For 20mm vs 9mm outdoor tiles, the deciding factor is the base. A 20 mm paver can be laid loose on gravel, sand or pedestals, because it carries load itself. A 9 mm tile must be fully bonded to a solid, flat base such as a concrete slab, because it relies on that support.
Choose 20 mm for driveways, loose-laid patios and raised decks. Choose 9 mm for balconies, terraces and walls where the surface is already built and you want a low profile.
What are the differences in performance?
Thickness changes load capacity and impact resistance. Thicker porcelain has a much higher breaking load, so it survives point loads such as furniture legs, heavy planters and occasional vehicle weight when laid on a proper sub-base. Thin tiles carry load only as well as the adhesive and slab underneath them. Floor tile thickness explains the relationship in more detail.
Frost, water absorption and slip resistance depend on the body and surface, not the thickness. Both products should meet the same low water absorption and an appropriate slip class. Ask for the test reports for each, not just the thickness.
How are they laid?
Laying methods differ and affect cost and speed. See laying 20 mm pavers for a full guide. In brief:
- 20 mm pavers can be dry-laid on compacted gravel, sand, adjustable pedestals or a mortar bed, so drainage and levelling can be adjusted later.
- 9 mm tiles need a flat, cured, sound substrate, a suitable flexible adhesive and movement joints, and rely on full adhesive contact with no voids.
- Pedestal systems for raised terraces use 20 mm, since the tile spans between supports.
- Wall cladding and vertical use suits thinner tiles, because weight matters.
What is the trade-off for cost and logistics?
A 20 mm tile weighs roughly twice a 9 mm tile of the same size. That reduces how many square metres fit in a container under the weight limit, and raises freight per square metre. It also changes handling on site. The 9 mm tile is lighter and cheaper to ship per square metre but often needs more installation labour and substrate preparation.
No single option is cheaper overall. Compare the whole installed cost, not the tile alone. A real quote for your container comes from a sourcing review once we know your sizes and destination.
How do you decide?
Ask three questions. Is the base solid and flat already? Will anything heavy stand or roll on it? Does the customer want a loose-laid, repairable surface? If you answer yes to the last two, use 20 mm. If the base is a finished slab with limited height, use 9 mm. Our guide to 20 mm outdoor porcelain pavers lists the specification points to ask a factory about.
What should you test and ask the factory?
Ask for a breaking-load result for the exact thickness, the water absorption, the slip class and the frost-resistance result if you sell into cold climates. Request the weight per square metre so you can plan pallet loads and the container weight limit. Look at the edge finish: 20 mm pavers are often rectified so they sit tight, and chamfered edges reduce chipping. Ask how the factory packs thick pavers, because heavy tiles damage each other if cartons are loose. Finally, lay a small trial area with your usual installer before committing to a large order.
Next step
We find and audit paver manufacturers, check samples and documents, and supervise production and loading. Book a free sourcing review to compare 9 mm and 20 mm options for your project.