What roofing system is best for Minnesota?
For most Twin Cities homes, a Class 4 impact-resistant architectural shingle system gives the best balance of cost, hail resistance and ice-dam protection. Standing seam metal lasts the longest and sheds snow. For flat commercial roofs, TPO and EPDM are the most common and are chosen by building use, foot traffic and budget.
What does Minnesota building code require for a new roof?
Minnesota's Residential Code (MN Rules Ch. 1309) adopts the 2018 International Residential Code with state amendments. For shingle roofs it requires an ice barrier from the eave to at least 24 inches inside the exterior wall, underlayment over the deck, drip edge at eaves and rakes, and attic ventilation. Most Twin Cities cities, including Minneapolis and St. Paul, require a permit for a full re-roof. Repair King pulls the permit.
Can you put a new roof over my old one in Minnesota?
Code limits re-covering: you can't re-cover over two or more existing layers, or over a roof that's wet or badly deteriorated. Even when it's allowed, we recommend a full tear-off. It's the only way to inspect the deck, add ice & water barrier at the eaves and get a full manufacturer warranty.
Are Class 4 impact-resistant shingles worth it?
In a hail-prone market like the Twin Cities, often yes. They carry the highest impact rating (UL 2218 Class 4), stay flexible in cold, and many insurers offer premium discounts for them. Ask your agent what your policy offers. They are impact-resistant, not hail-proof.
How long does a roof last in Minnesota?
Typical ranges: architectural shingles 25–30 years, Class 4 shingles 30–40, standing seam metal 40–70, TPO 20–30, EPDM 25–35 and modified bitumen 20–30. Attic ventilation, installation quality and hail exposure matter as much as the product.
What causes ice dams, and which roof layer stops them?
Heat escaping into the attic melts snow, and the water refreezes at the cold eave. Balanced attic ventilation and insulation prevent them. The ice & water barrier at the eaves stops the water that backs up from getting into the house.
Full technical spec sheet (all systems, all layers)
Architectural Asphalt Shingle System
The roof on most Minnesota homes, and the one hail hits hardest. A shingle roof is a system: the shingles you see are only the top of eight layers that keep water, ice and wind out. Typical Minnesota lifespan: 25–30 years. Minimum slope: 2:12 min · 4:12+ ideal.
- Architectural shingles: Laminated fiberglass-mat shingles with ceramic granules. They block UV and shed water. On their own they are not waterproof; the layers below are. Code: Installed to the manufacturer's instructions and IRC R905.2. Repair King: Installed to full manufacturer system specs, so the enhanced manufacturer warranty is available. (IRC R905.2, ASTM D3462)
- Ridge vent + hip & ridge cap: Exhaust vent at the peak with matching cap shingles. It lets hot, wet attic air out, which is the #1 fix for Minnesota ice dams and early shingle wear. Code: Net free vent area of 1/150 of the attic floor (1/300 when balanced). Repair King: Intake and exhaust sized for your attic, so the airflow is balanced top to bottom. (IRC R806.2)
- Starter strip: A factory-sealed first course at the roof edges. It locks the first row of shingles down, which is where wind lifts a roof first. Code: At the eaves, per the manufacturer. Repair King: Along the eaves and the rakes. (IRC R905.2.6)
- Synthetic underlayment: A tough woven secondary water barrier over the whole deck. It keeps water out if shingles blow off, and gives the crew safe footing. Code: Felt or synthetic over the whole deck. Two layers on 2:12–4:12 slopes. Repair King: Synthetic, never felt, over the entire deck. (IRC R905.1.1, ASTM D226 / D4869 / D8257)
- Ice & water barrier: A self-sealing rubberized membrane that seals around every nail. Minnesota's freeze-thaw ice dams push water uphill, and this is what stops it. Code: From the eave edge to at least 24 in. inside the exterior wall. Repair King: At the eaves past the code line, plus every valley and around chimneys, walls and penetrations. (IRC R905.1.2, ASTM D1970)
- Metal drip edge: Pre-finished metal at the roof edges. It sends water into the gutter instead of into your fascia and deck. Code: Required at eaves and rake edges. Repair King: New drip edge on every eave and rake, never reused. (IRC R905.2.8.5)
- Flashings & pipe boots: Step, counter, valley and pipe flashing where the roof meets walls, chimneys and vents. Most leaks start here, not in the middle of the roof. Code: Flashing required at walls, valleys and penetrations. Repair King: New step flashing and pipe boots on every replacement, never reused. (IRC R903.2, IRC R905.2.8)
- Roof deck (OSB / plywood): The structural wood sheathing everything is nailed to. Soft, rotted or delaminated boards mean nails don't hold. Code: APA-rated sheathing fastened to the framing. Repair King: Every sheet walked and checked at tear-off. Bad wood is replaced at the price we give you up front. (IRC R803)
Class 4 Impact-Resistant Shingle System
Same eight-layer system, with shingles built to take a 2-inch steel ball dropped from 20 feet without cracking. Polymer-modified (SBS) asphalt stays flexible in cold, so it bruises less in our hail. Typical Minnesota lifespan: 30–40 years. Minimum slope: 2:12 min · 4:12+ ideal.
- Class 4 impact-resistant shingles: SBS polymer-modified shingles rated UL 2218 Class 4, the highest impact rating. They flex instead of cracking when hail hits. Code: Installed to the manufacturer's instructions and IRC R905.2. Repair King: Installed to full manufacturer system specs, so the enhanced manufacturer warranty is available. (UL 2218, IRC R905.2)
- Ridge vent + hip & ridge cap: Exhaust vent at the peak with matching cap shingles. It lets hot, wet attic air out, which is the #1 fix for Minnesota ice dams and early shingle wear. Code: Net free vent area of 1/150 of the attic floor (1/300 when balanced). Repair King: Intake and exhaust sized for your attic, so the airflow is balanced top to bottom. (IRC R806.2)
- Starter strip: A factory-sealed first course at the roof edges. It locks the first row of shingles down, which is where wind lifts a roof first. Code: At the eaves, per the manufacturer. Repair King: Along the eaves and the rakes. (IRC R905.2.6)
- Synthetic underlayment: A tough woven secondary water barrier over the whole deck. It keeps water out if shingles blow off, and gives the crew safe footing. Code: Felt or synthetic over the whole deck. Two layers on 2:12–4:12 slopes. Repair King: Synthetic, never felt, over the entire deck. (IRC R905.1.1, ASTM D226 / D4869 / D8257)
- Ice & water barrier: A self-sealing rubberized membrane that seals around every nail. Minnesota's freeze-thaw ice dams push water uphill, and this is what stops it. Code: From the eave edge to at least 24 in. inside the exterior wall. Repair King: At the eaves past the code line, plus every valley and around chimneys, walls and penetrations. (IRC R905.1.2, ASTM D1970)
- Metal drip edge: Pre-finished metal at the roof edges. It sends water into the gutter instead of into your fascia and deck. Code: Required at eaves and rake edges. Repair King: New drip edge on every eave and rake, never reused. (IRC R905.2.8.5)
- Flashings & pipe boots: Step, counter, valley and pipe flashing where the roof meets walls, chimneys and vents. Most leaks start here, not in the middle of the roof. Code: Flashing required at walls, valleys and penetrations. Repair King: New step flashing and pipe boots on every replacement, never reused. (IRC R903.2, IRC R905.2.8)
- Roof deck (OSB / plywood): The structural wood sheathing everything is nailed to. Soft, rotted or delaminated boards mean nails don't hold. Code: APA-rated sheathing fastened to the framing. Repair King: Every sheet walked and checked at tear-off. Bad wood is replaced at the price we give you up front. (IRC R803)
Standing Seam Metal Roof System
Concealed-fastener steel panels with raised seams. Snow slides off, there are no exposed screws to leak, and it outlasts two or three shingle roofs. A top pick for Minnesota cabins, modern homes and low-slope porches. Typical Minnesota lifespan: 40–70 years. Minimum slope: 1/4:12 min (standing seam).
- Standing seam panels: Continuous steel panels with seams locked above the water line. There are no exposed fasteners and no holes through the roof surface. Code: Metal roof panels installed to IRC R905.10 and the manufacturer. Repair King: Panels sized for your roof, with continuous runs from eave to ridge wherever possible. (IRC R905.10, ASTM A792)
- Snow guards: Clamp-on bars that stop a whole winter of snow from sliding off onto walkways, decks, cars and people all at once. Code: Not required by code. Repair King: Placed over entries, walkways and lower roofs as standard Minnesota practice. (MN practice)
- Concealed clips: Hidden clips hold each panel while letting the steel expand and contract through Minnesota's 100°F+ temperature swings. Code: Fastened for design wind uplift. Repair King: Clip spacing tightened at the edges and corners, where uplift is highest. (UL 580 / ASTM E1592)
- High-temp ice & water membrane: Metal roofs run hot in summer, so we use a high-temperature self-adhered membrane that won't soften or bleed under the panels. Code: Underlayment per the manufacturer. Repair King: High-temp membrane over the entire deck, not just the eaves. (ASTM D1970)
- Trim, closures & vented ridge: Eave, rake and ridge trim with foam closures that keep out snow, bugs and wind-driven rain while the ridge still breathes. Code: Flashing at edges and penetrations. Repair King: Vented ridge closure, so the attic still exhausts under metal. (IRC R806.2)
- Roof deck: Solid wood sheathing, inspected and repaired before the membrane goes down. Code: APA-rated sheathing. Repair King: Walked and repaired at tear-off, priced up front. (IRC R803)
TPO Single-Ply Membrane System
The most-installed commercial flat roof in the country. A white, heat-welded thermoplastic membrane over tapered insulation that drains water off the roof and cuts summer cooling costs. Typical Minnesota lifespan: 20–30 years. Minimum slope: 1/4:12 min.
- TPO membrane: A reinforced white thermoplastic sheet. It reflects sun, resists ponding and punctures, and can be heat-welded again years later for repairs. Code: Thermoplastic single-ply per IBC 1507.13. Repair King: 60 mil minimum; 80 mil recommended where hail and foot traffic are heavy. (IBC 1507.13, ASTM D6878)
- Heat-welded seams: Seams fused with hot air into one continuous sheet. When done right, the seam is stronger than the sheet. Code: Seams per manufacturer. Repair King: Every seam probed at the end of each day. (Manufacturer)
- Cover board: A dense board under the membrane that takes the hits from hail and foot traffic so the insulation below doesn't crush. Code: Optional. Repair King: Recommended on most Minnesota projects for hail resistance. (FM / UL)
- Tapered polyiso insulation: Foam insulation boards cut in a slope that move water to the drains. No more ponding, and it adds the R-value the energy code requires. Code: Minimum slope 1/4:12. Continuous insulation to the MN Energy Code. Repair King: Tapered design with crickets at every drain and curb. (IBC 1507.13.1, MN Energy Code)
- Vapor retarder: Stops warm, humid indoor air from condensing inside the insulation during a Minnesota winter. Code: As required by design and climate zone. Repair King: Specified for your building's use and humidity. (MN Energy Code)
- Structural deck: The steel, wood or concrete deck that carries the roof and Minnesota's snow loads. Code: Designed for local snow load (50 psf ground snow in the metro). Repair King: Deck inspected and repaired before the new system goes on. (MN Rule 1303.1700)
EPDM Rubber Membrane System
Synthetic rubber that stays flexible to -40°F, which is why it has protected Minnesota flat roofs for decades. Fully adhered or ballasted, with seams bonded with factory tape. Typical Minnesota lifespan: 25–35 years. Minimum slope: 1/4:12 min.
- EPDM membrane: Large, flexible sheets of synthetic rubber with few seams. It shrugs off UV and extreme cold. Code: Thermoset single-ply per IBC 1507.12. Repair King: 60 mil minimum, with a 90 mil option for longer service life. (IBC 1507.12, ASTM D4637)
- Seam tape & flashings: Factory seam tape and pre-molded corners at the seams and penetrations, which are the spots EPDM roofs leak from. Code: Seams per manufacturer. Repair King: Pre-molded pipe boots and corners, with no field-cut patches. (Manufacturer)
- Cover board: A dense board that protects the insulation from hail and foot traffic. Code: Optional. Repair King: Recommended on most projects. (FM / UL)
- Tapered polyiso insulation: Sloped insulation that drains the roof and meets the energy code. Code: Minimum slope 1/4:12. Continuous insulation to the MN Energy Code. Repair King: Crickets at every drain and curb. (IBC 1507.12.1, MN Energy Code)
- Structural deck: The deck that carries the roof and the snow load. Code: Designed for local snow load. Repair King: Inspected and repaired first. (MN Rule 1303.1700)
Modified Bitumen (SBS) Roof System
A multi-ply, reinforced asphalt roof. It's the modern version of built-up tar-and-gravel. It's tough underfoot and redundant, a strong pick for porches, garages and busy commercial roofs. Typical Minnesota lifespan: 20–30 years. Minimum slope: 1/4:12 min.
- Granulated cap sheet: The top ply, surfaced with granules for UV protection and grip. It's the layer that takes the weather. Code: Modified bitumen per IBC 1507.11. Repair King: SBS cap sheet, which stays flexible in cold. (IBC 1507.11, ASTM D6164)
- Base ply: A second waterproof ply, bonded under the cap. It gives two layers of protection against leaks. Code: Per the manufacturer. Repair King: A full 2-ply system, not a single ply. (ASTM D6163)
- Cover board: A dense board for impact and heat protection during install. Code: Optional. Repair King: Recommended. (FM / UL)
- Tapered polyiso insulation: Sloped insulation that drains the roof and meets the energy code. Code: Minimum slope 1/4:12. Repair King: Crickets at every drain and curb. (IBC 1507.11.1)
- Structural deck: The deck that carries the roof and the snow load. Code: Designed for local snow load. Repair King: Inspected and repaired first. (MN Rule 1303.1700)
