Screwing 101 – The Importance of Understanding Torque
Are you over tightening your fasteners? Did you even know this was a possibility?
Sometimes we think that going as tight as possible will help our roofing or siding because the fasteners cannot move and therefore the panel will not go anywhere. When it comes to metal roofing and siding though, this can actually be detrimental to a project.
With hidden fastener panels, over tightening screws can cause pinch points in the metal which will be completely visible on the panel itself. The panel will look like it is buckling at every single fastening point. Even though the fasteners are not visible, anyone who understands metal will be able to tell that they were over-tightened just by looking at the completed job.
When working with metal, it is important to let the metal rest as it is being installed. What this means is that the metal should not be forced into place. By not over tightening fasteners and by working from the centre of the panel outward, this buckling at pinch points can be avoided.
Exposed fastener panels experience a different problem with over tightened screws. Though the same concept of letting the metal rest as it is being installed does apply, the main issue that can occur with exposed fastener panels is leakage.
Modern fasteners are made with a neoprene washer that is meant to expand and contract in the heat and the cold. When a fastener is too tight, the neoprene is crushed and has nowhere to go. Eventually, the elements will completely dry this washer out. Now, as the metal warms and cools in the different seasons, the metal around the hole is moving the fastener, causing the hole to grow. If the neoprene was sitting nicely on top of the metal, it would be absorbing this movement and the hole remains intact.