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Metal Tile Roofing Calculator (General)

General calculator for stamped metal tile roofing. Generates purlin spacing guides, screw schedules, and ventilation tape requirements.

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Category Roofing
Include Snow Guards
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About

Stamped metal tile roofing (stone-coated or painted) mimics the look of clay or concrete tiles but requires a specific framing substructure. The critical success factor is the Purlin (Batten) Spacing. Unlike standard metal sheets where purlins are spaced by load, metal tiles lock into each other at specific intervals (modules). If the battens are off by even half an inch, the tiles will not lock.

This tool calculates the exact framing requirements based on the tile brand's module length. It distinguishes between the heavy framing screws needed to secure the battens and the smaller stitching screws used to lap the tiles. It also accounts for essential accessories like snow guards and ridge vent tape, often overlooked in basic estimates.

metal tile decra gerard roof framing purlin spacing

Formulas

The number of purlins (Npurl) is determined by the rafter length (L) and the tile module (M):

Npurl = ceilLM

Fastener counts are derived from empirical ratios. For framing screws (Fframe) and stitch screws (Fstitch):

Fframe = Panels × 4
Fstitch = Panels × 1.5

Reference Data

Tile Brand/StyleModule LengthCoverage WidthTiles/Sq (100sf)Weight/SqMin Pitch
Generic Stone Coated14.5 in48 in21150 lbs3:12
Classic Tile14.5 in50 in20140 lbs3:12
Shake Profile14.5 in48 in21160 lbs4:12
Shingle Profile14.5 in48 in21120 lbs4:12
Barrel Vault14.0 in44 in24150 lbs3:12
Small Module (EU)12.6 in (320mm)40 in28135 lbs3:12
Large Module (US)16.0 in52 in18145 lbs3:12

Frequently Asked Questions

Some "direct-to-deck" profiles exist, but most stone-coated metal tiles are designed for a batten system (2x2 wood strips). The battens create an air gap that improves energy efficiency and prevents condensation buildup under the metal.
If the spacing is too wide, the nose of the tile won't lock into the clip/batten below. If it's too narrow, the tile will bow or not sit flat. Accuracy to within 1/8th of an inch is usually required.
On metal roofs, snow tends to slide off in large avalanches (roof shedding). If you have walkways, driveways, or landscaping below the eaves, snow guards are essential to break up the snow pack and hold it until it melts.
Framing screws (usually longer, 2 inch) go through the nose of the tile horizontally into the batten. Stitch screws (shorter) connect the side laps of the panels together to prevent wind uplift. They perform different structural functions.