Are you getting called in to fix an installation where metal roofing panels are leaking or loose? The installation may be suffering from old, worn, backed-out, or corroded roofing fasteners.
The good news is that you may be able to revitalize that metal roof without replacing the full roofing system by using replacement fasteners.
Also known as “goof screws,” replacement fasteners exist to help solve mechanical fastening failures in the original installation, which could have been caused by anything from incorrect fastener selection to poor workmanship.
Selecting the replacement fastener
When choosing the appropriate goof screw, you must consider:
- The substrate
- The original fastener size
- Service life expectations
Determining the substrate beneath the roofing panel is the first step. Are you dealing with dimensional lumber, plywood, oriented strandboard (OSB), or light- or heavy-gauge metal? Knowing your substrate will help you select the right goof screw from the get-go.
Replacement fasteners are larger in diameter than the original installation screws. Upsizing the shank diameter is typically the way to go when revitalizing an installation. (Unless you are driving replacement screws into dimensional lumber, an increase in fastener length will deliver little to no additional benefit.)
For wood substrates, upsizing two sizes is typically suggested: #9 to #12, #10 to #14, #12 to #17, and #14 to #20.
For steel substrates, going up just one size in diameter will often do the trick: #12 to #14, #14 to #17, and so on.
The next consideration is service life expectation and value for your investment.
The replacement fastener itself typically accounts for only 5% to 15% of the total cost of the revitalization project, with the bulk of the costs wrapped up in labor, logistics, and insurance.
That said, it’s still cheaper than a full roofing system replacement!
With that in mind, I suggest you not only upsize the shank diameter but also upgrade to long-life fasteners. Fastener manufacturers offer solutions such as stainless steel cap-headed fasteners like SCAMP, zinc alloy-headed fasteners like ZMAX, ZAC, or Ultimate.
Selecting the right replacement fastener is a small decision that can have a big impact on the service life of a metal roof. When the substrate, fastener size, and service life are all considered, a goof screw can be a practical fix that helps extend roof performance without the cost of full replacement.
Andrew Mullen is the CEO of a growing fastener group that includes Lakeside Construction Fasteners LLC and DMI Direct Metals LLC (formerly Direct Metals Inc.), which was founded by a team of metal and fastener professionals in 1993. The groups’ solutions are carried by over 1,800 distributors across the country.
