Metal & Specialty Roofing
Standing seam metal, copper roofing, cedar shingles, tile roofing, green roofs, and thermal movement.
- Describe standing seam metal roofing gauge and installation methods
- Explain thermal movement considerations for metal roofing
- Identify the minimum headlap for cedar shingles
- Describe the purpose of bird stops on tile roofing
- Explain green roof construction and typical slope requirements
Lección 1
Metal Roofing Systems
Standing Seam Metal Roofing
Standing seam is the premium metal roofing system, featuring raised seams that interlock panels without exposed fasteners. The typical gauge for standing seam metal roofing is 24 gauge for steel and 0.032 inch for aluminum.
The type of roof with the longest lifespan is copper roofing, which can last 100 years or more with proper installation. Standing seam steel and aluminum typically last 40-70 years.
Fastening Methods
The proper method for fastening metal roofing panels is to use concealed clips that allow the panel to float and move with thermal expansion. Fixed clips are used at one point (typically the ridge) while floating clips allow movement elsewhere.
Concealed Fastener (Standing Seam)
Clips hidden under seam
No exposed penetrations
Allows thermal movement
Superior weather resistance
Exposed Fastener (Corrugated)
Screws through panel face
Neoprene washers seal penetrations
Washers degrade over time
Lower cost, shorter lifespan
Thermal Movement
The purpose of thermal movement considerations in metal roofing is to accommodate the expansion and contraction of metal panels with temperature changes. Metal expands in heat and contracts in cold. A 20-foot steel panel can expand by nearly 1/4 inch between winter and summer extremes.
Without proper accommodation, thermal movement causes:
- Buckling (oil canning) of panel surfaces
- Fastener back-out and loosening
- Seam failure from cyclic stress
- Noise from expansion and contraction
Rake Edge
A rake edge is the finished edge of the roof at the gable end. On metal roofs, the rake edge trim covers the panel ends and provides a clean termination. It also prevents wind-driven rain from entering under the panels.
Standing seam metal roofing uses 24 gauge steel with concealed clips that allow thermal movement. Copper roofing has the longest lifespan of any roofing material at 100+ years. All metal roofs must accommodate thermal expansion and contraction with floating clips.