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Porcelain patio jointing compound

Updated: October 2026

The slabs are outdoor porcelain, the joints are tight, and a neighbour has offered a bag of block-paving sand. That sand is the wrong method on this surface. Porcelain is dense and low-porosity, the usual joint is about 3–5 mm, and a dry sand-and-cement brush-in can stain the face without ever becoming a rigid joint. This page is the porcelain patio jointing compound case. Block paving is [kiln dried sand vs jointing compound](/hub/flooring-tools-and-accessories/paving-joint-compound/sub/paving-joint-compound-vs-sand). The ranked bags are on the [paving joint compound comparison](/hub/flooring-tools-and-accessories/paving-joint-compound). Peter F. did not lab-test these tubs on porcelain. If you buy through our links, we may earn a commission at no extra cost to you.

The slabs are outdoor porcelain, the joints are tight, and a neighbour has offered a bag of block-paving sand. That sand is the wrong method on this surface.

Our top picks

Joint-It Joint-it Simple, dark grey, 12.5 kg

Best overall

Joint-It Joint-it Simple, dark grey, 12.5 kg
6.8/10about £155.58
View offer
Dansand Dansand Kerama grey, 15 kg

Rank 2

Dansand Dansand Kerama grey, 15 kg
0.0/10about £39.99
View offer
Households Direct Rock-Tite blanched almond, 15 kg

Rank 3

Households Direct Rock-Tite blanched almond, 15 kg
0.0/10about £34.99
View offer
On this page
  1. 1.Why porcelain is not block paving
  2. 2.What this comparison actually offers
  3. 3.Residue on a dense surface
  4. 4.When to leave this set

Why porcelain is not block paving

Marshalls tells you to keep porcelain joints at about 3–5 mm, filled to full depth, and not to brush dry or semi-dry sand-and-cement in. That mix stains the slabs and does not stay rigid. Rake bedding mortar out so the fill goes the full depth, then saturate and brush on a diagonal. Sweeping dry block sand across a dry face copies the step that guide is written to stop. Sika’s surface guide keeps setting sand for block paving and a flowable grout for porcelain. The buff bag in this comparison is the block product. A brush-in that starts at 5 mm can bridge a 3 mm joint and leave a skin on the arris. Measure the narrowest gap and test a corner. Compound will not stop a slab rocking. How to measure before you buy is the paving jointing compound buying guide.

What this comparison actually offers

Four listings mention porcelain. None is a reviewed UK grout with a 3 mm minimum you can check against Marshalls. Dansand Kerama grey, 15 kg (B0H3LXTHTQ) is £39.99, joints up to 10 mm, tiles 20–30 mm thick, coverage 5–10 m², and no reviews. Up to 10 mm does not show a 3 mm joint will fill. Rock-Tite blanched almond, 15 kg (B0GVL27DY9) is £34.99, a polymer-modified cement with porcelain named, no width and no reviews. That is the family Marshalls warns can stain when brushed in dry. Joint-it Simple, 12.5 kg (B0CMQYZCBF) is £155.58, with United States reviews and no millimetre width on the listing. The maker asks for joints of at least 3 mm by 25 mm. NVBFOL’s only review describes about 100 g.
Joint-It Joint-it Simple, dark grey, 12.5 kg

Testsieger

Joint-It Joint-it Simple, dark grey, 12.5 kg
6.8/10about £155.58
View offer

Residue on a dense surface

Porcelain keeps residue on the face, on pale slabs first and on dark ones as a veil in low sun. Test a corner you can live with, then leave it to cure before you judge the haze. Dry sand plus a jet drives dust into the micro-texture. Brush surplus off on a diagonal while you can still move it. Marshalls’ sequence is saturate, then brush diagonally, after the joint is raked to full depth. The water steps are on how to apply paving jointing compound.

When to leave this set

For a true 3–5 mm porcelain joint, the next step is outside this comparison. SikaCeram FlowFix is the flowable grout Sika points at porcelain, described as 3–10 mm and at least 15 mm deep. It is not an ASIN here, and this page will not quote a price. Verify the tub in front of you. Stay inside this set only if a listing states a width your narrowest joint meets. Kerama’s up to 10 mm is the closest sentence here, and it is unreviewed. If the slabs rock, stop.

Common questions

Can I brush block-paving sand into porcelain?
No. Marshalls says not to brush dry or semi-dry sand-and-cement into 3–5 mm porcelain joints, because it stains and does not stay rigid. Sika’s setting sand is the block-paving product in this comparison, specified for 2–5 mm on blocks, not for porcelain. Sweeping it across a dense slab copies the method the laying guide is written to stop. Use a joint product aimed at porcelain, and keep block sand on blocks.
What joint width do porcelain slabs usually need?
Marshalls states about 3–5 mm, filled to full depth, for a porcelain patio. Your narrowest measured gap is the one that has to fit the tub, not the nominal spacer size you started with. A brush-in that starts at 5 mm can bridge a 3 mm joint. Up to 10 mm, which is what Dansand Kerama states, does not prove the bag is happy at 3 mm. Measure before you treat a bullet as a match.
Which products in this comparison actually name porcelain?
Kerama grey at £39.99, with joints up to 10 mm, tiles 20–30 mm thick, and no reviews. Rock-Tite blanched almond at £34.99, with porcelain named, no width and no reviews. Joint-it Simple at £155.58 for this 12.5 kg ASIN, with porcelain on the listing and United States review texts. Bostik has one review mentioning no stain, not a porcelain bullet that sets a 3 mm joint. NVBFOL names porcelain on a tub the only review puts at about 100 g.
Will a brush-in leave a haze on dark porcelain?
It can. Dense porcelain keeps residue on the face, and dark slabs show a veil in low sun even when pale slabs show it first. The risk goes up if you leave dust and then wet it, which is the staining pattern in paving reviews in this set. Test a corner, brush surplus off on the diagonal, and do not jet the face to clean a mistake. A pressure washer is too late once the film has cured.
Is Joint-it Simple the porcelain product, given the price?
Price does not make it the porcelain answer. This ASIN is £155.58 for 12.5 kg, the listing names porcelain, and there is no joint width in millimetres. The 3.4 from nine reviews is written in the United States, so it is not UK opinion. The maker asks for a permeable base and joints of at least 3 mm by 25 mm, which the amazon page does not state.

Related pages

Best paving jointing compound

Paving joint compound

Paving jointing compound: width, surface, drainage

How to apply paving jointing compound without washout

Kiln dried sand vs jointing compound for block paving

Sources

Public UK sheets and guidance, plus the amazon.co.uk listing lines kept for these ten products. This is not a laboratory test.

  1. Sika Setting Sand product data sheet, January 2026 (retrieved October 2026)
  2. Bostik UK TDS02249, 25 April 2025 (retrieved October 2026)
  3. Sika UK surface guide: match the jointing compound (retrieved October 2026)
  4. HSE: dry sweeping and construction dust (retrieved October 2026)
  5. BS 7533-103:2026, permeable pavement design (retrieved October 2026)
  6. Marshalls: how to lay a porcelain patio (retrieved October 2026)
  7. Pavingexpert: pointing (retrieved October 2026)
  8. Joint-it Simple, maker page (retrieved October 2026)