STAINLESS STEEL SQUARE WOOD CONSTRUCTION WASHERS DIN 436

Square Wood Construction Washers DIN 436 — Most timber construction washers are round, but DIN 436 turns that on its head with a square bearing footprint - corner-to-corner, a square washer covers more area within a given overall envelope than a round disc of similar size, which is useful wherever load spreading in timber is the primary function and rotational symmetry is not required. That makes DIN 436 a common sight on heavier timber connections and structural or semi-structural fixings where a squared plate simply sits better against a timber face than a round washer would, spreading the clamping force from the bolt evenly across more of the surrounding fibres. It serves broadly the same purpose as DIN 440R - protecting timber from crushing and pull-through under a bolted connection - but the two are not dimensionally interchangeable; DIN 436's outside dimensions, bore, and thickness are set out separately, so a drawing or specification calling for one should not be read as equivalent to the other without checking. As with any timber fixing washer, material choice comes down to exposure: mild steel with a protective plating suits internal or short-life external connections, while A2 (304-equivalent) stainless is the sensible default for external timber structures exposed to ongoing weather, since corrosion staining and gradual section loss in a washer will undermine the timber joint around it long before the wood itself is a problem. A4 (316-equivalent) becomes worth the extra cost specifically in coastal, marine-adjacent, or heavily salted environments, where A2 would otherwise need replacing well within the structure's working life. To specify DIN 436 correctly, confirm the bolt diameter, check the square outside dimension and thickness against the DIN 436 table for that size, and choose material and finish to match how exposed and how long-lived the timber structure needs to be.

FAQs
Why use a square washer instead of a round one?
A square washer can provide a greater bearing area within a given envelope than a round washer, which is useful in timber where load spreading is the primary function rather than rotational symmetry.

Is DIN 436 the same size range as DIN 440R?
No. DIN 436 is a distinct standard covering the square form; outside dimensions, bore, and thickness are defined separately and should not be assumed to match DIN 440R's round washer sizes for the same bolt diameter.

Does the square shape need to align a particular way against the timber grain?
No - there is no functional requirement to orient it relative to the grain; the square shape is about bearing area, not directional grip.