Crack width and aesthetics
Design codes such as Eurocode 2 (as amended by the UK National Annex), and BS 8110 (withdrawn) limit crack widths to 0.3mm for aesthetic reasons. The value of 0.3mm is general accepted as being a reasonable limit as it is visible at a viewing distance of around 3m. As indicated in Concrete Society Technical Report 67, Movement, cracking and restraint in concrete structures, the crack width and the viewing distance could be linked to the type of structure, from īlittle used buildingsī to īmonumental buildingsī. Like all questions of appearance, this is highly subjective.
In general, the crack width could be greater if the viewing distance was greater. However, this approach should be treated with caution as cracks become more visible when a wetted surface starts to dry-out or when it becomes contaminated with dirt.