The Short Answer
When a commercial roof leaks, make the area safe first: isolate electrical hazards and wet floors, then protect stock and tenants and catch the water. Next, document the leak and the weather, and find the roof warranty, because some manufacturer warranties require written notice to the manufacturer within days. Call your insurer if there is damage. Keep untrained staff off the roof, and have a qualified commercial roofer make the temporary and permanent repairs.
Key Points
- Safety comes first: water near electrical equipment, slippery floors and saturated ceiling tiles injure people.
- Read the roof warranty's notice clause the same day. One Mule-Hide commercial warranty we reviewed requires written notice to the manufacturer within ten days, and notice to the contractor does not count.
- Unapproved repairs or alterations can be excluded from a manufacturer warranty, and asphalt products can damage single-ply membranes.
- Federal general industry rules require fall protection for work near the edge of a low-slope roof, so the roof is not the place for an untrained employee with a bucket.
- Log the time, weather and wind direction of every leak. Those clues are what a roofer uses to find the source.
The First Hour Inside the Building
- Step 1
Make It Safe
If water is near light fixtures, panels, outlets or equipment, shut off power to that area at the panel if it can be done safely, and call an electrician if it cannot. Cone off wet floors. Wet ceiling tiles get heavy and can fall, so keep people out from under them.
- Step 2
Protect Stock, Records and Equipment
Move what you can. Cover what you cannot with plastic sheeting, sloped so water runs into a container instead of pooling on top. Raise items off the floor on pallets.
- Step 3
Catch and Route the Water
Buckets, trash cans and wet vacuums. A short length of sheeting or hose taped under the drip can route water into a larger container. Empty them on a schedule.
- Step 4
Tell the People Affected
Tenants, department heads and the owner. Give one point of contact and a time for the next update. Tenants in a multi-tenant building should report any new leaks to that contact.
- Step 5
Call a Commercial Roofer
Describe the building, the roof type if you know it, where the water is, and whether it is active now. Have the warranty in hand when you call; see below.
Who Should Go Up on the Roof
It is tempting to send someone from maintenance up to look. Be careful. The federal general industry rule for work on low-slope roofs, 29 CFR 1910.28(b)(13), requires guardrails, safety nets, travel restraint or personal fall arrest for work less than 6 feet from the roof edge. Between 6 and 15 feet, the same applies, except that a designated area may be used for work that is both infrequent and temporary. At 15 feet or more, the employer must still enforce a rule keeping employees back from the edge without fall protection.
Michigan runs its own OSHA-approved state plan through MIOSHA, which covers most private-sector workplaces, so confirm the Michigan requirements with your safety officer. Edges are not the only hazard: skylights, roof hatches and soft spots are too. Manufacturer guidance adds that white membranes and coatings can hide ice and frost, and all membranes are slippery when wet.
A safe, useful job for staff is checking from inside and from the ground: where the water is, whether downspouts and overflow scuppers are running, and whether a rooftop unit was serviced recently.
Protect the Manufacturer Warranty From Day One
Commercial membrane warranties are contracts with conditions, and the conditions bite at exactly this moment. Wording varies by manufacturer, product and year, so pull your own document. As an example, here is what one Mule-Hide Premium Single-Ply NDL System Warranty for commercial buildings says.
Written notice, quickly
Mule-Hide form, item 1
Within ten days after the owner or its agents discover a leak, or a reasonable person would have, the owner must give written notice to Mule-Hide. The form says notice to the contractor is not notice to Mule-Hide.
No unapproved alterations
Mule-Hide form, exclusions
Alterations or repairs made on or through the roof without prior written authorization from Mule-Hide are excluded. The care guidelines add that work directly on the roofing system must be done by a Mule-Hide Warranty Eligible Contractor.
Temporary repairs, the right way
Mule-Hide care guidelines
For a temporary repair to the membrane, the guidelines name Mule-Hide JTS-1 or a quality one-part urethane sealant, and tell the owner to contact Mule-Hide. They warn against any asphalt product on a single-ply membrane; an area that gets one must be removed and replaced at the owner's expense.
Owner maintenance is the owner's
Mule-Hide care guidelines
The warranty is not a maintenance program. Exposed mastics and sealants, including pitch pan and metal flashing sealants, are listed as owner maintenance items, and leaks from other building components are not covered.
Other manufacturers' warranties set different deadlines and procedures. Read the notice clause on your own warranty the same day you find a leak, and send written notice even if you have already called.
What to Write Down While It Is Happening
- The date and time the leak was first noticed, and when it stops.
- The weather: light or heavy rain, snowmelt, wind direction, temperature. Manufacturer guidance lists these as key clues, along with whether the leak stops with the rain or keeps going.
- The location, marked on a floor plan or roof plan, with column lines or room numbers.
- Photos and video of the ceiling, the water and any damaged stock or equipment, with wide shots that show where in the building you are.
- A list of damaged inventory or equipment, with quantities.
- Any recent rooftop activity: HVAC service, new equipment, antenna or solar work, signage. Trades on the roof are a common cause of punctures.
- Every call and email: insurer, manufacturer, roofer, tenants. Who, when and what was said.
Notify the Insurer and Keep the Receipts
Property policies have a section on your duties after a loss. Look for the notice requirement and any duty to protect the property from further damage. Michigan's insurance code requires fire insurance policies issued in the state to state their notification requirements and sets a minimum one-year window to sue, paused from notice until a formal denial. Read the duties section of your own policy.
Keep receipts for temporary protection, emergency roofing, cleanup and equipment rental. Do not throw away damaged stock until the adjuster says you can. Whether a leak is covered depends on the cause and the policy; wear and maintenance problems are commonly excluded, and no roofer can promise a claim outcome.
What a Good Commercial Leak Diagnosis Includes
On a low-slope roof, the water inside is often far from where it gets in. Water can travel along the deck, through insulation joints or down a beam. A competent roofer starts with your log and then works the likely sources: drains and scuppers, perimeter and parapet flashings, curbs at rooftop units, pipe penetrations, pitch pans, seams, and anything that was recently disturbed.
If the insulation may be wet, the roofer may recommend a moisture survey and core cuts. A core cut is a small sample taken through the roof to see the layers and whether they are wet, then patched. Wet insulation matters because it decides whether a roof can be repaired, recovered or coated, or has to come off.
Ask for the findings in writing with photos, the cause as best it can be determined, and the options. A temporary repair that stops the water this week and a permanent repair or larger project afterward is a normal and honest sequence.
Repair or restore with a coating?
When the deck and most of the insulation are dry, a silicone restoration coating can be an option instead of a new roof.
Compare repair and coatingWhat the Michigan Building Code Says About Wet Roofs and Recovers
A serious leak often ends with a bigger question: patch it, put a new roof over the old one, coat it, or tear it off. In Michigan that decision runs through the Michigan Building Code, which LARA's rule R 408.30401 bases on the 2021 International Building Code. Its Section 1512 governs reroofing on commercial buildings.
The key line for a leaking roof is in Section 1512.2.1.1. A roof recover, meaning a new roof covering installed over the existing one, is not permitted where the existing roof or roof covering is water soaked or has deteriorated to the point that it is not an adequate base for additional roofing, or where the existing roof already has two or more applications of any type of roof covering. That is why the moisture survey and core cuts described above matter so much: they show whether a recover or a coating is even allowed, or whether the wet layers have to come off.
When the roof is replaced instead, Section 1512.2 says replacement includes removing all existing layers of roof assembly materials down to the deck. Section 1512.2.1 does allow a new protective coating over an existing single-ply, built-up, modified bitumen or metal roof without tear-off, which is the code basis for coating restoration on a roof that is still sound and dry.
Drainage gets one more rule. Section 1512.1 says recovering or replacing a roof with positive drainage does not by itself require adding secondary overflow drains or scuppers, but existing required overflows may not be removed unless they are replaced with ones that meet Section 1502.2. Leaks around drains and blocked overflows are common commercial leak sources, so that is worth checking whenever the roof is opened up.
Before a recover, coating or replacement starts, ask your local building department what permit and inspections it requires; the code sections here are a summary, not legal advice.
Drains, scuppers and overflows
What Michigan's plumbing and building codes require, and why drains fail.
Commercial roof drains and scuppersMake the Next Leak Smaller
- Inspect the roof at least twice a year, spring and fall, and after major storms. Mule-Hide's owner guidelines recommend exactly that, by an eligible applicator or someone trained in roofing systems.
- Keep drains and scuppers clear. The same guidelines say good practice is that water should not stand on the roof more than 48 hours after a rain.
- Install walkways to rooftop equipment if trades visit often, and keep a rooftop activity log of who went up and why.
- Treat sealants, pitch pans and counterflashings as maintenance items, because they are, and fix small items before winter.
- Keep the warranty, as-built information, past invoices and this action plan in one folder that the next manager can find.
Roof maintenance programs
Scheduled visits for commercial roofs that catch seams, flashings and drains before they leak.
See roof maintenanceHow Stellar Handles Commercial Leaks
We have roofed just over 1,600 commercial properties since 2012. Stellar is a Mule-Hide contractor for flat and low-slope roofs and GAF CoatingsPro certified for commercial silicone coatings. On the commercial side, Mihles Pena holds Haag Commercial certification in his own name.
The phone is watched around the clock, by call or text. For a true emergency we are usually on site within 24 hours, weather permitting and if the roof is safe to access, and we come prepared to stop the water the same day. When there are two honest options, such as a targeted repair or a root-cause fix with a stronger warranty, we lay out both.
Leak Response Timeline
| When | Task | Who |
|---|---|---|
| First 15 minutes | Isolate electrical hazards, cone wet floors, clear people from under wet ceilings | On-site staff |
| First hour | Protect stock and equipment, catch water, notify owner and tenants | Facility or property manager |
| Same day | Call a commercial roofer; pull the roof warranty and read the notice clause | Manager |
| Same day to a few days | Written notice to the manufacturer if under warranty; notify the insurer if there is damage | Owner or manager |
| First visit | Temporary repair to stop water; photos; likely cause | Roofer |
| After diagnosis | Written options: repair, coating, recover or replacement | Roofer, then owner decides |
| After the next heavy rain | Confirm dry ceilings; close out the log | Manager |
Deadlines in your warranty and policy override this table. Check both.
Water Coming Through a Commercial Roof?
Call or text any time. Emergency repairs typically start around $850, and for a true emergency we are usually on site within 24 hours, weather permitting and if the roof is safe to access.
Related Guides
Commercial Roof Repair vs Coating Restoration
When a silicone restoration makes sense on a flat roof, and when it does not.
Learn MoreHow Roofers Find Leaks
Visual tracing, water testing, moisture meters and infrared, and what each misses.
Learn MoreCommercial Roofing
TPO, EPDM, modified bitumen, coatings, repair and replacement across West Michigan.
Learn MoreFlat Roof Repair
Membrane, seam and flashing repairs on commercial and residential low-slope roofs.
Learn MoreQuestions We Hear
Who is responsible for a roof leak in a commercial lease?
The lease decides. Michigan's residential repair statute does not apply to commercial space, and commercial leases often split roof duties in detail: the landlord may own roof replacement while the tenant pays for maintenance through common area charges, or the reverse. Read the repair, maintenance, insurance and notice clauses, report the leak in writing, and let the lease drive who calls the roofer.
Can our maintenance staff patch a flat roof leak?
Be careful on two fronts. Fall protection rules apply to work near the edge of a low-slope roof, and many manufacturer warranties exclude repairs made without the manufacturer's authorization. If a temporary patch is needed, use only what the warranty allows; one Mule-Hide guideline names a specific sealant and warns against any asphalt product on single-ply membranes. Then call the contractor.
How soon do we have to report a leak under a commercial roof warranty?
It depends on the warranty. One Mule-Hide commercial warranty we reviewed requires written notice within ten days of discovering a leak and says notice to the contractor does not count. Other manufacturers use different periods. Find your warranty, read the notice clause the same day, and send written notice by the method it specifies, even if you have already called.
Should we close the area under a roof leak?
Close it if water is near electrical equipment or fixtures, if the floor is slippery, or if ceiling tiles or drywall are sagging. Those are injury risks, not just property damage. Keep people out until the area is dry and the ceiling is checked. If you cannot safely isolate power to the area, call an electrician.
Why does a roofer want to cut a sample out of our roof?
A core cut shows what is under the membrane: how many layers there are, what the insulation is, and whether it is wet. That changes the options. A roof with dry insulation may be repaired, recovered or coated; a roof with widespread wet insulation usually needs those areas removed. The sample hole is patched the same visit.
What This Page Cites
- 29 CFR 1910.28(b)(13), Duty to have fall protection: work on low-slope roofs, Occupational Safety and Health Administration (https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.28), accessed October 2026
- Premium Single-Ply NDL System Warranty for Commercial Buildings Ver. 4.0 and Building Owner's Roof Care and Maintenance Guidelines ver. 7, Mule-Hide Products Co. (issued copy in City of Steamboat Springs permit records, https://cityview.steamboatsprings.net/Portal/Permit/GetFile/35379), accessed October 2026
- Insurance Code, MCL 500.2833 (mandatory fire policy provisions: notice requirements, time to sue), Michigan Legislature (https://www.legislature.mi.gov/Laws/MCL?objectName=mcl-500-2833), accessed October 2026
- 2021 Michigan Building Code, Chapter 15 Roof Assemblies and Rooftop Structures, Sections 1502.2, 1512.1, 1512.2, 1512.2.1 and 1512.2.1.1, International Code Council (https://codes.iccsafe.org/content/MIBC2021P1/chapter-15-roof-assemblies-and-rooftop-structures), accessed October 2026
- Mich Admin Code R 408.30401, Applicable code (Michigan Building Code adopts the 2021 IBC), Legal Information Institute, Cornell Law School (https://www.law.cornell.edu/regulations/michigan/Mich-Admin-Code-R-408-30401), accessed October 2026
- Michigan State Plan, Occupational Safety and Health Administration (https://www.osha.gov/stateplans/mi), accessed October 2026
- Revised Statutes of 1846, MCL 554.139 (applies to residential premises), Michigan Legislature (https://www.legislature.mi.gov/Laws/MCL?objectName=mcl-554-139), accessed October 2026