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Square Washer Dimensions for Timber (DIN 436, M10 to M52)
Guide · Updated October 28, 2026
DIN 436 covers square plate washers mainly for timber construction, bolt size M10 to M52. Hole, side length and nominal thickness agree across the fasteners.eu DIN 436 table, the Westfield Fasteners DIN 436 spec, the Daniel-Gruppe DIN 436 sheet and the Unique Fasteners DIN 436 spec; thickness min and max agree across fasteners.eu, Westfield and Unique. Skipped: hole maximum, side length minimum and weights. Check your supplier for critical work.
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Step by step
- Pick the bolt size: Choose M10 to M52 to match the bolt or threaded rod through the timber.
- Read the hole: Hole d1 is the nominal minimum, the same clearance holes as other structural washers.
- Read the side length: Side length a gives the square bearing area that spreads load into the wood.
- Check thickness: Thickness h runs from 3 mm at M10 to 10 mm at M48 and M52.
- Allow for length: Add h to the grip length for each washer when sizing the bolt.
- Order it: Designate as Washer DIN 436 - 13.5 - St (hole size, material).
DIN 436 square washer dimensions (mm)
Columns: bolt size, hole d1 (nominal = min), side length a (nominal = max), thickness h nominal, min and max.
- Bolt | Hole d1 | a | h | h min | h max
- M10 | 11 | 30 | 3 | 2.4 | 3.6
- M12 | 13.5 | 40 | 4 | 3.4 | 4.6
- M16 | 17.5 | 50 | 5 | 4 | 6
- M20 | 22 | 60 | 5 | 4 | 6
- M22 | 24 | 70 | 6 | 5 | 7
- M24 | 26 | 80 | 6 | 5 | 7
- M27 | 30 | 90 | 6 | 5 | 7
- M30 | 33 | 95 | 6 | 5 | 7
- M33 | 36 | 100 | 6 | 5 | 7
- M36 | 39 | 110 | 8 | 6.8 | 9.2
- M39 | 42 | 125 | 8 | 6.8 | 9.2
- M42 | 45 | 135 | 8 | 6.8 | 9.2
- M45 | 48 | 140 | 8 | 6.8 | 9.2
- M48 | 52 | 150 | 10 | 8.8 | 11.2
- M52 | 56 | 160 | 10 | 8.8 | 11.2
Worked example: M16 bolt through a timber beam
An M16 DIN 436 washer is 50 x 50 mm, 5 mm thick (4 to 6 mm) with a 17.5 mm hole. With one under the head and one under the nut, add 10 mm to the timber thickness when choosing bolt length.
Common problems
- Washer sinks into wood: step up a size or use a thicker plate; check timber bearing strength.
- Rust streaks on timber: use hot-dip galvanized or stainless outdoors.
- Bolt too short: forgot both washer thicknesses.
FAQ
What is a DIN 436 washer?
A large square plate washer, mainly for timber construction, so a bolt head or nut does not crush into the wood grain.
DIN 436 vs DIN 7989?
DIN 7989 is a round 8 mm thick washer for steel work. DIN 436 is square with a much bigger footprint (for example 60 x 60 mm at M20) for soft materials like wood.
DIN 436 vs DIN 434 / 435?
DIN 434 and 435 are square too but tapered for sloped steel flanges. DIN 436 is flat.
What was skipped?
Hole maximum and side length minimum, because sources round or misprint some values (one table shows 27.2 mm for the M52 hole maximum). Weights were left out too.
What material?
Usually plain or galvanized steel; stainless A2 and A4 also exist.
Related guides and calculators
- Timber washers (DIN 1052)
- Large OD washers (DIN 9021)
- HV structural washers (DIN 6916 / ISO 7416)
- Square taper washer dimensions (DIN 434 / 435)
- Heavy-duty washer dimensions (DIN 7989)
- Flat washer size chart (SAE, USS, metric)
- Clamping washer dimensions (DIN 6340)
- All free machinist calculators
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