Porcelain Paving: What It Is, How It Compares and How to Lay It Properly

Porcelain paving is a dense, factory-made outdoor tile, usually 20mm thick, that absorbs almost no water, keeps its colour and wipes clean. It has become one of the most popular patio slabs in the UK, but it behaves differently from natural stone: it has to be primed and bedded on a full bed of mortar, or it comes loose.

What is porcelain paving?

Outdoor porcelain is made from fine clay and minerals pressed and fired at very high temperatures. The result is a slab with a water absorption rate of well under 1%, compared with several percent for most sandstones. That low porosity is where most of its advantages come from: moss and algae struggle to take hold, spills don't soak in, and frost has almost nothing to work on.

The pattern and colour are printed into the surface before firing, so porcelain can look like sandstone, slate, limestone, concrete or timber. The better ranges vary the print from slab to slab, so a laid patio doesn't show the same "stone" repeating every metre.

Porcelain vs sandstone paving

Both make a good patio. The difference is in maintenance, look and how forgiving they are to lay.

• Maintenance: porcelain needs a brush and the occasional wash with warm soapy water. Sandstone greens over in shaded spots and usually needs a clean every year or two, and many people seal it.

• Colour: porcelain stays the colour you chose. Sandstone weathers and mellows, which some people love and others don't.

• Surface: riven sandstone has a natural texture and slight unevenness; porcelain is flat and uniform, which gives a sharper, more modern finish.

• Laying: sandstone is porous and bonds well to mortar on its own. Porcelain has a glassy back and will not bond without a primer.

• Cutting: porcelain is hard and brittle, so it needs a diamond blade, patience and a steady hand. Chipped edges are a common sign of a rushed job.

• Cost: porcelain slabs usually cost more per square metre than Indian sandstone, and the extra care in laying adds labour. The gap has narrowed over the last few years.

If you want a clean, low-maintenance, contemporary look, porcelain is hard to beat. If you want something that ages with the garden and suits an older house, sandstone still has a place. For most of the patios in Kettering we've laid recently, clients have chosen porcelain for the maintenance alone.

Is porcelain paving slippery?

Good outdoor porcelain is not slippery, but you have to buy the right product. Indoor tiles and polished finishes should never go outside.

Look for a slip rating on the spec sheet. Manufacturers usually quote an R rating (R11 is the usual benchmark for outdoor paving) or a pendulum test value (PTV). The UK Slip Resistance Group treats a wet PTV of 36 or above as low slip potential. A textured or "structured" surface grips better than a smooth matt one, which matters around pools, on steps and in shady corners that stay damp.

How should porcelain paving be laid?

Porcelain fails when it's laid like sandstone. The method that lasts:

1. Proper sub-base. Dig out, lay and compact a granular sub-base (MOT Type 1 is the usual choice), typically around 100mm for a garden patio.

2. Set the falls. The patio needs a gentle fall away from the house so water runs off, usually somewhere between 1:60 and 1:80, and the finished surface should sit well below the house's damp proof course.

3. Prime every slab. A slurry primer is brushed onto the back of each slab just before laying. Without it the mortar has nothing to grip.

4. Full mortar bed. Each slab goes onto a full, even bed of mortar with no voids. Spot-bedding (dabs of mortar at the corners) leaves hollows that crack under load and let water sit.

5. Consistent joints. Joints are usually 3-5mm for a tight modern look, filled with a brush-in jointing compound or a cementitious grout designed for porcelain.

6. Clean as you go. Porcelain doesn't absorb much, but cement haze left to cure is hard to shift. Wipe residue off before it sets.

Which is the best patio slab?

There isn't one best slab, but there is a best slab for each situation, and the layout matters as much as the material (our patio ideas walk through the layouts that work in a typical UK garden). For low maintenance and a modern house, 20mm porcelain with a textured finish. For a period property or a cottage garden, sandstone or limestone. For a driveway or anywhere a car will park, neither on its own: that needs a slab or block rated for vehicle loads, laid on a deeper base, which is a different job from a patio. If a patio runs into the drive, it's worth planning both together so the levels and materials line up, and our driveways team handles that side.

What goes wrong with porcelain patios?

Most of the porcelain patios we're asked to repair have one of four faults:

• No primer. Slabs lift off clean, with no mortar attached to the back.

• Dot-and-dab bedding. Slabs rock or crack at the corners because they're only supported in five places.

• No fall, or the wrong fall. Water ponds on the surface or runs towards the house wall.

• Poor cuts. Chipped or uneven edges around drains, steps and borders.

All four are laying faults, not problems with the material. Laid properly, porcelain is one of the most durable patio surfaces available.

Porcelain paving questions, answered

Does porcelain paving need sealing?

No. Its low porosity means sealing isn't needed and most sealers won't bond to it anyway. Clean it with warm water, a mild detergent and a stiff brush.

Can porcelain paving crack in frost?

Well-laid porcelain handles UK winters well, because it absorbs so little water. Cracks in cold weather nearly always trace back to voids under the slab from poor bedding, not the frost itself.

Can you lay porcelain on sand?

Not as a permanent patio. Porcelain is too thin and rigid to sit on a loose sand bed; it needs a full mortar bed on a compacted sub-base. There are pedestal systems for roof terraces, but that's a different specification.

If you're weighing porcelain against stone for your garden, we're happy to bring samples out, look at the levels and drainage with you and give you an itemised quote. Just get in touch.