How to Lay Pavers Over a Concrete Patio

Key Takeaways

• Only overlay a slab that is level, stable and free of large or moving cracks; heaved or sunken slabs need repair or removal first.
• Measure door thresholds; most guidelines call for the finished patio to stay at least an inch or so below a door sill and slope away from the house.
• Thin overlay pavers about 1 to 1 1/4 inches thick keep the height gain small.
• Sand-set installations need drainage holes drilled through the slab at low spots so water does not pool under the pavers.
• Mortar-set installations are more permanent but must line up joints over existing slab control joints.

Is Your Slab a Good Candidate?

Condition	OK to overlay?	What to do
Hairline cracks, no movement	Yes	Clean and proceed
Cracks wider than about 1/4 inch, but level on both sides	Usually	Fill with patching compound; plan a sand-set install that tolerates minor movement
One side of a crack higher than the other (heaving)	No	Repair, mudjack, or remove the section
Sunken sections, standing water	No, without fixing	Level low spots, improve drainage
Spalling or flaking surface	Usually, for sand-set	Scrape loose material; avoid mortar bonding to a weak surface
Slab sloping toward the house	No, without correction	Build up with a leveling layer or remove the slab

Lay a long straightedge or a 6-foot level across the slab in several directions. Gaps under it larger than about 1/4 inch over 10 feet will show through the pavers unless you fill them. The slab should slope away from the house by about 1/8 to 1/4 inch per foot; check with a level and measure.

Check the Height Before You Buy

Add the paver thickness to the bedding layer, usually about 1/2 inch of sand or roughly 1/4 to 1/2 inch of mortar. With 1 1/4-inch thin pavers, plan on roughly 1 3/4 inches of added height. Then check:

• Door thresholds: the new surface should remain comfortably below any door sill. Measure from the slab to the bottom of each threshold.
• Steps: raising a patio changes the height of the first step; local codes limit variation between riser heights, so a step that becomes too short or too tall can create a trip hazard.
• Siding and weep holes: keep the paver surface below siding and brick weep holes.
• Transitions: where the patio meets lawn, walkways or a driveway, plan how the new edge will meet adjacent surfaces.

If height is too tight near the house, options include using even thinner porcelain pavers set in mortar, cutting back the slab near the door, or removing the slab and installing pavers on a conventional gravel base.

Choosing Thin Pavers

• Concrete overlay pavers: about 1 to 1 1/4 inches thick, the most common choice, sold in brick, square and rectangular formats.
• Thin clay brick pavers: classic look, often about 1 1/8 inches thick; color is fired through.
• Porcelain pavers: often about 3/4 inch, very hard, stain resistant; usually set in mortar or on pedestals.
• Natural stone veneer pavers: thin-cut bluestone, travertine or slate; usually mortar-set.

For help comparing materials, see brick vs concrete pavers and our overview of types of pavers.

Sand-Set vs Mortar-Set Over Concrete

Factor	Sand-set (flexible)	Mortar-set (rigid)
Difficulty	Easier for DIY	Harder; tile-setting skills help
Drainage	Water passes through joints; needs slab drain holes	Water sheds off surface
Tolerance of slab movement	Better	Poor; cracks transfer to pavers
Edge restraint	Essential	Less critical
Weeds and ants	Possible in joints; polymeric sand helps	Minimal
Freeze-thaw climates	Generally more forgiving	Needs proper materials and control joints
Repairs	Lift and reset individual pavers	Chisel out and re-mortar

Tools and Materials

• Thin pavers plus about 5 to 10 percent extra for cuts and breakage
• Concrete sand for bedding (sand-set) or polymer-modified mortar (mortar-set)
• Polymeric jointing sand
• Paver edge restraint, or a soldier course of pavers mortared at the perimeter
• Hammer drill with a masonry bit for drainage holes
• Two screed rails (1/2-inch conduit works well) and a straight board
• Rubber mallet, level, string line, chalk line
• Wet saw or angle grinder with a diamond blade, plus eye, ear and dust protection
• Landscape fabric strips for drain holes and edges

Step by Step: Sand-Set Thin Pavers Over Concrete

1. Clean the slab thoroughly. Pressure wash, scrape off loose material and let it dry.
2. Repair the slab. Fill wide cracks and patch spalled areas. Grind high spots and fill low spots so the surface is uniform.
3. Drill drainage holes. At low spots and along the downhill edge, drill 1/2- to 3/4-inch holes through the slab, roughly every 2 to 4 feet in problem areas. Cover each hole with a small square of landscape fabric so sand does not wash through.
4. Install edge restraint. Along open edges, mortar a border row of pavers (a soldier course) directly to the slab, or fasten a paver edge restraint. The border holds the field pavers in place and hides the slab edge.
5. Spread bedding sand. Lay screed rails on the slab, add about 1/2 inch of concrete sand, and screed it smooth with a straight board. Do not walk on screeded sand.
6. Lay pavers. Start at a straight edge or the house, placing pavers straight down rather than sliding them, using your pattern. Check alignment with a string line every few rows.
7. Cut pavers to fit at edges and around obstacles with a wet saw.
8. Set the pavers. Tap each paver with a rubber mallet, or run a plate compactor with a pad over thicker pavers if the manufacturer allows; many thin pavers should be set by hand only.
9. Fill joints with polymeric sand. Sweep it into joints, settle it with light tapping, sweep off all residue, then mist with water exactly as the bag directs.

Step by Step: Mortar-Set Pavers Over Concrete

1. Clean, repair and dampen the slab so it does not draw water from the mortar too fast.
2. Mark the slab’s existing control joints. Plan the paver layout so a joint in the pavers falls directly over each slab joint, and leave those joints flexible with sealant rather than mortar.
3. Apply a bonding slurry or polymer-modified mortar bed with a notched trowel, working small sections.
4. Back-butter each paver and press it into place, checking level and spacing.
5. Let mortar cure per the product directions, then grout joints with mortar or a suitable jointing compound.
6. Keep the work damp and protected from sun and freezing during curing.

Drainage Details That Prevent Problems

Water that seeps through paver joints has to go somewhere. On a sand-set overlay, if the slab beneath cannot drain, water sits in the sand, encourages moss and efflorescence, and in cold climates can freeze and lift pavers. Drain holes at low points, a slab that slopes away from the house, and an open edge or gravel strip where water can exit all keep the bedding layer dry. For mortar-set work, the surface should shed water off the edge; avoid creating a dam where the patio meets a wall.

Choosing a Pattern for an Overlay

Pattern affects both looks and how forgiving the job is. Running bond, where each row is offset by half a paver, is the easiest to keep straight and hides small variations in the slab. Herringbone at 45 or 90 degrees interlocks best and resists shifting on sand-set installs, but it needs more cuts at the edges. Basketweave suits brick-style pavers and traditional homes. Large-format squares and rectangles look modern but show any unevenness in the slab, so they work best mortar-set on a very flat surface. Whatever you choose, snap chalk lines on the slab as reference before you start, and dry-lay a few rows to confirm the pattern lands with reasonable cuts at the edges rather than thin slivers.

Common Mistakes to Avoid

• Skipping drain holes on a sand-set overlay, leaving the bedding sand saturated.
• Using too much bedding sand; more than about 1/2 inch lets thin pavers rock and settle unevenly.
• Ignoring slab control joints on mortar-set work, so cracks telegraph straight through the new surface.
• Running a plate compactor over pavers that the manufacturer says to set by hand, which can crack thin units.
• Leaving polymeric sand haze on the surface before wetting, which bonds and is hard to remove.

Maintenance

• Sweep regularly and rinse occasionally.
• Top up polymeric sand in joints if it erodes, usually every few years.
• Seal concrete pavers if you want to enhance color and resist stains; let new pavers weather for some weeks first if efflorescence appears.
• Lift and reset any pavers that settle or rock on sand-set installations.

See our guides on how to clean pavers and installing paver edging. If the slab turns out to be beyond saving, compare options in our concrete patio cost guide, and for more hardscape planning, the landscaping and hardscaping guide.