Penny Repair Mudguard Washers – Zinc

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.