[header] How to lay a porcelain tile exterior patio [title] Use a bonded cement/sand screed to level the concrete substrate if necessary. [step] To avoid problems with the screed shrinking (and causing the tiles to crack), allow it to dry out for 1 to 2 weeks. For minor surface irregularities simply use a levelling compound. 
[title] Ensure the surface that you are laying the porcelain tiles on is as level as possible, clean and dry, and remove any loose particles. [title] Select a " thin bed " adhesive for very flat surfaces with level differences of no more than 6 mm.