Bs 3921

BS EN 771-1 BS 3921 British Standard Specification for ...

BS 3921 Size of Voids Solid bricks have no perforations or frogs. Perforated bricks have holes not exceeding 25% of the gross volume of brick. The area of any one hole should not exceed 10% and the amount of solid clay across the width should not be less than 30%. Frogged bricks may have depressions in one or

  Standards, British, 1932, Sb 1932, Bs 3921 british standard