The codes we cite in every report — in language you can hand a contractor.

Requires net free ventilation area of 1:150 of the vented space (or 1:300 with balanced intake + exhaust). NM amendment: applies to all new construction and re-roofs with decking replacement.

Under-ventilated attics in NM sun bake shingle undersides, void manufacturer warranties, and drive summer AC bills up 15–25%.

Ridge vent installed with no soffit intake · gable vents blocked by insulation · powered fan without balanced intake (creates negative pressure, pulls conditioned air into attic).

Requires ASTM D226 Type II or ASTM D4869 Type IV felt (or approved synthetic) beneath all steep-slope roofing. NM: ice-and-water membrane at eaves is not required by code but is a standard-of-care recommendation above 6,000 ft elevation.

Underlayment is the second line of defense. When wind-driven rain gets past the primary roofing (common in NM monsoon), underlayment prevents deck rot.

Contractor skips underlayment on 'tear-off and re-cover' jobs · uses 15lb felt on high-slope where 30lb or synthetic is spec'd · omits ice-and-water at valleys where snow accumulates.

Requires base and counter flashing at all wall intersections, step flashing at sidewalls, and continuous flashing at head walls. Chimney flashing must include a cricket for chimneys wider than 30 inches on the upslope side.

Flashing failures cause 80%+ of steep-slope leaks in NM. Chimneys without crickets pond water and rot decking.

Reused old step flashing on new roof · surface-mounted flashing with only caulk (no reglet cut) · missing chimney cricket · kick-out flashing omitted at eave-wall termination.

Roofs shall be designed and constructed to prevent accumulation of water. Slopes less than 2:12 must use approved low-slope materials (built-up, single-ply, SPF foam, or modified bitumen).

Shingles on a low slope roof will leak — always. NM sees this constantly on room-additions where a contractor extended a shingle roof over a flat-roof porch.

Asphalt shingles installed at 1:12 pitch · flat roof with no crickets between drains · roof-to-wall transitions with no water diverter.

A cricket or saddle is required on the upslope side of any chimney more than 30 inches wide, and at any roof transition where water would otherwise pond.

Ponding water is warranty-void for every major shingle and single-ply manufacturer. In NM, ponding accelerates UV and freeze-thaw damage.

Missing cricket at wide chimneys · flat spots at HVAC curbs on TPO roofs · valleys with insufficient slope-to-drain.

Requires primary drainage sized for design rainfall, plus secondary (overflow) drainage set 2 inches above primary. Applies to flat roofs including residential porches, garages, and additions.

NM monsoon can dump 2+ inches in 20 minutes. A blocked primary drain with no overflow = a swimming pool on your roof + interior water damage.

Single scupper on flat roof with no overflow · overflow scupper set at same height as primary · undersized drain for the tributary area.

Roofing work over $7,200 requires a GB-2 (or GB-98) NM contractor license issued by CID. Homeowners can pull a permit for their own primary residence but the work still must meet IRC.

Unlicensed roofing above the threshold voids most homeowner insurance claims and manufacturer warranties. It also means no bond, no recourse.

Storm-chasers with out-of-state licenses only · handymen doing full re-roofs · 'permits pulled by homeowner' arrangements where the contractor is actually running the job.

Alternative to IRC 806 vented attics. Requires air-impermeable insulation (spray foam) applied directly to the roof deck underside, with a Class II vapor retarder in cold climates.

Increasingly common in NM new builds for HVAC efficiency. But retrofit spray-foam without addressing the existing vents creates moisture traps.

Spray foam applied over existing shingles without deck inspection · vent openings left unsealed after foam install · condensation forming at roof-wall intersections.