How to lay
porcelain paving.
Porcelain is unforgiving of a bad base and forgiving of nothing else. Get these six stages right and it will outlast the house.
Full mortar bed, slurry primer on every slab, and a proper fall away from the house. Those three things account for almost every porcelain patio that fails, and every one that lasts.
Dig out and set your levels
Excavate roughly 200mm below the finished paving height. Keep the finished surface at least 150mm below the damp proof course and run string lines so you can see your falls before anything goes down. On clay or made ground, dig deeper and put more sub-base in.
Compact the sub-base
100mm of MOT type 1 for a footpath or patio, 150mm if there is any vehicle or heavy load. Lay it in two layers and hit each one with a wacker plate. A sub-base that has not been compacted properly will settle, and no amount of good laying fixes that later.
Get the fall right
Aim for 1 in 80, about 12mm per metre, falling away from the building towards a drain or gravel border. Porcelain absorbs nothing, so every drop of rain has to run somewhere. A flat porcelain patio puddles the first week.
Mix and lay a full mortar bed
A 4:1 sharp sand to cement mix, moist rather than sloppy, laid 30mm to 40mm thick. Full bed under the whole slab. Dot and dab leaves voids, voids fill with water, water freezes, and the slab cracks. Only bed as much area as you can lay before it goes off.
Prime the back of every slab
Brush a slurry primer across the full back face of the slab and lay it straight away while it is still wet. Tap down with a rubber mallet, check level and fall as you go, and use spacers to hold a consistent 5mm to 10mm joint.
Joint, clean and leave it alone
Wait 24 hours before jointing. Use a brush-in resin compound rated for porcelain rather than a sand and cement slurry, which stains the surface. Wash off residue as you work and keep foot traffic off for another day or two.
The five mistakes we see most.
- Skipping the slurry primer, then wondering why slabs rock a season later.
- Dot and dab bedding on a 20mm slab.
- Laying dead flat because the client asked for it.
- Cutting dry and chipping the glazed edge on every cut.
- Jointing with sand and cement and staining the whole patio.
Do porcelain slabs need a slurry primer?
Yes. Porcelain is non-porous, so mortar will not bond to the back of the slab on its own. A slurry primer brushed onto the back of every slab immediately before laying is what creates the bond. Skipping it is the single most common cause of loose slabs.
Can porcelain be laid on sand?
Not for a patio. 20mm porcelain must go on a full wet mortar bed over a compacted sub-base. Sand bedding is for block paving. Pedestal systems are the only sand-free alternative, and those are for balconies and roof terraces.
What fall does a porcelain patio need?
Around 1 in 80, roughly 12mm drop per metre, running away from the building. Porcelain does not absorb water, so anything flatter will hold puddles.
How do you cut porcelain paving?
A wet cutter with a continuous rim porcelain diamond blade. Go slow, keep the water running, and score the glazed face first on tight cuts to avoid chipping.
How wide should the joints be?
5mm minimum, 8mm to 10mm is common. Use spacers and fill with a brush-in resin jointing compound rated for porcelain rather than a sand and cement mix.
Tell us what you need and we'll price it.
Send over your area in square metres and we'll come back with availability, pack sizes and a quote.