Nuts and Bolts: How and When to Use Them | DIY Guide 2026

To join metal parts without welding while keeping them separable, you use nuts and bolts… and washers! Each bolt type has a specific use: hex head bolts for metal assembly, square head bolts for wood carpentry, and countersunk or dome head nuts and bolts for precision work. The thread of the shank is standardized by international norms, ensuring interchangeability of nuts and washers.

The bolt shank may not be fully threaded to offer greater strength in the smooth section. Blind nuts are used decoratively on visible parts. For even stronger fastening, special nuts and bolts like cotter pins, taper pins, and special wing washers are employed.

International ISO Standards for Nuts and Bolts

International ISO standards define bolt sizes in a limited number of groups; hex, square, countersunk, and dome heads are specified.

• Hex head bolts: for general metal fastening
• Square head bolts: for wood construction
• Countersunk head bolts: for flush surfaces
• Dome head bolts: for decorative or safety applications

How to Use Nuts and Bolts

Using the inside tips of a caliper, measure the hole diameter for the screw. The bolt size should be slightly smaller. For through holes, use a bolt (screw + nut) with a longer collar and a flat or spring washer. Tighten by holding the nut steady.

Essential Tools for Your DIY Projects

Whether you're assembling furniture, building a garden shed, or upgrading your outdoor space, having the right supplies makes all the difference. Browse our home improvement collection for quality nuts, bolts, and fasteners.

Frequently Asked Questions

1. What is the difference between a bolt and a screw?

A bolt is typically used with a nut to fasten parts together, while a screw is threaded directly into a material. Bolts are ideal for applications where disassembly is needed.

2. How do I choose the right bolt size?

Measure the hole diameter with a caliper and select a bolt slightly smaller. For load-bearing projects, consider the length and thread type. Check our sheds collection for sturdy storage solutions that require proper fasteners.

3. When should I use a washer?

Use flat washers to distribute load and prevent damage to surfaces. Use spring washers to prevent loosening from vibration. Find everything you need in our garden supplies for outdoor builds.

4. Can I reuse nuts and bolts?

Yes, but inspect for stripped threads or corrosion. For safety-critical applications, use new fasteners. Our home improvement range includes durable options.

5. What are the best bolts for outdoor projects?

Stainless steel or zinc-plated bolts resist rust. Perfect for assembling pergolas, gazebos, or outdoor patio furniture.

Related Products and Collections

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Browse Grand Goldman Home Decor

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