These days, most people who want a new metal roof in Austin go with a standing seam metal roof.
Standing seam is superior to many other roofs because the “Panels” completely conceal and protect the fasteners. Fasteners of all kinds represent a major structural weak point of any roof. That’s true of the nails used for shingle roofs as well as the screws in the average metal roofing system.
Of course, standing seam isn’t the only type of metal roof out there in Austin.
If your metal roof is older, it is much more likely to be of the screw-down type.
What Is a Screw-Down Metal Roof?
A screw-down metal roofing system is a corrugated metal roof held together with lots of small, exposed screws. Corrugated metal, in turn, describes an older alternative to standing seam that was once very popular for industrial and agricultural buildings. Some Austin-area homes use it, too.
You might also hear this kind of roof referred to as:
"Exposed fastener roofing"OR
Whatever you call it, it’s synonymous with a past generation of roofing techniques. A screw-down metal roof suffers from leaks more often because every individual screw creates its own leak risk. Even if the roof is installed very well, screws with neoprene washers gradually weaken due to wind, rain, and pressures exerted in extreme heat and cold.
How to Repair Leaks in Screw-Down Metal Roofs
When a metal roof is leaking, one of the exposed screws is the most likely cause. Depending on how long ago the roof was installed, it may be that all of the screws need to be replaced. If the screws and washers are not degraded then It takes some expertise to narrow down the leak to the right screw and repair the roof. There is often no obvious damage to the screw. Instead, the issue comes down to poor installation practices.
Here are the most common malfunctions of metal roof screws and how they can be fixed:
1. Under-Driven Screw
If there’s not enough torque on the screw as it enters the metal roof, the rubber washer on the screw will not set against the metal panel. Without appropriate compression of the rubber portion of the screw, no gasket is formed and the screw is liable to leak. You may be able to fix this by tightening down the affected screws.
2. Over-Driven Screw
On the opposite end, a roofer might over-drive a screw in an effort to make sure the waterproof seal is formed. This usually destroys the rubber washer. If the washer remains intact, then reducing the torque on the screw can solve the dilemma. In many cases, though, an over-driven screw will be stripped.
3. Screw at Wrong Angle
Screwing down at the wrong angle means the rubber part of the screw cannot lie flat and create the waterproof seal. Usually, this does not mean the screw itself is damaged. Unscrew the screw in question and re-screw it at the correct angle. Be sure to check for damage to the screw and metal panel before you re-screw!
4. Screw Improperly Anchored
If the screw misses the wood decking or lathing, there is no way for it to create a seal. This can be a tough problem to diagnose, since there is no visual indication that the screw is not doing its job. Double-check the screw to be sure that it is fully seated.
5. Faulty Screws
Rarely, roofing screws used in a metal roof may be manufactured incorrectly. If you have a screw-down metal roof, be sure to get it inspected at least once a year in summer or winter. The high heat of summer followed by a cold Austin winter can damage the rubber on screws.