Spetz Specs No. 6017: step-by-step surface & covering guide

How to Lay a Porcelain Tile Patio Over an Existing Base

The complete step-by-step guide made from Tidybricks patio restore's YouTube video, free on Spetz. For the video, a step-by-step player and answers to your questions, see the How to Lay a Porcelain Tile Patio Over an Existing Base project page.

2 steps, 1 parts, 8 tools, 6 materials

Overview

The surface & covering

• Lay porcelain tiles (A) over an existing stable concrete base.
• Build up the base for a durable modern patio.

What it takes

• Requires basic mortar mixing, leveling skills and heavy lifting.
• Work over a couple of days to let the mortar set.

What decides success

• A solid, unyielding base that has not sunk.
• A consistent 10mm per meter drainage fall away from the house.
• Apply priming slurry to every tile for proper adhesion.

Layout at a glance

• Covering: Porcelain tile
• Laid on: existing 20-year-old concrete and hardcore base
• Pattern: running bond
• Offset: halves in between
• Start: flush with the edge of the step area to create one long, straight line
• Reference line: string lines set for the first course and height, dropping 10 mm per meter away from the house for drainage
• Expansion gap: a gap at the wall, spaced with a coin block
• Bond: 4:1 sharp sand and cement mortar bed, with priming slurry applied to the back of the tile
• step area: start the tiles flush with the edge
• wall: leave a gap using a coin block

Health and safety

Heavy Lifting and Posture

• Lift heavy porcelain tiles and bags of cement with your legs to prevent back injury.
• Avoid overloading the wheelbarrow with wet mortar to maintain control and prevent muscle strain.

Dust and Eye Protection

• Wear a dust mask and eye protection when mixing dry cement, sharp sand, and stone dust.
• Use a dust mask and safety glasses to avoid inhaling harmful particles when cutting porcelain tiles.

Chemical and Skin Safety

• Wear protective gloves when working with cement, mortar, and priming slurry to prevent skin irritation.
• Wash your skin immediately with clean water if it comes into contact with wet cement.

Pressure Washer Safety

• Wear eye protection when using the pressure washer to clean the existing concrete base.
• Never point the pressure washer nozzle at yourself or anyone else to avoid severe injury.

The surface & its prep

• The concrete and hardcore base is stable and has not sunk for at least 20 years.
• The surface is clear of debris.
• Build up and level the base with stone dust where necessary.

Tools

• String Line
• Spirit Level
• Wheelbarrow
• Shovel (Square-point shovel)
• Trowel (Pointing Trowel)
• Mallet (Rubber Mallet)
• Bucket
• Pressure Washer (optional)

Materials

• Porcelain Tiles (Khaki colored, London Stone)
• Cement (Blue Circle)
• Sharp Sand (four and one mix)
• Priming Slurry (Larsen)
• Stone Dust (2 tons, 210s)
• Tile Leveling System (Clips and caps, Tilers Tools)

Finishes & supplies, in the order they go on

Covering elements

Before you start

Protect & clear

• Clear the patio of furniture and debris.
• Check the 20-year-old base is stable and has not sunk.

Tool set-up

• Set up the wheelbarrow and shovel to mix mortar.
• Ready the bucket to mix the priming slurry.

Step by step

Step 1: Prepare the Base and Set Layout Lines

Establish the layout grid with string lines, factoring a 10mm per meter drainage fall.

Watch this step (1:08)

You'll need: String Line, Spirit Level

1. 1.1 Establish the Starting Line
   • Start flush with the existing step edge.
   • Run a string line straight across the patio.
   • Leave a gap at the house wall using a coin block spacer.
2. 1.2 Set Height and Drainage Fall
   • Set string lines to define the finished patio height.
   • Drop the line level 10mm for every 1 meter away from the house.
   • Check the lines with a spirit level to confirm the slope.
3. 1.3 Set Remaining Layout Lines
   • Run string lines to mark the outer edges and main courses.
   • Use a tingle on long string lines to prevent sagging.
   • Set the grid for a running bond pattern with halves between.

Key measurements

• Drainage fall: 10 mm for every 1 m away from the house

• Tip: For proper drainage, the patio must fall 10mm for every 1 meter away from the house.

Before you move on: Sight down the string lines to check they are straight, taut and slope consistently away from the house.

Step 2: Lay and Level the Porcelain Tiles

Set the porcelain tiles flush into the mortar bed with leveling clips, primed for adhesion.

Watch this step (3:46)

Parts in this step: (A) Porcelain tile

You'll need: Wheelbarrow, Shovel, Trowel, Mallet, Bucket, Porcelain Tiles, Cement, Sharp Sand, Priming Slurry, Tile Leveling System

1. 2.1 Mix the Mortar
   • Mix sharp sand and cement in a wheelbarrow with a shovel.
   • Use a 4:1 ratio of sharp sand to cement.
2. 2.2 Spread the Mortar Bed
   • Trowel a generous dollop of mortar onto the base.
   • Spread the mortar slightly higher than the final tile level.
   • Do not leave voids in the mortar bed to prevent weak spots.
3. 2.3 Apply Priming Slurry to the Tile
   • Mix the priming slurry in a bucket.
   • Trowel the slurry onto the entire back of the porcelain tile (A).
   • Spread the slurry close to the edges for a strong bond.
4. 2.4 Lay and Level the Tile
   • Set primed tile (A) onto the mortar bed against the string lines.
   • Tap gently with a rubber mallet until level with the line.
   • If too low, lift and add mortar underneath.
5. 2.5 Use the Tile Leveling System
   • Slide tile leveling clips under the exposed edges.
   • Never insert clips against set edges laid the previous day.
   • Spin leveling caps onto the clips to pull adjacent tiles flush.
6. 2.6 Continue Laying Tiles
   • Repeat spreading, priming, laying and leveling along the string lines.
   • Cover fresh tiles with a damp proof membrane overnight to prevent footprints.
   • Kick off the leveling caps the next morning once mortar sets.

Key measurements

• Mortar mix: 4 parts sharp sand to 1 part cement

• Tip: If a tile sits too low, lift and add mortar beneath.
• Tip: Use a tile leveling system for a perfectly flat finish.
• Heads up: Light tiles show footprints easily; cover them as you work.

Before you move on: Check the first tile with a spirit level to match the string line fall.

Finishing

Clean & cure

• Kick off the leveling caps the next morning.
• Clean the surface to avoid staining the light tiles.

Grout & edge

• Grout the tile joints across the patio.
• Cement the exposed edges the next day once the water dries.

Care

• Use a pressure washer for final cleanup and ongoing maintenance.
• Porcelain tiles are slippery when wet or icy.

Check before you call it done

These Specs are built from Tidybricks patio restore's video “How to Lay a Porcelain Tile Patio Over an Existing Base”. Open the How to Lay a Porcelain Tile Patio Over an Existing Base project page.