From ESE Machines
Installing metal roofing is a craft. It requires more skill and a greater knowledge than installing other roofing materials.
An important consideration for properly installing standing seam roofing is proper cleat installation. ESE Machines (www.esemachines.com) offers the following guidelines on its website.
How many cleats?
The rule of thumb is one (1) cleat should be responsible for every 1-1/2 square feet of roof area.
Therefore, the formula to get the total number of cleats required: Divide square footage of the roof area by 1.5 = number of cleats for that roof.
Cleat spacing considerations
Divide 216 by the width of your panel to determine cleat spacing because 216 is the number of square inches per 1-1/2 square feet. As an example, for a panel width of 18 inches, divide 216 by 18 = cleat spacing every 12 in.
— a 12-inch wide panel should have cleats every 18 inches
— an 18-inch wide panel should have cleats every 12 inches
— a 24-inch wide panel should have cleats every 9 inches
Perimeter areas are more critical!
The amount of fasteners used at the ridge, eaves and rakes should be doubled from the formula above. This means if you have a cleat every 12 inches up the roof then you should have two within 6 inches of each other at the eave, the ridge and every 6 inches along the rake.
Remember all perimeter details must be closed so no air can get under the panels.
To minimize movement of roofing panels, a combination of fixed cleats and expansion cleats are required. The top part of an expansion cleat can slide back and forth in the base allowing the metal to expand and contract.
Low slope (or low pitch) roofs generally use longer panels than a steep roof. The longer the panel — the more linear expansion can be expected. To reduce the effect this has on the ridge or eave the fixed cleats should be placed in the center with expansion cleats on either side. This will split the expansion at each end in half.
Installing a low pitch
Since a medium pitch roof will usually be shorter there is less material expansion to deal with. The fixed cleats can be placed closer to the ridge — approximately 2/3 of the way up.
Installing a medium pitch
On steep roofs the fixed cleats can be placed at the ridge with the expansion cleats towards the eave.