In general practice, the terms ‘gasket’ and ‘seal’ are often used interchangeably to describe a multitude of overlapping hardware pieces.  When it comes to fasteners across the construction and fabrication industries, this same terminology confusion is just as prevalent, notably concerning fasteners such as bolts and screws.  To help clear the water, we’ll begin our discussion here by differentiating gasketed and sealing fasteners, though please note that other sources may adopt different definitions.

Gasketed FastenerSealing Fastener
Coming from the construction world, a ‘gasket’ is most often understood to be a wide, thin material that covers a large area in a compressed connection, creating a debris-resistant assembly.  A Gasketed Fastener shares this same wide, thin seal, such as with the gasketed self-tapping screw below.  Rooted in the machining and fabrication world, a ‘seal’ is most often understood to be an O-ring or other symmetrically-shaped material that covers a small area in a compressed connection, also creating a debris-resistant assembly.  A Sealing Fastener is similar, using a retained O-ring or Square-ring seal, such as with this O-ring Bolt below.   
Gasketed FastenerSealing Fastener

In both cases, the role of the gasket and seal are to deter dust, liquid, and other debris from flowing through the fastener penetration, addressing contamination, cleanliness, moisture, or other similar concerns.  A gasketed fastener offers a wider sealing surface thanks to its larger face, whereas a sealing fastener offers higher pressure ratings thanks to its retained O-ring that withstands blow-out.  Said another way, sealing fasteners are more technical, as they provide a mechanically-engineered interface for critical applications.  For comparison, a gasketed fastener is more likely to be used for roofing projects, and a sealing fastener for industrial machinery projects.       

For the rest of this article, we’ll discuss Gasketed Fasteners as defined above, and will revisit Sealing Fasteners in a future article. 

Do you have a Gasketed Fastener application but are unsure of which fastener meets your project’s requirements?  E&T Fasteners offers expert support and product selection between the above options and more!  Contact us to discuss your application, see our Screw and Bolt catalog here, or to see our entire fastener catalog, visit our product selection here

Gasketed Fastener Types & Applications

Gasketed fasteners are most often found in applications involving sheet metal components, and so share the common design feature of sealing up building penetrations to keep indoor and outdoor environments positively separated. 

Self Tapping Metal Roofing Gasketed ScrewSelf-Tapping Metal Roofing Gasketed Screw A hardware store standard offering, self-tapping metal roofing screws are used to secure thin-gauge metal roofing panels to structure below (usually wood), and include a sealing gasket by default.  The wide washer diameter allows for the screw’s hold-down force to be spread over a larger area around the hole drilled in the roof sheet, providing a good weather-resistant seal as well as deterring the screw from popping through the panel (given how thin common roofing panels are).  
Self Drilling Gasketed ScrewSelf-Drilling Gasketed Screw These screws provide the same sealing benefits as above, but with an added feature found in the screw’s self-drilling tip.  Self-drilling screws are designed for use with wood, fiberglass, metal, and plastic materials.  Most often, these screws are used for leak-free application between sheet metal components (such as in HVAC ducting fabrication), or between sheet metal panels and structures below (such as in siding installation on metal buildings).   
Wide Gasket ScrewWide Gasket Screw For any roofing, siding, panel, or other sheet metal applications that would benefit from a higher degree of weather-resistant sealing or forceful retention compression, large diameter gaskets can be specified on roofing and self-drilling screws.     
Gasketed WashersGasketed Washers Washers with gaskets can be purchased separately from screws, such as when performing a retrofit using existing fasteners, when a removable washer is desired, or when a custom sealing dimension / detail is needed.  (The above fasteners typically come with bonded gaskets, meaning that they cannot be removed.) 

Common Gasketed Fastener Specifications

From the above, we get the sense that gasketed fasteners are typically used in high-volume, lower-complexity applications in commercial and residential construction, as well as in general fabrication and light industrial work.  For this reason, gasketed fasteners are commonly available in a multitude of sizes and materials, at competitive pricing.  Below we’ll list out the most common gasketed fastener specifications, though please inquire about unique options that can be special ordered: 

  • Materials:                  Steel, Carbon Steel, 18-8 Stainless Steel, 304 Stainless Steel  
  • Finishes:                    Galvanized, Zinc Plated, Silver Ruspert, Powder Coated, Polyurethane UV-Resistant Paint
  • Colors:                      Unpainted, or with Paint Colors to match OEM metal and roofing panels
  • Diameters:                #9, #10, #12, #14, 1/4”, 5/16”
  • Lengths:                    3/4” through 3-1/2” long  
  • Gasket Material:        EPDM, Neoprene, Rubber
  • Drive Type:               Hex Head, Phillips, Flat
  • Box Quantities:          250, 500, 1M, 1.5M, 2M, 3M, 5M, 10M (M=1,000)

When ordering gasketed fasteners, be sure to request the manufacturer’s installation instructions for each size and specification ordered.  Fastener torque is very important to properly achieve during installation.  Too tight of torque, and the fastener or material being secured may be damaged.  Too loose of torque, and the seal may not be fully formed.

Many manufacturers of specialty roofing and siding panels will offer their own branded gasketed fastener, specifically designed to work with their panels.  Thread pitch, screw diameter, gasket material, gasket size, and torque requirements are technical details that may be selected to provide a precise hold-down force, weather seal, and other joint specifications.  These fasteners may look interchangeable with common varieties, driving some customers to want to purchase commodity versions to cut costs, however be sure to check the panel’s warranty documentation to confirm if the OEM fasteners must be used.  Very often, using a non-OEM fastener will void panel warranties.  In addition, some specialty panel systems may require use of OEM fasteners in order to achieve and warranty overall system performance, such as with insulated metal panel (IMP) systems.     

E&T Fasteners is here to help you navigate fastener and accessory options.  Price quotes, availability, lead times, delivery confirmations, unique application suggestions – whatever your need, we’re here to take your call or email.  For support and advice from our fully trained staff, speak with an E&T sales representative today. 

About E&T

With sales and support teams spanning the Continental US, E&T Fasteners is here to serve your hardware, fastening, and component needs both domestically and internationally.  We are a stocking distributor of metallic, plastic, and exotic alloy fasteners, backed by our technical staff directly experienced in your unique applications.  We can assist your specifying and selection efforts, providing engineered solutions, record-fast lead times, and stellar customer service from quote through delivery.  Please let us know how we can help!