Specialty Roofing Systems

The first question on any tile or slate roof is whether the structure can carry it, and it is a question for a structural engineer, not a salesperson. Asphalt shingles run roughly two to four pounds per square foot. Clay tile lands around six to ten. Concrete tile is heavier still, commonly nine to twelve. Natural slate varies enormously with thickness and quarry, from about eight pounds per square foot to well over fifteen for heavy graduated slate.

A house framed for shingles may need reinforced rafters, added purlins, or a redesigned framing plan before it can accept tile. That is why a lightweight composite is often the honest answer on a retrofit: it delivers the profile without the structural work.

• Asphalt shingles — roughly twenty to thirty years, less under intense sun and repeated hail.
• Metal — commonly forty to seventy years for a properly detailed standing-seam system, with the coating and the fasteners usually aging before the panel does.
• Concrete and clay tile — fifty years and often much longer. In practice the tile outlives the underlayment beneath it, which is the point most owners miss.
• Natural slate — the longest-lived roofing material in common use, with hard slates measured in generations rather than decades. The fasteners and flashings, not the stone, typically set the replacement date.
• Synthetic and composite slate — engineered products carrying long manufacturer warranties, with impact and fire ratings that natural slate does not offer.

This is the most important thing to understand about a tile roof. Tile sheds the bulk of the water and shields what is beneath it from UV, but tile is not a watertight surface — wind-driven rain gets past it. The membrane on the deck is the actual waterproofing layer, and it is the component that ages out first.

That produces a maintenance event most owners are never told about: the relay. Somewhere in a tile roof’s life the tile gets carefully removed and stacked, the underlayment is replaced, and the same tile is reset. Deck temperatures under tile and metal run far hotter than under shingles, which is why high-temperature synthetic underlayment such as Sharkskin is specified there — standard felt cooks and fails early in that environment.

Natural slate is heavy, brittle underfoot, expensive to install, and requires a trained slater whose skills are increasingly rare. Composite slate and shake were engineered around every one of those constraints: a fraction of the weight, consistent thickness and shape, installation with standard roofing tools, and blended color ranges that read as natural variation from the ground.

In hail country the impact rating is the deciding factor for many owners. Class 4 is the top rating under the UL 2218 impact standard — a steel ball dropped on the product from a set height, twice on the same spot, with no cracking or rupture permitted — and many carriers offer a premium credit for a Class 4 roof. CMAC installs composite slate and shake from DaVinci Roofscapes, Brava Tile, and Inspire Roofing Products.

Metal roofing splits into exposed-fastener panels, where screws with neoprene washers go through the face of the panel, and concealed-fastener standing seam, where clips hold the panel and the fasteners never penetrate the weather surface. Standing seam costs more and lasts longer, largely because the clips let the panel expand and contract with temperature instead of working against a fixed screw. Snap-lock seams suit steeper slopes; mechanically seamed double-lock panels are what you use as slope decreases.

Batten seam is the traditional alternative: the panel edges turn up against a wood batten and a separate cap covers it, producing a heavier, more architectural shadow line. It is the classic copper detail on historic and high-end residential work. On any metal roof, some degree of oil-canning — visible waviness in the flat of the panel — is inherent to flat sheet metal, and it is managed with striations, heavier gauge, and a flat substrate rather than eliminated.

Copper is chosen for how it ages. It starts bright, darkens to russet and then chocolate brown over the first years, and eventually develops the green patina people associate with it — a process that takes decades and runs faster in humid, coastal, and industrial air than in dry inland climates. Two practical notes: copper runoff will stain masonry, stone, and concrete beneath it, so terminations get planned; and copper must never be fastened with steel or paired downstream of galvanized metal, because the galvanic reaction destroys the lesser metal.

Copper slate and metal slate are individual pressed shingles with a slate-like profile that interlock on all four sides, available in copper, steel, and aluminum. They give the geometry of a slate roof at a metal roof’s weight, and copper versions patina like any other copper roof.

Concrete tile from West Lake, Eagle Roofing Products, and Crown Roof Tile. Clay tile from Ludowici, MCA Clay Roof Tile, Verea Clay Tile, and Crown Roof Tile. Natural quarried slate including Vermont Slate. Composite slate, shake, and tile from Brava Tile, DaVinci Roofscapes, and Inspire Roofing Products. High-temperature synthetic underlayment from Sharkskin beneath tile and metal systems.