Fasteners are the most ubiquitous product on the construction site. You find boxes of them sitting around, often soggy bottomed with fasteners spreading out across a concrete floor. We don't treat them well, and that's surprising since nothing can get completed on a site without a fastener.
Simple fastener mistakes can cause huge problems in construction
Even worse, make a mistake with a fastener, and it can cause huge problems. Warranties can be voided, product failures can occur and reputations can be ruined. According to Robert Cannick, marketing manager, Atlas Bolt & Screw Co., Ashland, Ohio, “Strip outs cause leaks and callbacks, and the resulting costs decrease the contractor profit. Contractor callbacks to ensure the building looks good and functions properly will cost the contractor a minimum of $300 to $500 per callback visit. This may not even include the cost of the repair in some cases, just the cost of personnel and travel costs.”
We turned to Cannick and others in the fastener world to ask them about the most common fastener errors they see. We asked them to talk about the errors on the job site, but also up and down the supply chain.
Wrong Tool
What tool did you pick up to fasten that metal? Screw gun? Impact driver? Screw gun with impact feature? The difference between the three can adversely affect the holding power of the fastener. “Use of impact-style screw guns can lead to damaged coatings on fasteners heads and micro fractures in fasteners,” says Cannick. “That can result in structural failures.”
Alan Belcher, branch manager for Pittsburgh-based Triangle Fastener Corp. says, “Self-drilling fasteners should be installed with a tool that has a depth-sensitive, multiple settings clutch; sufficient torque; and variable speed trigger. Cordless impact drivers are being used frequently for this task, and it’s easy to see why. They are light, compact and powerful. Too powerful, actually. Impact tools can generate torque that is six to 10 times greater than the strength of the screw. It results in broken and stripped fasteners, as well as damage to the sealing washer.”
But having the right tool doesn’t begin just on the job site. It starts at the estimating stage. “Estimators need education on proper drill points from stitch to drill capacity to ensure the use of the correct fastener,” says Cannick. “These ordering mistakes force the field crews to use the wrong self-driller point for the intended application. This can cause the driller to burn up especially if the pilot or drilling portion of the fastener is too short for the gauge of steel that the metal panel is being fastened to. The pilot portion of the fastener must always be longer than the thickness of the steel that you are drilling into. Estimators need to follow the panel manufacturers’ established fastening guidelines.”
Wrong Cord
The wrong tool includes more than just the machine you’re holding in your hands. It also includes accessories, such as power cords. Too often, crews working far from power sources will use longer, yet smaller gauge cords to get the distance. “An 18-gauge cord instead of the recommended 14-gauge cord leads to slower drill speeds and loss of drilling performance,” Cannick says. Of course, with most tools on the job site running off batteries, this becomes less of an issue. But younger field personnel, who may not have worked with corded tools as much, need to be trained on this topic.
Wrong Bit
“When using a self-drilling fastener, choose the correct drill point for the application,” says Ken Webb, sales manager, Dynamic Fastener, Kansas City, Mo. Trying to force a slender fastener through a thick hunk of steel can be both an exercise in frustration as well as a potential liability. For Dynamic Fastener products, Webb says, “a T-1 is used for sheet-to-sheet stitching with a total steel thickness of 0.024 inches to 0.095 inches. T-3, or purlin screw, is used for a total steel thickness of 0.036 inches to 0.21 inches. T-4s are used for a drilling capacity of 0.125 inches to 0.375 inches. T-5s have a drilling capacity of 0.25 inches to 0.5 inches. Our #14 diameter T-5 Steel-to- Structural Fenderhead has a drilling capacity of 0.25 inches to 0.625 inches.”
Overdriving
Everybody, especially the folks on the job site want to make sure that everything is buttoned up tightly and snugly. That means making sure the fastener is fully seated. Cannick warns, though, against overdriving fasteners. “Overdriving leads to over compression of the washer and loss of sealing performance,” he says, “and a greater probability of roof leaks over time.”
Overdriving can be exacerbated by not letting the screw do the work. “Not letting the screw do the work,” Cannick says, “using excessive pressure or excessive RPM of the screw guns” puts added stress on both the tool and the fastener. “The screw point either fails to drill properly and time is wasted, or washers are damaged, which can cause leaks and result in melted or burned-up drill points.”
Wrong Fastener
Selecting the right fastener begins with something as basic as knowing what the substrate material is. Do you need wood screws?
Self-tapping screws? Self-drilling screws? Too often crews pick up what’s available on-site even though it may be left over from a previous job. Even if you get the substrate correct, Belcher adds, “The contractor may order fasteners that have an incorrect drill point or length, which causes problems during installation.”
“Using the wrong fastener for a particular application,” says Cannick, is the most common error he sees among field personnel. “The fastener may not install at all or it may install but have an inferior connection strength.”
Belcher identifies another common problem with fastener selection: corrosion from dissimilar metals. “Contractors may use a fastener made of a material that is not compatible with the roof panel,” he says. “This can lead to corrosion caused by galvanic reaction.”
Incorrect Tool Setting
Even if you have the right tool, right cord and right bit, you can get the setup incorrect. “Crews failing to set their hex drive sockets before starting the installation is a common error,” says Cannick. Taking that extra moment to ensure the socket is engaging the fastener ensures a much cleaner and smoother drive.
Not getting the set correct, “Leads to excessive wobble which damages the paint on fastener head is damaged,” says Cannick. “Or the fastener won’t stay in a nutsetter during installation and the hex corners round out on zinc-cast type fastener heads.” Making the issue worse is using old or worn out nutsetters as well as making sure the nutsetter is clean of any chips.
Safety
The final most common fastener error comes from Belcher, and it can be extended to almost any aspect of construction: safety. OSHA has identified falls on construction sites as one of the greatest hazards workers face, and devotes a special blitz every year to promoting fall protection. Too often, Belcher says, “installers don’t wear the proper personal protection equipment on roofs and in aerial lifts.”
Wishes
Cannick and Belcher add one wish each for contractors when dealing with fasteners. They’re not common errors, but they can improve the quality of the performance and service contractors get from their fastener suppliers. “Spend just a little more and buy premium fasteners,” says Cannick. “Long-lasting products, such as our ‘Long-Life’ products are now widely available in the market and will add a tiny fraction of a percent to the overall cost of a building. The benefit to the owner is no head rust issues for the life of the building and the contractor will not have callbacks and warranty claims for rusting heads.” Belcher’s wish falls on the service side. “When a contractor orders over the phone,” he says, “they should have all the information related to the job prior to the call. Accurate substrate info, etc. Their odds of getting the right fastener for the task go way up.”
