Mississippi Residential Roofer

Key Concepts

Asphalt Shingles

• ASTM D3462: Standard for asphalt shingles made from glass felt — the primary standard for fiberglass-based shingles.
• ASTM D3018: Standard for asphalt shingles made from organic felt (less common today but still tested).
• Shingles must be self-sealing and labeled with fire classification; packaging must identify the ASTM standard met.

Underlayment Types & Standards

• Asphalt-saturated felt (Type I = #15 felt, Type II = #30 felt): Traditional underlayment; heavier felt provides greater protection.
• Synthetic underlayment: Polypropylene or polyester-based; lighter and stronger than felt; must be listed and labeled.
• Self-adhering polymer-modified bitumen (ice and water shield): Fully adhered; required in eave areas in cold climates; provides waterproofing barrier. IRC requires it from eave to a point 24" inside the exterior wall line in ice dam zones.

Roof Deck Substrates

• Plywood: Must be exterior-rated; minimum 3/8" thickness for most shingle applications, though 7/16" OSB or 15/32" plywood is common for structural decks.
• OSB (Oriented Strand Board): Minimum 7/16" thickness for rafter spans up to 24" o.c.
• Wood planks/boards: Solid board decking must be minimum ¾" nominal thickness (19/32" actual); spaced decking permitted for wood shakes.
• Deck must be dry, structurally sound, and free of voids before any covering is applied.

Key Concepts

Fire Classification (IRC R902)

• Class A, B, or C roofing is required when the roof edge is less than 3 feet from a lot line or where mandated by law.
• Fire ratings tested per ASTM E108 or UL 790.
• Class A exceptions: brick, masonry, exposed concrete roof deck, and certain assemblies using Class A components over combustible decks.
• Class A = highest fire resistance; Class C = lowest of the rated categories.

Roof Deck Requirements

• Decking must be structurally sound, clean, dry, and free of warped or deteriorated sections before any covering is applied.
• Common deck types: OSB, plywood, and boards. Minimum thickness and span ratings must be verified before installation.
• Inspect for soft spots, delamination, and improper fastening before re-cover or new installation.

Underlayment by Roof Type (IRC R905)

• Asphalt shingles: One layer of #15 felt (or approved synthetic) for slopes ≥ 4:12; two layers required for slopes 2:12–4:12 (low-slope application).
• Ice barrier required in areas subject to ice damming — extends from eave to a point 24 inches inside the exterior wall line.
• Wood shakes: One layer #30 felt as interlayment between courses; base sheet also required.
• Wood shingles: No interlayment required, but underlayment required on deck.
• Slate & clay/concrete tile: Minimum #30 felt underlayment; self-adhering polymer-modified underlayment may be required at eaves.
• Metal shingles: Minimum one layer #30 felt.

Key Concepts

Primary Roof Drains (R903.4) Roof drains must be installed at each low point of the roof unless the roof is sloped to drain over the roof edges. Placement at low points is mandatory — the code does not allow water to pool without a drain path.

Secondary (Emergency Overflow) Drains and Scuppers (R903.4.1) Required whenever roof perimeter construction (parapet walls) extends above the roof surface and could trap water if primary drains fail. - Overflow drains: Same size as primary drains; inlet flow line set 2 inches above the low point of the roof. - Overflow scuppers: Must be 3× the size of the roof drains, minimum opening height of 4 inches, with inlet flow line also 2 inches above the low point. - Overflow drains discharge to an approved location and cannot connect to roof drain lines. - Sizing must comply with IPC Sections 1106 and 1108.

Crickets and Saddles (R903.2.2) A cricket or saddle is required on the ridge side of any chimney or penetration more than 30 inches wide (measured perpendicular to the slope). Cricket coverings must be sheet metal or the same material as the roof covering. Exception: Unit skylights flashed per manufacturer's instructions are exempt.

Flashing (R903.2 / R903.2.1) Flashing is required at: - Wall and roof intersections - Changes in roof slope or direction - Around roof openings - Where a sloped roof eave meets a vertical sidewall

Metal flashing must be corrosion-resistant, minimum 0.019 inch (No. 26 galvanized sheet) thickness.

Key Concepts

Roof Deck Types & Requirements

• Plywood and OSB: Most common structural panel decking. Must be APA-rated sheathing with grade stamps. Minimum thickness varies by rafter spacing and cover type — asphalt shingles typically require 3/8" minimum, but 7/16" OSB or 15/32" plywood is standard for 24" o.c. spacing.
• Wood plank decking: Spaced or solid. Spaced decking (skip sheathing) is permitted only under specific coverings like wood shakes/shingles. Solid decking required under most other coverings.
• Deck inspection before installation: Inspect for soft spots, delamination, rot, improper fastening, and nail pops. Decking must be dry, flat, and securely fastened. Damaged sections must be replaced — do not cover over bad decking.

Attic Ventilation (IRC R806)

• Minimum net free ventilation area (NFA): 1/150 of the attic floor area, OR 1/300 if at least 40–50% of required ventilation is provided in the upper portion of the space (upper half of attic, within 3 feet of ridge), with the remainder at eave/soffit level.
• Intake/exhaust balance: Intake vents (soffit) should roughly equal exhaust vents (ridge, gable, or power). Imbalanced systems cause moisture and heat problems.
• Ridge vents + soffit vents: The preferred combination. Ridge vents serve as exhaust; soffit vents serve as intake. Do not block soffit vents with insulation — use baffles.

Key Concepts

Fall Protection Requirements (29 CFR 1926 Subpart M)

• Low-slope roofs (4:12 pitch or less): Use a warning line system + safety monitoring system, or guardrail/personal fall arrest system. Warning lines must be set at least 6 feet from the roof edge.
• Steep roofs (greater than 4:12 pitch): Require guardrail systems, personal fall arrest systems, or safety net systems — no warning line option.
• General trigger height for fall protection in construction: 6 feet above a lower level.

Personal Fall Arrest Systems (PFAS)

• Components: Full-body harness, shock-absorbing lanyard or self-retracting lifeline, anchorage connector.
• Anchorage must support 5,000 lbs. per worker or be designed with a safety factor of 2 under the supervision of a qualified person.
• Must limit free fall to 6 feet and prevent contact with the lower level.
• Deceleration distance: maximum 3.5 feet.
• Inspect before each use. Any PFAS that has arrested a fall must be removed from service immediately — it cannot be reused.

Guardrail Systems

• Top rail height: 42 inches (± 3 inches) above walking/working surface.
• Mid-rail: positioned at 21 inches (midway between top rail and surface).
• Top rail must withstand 200 lbs. of outward or downward force.
• Mid-rail must withstand 150 lbs.
• Openings in guardrail systems must not allow a 4-inch diameter sphere to pass through.