Porcelain plank over concrete

[TBHI]

Good day gents

Some advice please...

~30m² = 4.3 x 6.8 , rectangular area, all same level, 1:80 fall

- 900x220x20mm Bradstone Madera Antigua porcelain
- Mapei exterior S1 adhesive & Mapei Flexible grout
- 75mm dry/damp site mixed concrete/screed
- ~250mm DTP1 subbase (not because it needs it, just building up level)

Do I need to be thinking about movement joints/ slab cracking? Do normal rules for concrete span/thickness apply?

Thanks in advance

[Tony McC]

You have a flexible/unbound sub-base, rather than a rigid/bound base, so no real need for a MJ. The joints between courses will act as 'crack lines' if any stresses build up within the structure.

[TBHI]

Thanks.