Large diameter zinc plated washers for spreading clamping load, reducing oversized holes, and packing out fixings. Available in M5 through M12. Zinc plated with CR3 passivation for corrosion resistance. Sold in boxes of 100.
Size
Price
QTY
M10 x 25 (box 100)
£1.59£1.91
M10 x 30 (box 100)
£2.49£2.99
M10 x 40 (box 100)
£3.92£4.70
M12 x 40 (box 100)
£4.95£5.94
M6 x 30 (box 100)
£2.49£2.99
M6 x 40 (box 100)
£3.92£4.70
M8 x 25 (box 100)
£1.69£2.03
M8 x 30 (box 100)
£2.49£2.99
M8 x 40 (box 100)
£3.95£4.74
M5 x 25 (box 100)
£1.59£1.91
M6 x 20 (box 100)
£1.19£1.43
M6 x 25 (box 100)
£1.59£1.91
Zinc penny repair mudguard washers might not be the most glamorous item in the toolbox, but they quietly solve problems that a standard washer simply cannot. The oversized diameter is the whole point — spread the clamping force across a wider area and you avoid pull-through, crushing, or working a soft material to death around a bolt head. Available in sizes from M5 right up to M12, and supplied in boxes of 100, these are the kind of fixing that once you run out of, you feel it immediately.
The zinc plating here uses a CR3 (trivalent chromium) process with passivation applied at 3 to 5 microns. That matters in practice because older hexavalent chromate coatings are now restricted under RoHS and REACH regulations, so CR3 is the current compliant standard. It gives a decent level of corrosion resistance for general construction, fabrication, and outdoor use without going to the expense of stainless. Good for most applications where you’re not directly in a marine or permanently wet environment.
Where Zinc Mudguard Washers Earn Their Place
The name says it all, really. Originally used on vehicle mudguards where sheet metal fixings needed a wide bearing surface, the design crossed over into construction and now shows up everywhere. Flat roof work is a classic application — fixing through insulation boards, membrane layers, or thin deck materials where a standard washer would just pull through under any real load. Timber repairs, garden structure builds, gate hanging, sheet metal work, cladding fixings, fence rails — this washer turns up on most sites eventually.
Reducing an oversized or damaged hole is another underrated use. If a hole has been drilled too large or has worn out over time, a mudguard washer spans the gap and gives the bolt something solid to bear against. Not a structural fix, obviously, but perfectly adequate for a lot of repair and maintenance work.
Sizing and Pack Convenience
The range covers M5 x 25mm through to M12 x 40mm, with several intermediate sizes in M6, M8, and M10. Buying in boxes of 100 keeps unit cost low and means you’re not rummaging through loose washers at the bottom of a site bag. At this price per box, it makes sense to stock a couple of sizes. You will use them.
Pro Tip: When fixing through soft insulation board or thin ply, stack two mudguard washers if pull-through is a concern — it doubles the bearing area for almost nothing and takes far less time than going back to sort a failed fixing later.
Zinc penny repair mudguard washers are used wherever a standard washer would be too small for the job. Flat roofing, cladding installation, timber frame repairs, fence and gate construction, sheet metal fabrication, and general maintenance work all call for this style of washer regularly. They are particularly useful when fixing into soft or thin materials, or when bridging a hole that has been drilled oversize.
Best For
Spreading clamping load over soft or thin materials
Reducing oversized or worn holes
Flat roof board and membrane fixings
Cladding and sheet metal work
Fence, gate, and outdoor timber fixings
General repair and maintenance
Available In
M5 x 25mm
M6 x 20mm
M6 x 25mm
M6 x 30mm
M6 x 40mm
M8 x 25mm
M8 x 30mm
M8 x 40mm
M10 x 25mm
M10 x 30mm
M10 x 40mm
M12 x 40mm
Key Properties
Zinc plated with CR3 trivalent chromium process
Passivated at 3 to 5 microns
RoHS and REACH compliant coating
Large diameter for wide load distribution
Sold in boxes of 100
Not suitable for: Not recommended for marine environments or permanent immersion in water where stainless steel washers would be more appropriate. Not a structural repair for significantly overloaded or compromised fixings.
Select the washer size to match your bolt diameter and ensure the outer diameter is wide enough to bridge the hole or spread the load adequately for the material you are fixing into. Fit the washer flat against the surface with the bolt passing cleanly through the centre hole. Tighten to the required torque for the application — over-tightening into soft materials can still cause pull-through even with a mudguard washer, so apply reasonable force and let the washer do the work.
Select the correct bolt diameter to match your washer size (M5, M6, M8, M10 or M12)
Check the outer diameter is sufficient to bridge any gap or spread load across the target material
Position the washer flat against the surface with the bolt or screw through the centre
Tighten firmly but avoid over-torquing into soft or compressible materials
What is the difference between a penny washer and a mudguard washer?
In practice the terms are used interchangeably on most building sites and in most fixings catalogues. Both describe a washer with a significantly larger outer diameter relative to its hole size compared to a standard form A or form B washer. Some suppliers draw a distinction by outer diameter or thickness, but for most trade applications they refer to the same thing.
Are these suitable for outdoor use?
Yes, for most general outdoor applications the CR3 zinc plating and passivation layer gives reasonable corrosion resistance. They are used regularly in fence and gate work, cladding, and outdoor timber construction. For environments with constant moisture exposure or coastal locations, stainless steel washers would be a better long-term choice.
These washers are manufactured to a large outer diameter profile and zinc plated using a trivalent chromium (CR3) process, passivated to a depth of 3 to 5 microns. CR3 plating is the current compliant replacement for hexavalent chromate coatings, meeting RoHS and REACH requirements. The plating provides a useful level of corrosion resistance for indoor and general outdoor use in non-aggressive environments.
Thread Sizes Available
M5, M6, M8, M10, M12
Outer Diameter Range
20mm to 40mm depending on size
Finish
Zinc plated, CR3 trivalent chromium passivated
Passivation Depth
3 to 5 microns
Pack Quantity
100 per box
Compliance
RoHS and REACH compliant
Size
M10 x 25 (box 100), M10 x 30 (box 100), M10 x 40 (box 100), M12 x 40 (box 100), M5 x 25 (box 100), M6 x 20 (box 100), M6 x 25 (box 100), M6 x 30 (box 100), M6 x 40 (box 100), M8 x 25 (box 100), M8 x 30 (box 100), M8 x 40 (box 100)
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