UK Standard
BS EN 13139 — Aggregates for Mortar (Building Sand)
BS EN 13139 — Aggregates for mortar
In short: BS EN 13139 specifies UK mortar aggregates, covering soft building sands used for workable blockwork and bricklaying mortar mixes.
What BS EN 13139 covers
It covers building (soft) sand used for bricklaying, blockwork and repointing mortar.
Building sand to BS EN 13139 should be used for mortar; sharp sand (BS EN 12620) makes mortar harsh and is for beds and concrete instead.
Apply this standard
Calculators that use BS EN 13139
Official source: BSI Knowledge — BS EN 13139. Figures on this page are a plain-English summary for estimating purposes — always refer to the published standard for compliance.