Flat roofs are a popular option for Michigan homes and commercial buildings, offering a modern aesthetic and easier access for maintenance. But summer can be especially harsh on flat roofing systems and not always in ways that are easy to spot.
Unlike sloped roofs that shed water and heat more efficiently, flat roofs absorb and retain more heat, making them vulnerable to issues that could lead to structural problems, leaks, or even safety concerns if left unchecked.
Let’s look at the most common heat-related issues Michigan homeowners should watch for during the summer and what you can do to prevent them.
1. Thermal Expansion and Contraction
Flat roofs take the brunt of direct sunlight, especially during Michigan’s hot, humid summer months. As the roofing materials heat up, they expand, and when temperatures drop at night, they contract.
This continuous thermal cycling stresses seams, membranes, flashing, and joints. Over time, the movement can cause:
- Cracking or splitting in roofing materials
- Seam separations
- Loosening of flashing
- Premature wear of roof coatings
👉 Learn more about heat-related degradation in Cutting-Edge Ways to Make Your Roof More Energy Efficient
2. Blistering and Bubbling
When moisture becomes trapped under the roofing membrane, and the roof heats up, that moisture turns to vapor and has nowhere to go. This causes blisters or bubbles to form in the membrane.
Blistering might seem like a cosmetic issue at first, but it weakens the structure of the roof and opens the door for future leaks, especially when that blister eventually pops during summer storms or foot traffic.
3. Ponding Water + Sun = Disaster
Flat roofs often struggle with drainage, and even a slight dip can cause water to pond after heavy summer rains. If that water sits for more than 48 hours, it heats up under the sun and creates the perfect environment for:
- Algae and mold growth
- Roof membrane degradation
- Premature failure of seams and flashings
- Structural stress beneath the pooling area
👉 Prevent this by combining proper drainage systems with regular maintenance, as outlined in
Flat Roof Tips
4. UV Degradation
Even on cooler days, ultraviolet (UV) radiation wears down roofing materials. Flat roofs, with their wider sun exposure and less natural shade, are more vulnerable to:
- Surface erosion
- Fading and brittleness of materials
- Loss of elasticity in rubber or TPO membranes
This weakens your roof’s ability to handle expansion, storms, and impact from debris. By late summer, these issues can quietly set the stage for costly fall or winter repairs.
5. Higher Indoor Temperatures and Energy Costs
Because flat roofs absorb and trap more heat, it often results in higher interior temperatures especially if your insulation isn’t up to par. That means your HVAC system works harder to keep your home or building cool.
If your home feels hotter this summer than usual, it may not be your AC, it might be your roof.
👉 Check your attic and roofline for clues with
How to Check If Roof Insulation Is Working
6. Flashing Failures Around Edges and Roof Penetrations
Flat roofs rely heavily on flashing to keep water out at the edges, vents, skylights, and other penetrations. Summer heat dries out sealants and can warp metal, leading to:
- Small, slow leaks
- Pooling around vulnerable joints
- Insulation damage hidden beneath the surface
This kind of failure is often invisible until it becomes a major leak, especially after the first fall storm or heavy rainfall.
👉 Curious what roofers look for when checking these areas? Read
What to Expect in a Roofing Inspection
How to Protect a Flat Roof During Michigan Summers
Here’s what you can do right now:
✅ Inspect regularly – especially after storms or extreme heat
✅ Check for ponding water after every rainfall
✅ Keep drains clear of leaves, debris, and bird nests
✅ Monitor interior ceilings for signs of leaks or discoloration
✅ Consider reflective roof coatings or white membranes to reduce heat absorption
✅ Book a professional inspection to catch what you can’t see
Don’t Wait Until It Leaks
Flat roofs don’t often show signs of failure until it’s too late. Heat-related damage accumulates silently and the costs of inaction rise quickly.
At Weather Vane Roofing, we specialize in helping Michigan homeowners maintain and repair flat and low-slope roofing systems, especially when summer heat puts pressure on your property.
👉 Need a professional opinion? Book your free roof inspection today
Contact Us
Michigan summers can be brutal on your flat roof, even if there’s no obvious damage at first glance. From hidden moisture problems to rising energy bills and weakened seams, the cost of ignoring the heat can be high. But with the right maintenance and regular inspections, your roof can beat the heat and be ready for fall.
