Penny Washers

About Penny Washers

Penny washers are large, flat washers with an oversized outer diameter compared to their central hole, designed to distribute load across a wider surface area than standard washers. Named for their coin-like appearance, these essential fastening components prevent damage to softer materials, reduce the risk of pull-through on thin sheet materials, and provide a stable base for bolts and screws. Available in various materials including stainless steel, zinc plated steel, galvanised steel, and aluminium, penny washers are indispensable for construction, roofing, automotive repair, and general fabrication work.

The selection at Tooled-Up.com includes penny repair washers in multiple finishes and sealing washers with EPDM rubber bonding for weatherproof applications. Sealing penny washers combine the load distribution benefits of traditional penny washers with an integrated rubber seal, making them ideal for roofing applications where preventing water ingress is critical. These specialised washers create a watertight barrier between fixings and roofing materials, protecting against leaks and corrosion in exposed outdoor environments.

Quality penny washers from trusted brands like Timco ensure reliable performance across demanding applications. Whether securing roofing sheets, repairing bodywork, or fastening into soft materials like timber or plasterboard, the right penny washer prevents material crushing, spreads clamping pressure evenly, and extends the lifespan of assembled structures by reducing localised stress points.

Jargon Buster

• Penny Washer: A flat washer with an external diameter significantly larger than standard washers, typically three to four times the bolt diameter, designed to spread load over a wider area and prevent pull-through on thin or soft materials.
• EPDM (Ethylene Propylene Diene Monomer): A synthetic rubber material bonded to sealing washers that provides excellent weather resistance, UV stability, and waterproofing properties, particularly suited to outdoor roofing applications.
• Repair Washer: Another term for penny washers, commonly used when the washer's purpose is to reinforce or repair existing fixings by distributing load across damaged or weakened material.
• Load Distribution: The spreading of clamping force across a larger surface area to prevent localised crushing, deformation, or pull-through of the fastener through the material being secured.
• Zinc Plated: A protective coating applied to steel washers through electroplating, providing moderate corrosion resistance suitable for interior applications and some sheltered outdoor use.
• Galvanised: A hot-dip zinc coating process that provides superior corrosion protection compared to zinc plating, making washers suitable for more demanding outdoor and weather-exposed applications.

Who Uses Penny Washers?

• Roofers and Cladding Specialists: For securing corrugated sheeting, metal roofing panels, and polycarbonate sheets with weatherproof sealing washers
• Builders and Construction Professionals: For general structural fastening, timber frame construction, and repairing fixings in masonry or blockwork
• Vehicle Body Repair Technicians: For automotive and trailer bodywork repairs where large washers prevent damage to thin metal panels
• Agricultural Engineers: For maintaining farm equipment, securing corrugated structures, and repairing machinery where vibration and weathering are concerns
• Maintenance Engineers: For industrial equipment repairs, fabrication work, and reinforcing existing bolt connections
• Shopfitters and Joiners: For securing fixtures to plasterboard, fixing into soft timbers, and installing signage
• DIY Enthusiasts: For home repairs, garden structure assembly, shed construction, and general maintenance projects requiring secure, damage-free fastening
• Fencing Contractors: For securing fence panels, gates, and post fittings where weather resistance and load spreading are essential

How to Choose the Right Penny Washers

Material Selection: Choose stainless steel penny washers for maximum corrosion resistance in coastal or chemically aggressive environments. Galvanised washers offer excellent weather protection for general outdoor use at a lower cost, while zinc plated washers suit interior applications. Aluminium washers with EPDM seals are ideal for roofing applications where lightweight, non-corroding properties are beneficial.

Hole Size and Bolt Compatibility: Match the washer's internal hole diameter to your bolt or screw size, ensuring a snug fit without excessive play. Common hole sizes include 6mm, 8mm, 10mm, and 12mm. A properly sized washer should slide freely onto the fastener shaft but not leave gaps that reduce load distribution effectiveness.

Outer Diameter: Consider the material being fastened—softer materials like timber, plastic, or thin sheet metal require larger outer diameters to prevent pull-through. For roofing applications, ensure the washer completely covers the corrugation profile at fixing points. Standard penny washers typically range from 25mm to 50mm in outer diameter.

Sealing Requirements: When weatherproofing is critical, select EPDM sealing washers that create a watertight barrier around fixings. The rubber bonding should be continuous and firmly attached to prevent separation during installation. Tooled-Up stocks sealing washers engineered specifically for roofing applications where leak prevention is paramount.

Load and Application: For high-stress applications or where fasteners bear significant weight, choose thicker washers with greater material strength. Structural applications may require washers meeting specific load ratings, whilst light-duty repairs can use thinner, more economical options.

Quantity and Pack Sizes: Professional tradespeople benefit from bulk packs offering better value, whilst DIY users may prefer smaller quantities. Consider your project scope—roofing jobs typically consume large quantities of sealing washers, making bulk purchases more economical.

Popular Accessories

• Roofing Screws and Tek Screws: Self-drilling screws specifically designed for use with sealing washers in metal roofing and cladding applications
• Standard Washers and Form A Washers: Complementary washers for applications where penny washers aren't required but load distribution is still beneficial
• Bolts, Nuts and Threaded Rod: Fasteners that work in conjunction with penny washers for structural connections
• Spring Washers and Lock Washers: Anti-vibration washers used alongside penny washers in applications subject to movement or vibration
• Rawlplug and Fischer Fixings: Anchor systems for masonry applications where penny washers improve holding strength in softer substrates
• Drill Bits and Driver Bits: Essential tools for preparing pilot holes and driving fasteners when installing with penny washers
• Silicone Sealant: Additional weatherproofing for particularly exposed roofing applications
• Socket Sets and Spanners: Hand tools for tightening bolts and nuts used with penny washers in structural applications

Frequently Asked Questions

What's the difference between a penny washer and a standard washer?
Penny washers have a significantly larger outer diameter relative to their hole size compared to standard washers—typically three to four times the bolt diameter. This increased surface area provides superior load distribution, making them ideal for soft materials, thin sheets, or situations where pull-through is a concern. Standard washers are smaller and suited to general-purpose fastening where material strength isn't compromised.

Can I use penny washers for roofing without the EPDM seal?
Whilst plain penny washers provide load distribution, they don't create a waterproof seal around fixings. For roofing applications exposed to weather, EPDM sealing washers are essential to prevent water ingress around screw holes, which can lead to leaks and accelerated corrosion. The integrated rubber bonding compresses against roofing materials, forming a watertight barrier that plain washers cannot achieve.

Are stainless steel penny washers worth the extra cost?
Stainless steel penny washers offer superior corrosion resistance and are worth the investment in marine environments, coastal locations, or chemically aggressive settings where galvanised or zinc plated washers would deteriorate prematurely. For standard construction and sheltered outdoor applications, galvanised washers provide excellent durability at lower cost. Consider your specific environment and expected lifespan when choosing materials.

What size penny washer do I need for M8 bolts?
For M8 bolts, select penny washers with an 8mm or 9mm internal hole diameter. The outer diameter depends on your application—25mm to 38mm outer diameters are common for general use, whilst softer materials or thin sheets may require 40mm to 50mm diameters for adequate load spreading. Always ensure the washer doesn't interfere with adjacent components or extend beyond the material edge.

How many sealing washers do I need per square metre of roofing?
Roofing screw density varies by material and manufacturer recommendations, but typically ranges from 5 to 8 fixings per square metre for corrugated sheets, with higher densities at sheet overlaps and edges. Always follow the roofing material manufacturer's specifications for fixing patterns, as under-fixing compromises weather resistance whilst over-fixing can create unnecessary penetration points. Purchase approximately 10% extra to account for wastage and edge details.