How to install a 20mm Porcelain Patio
Nothing quite compares to the sharp and refined look of a patio installed with porcelain tiles. Its not as hard to achieve as you might think. In many respects, laying porcelain slabs is very similar to how a more traditional patio is installed using natural stone or concrete slabs.
In this tutorial, we will guide you through the most common method of laying 20mm porcelain tiles on a compacted stone sub-base. Other methods are possible but this is the most common and when executed correctly, it will stand the test of time.
Preparation Overview
This cross section diagram is effectively what your trying to achieve. The finished patio level should ideally be 150mm below the damp course on the stone/bricks. This will ensure no damp gets into the bricks through water run-off and rain splash
The ground should be excavated to an appropriate depth until hard compacted undisturbed soil is reached (Ideally at least 150mm). Your patio design should incorporate a gap between walls and the pavers for a stone soak away. This will give standing water a chance to drain away.
Working out your levels
Working out your levels is one of the most challenging aspects of the build - especially if there are terraces and a slight pitch for water run off on large areas. Whatever your design or considerations, there are methods to help. "Old school" methods can involve pegs or string, which work very well in skilled hands. A more modern approach would be to use a laser line.
Getting your levels right means using the right amount of material for each layer.
Compacting the stone sub-base
This is a very important stage which is the most responsible for your patio to either move or not over the years. Compacting the stone thoroughly with a “Wacker Plate” is the best practice to reduce any settlement over the years.
It’s a good idea to wacker the soil before the stone goes down as well. Damp conditions will help achieve maximum compression.
Mortar screed
Your tiles are laid on a solid bed of mortar which must be wet and ideally mixed with sharp sand, 30-50cm minimum depth. Always lay to a string line when starting so your row is dead straight. Tap down in small increments with a rubber mallet to achieve the desired level. "Spot laying" is not advised as you need to avoid any cavities / hollows spaces under each tile - it is then less likely to crack if something heavy is dropped on them.
You should lay rows all at the same time, one tile behind on each row on a diagonal direction.
Priming the tiles
A primer which is applied to the back of each tile prior to laying, is an absolute must. Porcelain tiles / slabs are non-porous, so cement mortar will not naturally stick to the tile. A cement based priming slurry will provide a key to the back of the tile so it sticks to the mortar bed. It is easily applied by brush or roller just prior to laying.
Applying the grout
The last stage is to apply grout to the joints. The joint gap can vary depending on the look you want to achieve. In some cases a large gap is deliberately left to create a stepping stone effect. In which case no grout is needed. For most designs where the tiles a laid as a large single flat surface, a gap of 2-8mm is recommended. There are different products on the market for this application. We recommend a suitable outdoor grade traditional grout. Apply by hand and push as deep as you can into the joints. Take care not to leave it to long before you clean up the excess.