Choosing the best roofing system for your Minnesota building can be tricky, especially when considering your budget and flat roof costs. Our roofs take direct hits from heavy snow, ice, rain, powerful winds, and lots of freeze-thaw cycles throughout the year. While sloped roofs may be the first option that comes to mind for most homeowners, commercial flat roofing systems and low-slope roofing have remained popular choices for businesses and residential properties alike.
Many people envision roofs as being sloped, however flat roofs are anything but flat. As part of the design process, they should always be built to allow for proper drainage with a slight slope toward drains, scuppers, or gutters.
When installed correctly, maintained regularly, and paired with the right materials, flat roofs can perform incredibly well in Minnesota.
However, not every roofing material, drainage solution, or installation option is ideal for your building.
What Is a Flat Roof?
While we typically think of roofs as sloped, a flat roof is technically a low slope roofing system. They don’t drain as quickly as steep roofs, so rain and melting snow take longer to find the nearest exit. Low slope roofing in Minnesota is especially popular for commercial buildings because it balances durability with efficient drainage when properly engineered.
Flat roofs can be found on many types of residential and commercial buildings, including:
- Garages
- Home additions
- Apartment buildings
- Porches
- Industrial buildings
Flat Roof vs. Low-Slope Roof
As we mentioned above, flat roofs and low slope roofs are technically the same thing. However, most so-called “flat roofs” do have a slight slope that allows water to drain off of the roof. Whether it drains into gutters, internal roof drains, scuppers, or tapered insulation systems, proper drainage is critical on low slope roofing systems in Minnesota. Standing water can lead to more leaks, a shorter lifespan, and put more stress on your building during the winter.
Understanding the pros and cons of flat roofing helps property owners make the right decisions based on budget, maintenance needs, and long-term performance. Flat roofs in Minneapolis must be designed to handle extreme freeze-thaw cycles, heavy snow loads, and seasonal ice buildup common in the region. Common flat roof disadvantages include drainage challenges, higher maintenance requirements, and reduced lifespan compared to some pitched roofing systems.
Why Flat Roofs Need Different Materials Than Sloped Roofs
Roofs with higher slopes allow water to flow off of the roof quickly. This is why traditional asphalt shingles work so well for residential roofing. In fact, the Minnesota Residential Code requires asphalt shingles to be used only on slopes of 2:12 or greater, which means they are not an approved option for truly flat or low-slope applications.
Flat roofs need materials that can hold up under much harsher conditions. Water pools longer on flat roofs, they accumulate more snow in the winter, and they’re exposed to more UV sunlight. Flat roofing materials are engineered to be able to handle standing water, heavy snow loads, UV exposure, and freeze-thaw cycles.
Benefits of Flat Roofing in Minnesota
Flat roof benefits include lower installation complexity, usable rooftop space, and easier access for maintenance and inspections.
Lower Installation Cost in Some Applications
The material and labor costs can make installing a new flat roof less expensive than building up a complex, multi-dimensional sloped roof. However, the price will still vary depending on the roofing material, insulation needs, drainage system, and other factors.
Easy Access for Repairs and Maintenance
Maintenance and repairs are another area where flat roofs have an advantage. Contractors can move around easily when on a flat roof versus a steep slope. Having easy access to the roof makes it simpler to:
- Perform roof inspections
- Clear drains
- Maintain HVAC units
- Inspect flashings
- Complete flat roof repairs
- Clear debris
Provides Additional Space
Installing a flat roof can open up all kinds of possibilities for your home or commercial building. Some things you could add to a flat roof include:
- Rooftop patios/decks
- Outdoor gathering area
- Green roof
- Solar panels
- HVAC units
- Other mechanical equipment
Modern Look
Another reason why many homeowners are swapping out their traditional roof for a flat roof is curb appeal. Many homeowners have also installed flat roofs on additions in order to match with modern design features while gaining space on their roof for decks or outdoor kitchens.
Energy Efficient Flat Roofing Materials
Thanks to advances in technology, many flat roofing materials are designed with energy efficiency in mind. For instance:
- TPO roofing comes in white which can reflect sunlight and heat
- PVC roofing is also highly reflective and very durable
- EPDM roofing is typically black, which means it absorbs more sunlight. However, when installed with proper insulation, it can still be effective in cold climates like Minnesota
No matter which type of membrane you choose, having the right insulation installed is equally important for maximizing energy efficiency.
Drawbacks of Flat Roofing in Minnesota
Ponding Water and Drainage
Drainage is one of the biggest downsides of flat roofs. Flat roofs are designed to drain, but water should always be flowing toward a drain or away from the building. Ponding water can lead to:
- Faster membrane degradation
- Greater chance of roof leaks
- Unnecessary weight on your roof
- Shorter roof lifespan
Good flat roof drainage is achieved by installing the roof with a slight slope, having working drains, keeping gutters clear, and having your roof inspected regularly.
Snow and Ice Accumulation
Minnesota winters can also create problems for flat roofs. Heavy snow load and drifting snow and ice can put extra pressure on the roof membrane and building structure. While flat roofs are designed to manage water run-off, too much snow and ice can still cause problems.
Your roofing system should be engineered to support the weight of snow and your building should drain as soon as the snow starts to melt. Minnesota’s snow load requirements reflect just how serious winter weight can be.
According to the University of Minnesota Extension, residential roof snow loads are set at approximately 42 psf in northern Minnesota and around 35 psf in southern Minnesota on average. Flat and low-slope roofs must be engineered to handle these loads.1
Requires More Maintenance
Although they are low maintenance when they’re functioning correctly, flat roofs can require more maintenance than pitched roofs. Ideally, your flat roof maintenance should include:
- Annual inspections by a professional roofing contractor
- Clean drains and scuppers
- Removal of leaves and debris
- Checking membrane seams
- Flashing inspections
- Monitoring snow and ice
Won’t Last Quite as Long
The lifespan of your flat roof will depend on the material you choose, the quality of installation, and how well you maintain your roof. Some flat roofs may only last around one decade and a half to two decades. However, high-quality membrane materials can last 30 years or more with proper maintenance. This is why hiring experienced flat roof contractors in Minnesota is so important.
Difficult to Find Leaks
Lastly, roof leaks aren’t always easy to identify on flat roofs. Since water can run from its original entry point underneath the roofing membrane, you might not notice the leak until it’s too late.
For example, the roof leak begins on one side of the roof but runs under the membrane and into a wall cavity on the other side. You may notice a water stain near the interior wall, however the leak is actually on the opposite side of the roof. Getting low slope or flat roof repair as soon as you notice water damage can help limit the problem.
Best Flat Roof Materials for Minnesota
EPDM Roofing
EPDM roofing, or ethylene propylene diene monomer, is one of the oldest membrane materials used on commercial roofs and residential low-slope roofs. EPDM is a synthetic rubber membrane that excels in cold climates. Because the material remains flexible during thermal changes, EPDM can stretch as buildings naturally expand and contract.
TPO Roofing
TPO roofing is one of the most popular commercial flat roofing options. Not only is it durable, but it’s also very energy efficient. TPO sheets are installed with seams welded together to create a waterproof system. Because TPO sheets are usually white, they also reflect sunlight and reduce temperatures on your roof.
PVC Roofing
PVC roofing offers nearly all of the benefits of TPO with improved resistance to chemicals, grease, and other industrial byproducts. Many restaurant roofs are PVC because of its incredible grease resistance. Other commercial buildings with active chimneys or exhaust vents on the roof may also benefit from PVC roofing.
Modified Bitumen Roofing
Modified bitumen roofing is essentially asphalt surrounded by either fiberglass or polyester for reinforcement. Modified bitumen roofing is common on garage roofs, porch roofs, home additions, and other low slope roofing projects.
Built-Up Roofing
Built-up roofing (BUR) is one of the oldest roofing systems in commercial roofing. Also known as “torch-down roofs,” built-up roofs are multiple layers of roofing felt and asphalt.
| Material | Best For | Pros | Cons |
| EPDM | Residential low-slope areas, northern climates | Flexible, proven, fewer seams possible | Usually black, appearance less modern |
| TPO | Commercial roofs, energy efficiency | Reflective, heat-welded seams, popular | Installation quality matters |
| PVC | Restaurants, industrial buildings, premium projects | Chemical/grease resistant, durable | More expensive |
| Modified bitumen | Small low-slope sections | Rugged, waterproof, good for subtle slope | More seams |
| Built-up roofing | Commercial flat roofs | Multi-layer protection | Heavy, labor-intensive |
What Affects the Cost of a Flat Roof?
Here are some factors that can affect the price of your roof.
Roof Size
Square footage is the biggest driver of cost because large roofs require more materials and man-hours. That being said, economies of scale can come into play on large commercial roofs.
Type of Material
You’ll pay more for premium material like PVC and additional features like insulation.
Removal of Existing Roof
If your roof needs to be replaced, account for demolition and removal costs.
Insulation
While not technically part of the roof itself, insulation greatly affects energy efficiency. Many factors determine how much insulation is needed on your roof.
Drainage
Installing roof drains involve adding tapered insulation, extra drains, or redesigning existing scuppers.
Roof Penetrations
Roof vents, skylights, HVAC units, and plumbing stacks all add complexity to roofing projects. Each penetration needs specialized flashing to prevent leaks.
Parapet Walls
Parapet walls may require additional flashing and waterproofing at intersections.
Roof Height
Roofs that are hard to access will require lifts or cranes. These can significantly increase your installation costs.
Commercial vs. Residential
Commercial roofing projects are typically much larger than residential roofs. This typically means additional drainage, HVAC units, and complicated building codes.
Warranty level
Manufacturer and contractor warranties vary significantly by material and installer. Longer or more comprehensive warranty coverage may affect overall project cost.
Flat Roof vs. Pitched Roof: Which Is Better?
| Factor | Flat Roof | Pitched Roof |
| Water drainage | Requires engineered drainage | Naturally sheds water |
| Snow shedding | Snow can sit longer | Snow sheds more easily |
| Maintenance access | Easier | Harder on steep slopes |
| Style | Modern/commercial | Traditional/residential |
| Usable rooftop space | Yes | Limited |
| Material options | EPDM, TPO, PVC, mod bit, BUR | Asphalt, metal, cedar, slate, tile |
When a Pitched Roof Is the Better Choice
Pitched roofs naturally shed water and snow more quickly than flat roofs, which makes them a strong option for many Minnesota homes. Because rain and melting snow flow off a steep slope quickly, pitched roofs are generally less vulnerable to ponding water and ice buildup. They’re also compatible with a wide range of materials, including asphalt shingles, metal roofing, cedar shakes, slate, and tile. For traditional residential properties where a steep roofline fits the architecture, a pitched roof is often the more practical long-term choice.
When a Flat Roof Is the Better Choice
Flat roofs can be a better fit for commercial buildings, modern homes, additions, garages, porches, apartment complexes, and institutional buildings where a pitched roof doesn’t suit the design or function. They offer usable rooftop space for HVAC units, solar panels, rooftop patios, and green roofing systems. They’re also easier for contractors to access and service, which can reduce maintenance costs on larger commercial properties. When properly engineered for Minnesota’s snow loads and freeze-thaw cycles, flat roofs can be a durable and cost-effective solution.
When Does My Flat Roof Need Replacement or Repair?
Like any roof in Minnesota, flat roofs degrade with age and experience. By knowing the signs that your roof needs repair, you can stop minor issues from becoming large (and costly) problems.
Water That Doesn’t Drain
After a heavy rainstorm, some ponding water is normal. However, if large puddles remain on your roof for more than two days, you may have a drainage problem. Ponding water not only damages the roof membrane faster but also leaves your building vulnerable to leaks. In many cases, ponds form due to improper roof slope, meaning you’ll have to correct the slope rather than apply a simple patch.
Read More: Storm Damaged Roof FAQs
Cracks or Blisters
Exposure to the elements, routine foot traffic, and general material wear can cause damage to roofing membranes over time. Without prompt flat roof repair, these small tears can allow water to get underneath the membrane and into your building.
Separating Seams
Roof membranes are usually installed in sections that are sealed together. If your roof has open seams or loose flashing, water can seep into your building at these weak points.
Water Stains On the Interior
While brown water spots on your ceilings are easy to identify, not all water stains are so obvious. If you notice bubbling paint or wallpaper, peeling drywall, or moisture on the inside of your building, you may have a roof leak. Since roofing leaks can spread throughout your roof before dripping onto the interior, it’s best to let a professional assess the situation.
You’ve Made Many Repairs to Your Roof
Every roof will need occasional repairs. However, if you constantly find yourself patching the same area or fixing leaks, it may be time to replace your roof. While some leaks are caused by damaged roofing material, many are caused by poor drainage. By fixing your roof’s drainage, you may improve your roof’s overall performance and reduce your maintenance costs.
Are Flat Roofs Actually Worth It for Minnesota Businesses?
Flat roofs can be a smart investment for Minnesota property owners, but only when they are designed, installed, and maintained correctly. The biggest advantages are usable rooftop space, modern appearance, easier contractor access, and flexible material options that can handle northern climates well. The biggest challenges are drainage, snow load management, ponding water, and more frequent maintenance compared to pitched roofs.
For most homeowners and commercial property owners, the right answer comes down to five things: roof structure, material selection, insulation, drainage design, and a long-term maintenance plan.
A flat roof that is engineered for Minnesota’s freeze-thaw cycles and snow loads combined with regular inspections can perform reliably for decades. One that isn’t will cost significantly more to maintain and repair over time.
If you’re weighing your options or already noticing signs of wear on an existing flat roof, the best next step is a professional inspection.
Contact Summit Construction Group Today to Learn More About Flat Roofing
For your business’ next roofing project, contact the experts at Summit Construction Group. Our experienced team can inspect your roof’s condition, drainage system, insulation, ventilation, and structure to recommend your best options.
From low slope roof repair to total roof replacements, we offer a variety of commercial flat roofing services for Minnesota businesses. Call us today to schedule your free roof inspection or consultation.
Sources:
- Kevin A. Janni, “Prevent Roof Collapses From Snow and Ice,” University of Minnesota Extension, https://extension.umn.edu/farm-safety/prevent-roof-collapse, reviewed in 2026.