A commercial roof rarely fails all at once. It fails at a seam nobody looked at, at a drain that filled with leaves in October, at a flashing a technician stepped on while servicing a rooftop unit. Almost all of it is findable in advance, and most of it is cheap to fix while it is still small. Here is what a maintenance programme should actually contain in this climate.
Inspection frequency, and why the timing matters here
The baseline the industry works to is twice a year. Carlisle SynTec’s owner’s manual, representative of what major single-ply manufacturers require, tells building owners to inspect at least every six months, preferably spring and fall, and immediately following any weather event involving excessive rainfall, high winds or hail warnings.
In Michigan the “preferably spring and fall” is not a formality — it brackets the season that does the damage. The Great Lakes region averages about 42 freeze-thaw cycles a year across the long climate record kept by the University of Michigan’s GLISA programme. Every cycle takes water that has found a gap, expands it as ice, and leaves the gap slightly bigger.
The two visits do different jobs:
- Autumn, before the first hard freeze. Clear drains and gutters of leaves, check every seam and flashing, close anything open. This visit determines what winter can do to you.
- Spring, after the last thaw. Find what the freeze-thaw season opened: split seams, lifted edge metal, cracked flashing at penetrations, splits at parapet bases, and any new low spot where insulation has compressed.
Then add the event-driven visits. After a windstorm, after hail, after any heavy rain that produced a leak call anywhere in the building, someone competent should be on the roof.
Drains, scuppers and the water that never leaves
Drainage is the highest-value item on the list, and it is mostly housekeeping. Clear every drain basket, strainer and scupper opening of leaves, wrapper debris, gravel and silt. Check that strainers are present and secured — a missing strainer sends debris into the leader, and a blocked leader is a far larger problem than a blocked basket. Check that the surface around each drain still sits lower than the field.
ARMA defines ponding water as water that remains on a roof 48 hours or longer, and manufacturers use a similar window — Carlisle’s manual states that ponded water should evaporate within 48 to 72 hours. Anything still standing beyond that is a defect to investigate, not a quirk of the building. ARMA lists what ponding does: the added load deforms the deck, ice forming and moving damages the membrane, vegetation grows in it, and it collects the debris that blocks the drains.
Secondary drainage deserves its own check because it is the item most often forgotten. The IBC requires emergency overflow drains or scuppers wherever roof drains are required and water would otherwise be trapped if the primary drains fail, with scupper openings not smaller than four inches and sizing referred to the plumbing code. Those overflows prevent progressive deflection under trapped water, the failure mode that collapses roofs — and nobody notices them until the primary drains block and the overflow turns out to have been sealed over during a re-roof.
Seams, flashings and terminations
Membrane roofs rarely fail in the middle of a sheet. They fail at joints, and which joints depends on the system. EPDM is a thermoset, so its seams are made with adhesive or seam tape, and those seams are the priority item on an EPDM roof: lifted edges, fishmouths, any point where a lap has opened. TPO is a thermoplastic with hot-air welded seams, effectively continuous when made correctly, so attention shifts to weld defects at corners and detail work, and to punctures in the field.
At the details, the list is the same on any system:
- Perimeter. Edge metal, copings and membrane terminations secure, fasteners tight, no lifting at corners where uplift pressures are highest.
- Penetrations. Pipe boots, curbs, conduit supports and equipment stands. Sealant at the top of a pitch pocket has a shorter life than the roof and needs topping up on a schedule.
- Walls and parapets. Counterflashing still lapped correctly, reglets sealed, no splits at the base of the upstand.
- The field. Punctures, scuffs and cuts from dropped tools or blown debris.
Rooftop equipment is the most reliable source of damage on a commercial roof, because the people servicing it are not roofers. Carlisle’s manual requires walkways where regular traffic occurs or where rooftop equipment is on a maintenance schedule of thirty days or less. Walkway pads are inexpensive and they settle the argument about who damaged the membrane before it starts.
Snow, and what not to do about it
Michigan’s code tables set the ground snow load at 25 psf for both Macomb and Oakland counties. For most commercial roofs an ordinary snowfall is not a structural concern. The concerns are more specific: drifting behind parapets, against taller adjacent walls and around large rooftop units piles snow far deeper than the open field; rain onto an existing pack adds weight quickly; and ice forming across a drain in a thaw-freeze sequence turns a working drain into a dam.
If snow does need removing, method matters more than schedule. Never use metal tools or ice chippers on a membrane — the repair costs more than the snow ever weighed. Leave a layer of snow rather than scraping to the surface. Clear the drains and their approaches first, because that alone resolves most of the risk. And treat rooftop snow work on an occupied building as work needing fall protection and a plan.
One aside on reflective roofs here: DOE and Lawrence Berkeley National Laboratory guidance identifies Climate Zones 5 through 8 as cold climates where less heat is available to dry out a roof. That is worth knowing when a wet insulation problem is diagnosed on a white membrane in Michigan, because the assembly has less capacity to recover on its own.
Documentation, because the warranty depends on it
This is where owners lose money that had nothing to do with the roof’s condition. Carlisle’s owner’s manual requires the owner to retain records related to the roofing system — warranty documents, serial numbers, maintenance inspection logs, rooftop traffic logs, service logs and invoices for work performed. It also states plainly that the warranty becomes null and void if any alterations or repairs are made on or through the roof without first obtaining written authorisation.
The practical consequences catch good building managers:
- A new satellite dish, sign anchor, conduit run or condenser stand installed through the membrane by another trade can void coverage on the entire roof.
- A quick patch by a handyman counts as an unauthorised repair.
- An inspection you performed but did not log did not happen, as far as a warranty claim is concerned.
Keep one file per building: dated inspection reports with photographs, every invoice, a log of who went on the roof and why, and copies of the written authorisations for any work through the membrane. It is the difference between a covered claim and an argument.
| When | What gets done | Why it matters here |
|---|---|---|
| Autumn, before first freeze | Clear drains, strainers, scuppers and gutters; walk all seams, flashings and terminations; close any open detail | Determines what the freeze-thaw season can do; leaf fall is the main blockage risk |
| Spring, after last thaw | Look for split seams, lifted edge metal, cracked penetration flashings, parapet base splits, new low spots | About 42 freeze-thaw cycles a year in the Great Lakes region opens what winter found |
| After high wind, hail or heavy rain | Full walk of perimeter, field and penetrations; photograph anything found | Manufacturer manuals require inspection after these events, and claims need dated evidence |
| Quarterly, or with each equipment service | Check walkway pads, look for new punctures and tool damage, log who was on the roof | Servicing trades cause more membrane damage than weather does |
| During winter, as conditions require | Keep drains and their approaches clear of ice; monitor drift areas behind parapets and beside tall walls | Drifting and blocked drains concentrate load far beyond the 25 psf ground snow load |
| Ongoing | File dated reports, photographs, invoices, traffic logs and written authorisations | Warranties require records, and unauthorised work through the membrane can void coverage |
Budgeting repair against replacement
The decision turns on three questions rather than on the age of the roof.
Is the insulation wet, and over how much of the roof? A membrane can be patched. Saturated insulation cannot be dried in place, and it stops insulating. Confined to identifiable areas around known leak points, sectional repair is genuine value. Spread across the field on a moisture survey, you are paying to maintain a roof that has already failed.
Does the roof drain? If ponding is a design or deflection problem rather than a blocked-drain problem, repairs repeat indefinitely. Tapered insulation, additional drains or retrofit drains address it; sealant does not.
How many repairs, and where? Repairs clustered at details are normal maintenance. Repairs appearing in new places across the field each year mean the membrane is at the end of its service.
Set against the service lives the systems publish — the EPDM Roofing Association’s expected 38 years for a properly designed, installed and maintained membrane — the honest reading is that maintenance buys the back half of that number.
Keeping the business running while the work happens
On an occupied building, disruption is a scheduling problem with known solutions. Work in sections, and never open more than can be closed and made watertight the same day. Sequence around tenants: over the stockroom before the dining room, over the warehouse before the offices. Stage materials where deliveries do not block customer access. Agree in advance where the crane or loader sits and for how long. Where a torch is not necessary, cold-applied and self-adhered methods keep open flame off the building entirely.
Most of that is decided at the estimate stage rather than on site. Our commercial roofing scopes set out sequencing and access as part of the written proposal, and where a problem turns out to be localised we will quote it as roof repair rather than talk you into a system replacement you do not yet need.
Questions about commercial roof maintenance
How often does a commercial roof really need inspecting?
Is standing water on a flat roof always a problem?
Water that clears within a couple of days is normal. Water still there after 48 hours is what ARMA defines as ponding, and manufacturers typically expect evaporation within 48 to 72 hours. Persistent ponding adds structural load, damages membrane as ice forms and moves, grows vegetation and traps the debris that blocks drains. Diagnose it rather than live with it.
Can having someone else work on the roof void my warranty?
Yes, and this catches people regularly. Manufacturer warranties commonly state that they are void if alterations or repairs are made on or through the roof without prior written authorisation. A sign anchor, a new conduit run, an added condenser stand or a handyman patch can all qualify. Before any trade goes through the membrane, get the authorisation in writing and file it with your inspection records.
Should snow be cleared off a flat commercial roof?
Sometimes, and carefully. Macomb and Oakland counties are set at a 25 psf ground snow load, so ordinary snowfall on a sound structure is not usually the issue — drifting behind parapets and beside taller walls, rain onto an existing pack, and ice blocking drains are. If it is cleared: no metal tools or chippers on the membrane, leave a layer of snow rather than scraping to the surface, and clear the drains and their approaches first.
