Question 1

1. What are the standard nut and bolt sizes used for UK building projects?

Accepted Answer

UK construction uses metric dimensions, indicated by an ‘M’ followed by a number (e.g. M8, M12). The “M” stands for metric, and the number refers to the nominal outer diameter of the bolt in millimetres (mm).

For example, an M10 bolt has a 10mm thread diameter. M6 to M10 are common for timber and light fixings, while M12 to M20 are typically used in structural steel and concrete work. Matching nuts will have the same M-size and thread pitch as their bolts.

Question 2

2. What are the most common types of nuts, bolts and washers used in UK construction?

Accepted Answer

Hex bolts, coach bolts, nyloc nuts and plain washers are most frequently used across joinery, steelwork and structural jobs.

Question 3

3. When should I use stainless-steel nuts and bolts?

Accepted Answer

Use stainless-steel nuts and bolts in situations exposed to moisture, chemicals or outdoor conditions to make sure of long-term corrosion resistance.

Question 4

4. How do I know which size of bolt or washer I need?

Accepted Answer

Refer to your building spec or the material load needs of the situation. M6 to M12 is common for timber and light steel; larger sizes suit heavier structural joints.

Nuts, bolts and washers

Rawlplug Through Bolt 8 X 75mm

Cup Square Carriage Bolt & Nut BZP M12x50mm

Cup Square Carriage Bolt & Nut BZP M16x100mm

M12 50mm X 50mm Speed Pro Square Plate Washer Bright Zinc Plated Pack Of 100

Thunderbolt Hexagon Flange Head Bolt 50 X 6mm Zinc Yellow Passivated

M10 x 100 Bright Zinc-Plated Steel Coach Bolts (50/Pack)

Calder Brass Cup Washers - Pack of 100

Steel Washer Form C M12 BZP

OJ Unifix Concrete Bolt Hex Head 10[12]x150mm (2)

Fischer FWB Wallbolt M 10/75 L (pack Of 4)

OJ Square Plate Round Hole Washers BZP - Small Bag - 50x50x3x16

OJ Economy - Mudguard Washers BZP - M12x38x1.5

Speed Pro M12 X 1m Zinc Plated Threaded Bar

TIMCO Hex Head Multi-Fix Bolts Micro Plating 130 x 12mm Box of 25

TwinQwik M20 Metric Studding 1m L Brown

TQ Metric Studding M8 Threaded Rod 1m L Bright Zinc Plated

Suki Drill-In Threaded Sockets M8 x 12.5mm 4 Pack

Rawlplug Drop-In Anchors M12 x 50mm 50 Pack

Nylite Washer - Pack of 100

OJ TQ Hex Head Coachscrew DIN571 BZP - M6x70

Dome Caps and Retaining Washers White

Inter Screws M6 x 10 Pack

Easyfix Brass Mixed Rivet Nut Handy Pack 250 Pcs

Cup Square Carriage Bolt & Nut BZP M8x100mm

Trex® Universal Clip For Grooved Decking Board 90pk