Madison commercial roof repair: a guide for building owners

Who this page is for

Commercial roof repair in Madison mostly means small buildings: a two-story brick storefront on Williamson Street or Atwood Avenue with apartments upstairs, a one-story office or clinic on the west side, a church fellowship hall, a strip of shops with a shared roof, or a 1960s–70s walk-up apartment building with a flat roof and a row of scuppers along the back. Those roofs are low-slope, which means they hold water for a while instead of shedding it, and the whole roof depends on a continuous membrane and on drains that work in January.

This is a free guide for owners and property managers, not a roofing company. Estimate requests go to an independent local roofing contractor partner, and for low-slope work you should confirm that whoever comes out does membrane repair regularly. A big warehouse or a campus building is a different scale of job and a different kind of contractor.

What a Madison winter does to a flat roof

A pitched shingle roof in Madison fights ice dams at the eave. A flat roof fights the same physics everywhere at once.

Snow load and drifting. Commercial roofs are designed to carry snow, but the load is rarely even. Wind piles drifts against parapet walls, behind rooftop units and on a lower roof next to a taller building, and a wet late-season snow on top of an old pack is heavy. Older buildings that had rooftop equipment added over the years are the ones to watch. Signs a section is struggling: interior doors that start to stick, new cracks in drywall near the top floor, or a ceiling that visibly dips. Those are reasons to call an engineer or roofer that day, not after the thaw.

Ice at the drains. On a low-slope roof the "ice dam" forms where the water tries to leave. Heat from a poorly insulated deck melts the snow from below, the water runs to a scupper or an internal drain, and the drain bowl or the scupper box, which sits colder than the roof around it, freezes shut. The water backs up into a shallow lake, finds a seam or a flashing that sits a little low, and comes in. The same thing happens at the edge where a gutter is hung off a flat roof over a sidewalk.

Freeze-thaw on seams and laps. Madison spends weeks of every winter swinging across 32°F. Water that gets into an open lap, a blister in modified bitumen or a crack in old flashing cement freezes, expands and opens it a little further each cycle. A seam that was marginal in October can be a leak in March.

Ponding that freezes in place. Standing water still there 48 hours after the rain or the melt is ponding. In summer it ages the membrane and grows algae; in winter it becomes a sheet of ice that loads one spot of the deck and grinds at the surface as it moves.

What fails first on small commercial roofs

The middle of the sheet is rarely the problem. Most leaks start at an interruption:

• Parapet walls and coping. Open joints in the metal cap, loose termination bar, and brick that soaks up water and lets it run down behind the base flashing.
• Drains, scuppers and conductor heads. Clogged with leaves from the street trees, cracked clamping rings, a strainer missing so debris goes down the pipe.
• Rooftop HVAC curbs. Every unit has a curb, a condensate line and a service technician who walks to it. Cut membrane, screws left lying on the roof, and panels set down on the membrane are common causes.
• Pipe and conduit penetrations. Pitch pans that have shrunk away from the pipe, and conduit run across the roof on wood blocks that rot and puncture the sheet.
• Seams. Especially older glued EPDM, where the adhesive gives up after twenty-odd winters.
• Transitions. The place where the back addition's flat roof meets the main building's wall, or where a pitched front section meets the membrane behind it. Many near east side buildings have both kinds of roof, and the joint between them is a classic leak.

The roof systems you are likely to have

Knowing the system tells you what a repair should look like.

EPDM. Black synthetic rubber, usually in large sheets with glued or taped seams. Common on older Madison buildings and easy to patch. Repairs are cleaned, primed and covered with seam tape or a patch; a smear of roof cement over rubber is not a repair.

TPO. A white or gray single-ply sheet with seams welded by hot air. The weld is the strong point. Repairs are welded patches, which means the surface has to be cleaned well, because an aged TPO sheet can be hard to weld to.

Modified bitumen. Asphalt-based rolls, torched, mopped or self-adhered, often with a granule surface. Tough underfoot around equipment. Common problems are blisters, open laps and granule loss. Ask how the crew will handle torch work next to a wood parapet or a building with tenants inside.

Built-up roofing (tar and gravel). Layers of felt and hot asphalt with gravel on top, common on buildings from before the 1990s. It can be repaired in spots, but the gravel hides what is happening underneath, so leaks can be hard to trace.

Metal. Standing-seam or through-fastened panels on some low-slope buildings and additions. Problems tend to be fasteners that have backed out after years of thermal movement, failed sealant at laps, and snow and ice tearing at the eave trim.

What to check yourself, safely

You do not need to walk the roof to learn a lot. If you do go up, use a proper access hatch or ladder, stay well back from the edges and skylights, and never go up on ice.

1. From inside: stained or sagging ceiling tiles, rust on the top of steel deck you can see in a mechanical room, water marks at the top of exterior walls and around HVAC returns.
2. After rain or a melt: where water stands and how long. Note the spots on a simple sketch of the roof.
3. At the drains: strainers in place, no leaves or gravel packed around them, water moving.
4. At the parapets: coping joints that look open, and brick that stays dark long after a rain.
5. Around equipment: loose panels, screws and debris left by service visits, and soft or wrinkled membrane at the curb.
6. Keep a roof file: install year if known, the system, any warranty paperwork, and every repair with a date and photos. The next roofer, a buyer or your insurer will ask for it.

Inspection cadence that fits this climate

A small commercial roof in Madison is worth a look twice a year plus after big weather. A spring visit in April catches what the freeze-thaw opened and clears the winter debris from the drains. A fall visit in October clears leaves before they freeze into the drain bowls and checks the flashing before snow covers it. Add a check after any hail or high-wind storm and after a winter with heavy drifting. Photographs from each visit make it much easier to tell a new problem from an old one, and they help if you ever need to talk to your insurer about a storm. Our roof inspection page explains what a written inspection report should include.

Commercial roof repair step by step

A well-run repair on a low-slope roof usually goes like this:

1. Find the source, not just the drip. Water travels along the deck and under the insulation, so the stain inside can be far from the hole. A roofer works back from the interior mark, checks the drains and flashings uphill of it, and may flood-test a section.
2. Check for wet insulation. If the roof has been leaking for a while, the insulation under the membrane may be soaked. Ask whether they will do test cuts, called core cuts, or a moisture survey with an infrared or capacitance meter. Wet insulation does not dry out under a membrane, and patching over it just moves the leak.
3. Make the repair to match the system. Taped or patched EPDM, welded TPO, new plies of modified bitumen, re-set termination bar and new base flashing at a parapet, or a rebuilt pitch pan.
4. Fix the drainage that caused it. Clear and re-clamp a drain, enlarge or reline a scupper, or add a small cricket to move water off a low spot behind a curb.
5. Photograph before and after. You should get pictures of the problem, the repair and anything else they noticed on the roof.

Repair, restore or replace

A repair makes sense when the problem is at a detail and the insulation is dry. A coating or restoration system may make sense on a membrane that is tired but sound and dry; it does not fix wet insulation or failed seams underneath it. Replacement is the conversation when large areas of insulation are wet, when the membrane is cracking across the field, or when repairs keep turning up somewhere new. Whether a new roof can go over the old one or needs a full tear-off depends on what is there now and on code; check with the City of Madison Building Inspection Division or your town's building department, and ask each bidder how they handled that question.

How commercial bids differ, and how to compare them

Two bids for the same leak can look nothing alike. When you line them up, check that each one names:

• The cause in plain words, and where on the roof it is.
• The method: patch, weld, new flashing, or a section replaced.
• Wet insulation: whether they tested for it, how much they found, and the unit price to replace more if it turns up.
• Drainage work included, or excluded.
• Access and protection: how tenants, parked cars and the sidewalk are protected, and whether torch work is involved.
• Warranty on the repair, in writing, and who stands behind it.

For a larger project, ask whether the price includes tapered insulation to fix ponding, new edge metal and coping, and the permit. A low number that skips the wet insulation is usually not the cheaper job. Small commercial roofs are priced per square foot, so the pricing page is mostly about houses; ask for a separate written quote for the building.

Warranty types you will hear about

• Contractor workmanship warranty. The roofing company stands behind its own labor for a set number of years. Get the term and what it covers in writing.
• Manufacturer material warranty. Covers defects in the membrane itself, usually not the labor to replace it.
• Manufacturer system warranty. On a new roof installed by a contractor the manufacturer approves, sometimes with a final inspection by the manufacturer. Ask what maintenance the warranty requires, because skipped drain cleaning and unrecorded repairs by others can void it.

On an existing roof under warranty, call the warranty holder before anyone else cuts into it.

Questions to ask before you hire

• How many low-slope roofs like this one did you repair in the last year, and can I see photos or talk to an owner?
• Which systems do you work on, and do you handle both the membrane and a pitched section if my building has both?
• Will you check for wet insulation, and how?
• Who pulls any permit, and is it in the price?
• How will you protect tenants, the interior and the sidewalk?
• Can I see your certificate of insurance before work starts?

You can check a contractor's Wisconsin credentials with the Department of Safety and Professional Services (DSPS) and your city's permit office. If you lease the building, read the roof clause first: many leases split maintenance and replacement between landlord and tenant, and the wording controls. Ask an attorney if it is unclear.

Get a written estimate

If water is coming in now, move what you can, protect electrical equipment, and photograph the damage with the date. Then call or request an estimate. For a mixed building with a shingle section, the roof repair page covers the pitched side, and the ice dam page explains the attic heat that also melts snow on flat roofs.