5285 Williams Hwy., Grants Pass, OR • M-F 7 to 5:30, Sat. 8 to 5, Sun. 9 to 4

Metal Roofing Installation Tips

The following information is for reference only and does not constitute the only way to install metal roofing and siding. It is provided as a starting guide to begin installing the panelling. This information refers to the exposed fastener system. Installation of the concealed fastening system varies with panel type. An installation guide may be obtained for the exact system you are installing on each system from the manufacturer.


Screw gun (or drill), magnetic bits, tin snips (straight, left, & right), tape measure, chalk line, drill bits, skill saw with abrasive saw blades, safety goggles, gloves, ear plugs, & saw horses.


For a clean and successful installation of the metal panels, it is important that the building and substructure are square. The first panel must be square as the remaining panels will follow the path of the first one. If the first panel is not square, the resulting installation will look like a saw tooth.


Roofing and siding should be started at the end of the building. Begin your panelling into the direction of the prevailing wind & rain so that the weather goes over the lap, not into it.


There is an underlap leg and an overlap leg on most panels (see below). It is therefore important to determine in advance of installing the first panel, which is which. The end leg on the overlap side does not reach the deck/purlins when in place. The end leg on the underlap side touches the deck/purlins when in place. This underlap side is called the purlin leg. The overlap leg will always be the outside leg on your first panel, regardless if starting on the right or left side of the building.


Depending on the panel profile on the panel, side lap sealant (above) is recommended on pitches of 2:12 or less. Side lap sealant is a double stick tape, placed on the underlap leg of each panel at the lap leg.


We recommend that metal panels be cut with tin snips or for long cuts a shear or nibbler. The shear & nibbler are expensive tools and in their absence, a skill saw with a metal carbon cutting blade may be used. Panels should be turned upside down and held securely while cutting. Always wear safety goggles when cutting metal panels. It is critical to clean all metal particles from the panel to prevent pitting and rusting.


Fastener placement (see below) varies by area, but the general rule is one fastener next to each side of the high rib, with 2′ – 5′ vertical spacing, depending on substrate.


  • Screw fasteners have been proven to have 2 to 3 times the holding power of nails.
  • For maximum holding power, it is recommended that the minimum wood penetration be one inch.
  • Utilizing screw fasteners with neoprene and metal washers have an excellent sealing quality and are specifically designed for fastening in the sheet pan of trapezoidal rib metal roofing panels.
  • Screw fasteners can also be used on the panels high rib, particularly for sidelap attachment.
  • If nails are utilized, application is recommended only thru the panel’s high rib. Again, the fasteners length should assure penetration of at least 1″ into wood. For plywood 1/2″ or less, use #14 woodscrews.

Fastener placement for 9″ high-rib centered profiles:

Sidelap fasteners through wood #10 woodscrews recommended at side of major ribs
Fastener placement for 8″ and 12″ high-rib centered profiles:

Sidelap fasteners through wood
Trims and Accessories

Gable Trim Application
Apply gable trim to both roof sheeting ends. Fasten at top and sides as shown at intervals of 24″ o.c.

Ridge Cap Application
Apply ridge cap as shown, fastening through cap and roofing at every rib. If using formed ridge cap be certain to align sheets properly.



Endwall Application
Secure upstanding leg to wall by fastening at 24″ intervals. Then fasten through lower leg near edge of flashing on every rib.






Vented Ridge Application

Apply C-Metal to end of roof panels and secure by fastening at 24″ o.c. Insert Closures and caulk. Install screen (by others). Then apply vented Ridge cap as shown, fastening through cap and roofing at every rib.

Vent Flashing Application – Flexible On-Site Customization

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Step Five






Check your state and local codes before starting any project. Follow all safety precautions. Information in this document has been furnished by the National Retail Hardware Association (NRHA) and associated contributors. Every effort has been made to ensure accuracy and safety. Neither NRHA, any contributor nor the retailer can be held responsible for damages or injuries resulting from the use of the information in this document.