Roofing Systems & Materials: Shingles, Metal, Tile & Membranes

Welcome

Hello, and welcome. This is Super Structures General Contractors — a national general contractor headquartered in Powhatan, Virginia — here to help you and your clients build something that lasts. We're glad you're with us, and we look forward to connecting with you.

Here's one that matters more than its name lets on — Roofing Systems & Materials: Shingles, Metal, Tile & Membranes. If you remember one thing, make it this: A roof is a system, not a surface — the covering gets the credit, but the deck, underlayment, flashing, insulation, and ventilation underneath decide whether it keeps the water out. Do this right and you'll know what's actually under the roof you're buying, building, or repairing.

Steep-slope coverings

• Asphalt shingles — the most common residential roof in the country. Fiberglass-mat shingles (ASTM D3462) come as three-tab and heavier laminated "architectural" shingles, nailed in courses with a starter strip at the eaves and cap at hips and ridges. Wind ratings follow ASTM D3161 or D7158 classes.
• Metal — standing-seam panels with concealed clips, exposed-fastener panels screwed through the face, and metal shingles, in Galvalume or galvanized steel, aluminum, copper, or zinc. Long-lived and light, with thermal movement the detailing must allow.
• Clay and concrete tile — durable and heavy; the structure must carry the load and the underlayment does much of the waterproofing.
• Slate — natural stone, a century-plus life, specialized installers, heavy.
• Wood shingles and shakes — cedar, with fire-rating limits in many jurisdictions.

Low-slope coverings

• Single-ply membranes — TPO (ASTM D6878) and PVC (ASTM D4434) are thermoplastics with hot-air-welded seams; EPDM (ASTM D4637) is a thermoset rubber seamed with tape or adhesive. Attached by mechanical fastening, full adhesion, or ballast.
• Modified bitumen — asphalt sheets modified with SBS (rubber-like) or APP (plastic-like) polymers, applied by torch, hot asphalt, cold adhesive, or self-adhering, as a base sheet plus a granule-surfaced cap sheet.
• Built-up roofing (BUR) — multiple plies of felt in hot asphalt or coal-tar pitch, surfaced with gravel or a cap sheet. The oldest low-slope system, still common on institutional buildings.

What's underneath

• Deck — plywood or OSB on houses; steel, concrete, wood plank, or gypsum on commercial buildings. Every attachment method depends on the deck.
• Underlayment — asphalt-saturated felt (ASTM D226 or D4869) or synthetic underlayment (ASTM D8257) on steep-slope roofs; a base sheet on low-slope bitumen systems.
• Ice barrier — a self-adhering modified-bitumen sheet at eaves and valleys where ice dams form, required by the IRC in those climates.
• Flashing — step flashing at sidewalls, headwall and apron flashing, counterflashing at chimneys, pipe boots, valley metal, drip edge, and on commercial roofs the base flashing, termination bars, and edge metal at every change in plane.
• Insulation and cover boards — on low-slope roofs the insulation sits above the deck: polyisocyanurate is the workhorse, with EPS, XPS, and mineral wool for specific uses, often tapered to create slope to drains. A cover board (gypsum-fiber, high-density polyiso, or perlite) protects the insulation and gives the membrane a hard, fire-resistant substrate.
• Ventilation — on steep-slope roofs, soffit intake and ridge exhaust keep the attic dry and the shingles cooler; the IRC sets the net free vent area.

Going Deeper (Intermediate)

Each covering has a minimum slope in the code because each sheds water differently; a shingle that works at 4:12 leaks at 1:12 no matter how well it is nailed. Low-slope membranes tolerate standing water briefly but still need positive drainage — ponding shortens the life of every membrane and voids most warranties.

Attachment is engineered, not guessed. On a mechanically attached single-ply the fastener rows tighten at perimeters and corners where wind uplift is highest. Shingle nailing — four or six nails per shingle, on the nail line, flush and straight — is the detail most often blamed when shingles blow off.

Advanced / Pro-Level

Pros match the system to the building: a hospital gets a fully adhered PVC or a two-ply mod-bit because leaks are intolerable; a warehouse gets a mechanically attached TPO because square footage drives the budget; a coastal house gets Class H wind-rated shingles or standing-seam metal with engineered clip spacing. They understand fire classification (ASTM E108 / UL 790 Class A, B, C), wind uplift listings, cool-roof reflectivity requirements, and how the vapor retarder, insulation R-value, and air barrier interact.

They also understand compatibility: asphalt and PVC don't touch, EPDM and asphalt adhesives don't mix, and a new membrane over an unknown old one is a core cut and a manufacturer's letter away from approval.

Practice Challenge

An owner wants to recover an existing low-slope roof that ponds near two drains and has a mix of wet and dry insulation. The sub proposes laying a new TPO directly over the old membrane. What's wrong? (Answer: wet insulation has to come out, the code limits recovers over a water-soaked or deteriorated roof, the ponding has to be corrected with tapered insulation or added drains before a new membrane goes down, and the manufacturer will not warrant a recover over an unknown or wet substrate without core cuts and approval.)

In Practice

A roof with a good underlayment, correct flashing, and real drainage runs thirty years with routine maintenance. A beautiful covering over a bad substrate leaks in two.

Common Mistakes to Avoid

• Choosing a covering by looks without checking the minimum slope
• Leaving ponding water in place and expecting a new membrane to fix it
• Mixing incompatible materials (asphalt products against PVC, or EPDM against asphalt adhesives)
• Treating flashing and underlayment as filler items instead of the waterproofing

Takeaway: A roof is a system, not a surface — the covering gets the credit, but the deck, underlayment, flashing, insulation, and ventilation underneath decide whether it keeps the water out.

Educational overview only — not hands-on roofing instruction, a fall-protection program, or a substitute for training under a licensed roofing contractor. Follow OSHA 29 CFR 1926 Subpart M, the IRC and IBC as adopted in your jurisdiction, the manufacturer's installation instructions, your state's contractor licensing rules, and your employer's procedures.