MN Roofing Contractor cheat sheet

Minnesota roofing contractors must hold a state residential building contractor or residential remodeler license (or be a qualifying roofer under one) before contracting for roof work; local permits are issued only to licensed entities.

Written contracts for residential roofing must include the contractor's license number, a description of work, and a notice of the homeowner's right to cancel; Minnesota law also requires a written contract for jobs over $500 under the home improvement statute.

Minnesota's contractor recovery fund can reimburse homeowners for losses caused by licensed contractors; claims require a court judgment or arbitration award and are capped per claimant and per licensee.

Mechanic's lien deadlines: a lien statement must generally be recorded within 120 days after the last labor or material is furnished; a pre-lien notice is required for subcontractors on improved property.

The statutory right to cancel a home solicitation sale gives the owner three business days; the cancellation notice must be given in writing and cannot be waived at the time of signing.

Minnesota requires a certificate of insurance showing at least $100,000 per occurrence and $300,000 aggregate for general liability, plus workers' compensation coverage where employees exist.

Independent contractor status depends on the right to control the manner and means of work; misclassifying employees exposes the contractor to unpaid payroll taxes, penalties, and workers' comp liability.

Bids and estimates are generally not binding offers unless stated; a signed contract supersedes prior estimates, so include scope, exclusions, and payment schedule in the contract itself.

Asphalt shingle slope limits: standard 3-tab and laminated shingles require a minimum 2:12 slope with underlayment; below 4:12, double underlayment or a self-adhering membrane is required.

Low-slope roofs (below 2:12) use built-up roofing, modified bitumen, EPDM, TPO, or PVC; standing-seam metal panels can go down to 1:12 or lower with proper seams and underlayment.

Ice dam protection membrane must extend from the eave edge to at least 24 inches inside the exterior wall line on heated structures; Minnesota code commonly requires it at all eaves.

Underlayment: No. 15 felt for slopes 4:12 and steeper, No. 30 felt for 2:12 to 4:12; synthetic underlayment must be rated for the slope and installed per manufacturer.

Fastener rules: 4 nails per shingle for slopes under 20 units, 6 nails for steeper roofs or high-wind areas; fasteners must penetrate at least 3/4 inch into wood decking or through the sheathing.

Ventilation balance: total net free vent area should be roughly 1/150 of the attic floor area, split between intake (soffit) and exhaust (ridge or roof) vents; 1/300 is allowed with a vapor barrier.

Metal roofing requires thermal movement allowances: panels expand and contract with temperature, so fasteners in slots and proper clip spacing prevent oil-canning and seam failure.

Flashing details: step flashing at sidewalls, counterflashing into masonry, and kick-out flashing at roof-wall intersections direct water into the gutter rather than behind siding.

Roof area = footprint area x slope multiplier: 4:12 = 1.054, 5:12 = 1.083, 6:12 = 1.118, 7:12 = 1.158, 8:12 = 1.202, 9:12 = 1.250, 10:12 = 1.302, 12:12 = 1.414.

Shingle bundles: 3-tab covers about 33.3 square feet per bundle (3 bundles per square); laminated shingles vary from 3 to 5 bundles per square, so verify the manufacturer's coverage.

Waste factor: add 10 percent for simple gable roofs, 15 percent for hip roofs with valleys, and up to 20 percent for complex cut-up roofs with multiple dormers and valleys.

Ridge cap coverage is typically 20 linear feet per bundle for standard ridge cap; starter strip covers about 100 linear feet per bundle.

Nail quantities: roughly 320 nails per square for 4-nail patterns and 480 per square for 6-nail patterns; order nails by the pound (about 150-160 roofing nails per pound for 1-1/4 inch).

Labor production rates: tear-off runs about 1 to 1.5 squares per worker-hour; shingle installation about 0.5 to 0.75 squares per worker-hour for a crew, adjusted for pitch and complexity.

Critical path for a re-roof: permit, material delivery, tear-off, deck inspection and repair, underlayment, flashing, shingles, ridge vent, cleanup, and final inspection; schedule inspections before covering.

Estimate contingency of 5 to 10 percent for hidden deck damage, and price change orders separately with written owner approval before proceeding.

OSHA requires fall protection at 6 feet or more in construction; roofing work on low-slope roofs triggers a fall protection plan, guardrails, safety nets, or personal fall arrest systems.

Ladder rules: extend 3 feet above the landing, set at a 4:1 slope, secure the top, and maintain three points of contact; ladders must be rated for the load and inspected before each use.

Minnesota adopts the Minnesota Residential Code (based on the IRC) and Minnesota Commercial Energy Code; roof assemblies must meet the state's ice barrier and attic ventilation requirements.

Ice barrier membrane is required from the eave to at least 24 inches inside the warm wall line; in Minnesota, many jurisdictions require it along all eaves regardless of overhang.

Drip edge is required at eaves and gables and must be installed under the underlayment at eaves and over it at rake edges, per manufacturer instructions and the IRC.

Attic ventilation must provide net free area of 1/150 of the attic floor space unless a balanced intake/exhaust system or vapor barrier allows 1/300.

Roof decking: minimum 3/8-inch or thicker wood structural panel rated for roof use, with fasteners spaced per code; re-nailing or re-sheathing may be required when the existing deck is deteriorated.

Jobsite hazard controls: keep a 10-foot clearance from power lines, use ground-fault protection on temporary power, and provide fall-protection training and rescue plans for workers using harnesses.