamped under the drain ring and a tapered sump around the bowl.
• Pipe penetrations sealed with pre-molded boots and stainless clamps.
• Scuppers lined with membrane and set in sealant at the wall opening.

EPDM is common on older flat roofs, schools, churches, cold-storage buildings and wide warehouse roofs. The rubber shrugs off ultraviolet light and handles freeze-thaw swings at the laps.

Black EPDM absorbs heat, which helps snow clear from the surface and adds summer heat load under the roof. A white-on-black version gives buildings with air conditioning a cooler surface while keeping the same seam and flashing methods.

Primer and seam tape join EPDM seams, pressed with a silicone roller and finished with lap sealant at the exposed edge and T-joints. Older EPDM roofs used liquid splice adhesive, which explains why so many aged seams peel open at the lap edge.

1. Mark and clean the lap area on both sheets.
2. Prime both surfaces and let the primer flash off.
3. Lay seam tape and roll it with firm pressure across its width.
4. Apply lap sealant at T-joints and along the tape edge.

Cold, damp mornings slow primer drying, so seam work waits for dry membrane and steady temperatures.

Three methods hold EPDM down: fully adhered, mechanically attached, or loose-laid under ballast, and the deck, the structure and the parapet height drive the choice.

Ballast adds heavy load, so a structural check of the deck and framing comes first. Stone also covers the membrane, which slows down leak tracing at seams and drains years later.

The U.S. Department of Energy's says a reflective roof's winter heating penalty is usually smaller than its summer cooling savings in mixed climates, a group that fits Kentucky's humid summers and cold winters.

Rated reflectance values for specific membranes appear in the . White sheets show dirt near exhaust fans and walkway routes, so those areas look gray sooner.

EPDM gets cured rubber flashing up walls and curbs, uncured rubber formed at inside and outside corners, and seam tape wherever flashing meets the field. Metal holds the upper edge.

• Parapets get membrane run up the wall and across the parapet, under a metal coping cap.
• Curbs around RTUs get cured flashing, with uncured pieces molded at each corner.
• Gravel stops and drip edge get a cover strip of seam tape sealing metal to rubber.
• Drains get the sheet clamped under the ring over water cutoff mastic.
• Pipes get pre-molded EPDM boots with a stainless clamp at the upper collar.

Termination bars screwed through the flashing at the wall keep it from sliding as the rubber shrinks with age.

Industrial roofing covers roofs on factories, plants, warehouses and distribution centers, where the roof carries heavy equipment, exhaust stacks and process vents over operations that keep running. The membranes and metal panels match those on other commercial roofs, with heavier detail work around everything the plant puts up there.

Common features of an industrial roof.

• Large RTUs, make-up air units and exhaust fans on curbs.
• Process stacks and vents carrying heat, steam or chemicals.
• Walkway pads from roof hatches to service points.
• Long steel decks spanning wide bays with many interior drains.

Each penetration is a flashing detail, and a plant roof can carry hundreds of them.

The material that lands on the roof from each fan and stack sets the membrane choice around it, because oils, fats and solvents attack membranes differently. PVC holds up well to oils and animal fats, TPO handles moderate exposure, and EPDM swells when oil soaks into it.

Steps for a plant roof with exhaust.

1. List what each stack, fan and vent discharges.
2. Pick the membrane for the whole roof, or a resistant sheet around those curbs.
3. Add grease containment boxes at kitchen and process exhaust fans.
4. Run walkway pads to every fan that crews service.

A stained, swollen or soft membrane ring around a fan curb is a sign that the current sheet reacts with what the fan blows out.

Industrial roof work runs around shifts, production lines and stored product, with tear-off sections sized so each area is watertight by the end of the day.

• Air intakes near tear-off areas get shut down or covered against fumes and dust.
• Crane picks of insulation and membrane happen in off-shift hours or blocked zones.
• Tarps and poly go over racked product under open deck sections.
• Hot work permits cover torches and welders near combustible materials.
• Daily tie-ins seal the edge of new roof to old so overnight rain stays out.

Plant managers mark the areas that need extra care, such as clean rooms, electrical rooms and server spaces, before any deck opens.

Walkway pads and raised equipment curbs protect the membrane from the foot traffic, tools and loads that service crews bring onto an industrial roof every week. Dropped screws, ladder feet and heavy boots puncture single-ply membrane.

• Walkway pads get welded or adhered along routes from hatches to RTUs.
• Equipment rails and curbs rise high enough for full flashing.
• Pipe supports sit on pads instead of crushing insulation.
• Sacrificial sheets go under grease and condensate drains.

During a replacement, crews check each curb height against the new roof thickness, since thicker insulation can leave an old curb too short to flash.

Tapered insulation sets the slope on big industrial roofs, carrying water to each interior drain, scupper and gutter. Long bays and deflected steel deck often leave ponding between drains.

Drainage work during a new roof includes these items.

• Tapered crickets between drains and behind RTU curbs.
• Sumps at each drain bowl that drop water into the outlet.
• Overflow scuppers or secondary drains through parapet walls.
• Larger conductor heads and downspouts at scupper outlets.

Drain piping inside the building falls under plumbing review, so drain body changes can bring in the state plumbing inspector listed on the county contact sheet.

Standing seam panels join at raised seams held by concealed clips, while R-panel panels are screwed through the face into the purlins with gasketed fasteners.

R-panel costs less to install, and standing seam leaves far fewer holes in the roof surface. Many owners pick standing seam for occupied buildings and R-panel for storage and ag buildings.

A commercial metal roof in Radcliff gets a full walk in spring and fall, plus a look after any storm with hail or strong wind. Each visit follows the same route from gutters to ridge, so every trim line and penetration gets seen.

Small finds such as a clogged downspout or a few loose screws are simple to fix while a crew is already on the roof.

Retrofit framing of light-gauge steel purlins and posts can set a sloped metal roof over an existing flat roof, which moves water off a roof that ponded for years. The old membrane stays in place under the new framing, or comes off first when it holds water.

1. Check the existing structure for the added load.
2. Set framing over the old roof to the planned slope.
3. Install panels, trim and gutters on the new framing.
4. Vent the space between the old and new roofs.

A structural engineer designs the framing connections, and the local building official reviews the work under the Kentucky Building Code.

Most repairs on an aging commercial metal roof happen at the fasteners, the panel laps and the flashing, because daily expansion and contraction loosens those joints well before the panels wear out.

Long panel runs on warehouses show the most movement damage, so crews check their eave and ridge ends first.

Insulation and a vapor retarder belong under any metal roof over heated or cooled space, because warm, moist inside air turns to water when it meets cold steel on the panel underside. For commercial buildings, Kentucky lists the 2012 International Energy Conservation Code, which sets roof insulation levels for conditioned space.

Common insulation setups on metal buildings.

• Faced fiberglass blanket draped over purlins, facing toward the warm side.
• Rigid board over the purlins with thermal spacer blocks.
• Spray foam on the panel underside in shops and barns.

Unheated equipment sheds often skip insulation, and a drip-stop fabric on the panel back catches condensation before it drips onto stored gear.