MI Roofing Contractor common mistakes
MI Roofing Contractor · Understand the traps and how to avoid them.
Sizing roof ventilation by habit ("one vent per 300 sq ft") instead of calculating net free area against the actual attic floor area and ceiling/roof slope combination.
Ventilation questions are the most calculation-heavy item on the code portion, and candidates memorize a single ratio without the slope and vapour-retarder exemptions that change the answer to 1/150 or 1/300.
What to do instead
For every practice problem, write the three-step chain: net free area required = attic floor area / 150 (or / 300 only when a Class I/II vapour retarder is present and the slope window is satisfied), then split 50/50 intake-to-exhaust, then subtract for screened/louvered vent reduction factors. Drill until the exemption conditions are recited before the numbers.
Treating steep-slope and low-slope as interchangeable - specifying standard asphalt shingles on a 2:12 or lower porch/shed roof without the required underlayment or a change to a low-slope membrane.
Candidates picture a typical house roof and skip the slope check; the 2:12 break point and the double-underlayment rule for 2:12 to 4:12 are easy to lump together from memory.
What to do instead
Memorize the slope ladder as a single line: below 2:12 = low-slope membrane only; 2:12 up to 4:12 = shingles permitted only with double underlayment per the code/manufacturer; 4:12 and above = standard underlayment. Practise reading slope off a rise/run sketch and converting before choosing materials.
Placing shingle fasteners above the nail line, in the exposure, overdriven, or at the panel edge - and answering fastener questions on count alone.
Count (4 vs 6) is the number candidates memorize; placement rules, edge distance, and the prohibition on staples are learned as trivia and never visualised on a shingle.
What to do instead
Draw a shingle once and label it: nail line 1/4 in. to 1 in. above the exposure line, fasteners not less than 1/4 in. from any edge, high-wind zones add fasteners per the table, staples not permitted. Answer placement questions by referencing that drawing, not the count.
Detailing sidewall and roof-to-wall junctions with a single piece of flashing or surface-caulked step flashing instead of individually stepped, lapped flashing integrated with the weather barrier and a kick-out at the eave.
Leak-callback scenarios in the field are frequently fixed with sealant, so candidates default to that and forget the water-shedding principle of shingle-lap-over-flashing-lap-over-underlayment.
What to do instead
Rehearse the assembly order out loud for each penetration type: underlayment, then step flashing woven with each shingle course, then housewrap/membrane lapped over the flashing leg, then counterflashing 4 in. minimum above the roof surface, plus a kick-out diverter at the wall base. Never accept sealant as the primary defence in an answer option.
Answering licensing questions as though Michigan issues a stand-alone "roofing licence," or skipping the distinction between the residential builder licence and the maintenance-and-alteration contractor licence held through a qualifier.
Most states are described loosely in study material, and candidates generalise; Michigan regulates roofing work under the residential builder/maintenance-and-alteration framework administered by the state licensing agency, not under a roof-specific credential.
What to do instead
Build a one-page licence card: licence type, qualifying officer requirement, what work each category may and may not perform, and the consequence of contracting without it. When a stem mentions a licence class, match it to the scope of work described before choosing.
Ignoring eave ice-dam protection or applying it only to the overhang, rather than installing an ice barrier from the eave edge to at least 24 in. inside the warm wall line in the required climate zones.
Southern-trained intuition treats ice damming as an insulation problem only; the membrane requirement is triggered by winter design temperature, and the 24-in. inside-the-wall dimension is the part most often dropped.
What to do instead
Memorise the trigger (average January temperature of 25°F or lower, or a history of ice damming) and the geometry (from the lowest roof edge to a line 24 in. horizontally inside the interior warm wall). For Michigan conditions, treat the ice barrier as default rather than optional.
Quoting jobs by adding a percentage to material cost and calling it profit, and leaving tear-off, disposal, permits, and underlayment/accessories out of the takeoff.
Material-plus-percentage is how many small operators actually price, and the difference between markup on cost and margin on price is a classic arithmetic trap that reverses the right answer.
What to do instead
Price from a full takeoff with separate lines for tear-off, dumpsters, permits, underlayment, flashing, vents, and labour hours; then convert margin to a multiplier (price = cost / (1 - margin)) and check the result by computing gross margin back out. Do ten conversion drills so the direction of the formula is automatic.
Missing the statutory notice and deadline items in contract questions - the buyer's cancellation window on a home-solicitation sale and the notice-of-furnishing deadline for a subcontractor or supplier protecting lien rights.
These are pure recall items with short, unforgiving time periods, and candidates conflate them with general contract-law concepts like offer and acceptance.
What to do instead
Keep a dated timeline card for each statutory clock (cancellation period, notice of furnishing, lien recording), and for each practice question write the trigger event first, then count the days. If a stem describes a supplier or sub who has not been paid, check the notice deadline before considering any other answer.
Working a residential roof without a fall-protection system, or relying on the "safety monitor" alone on a roof where it is not permitted.
Residential roofers routinely work at heights for short durations and convince themselves that low slope, short duration, or experience substitutes for a system; the trigger height and the conditions for each system type get blurred.
What to do instead
Commit the decision tree to memory: fall protection is required at the trigger height, and the choices are guardrail, safety-net, personal fall-arrest, or - only where the specific conditions and worker-training requirements are met - a warning line with safety monitor. For each scenario, state the roof height, slope, and access first, then select the one system the standard allows.
Setting extension ladders by eye - wrong pitch, top not extending past the roof edge, or not secured - and answering ladder questions on the "three points of contact" phrase alone.
Ladder rules are learned as slogans, so the numerical set-up dimensions and the securing requirement are never attached to the slogan.
What to do instead
Memorise the numbers as a set: 4:1 rise-to-run pitch, top extending a safe distance above the landing surface, secured against displacement, and three points of contact maintained while climbing. In practice questions, check the ladder set-up dimensions before evaluating anything else about the access scenario.