NM GS-21 Roofing Contractor cheat sheet

New Mexico roofing scope covers installation, repair, replacement, and coating of roof coverings and associated flashing, roof deck attachment, underlayment, and roof drainage components on residential and commercial structures.

Low-slope is conventionally a roof slope below 2:12 (rise:run); steep-slope is 2:12 and above. Asphalt shingles are generally limited to slopes of 2:12 or steeper, with a double underlayment requirement between 2:12 and 4:12.

Slope ratio = rise / run. Convert to percent by multiplying the ratio by 100 (4:12 = 33.3%); convert to degrees with arctangent.

Minimum slope for mechanically seamed metal roof panels is typically 1/4:12; for lapped, non-seamed metal panels and most through-fastened systems it is commonly 3:12.

Built-up roofing (BUR) requires a base sheet or ply over the deck and a minimum slope of 1/4:12; modified bitumen and single-ply membranes are also commonly specified at 1/4:12 minimum.

Ice dam protection membrane is required along eaves in areas subject to ice damming; the membrane extends from the eave edge to a point at least 24 inches inside the interior wall line.

Flashing scope includes step flashing at sidewalls, counterflashing, valley flashing, headwall and apron flashing, chimney flashing, and pipe boots; each penetration type requires a distinct detail.

Attic ventilation balance: net free vent area is typically 1/150 of the vented ceiling area, reduced to 1/300 when a vapor retarder is present or when balanced intake and exhaust vents are provided.

New Mexico construction contractors are licensed by the Construction Industries Division (CID) of the Regulation and Licensing Department; the division is organized into the Construction Industries, Manufactured Housing, and Electrical/Mechanical/Plumbing bureaus.

Contractor license classifications are defined by the work performed and by dollar threshold; a general contractor may perform or subcontract all phases, while a specialty contractor is limited to the specific trade scope of the license.

Roofing work in New Mexico falls under the specialty contractor classification for roofing; a contractor may not bid or contract for work outside the licensed classification.

Licensing requires proof of experience, passage of a trade and business/law examination, and a surety bond; qualifying party status ties the license to a named individual who must meet experience requirements.

Contractors must maintain a qualifying party; if the qualifying party leaves, the license is affected and the contractor must notify the division and obtain a replacement within the allowed period.

Licensed contractors must include the license number on contracts, bids, and advertising, and must carry workers' compensation insurance as required by New Mexico law.

The Construction Industries Division enforces the New Mexico building codes adopted by rule, including the IRC and IBC families with New Mexico amendments; local jurisdictions may adopt and enforce their own codes.

Unlicensed contracting is a violation subject to administrative penalties and may bar the contractor from recovering compensation for the work performed.

New Mexico gross receipts tax (GRT) is imposed on the seller for the privilege of doing business; it is not a true sales tax, though it is commonly passed to the customer. Rates vary by location because local option and municipal taxes are added to the state rate.

Contractors may deduct receipts from the sale of construction services on real property if the contractor paid GRT on the materials, or may instead pay GRT on the materials and deduct the service; the choice must be applied consistently.

Change orders must be in writing, signed by the owner, and must state the scope change and the resulting price and time adjustment before the work proceeds.

A written contract should identify parties, scope, price and payment schedule, start and completion dates, change-order procedure, warranty terms, lien rights, and dispute resolution.

Retainage is commonly 5 to 10 percent of each progress payment; the contract should specify the retainage percentage, the conditions for release, and the release timeline.

Mechanic's lien rights in New Mexico are governed by statute; a claimant must generally record a claim of lien within 120 days after the last furnishing of labor or materials and must enforce the lien by suit within the statutory period.

Payroll requirements: employers must pay at least the applicable minimum wage, provide the required pay frequency, and carry workers' compensation insurance for employees; misclassifying employees as independent contractors creates liability for taxes and premiums.

A bid estimate should separate labor, material, equipment, overhead, and profit; markup applied to cost is not the same as gross margin, and margin = (price - cost) / price.

OSHA fall protection for residential roofing under 29 CFR 1926.501(b)(13): workers engaged in roofing activities on slopes greater than 4:12 must use fall protection, with limited exceptions; conventional fall protection includes guardrail systems, safety net systems, and personal fall arrest.

Fall arrest systems must limit maximum arresting force to 1,800 pounds and prevent free fall of more than 6 feet; anchorages must support at least 5,000 pounds per worker or be designed by a qualified person.

Ladder duty rating must equal or exceed the combined weight of worker and tools; the 4:1 rule sets the setup angle, with the base one-quarter of the working length from the wall, and extension ladders must extend 3 feet above the landing.

Ladder inspection, three points of contact, and securing the top of the ladder are standard practice; portable ladders must not be loaded beyond their rated capacity.

Jobsite housekeeping and fire prevention: keep roofs and decks clear of debris, store flammable materials away from ignition sources, and maintain a fire watch during hot work such as torch-applied modified bitumen.

Personal protective equipment for roofing includes head, eye, hand, and foot protection, plus respiratory protection when applying solvent-based coatings or adhesives in confined or poorly ventilated areas.

Codes: the IRC governs one- and two-family dwellings and townhouses; the IBC governs commercial and multifamily construction. Roof assemblies must meet the required fire classification and, where required, impact resistance.

Roof deck and structural requirements: sheathing thickness and fastener spacing are set by the code and manufacturer instructions; fasteners must penetrate framing as specified, and roof-ceiling assemblies must maintain required fire-resistance ratings.

Excavation and overhead hazards: maintain clearance from energized overhead lines (commonly 10 feet for lines up to 50 kV), and use ground-fault protection on temporary circuits.