M16 square plate washer, 100 x 100 x 10mm. For M16 holding down bolt connections on portal frame base plates. Spreads clamping force to prevent base plate deformation.
What Is a Square Plate Washer?
A square plate washer sits between the holding down bolt nut and the base plate. It spreads the clamping force over a wider area than a standard washer, preventing the nut from pulling through or deforming the base plate under load. On portal frame buildings, plate washers are essential at every holding down bolt position.
Without a plate washer, the nut bears directly on the base plate through a standard washer. Under wind uplift or moment loading, this small bearing area can allow the base plate to flex or the bolt hole to elongate. The square plate washer eliminates this by distributing the load across a 100 x 100mm area.
Which Size Do I Need?
Match the plate washer to your holding down bolt diameter:
- M16 x 100 x 100 x 10mm — for M16 holding down bolts on lighter portal frames (152-178 UB columns)
- M20 x 100 x 100 x 10mm — for M20 holding down bolts, standard size for most portal frames (203-254 UB columns)
- M20 x 150 x 100 x 10mm — larger plate washer for M20 bolts where increased load spread is specified by the engineer
Your structural engineer’s base plate detail will specify which plate washer size to use. If it’s not shown on the drawing, M20 x 100 x 100 x 10mm is the most common for standard agricultural portal frames.
How Many Do I Need?
One plate washer per holding down bolt. A typical portal frame base plate has 4 holding down bolts, so you need 4 plate washers per base. For a 6-bay building with 7 frames, that’s 28 plate washers minimum. If your gable posts also have base plates, add those too.
What Else Do I Need?
Each base connection needs: holding down bolt sets, square plate washers, wax cones (for casting into concrete), and the base plate itself. We sell all of these — check our full holding down bolt range.
Why Buy From Us?
- Sold individually — order exactly what you need
- 10mm thick steel — heavy-duty, won’t deform under load
- Precision cut — clean hole, flat bearing surface
Delivery Information
Next-Day Dispatch
Orders placed before 12pm (Mon–Fri) are dispatched the same day for next working day delivery (subject to courier availability).
Standard Delivery Cost
Shipping is calculated at checkout based on weight. Depending on weight or order we will send components in boxes or pallet delivery.
Packaging
All components are securely pallet-wrapped and labelled, ensuring safe and tidy arrival on-site.
Order Tracking
You’ll receive an email with tracking info once your order leaves our workshop.
Returns
We supply components made to spec, if you’ve ordered the wrong item or something’s arrived damaged, just let us know within 5 working days and we’ll sort it.
For full details, see our Returns Policy.
