Choose fasteners by starting with the materials being joined and the job the connection must do. Then match the fastener type, dimensions and thread; select a compatible material and finish for the environment; and check installation requirements, governing standards and local code. No single fastener suits every joint.
What counts as a fastener?
Fasteners mechanically join two or more parts or help form a fastened connection. The category includes screws, bolts, nuts, washers, pins and rivets, as well as anchors and application-specific systems. ISO/TC 2’s scope covers fastener terminology, dimensions and tolerances, properties, coatings, testing, quality, joint design and assembly. ISO’s fasteners committee lists the principal fastener classes and its standardization scope.
How the main fastener types differ
Screws
Screws are threaded fasteners driven into or through a material. Their head and drive, point, thread and substrate all matter. A screw intended for drywall attached to metal framing, for example, is not automatically suitable for drywall attached to wood or for cement board. Hilti’s product technical guides include application-specific guidance for screws and other fastening systems.
Bolts and nuts
A bolt passes through the workpieces; a compatible nut tightens against them to clamp the parts together. Match the nut to the bolt’s diameter and thread, and check that their materials and finishes suit the application. A bolt-and-nut connection is not interchangeable with a screw connection simply because the parts appear similar.
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Washers
A washer may spread load, help resist loosening or act as a spacer, depending on its type and the joint. Choose it for the role required by the connection, rather than treating it as a decorative add-on.
Rivets and pins
Rivets and pins are also recognized fastener classes. They serve different joint and assembly needs from a typical bolt-and-nut connection; NASA’s Fastener Design Manual discusses rivet and lockbolt selection alongside other design considerations.
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Anchors
Anchors connect components to a substrate such as concrete or masonry. Mechanical and adhesive anchor systems have distinct design data and installation requirements. Use the guide for the specific anchor system and substrate, not general advice for household bolts or screws. Hilti provides separate technical guides for fastening and anchor applications.
A practical method for choosing hardware
- Identify the materials and task. Establish whether the connection is into wood, metal, masonry, concrete or a specialized assembly. The joined materials and application help determine the fastener family; an ordinary screw or bolt is not a universal substitute for an anchor or application-specific system.
- Define dimensions and thread compatibility. Check diameter, length, thread form and the mating part. Avoid mixing metric and inch hardware, or coarse and fine threads, unless the design specifies that combination.
- Select material and finish for the environment. Consider moisture, corrosion exposure, chemicals and contact with other materials. Exterior use and contact with pressure-treated lumber can affect the choice. Stainless steel is described as suitable for many exterior and treated-lumber projects in Lowe’s consumer guide to nuts, bolts and washers, but verify the specific product’s suitability for the project.
- Check the joint’s mechanical demands. Consider load direction, joint design, strength and, for engineered work, fatigue, thread engagement, friction, preload, torque and installation method. NASA’s manual and Bossard’s technical information on fastening technology cover these design and assembly topics; they are technical references, not a project-specific design approval.
- Confirm the installation method and tools. Check head and drive style, access, required tooling and the manufacturer’s current installation instructions. For anchors and other system products, follow the instructions and technical data for that exact product and substrate.
- Check the governing requirements. Confirm the project documents, applicable standard, local code and manufacturer instructions before buying or installing hardware. ASTM’s fastener standards catalogue includes a range of specifications and labels some entries withdrawn, so verify a standard’s current status rather than assuming a listed number remains active.
Why compatibility matters
Fastener components must work together. For a bolted joint, size and thread compatibility are essential; material and finish also need to suit the joint and its surroundings. Matching parts only by appearance can lead to an incorrect fit or an unsuitable connection. Lowe’s guide gives consumer-level advice on matching nuts, bolts and washers and cautions readers to follow application requirements.
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The fastener’s intended use matters as much as its dimensions. A product suitable for a small household repair should not be presumed suitable for a deck, structural connection or other load-bearing application. Some construction applications specify particular hardware, and code or manufacturer requirements may govern the choice.
When general hardware advice is not enough
For structural construction, lifting, pressure systems, vehicles or other consequential work, do not infer capacity from a fastener’s appearance or choose from a generic assortment. The right specification depends on the project’s substrate, loads, geometry, environment, installation and jurisdiction. Use the design documents, applicable code and standard, and current manufacturer technical data. An exact grade, dimension, anchor or capacity cannot be responsibly selected without those project details.
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Standards also need checking at the time of specification: ASTM’s live fastener catalogue distinguishes current entries from withdrawn specifications. Treat a standard number as a starting point for verification, not proof of current approval for a particular project.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Are assorted fastener kits useful?
A mixed kit of screws, nuts, bolts and washers can be convenient for compatible, noncritical household repairs when its contents and dimensions match the job. Check what sizes, threads, materials and finishes are included before relying on it. Do not treat a general-purpose assortment as structural or code-approved hardware.
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