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How It Started

Mike Grennan has been caring for roofs for over 34 years. It started with his first bundle of shingles, carrying them one bundle at a time, up a ladder, to the roof. Roofing is hard work! “We didn’t have rooftop deliveries in 1989,” says Mike.

Mike’s first roofing job was for one of his youth hockey coaches. He offered him a summer job. Both Mike and one of his hockey buddies labored as a human roof-top delivery service. Mike would tell you with a laugh, “On the second day of work, my buddy showed up with a suspicious smile and a makeshift shoulder pad for both of us. This was to ease the pain of the shoulder bruising from all those bundles we carried up on our first day.”

For a year or two, as most roofers do, he jumped around from crew to crew. “Some crews didn’t have steady work,” Mike says. “Other times, when one crew was unsteady, a better opportunity would present itself, and I’d jump right on it.”

When Mike was 19 or 20 years old, he met a pair of roofing partners who were willing to give him a shot. “As a kid, one of the things I liked about roofing,” he says, “was that you could start the day as a new guy on a roofing crew with an honest approach. It was incentive driven. I’d offer to work the first day with an open payment arrangement. The terms were that at the end of the day, they’d evaluate my performance, and pay me what they thought I was worth. “They were the first ones to pay me $100 a day.”  Again, Mike offers, “That was a big deal back then, $100.00 a day; I felt rich. They spent extra time with me, and I paid attention. They taught me my first set of real flashing techniques. They taught me priceless lessons about real life stuff.”

In 1992, jumping around from crew to crew, Mike landed a position as a “shingler” on a new construction crew.  “There were tons of new homes to be roofed, and the pay was fifteen dollars a square; I loved getting paid by the square,” says Mike. (For those who are wondering, a square is three bundles of shingles.)

That winter, chasing squares, he fell off a roof. He believes something protected him that day. He has a hunch mixed with a lot of uncertainty. Maybe an angel? Maybe Divine intervention?  One thing he’s certain about is this: he knows he is grateful!

The day prior to the fall, he had noticed that one of the only two, two-story ladders, was broken. When he showed up that cold, snowy morning, his goal was to “lay some squares, and earn a paycheck.” It was a steep, sloped roof. “It was a borderline; you can or can’t walk this kind of roof. It was probably a 10 pitch, and it was slick,” Mike remembers.

Because he was the low man on the totem pole, and the other guy was using the only ladder to nail off his jacks and boards (safety stuff for walking on steep roofs), Mike had to wait. “There’s a bunch of upsides for getting paid by the square, opposed to being paid by the hour,” says Mike.  “Like, the harder you work, the more you’ll get paid; it’s your choice.” Maybe.

Sitting in the van, avoiding the cold, waiting impatiently to lay some squares, a bad idea came to Mike. He thought, “I can walk up the ladder, shimmy down the back slope of the roof, cradle myself in the valley, and nail off my first couple roof jacks.” He did just that.  

He doesn’t remember the fall. What he says though is, “When I woke up, I was on my back. I saw a few faces standing over me. It was the EMS workers and my boss.”  Mike talks about what he remembers last before he took the fall.  “I had nailed off the first roof jack. I remember being crouched on that jack, reaching out as far as I could to get that second jack nailed off. And that’s it, other than a literal split-second, flash-back memory of seeing the fascia board pass my eyes. I woke up on the ground.”  It was December in Michigan, and the ground was like concrete. Mike had sustained numerous injuries. He had to undergo a few surgeries, physical therapy, and more. He progressed from wheelchair, to crutches, to a cane, and back to roofing.  Mike was blessed to be alive, move, and think.

Mike Grennan, 1995, roofing a house.

Mike Grennan 2003.

Along the way, working as a sub-contractor, Mike met a contractor whom he regards as his roofing role model. “It was good timing,” Mike says.  “He polished the skills I had already been taught.  He had a way to keep me on my toes. He inspected every roof.  In doing so, he always pointed out a thing or two I could always do better. He demonstrated the values that go into creating and generating a successful service-oriented roofing company.

Due to corporate restructuring, Mikes Dad- Phil, faced early retirement. When this happened, Mike and his dad spent a few years together messing around with roofs. It was good timing.  Among other evident virtuous qualities, Phil was a mathematical genius. He loved math and made it a point, at early ages, for all his grandkids to begin memorizing their times tables.  Mike noticed, in his dad’s worldview, math was of the utmost importance.

Phil Grennan in his new coat from Mike, Christmas 1997.

Phil Grennan working with his hands.

One of the surface reasons for the good timing was that those roofing years for Mike (and Phil) were spent leading teams of production roofers tearing off and replacing roof systems. It moved from single-family detached homes onto a different focus. The aim was condominium and apartment-style residential roof system replacements. With his dad at his side, Mike led teams of 6-12 workers, with production levels anywhere from 25-50 squares per day, while Phil ran the books. Phil was also known for having an eagle eye. Hand in hand with the ground workers, he made certain that not one nail or shingle wrapper went unaccounted for. When the roofing role model showed up on-site, production was always up, and the grounds were always clean.

Phil, Mike and Crew roofing a country club.

Phil, Mike, and Crew roofing a senior facility.

Mike spent years in and out of roofing. He studied with carpenters for a while, building a few houses and decks.  Then, he went back to college for a semester and faced some serious life challenges. Mike took on management and sales roles for sales-based roofing and siding companies. “I didn’t sleep well at night in those sales driven systems,” says Mike. “The goal for me is to stop the leak, not sell the repair.”

Mike acquired licensure from the state of Michigan in 2021 to work as a building contractor. “For years, I dreamed about leading a company whose foundation was built upon service and integrity,” says Mike. An idea came to him: Saint Roof. He believes, maybe, his dad with his virtuous spirit- is president of Saint Roofs’ board of directors. And Mike’s dad always says, “Keep up the good work.”

Phil and Mike Grennan, 1980. Phil passed in 2017 from brain cancer.

“Like strong winds, core beliefs can steer a ship.” MG 2023


If you can see water dripping from your ceiling, it’s a good idea to immediately catch the dripping water with a bucket or can in order to minimize interior water damage. These days, it’s also a good idea to capture some photo images of the leaking/dripping area. Next call Saint Roof at (810) 710-ROOF or utilize our Contact Page. We can then share a phone conversation, look over the captured photo(s) of the roofs’ leaking areas, identify an initial plan to address your roof leak, and, if you choose, schedule a Roof Repair Service Visit. We value your home and want your family to feel safe.

Not necessarily. Roof leaks can be caused by a multitude of scenarios.

  • • Loose or missing shingles.
  • • Improper flashing techniques or missing flashing elements.
  • • Exposed or improperly driven roof nails.
  • • Degraded or non-existent roof sealants.
  • • Falling tree limbs.
  • • Hail strikes.
  • • Ice dams.
  • • Wind-driven rain.
  • • Cracks or gaps on your shingles or somewhere else in your roof system
  • • And more.


Often a leak can be traced, identified, and solved without having to replace your entire roof system. Contact Saint Roof to explore your options.

The answer varies depending on the severity and/or complexity of the roof leak. Saint Roof has a minimum roof visit fee associated with Roof Repairs. See our Roof Repair Service page for details.

No. However, with Saint Roof leadership, rest assured we’ve traced, identified, and solved some of the most complex/elusive roof leaks. The goal for Saint Roof is to solve your leak, not sell you a repair! If you’re interested in roof leak guarantees and warranties, we offer the Certainteed Integrity Roof Replacement System, which will address every aspect of the roof system at today’s residential roofing’s’ highest standards. This will provide you with industry-leading warranty coverage.

Yes. Saint Roof offers a Roof Treatment Service which will extend the life of your roof system.

These days, the average cost to replace a roof is $7,000-$15,000. If you would like a free roof estimate, please check out our Instant Estimator.

The answer is dependent upon a multitude of variables, including,

  • • The size, slope, and layers of shingles currently on your roof.
  • • The weather. Roofers are constantly watching weather reports to schedule removing and replacing sections of your roof system, so we don’t get “caught in a storm” and jeopardize your most valuable possession (your home).
  • • Delays in scheduling are common within the roofing industry. We cannot fully account for weather delays. At other times, we have experienced material shortages/delays.
  • • The size of the roofing crew assigned to your project. On average, a roof system replacement crew is 5-8 workers. On larger projects, it is not unusual to see a dozen or more workers, working as a team, replacing your roof system.



  • • Small-sized residential roof system replacements: 1-3 days or more.
  • • Medium-sized residential roof system replacements: 2-5 days or more.
  • • Large-sized residential roof system replacements: 3-7 days or more.
  • • Extra-Large (apartments, condominiums, etc.) sized residential roof system replacements: 14-90 days or more.

Saint Roof holds the highest credentials Certainteed Roofing has to offer. We align our Integrity Roofers with the Certainteed Integrity Roof System process, and this gives us the results that helps us all sleep well at night. There are though parts of the roofing system which Certainteed does not produce. Wherever this is the case, Saint Roof will utilize the highest qualities of materials necessary to complete your roof replacement system.

Yes, when replacing your roof with the Certainteed Integrity Roof System, (which will address every aspect of the roof system at today’s’ residential roofing’s’ highest standards) you will be provided you with an industry leading Warranty Coverage.

Yes, we offer free roof estimates through our online instant estimator.

After you’ve received your free instant roof estimate, contact us to schedule your roof assessment. Our 4-Point Roof Assessment will raise our mutual awareness regarding the current state of your roof. This will help us to determine a proper outline/proposal for your roof system replacement.

Yes, Monday – Friday, 9 AM – 5 PM. Please give us a call. We love to talk about roofing.

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