- Caulk gun
- Chalk line
- Leather gloves
- Plate compactor (rental)
- Scrub brush with handle
- Tape measure
- Utility knife
- Concrete cleaner
- Landscape fabric
- Polyurethane construction adhesive
- Screed pipe
Overview: Build a paver patio with less work
Concrete patio slabs
Concrete patios are typically plain and often show cracks.
Patio after setting pavers over concrete patio slabs
Pavers dress up the patio and make it an attractive outdoor living space. A concrete patio is made for practicality, not beauty. It starts out looking plain and goes downhill from there. As craters, cracks and stains accumulate, it can go from dull to downright ugly in just a few years. But there's a simple solution, whether you want to dress up a bland patio or hide an aging one. Covering concrete with paver bricks is much easier than pouring new concrete or laying paving stones the traditional way. It requires less skill and less time, and it's a whole lot easier on your back. Here we'll walk you through how to lay paving stones over concrete.
Assess your slab
This project will work with most patios. Surface damage like flaking, chips and craters is no problem. But a few conditions make this method a no-go:
- A too-low threshold. Door thresholds have to be high enough above the existing patio to allow for the thickness of the border pavers, plus an extra 3/4 in. to allow for “frost heave”—rising of the slab when the soil freezes.
- Expanding cracks. This method will work over most cracks—which grow and shrink with seasonal ground movement. But if you have a crack that has noticeably grown in recent years, this method is risky. The crack may eventually “telegraph” through the pavers, creating a hump or gaps.
- Search for “patio” or “path” to find paving projects galore.
- Cool your scorching deck or patio! Search for “shade” to see ideas and projects.
- Search for “patio furniture” and get complete plans for chairs and tables.
Save 12 Tons of Soil
A standard paver patio rests on a thick base of compacted gravel. This patio cover-up will save you the cost of that gravel. More important, it eliminates the backbreaking drudgery of breaking up concrete, digging up soil, hauling it all away and hauling in gravel. On this 12 x 14-ft. patio, a patio tear-out and new gravel base would have meant more than 12 extra tons of wheelbarrow work.
Project step-by-step (7)
Pavers Over Concrete: Assemble the materials
The materials for this 12 x 14-ft. patio cost about $850, or $5 per sq. ft. Using less expensive pavers, you could cut the cost by almost half. Most landscape suppliers and home centers stock all the materials, but you may have to do a little hunting for the right combination of pavers. The pavers used for the border must be at least 3/4 in. thicker than the “field” pavers, which cover the area between the borders. That thickness difference will allow for a bed of sand under the field. A difference of more than 3/4 in. is fine; you'll just need a little more sand. If you can't find thick pavers you like, consider retaining wall cap blocks for the border. We used cement pavers (concrete patio blocks) for the border and clay pavers for the field.
To estimate how much sand you'll need, grab your calculator. First determine the square footage of the sand bed. Then divide that number by 12 for a 1-in. bed or 18 for a 3/4-in. bed. That will tell you how many cubic feet of sand to get. You can have a load of sand delivered or save the delivery fee by picking up a load yourself with a truck or trailer. Most home centers also sell bagged sand. A 50-lb. bag (1/2 cu. ft.) costs about $3.
Figure A: Pavers Over Concrete Slab
This technique requires two types of pavers. Glue thicker pavers to the concrete on the perimeter and lay thinner pavers on a sand bed. The resulting look is one of our favorite patio block ideas.
Lay the border first
Scrub the perimeter
Clean the edges of the patio where you'll later glue down the border pavers over concrete. Clean concrete means a stronger glue bond.
Glue down the border pavers over concrete
After setting each paver, run a bead of construction adhesive up the side of it. That will keep the sand from washing out between pavers. How to lay paving stones
To get started, scrub the border area (Photo 1) with a concrete cleaner or muriatic acid mixed with water (check the label for mixing and safety instructions). Any stiff brush will do, but a deck stripping brush on a broom handle makes it easier. Hose down the patio when you're done scrubbing the border.
While the concrete is drying, grab a tape measure and a chalk line and carefully plan the locations of the borders (see Figure B). Using the chalk lines as a guide, glue down the border pavers along the house and two sides of the patio (Photo 2). We used polyurethane construction adhesive for a strong, long-lasting bond (about $5 per 10-oz. tube). If adhesive squishes up between pavers, don't try to wipe it off. Just let it harden, then trim it off of the concrete patio blocks with a utility knife.
Figure B: Border Layout
A Snap a chalk line parallel to the house to mark the location of the border decorative pavers. Remember to leave a gap of at least 1/4 in. between the border decorative pavers and the house.
B Lay out field pavers to locate the side borders. A simple row of pavers will work even if you plan to lay them later in a “herringbone” pattern as we did. The goal is to establish a field width that allows each course to end with a full or half paver, but not smaller pieces. That means less cutting, less waste and a neater look.
C Position the border pavers and mark their locations. It's OK if the border decorative pavers don't quite reach the edge of the patio, but don't let them overhang. Nudge one border patio block outward by 1/4 in. to allow a little extra space for the field pavers.
D Snap a chalk line to mark one side border. To make this line square with the line along the house, use the 3-4-5 method.E Mark the other side border. Measure from the first side to make sure the two sides are parallel.
F Leave the final border unmarked and install the border after the field is complete. That open end makes screeding off the excess sand easier and lets you position the final border perfectly.
Spread a flat bed of sand
Spread fabric, then sand
Lay down landscape fabric to keep the sand from washing down into cracks. Then position the screed pipe and spread the sand.
Flatten the sand
Notch one end of a 2x6 to match the depth of the field pavers over concrete. The other end rides on the screed pipe. Screed both halves of the field, moving your screed pipe as you go. If the field area is more than 10 ft. wide, you'll need a screed pipe in the center of the patio (Photo 3). A 10-ft. section of black or galvanized steel plumbing pipe ($14) works best. For a 1-in. bed, use 3/4-in. pipe; for a 3/4-in. bed, use 1/2-in. pipe. Keep in mind that each pipe size is listed by its inner diameter, but the outer diameter is what matters here: 3/4-in. pipe has an outer diameter of about 1-1/8 in.; 1/2-in. pipe, about 5/8 in. In both cases, you'll get an extra 1/8 in. of sand bed thickness and the field pavers will stand about 1/8 in. above the border pavers. Then, when you “tamp” the field with a plate compactor, the sand will compact and the field pavers will settle flush with the border.
“Screed” the sand flat with a notched 2x6 (Photo 4). The depth of the notch should be 1/8 in. less than the thickness of the field pavers. If the field is less than 10 ft. wide, notch both ends of the screed board and skip the pipe. Screeding is hard work and it's best to have a helper.
Lay the pavers and finish the border
Lay the pavers
Cover the sand with field pavers. When the field is complete, glue down the final border pavers. Then tamp the field with a plate compactor and sweep sand over the pavers to fill in the gaps. From here on out, this is mostly a standard paver job. Lay the field pavers over concrete as you would on any paver patio. Scrape away the excess sand and cut off the excess landscape fabric with a utility knife. Glue down the last border patio blocks. Let the glue dry for a few hours before you tamp the field pavers and sweep sand across the patio to fill the joints.
Q: Why not skip the sand and glue down all the pavers?
A: You could do that. But gluing down hundreds of pavers will add a few hours to the job and you'll spend at least $100 on adhesive.
Q: I want a bigger patio. Can the pavers extend beyond the current footprint?
A: The pavers could continue onto a standard gravel base. But the gravel base and the existing slab might shift in different ways, creating a gap or hump where they meet. So it's best to keep them separate. If you want to add a grilling area, for example, separate it from the main patio and set a steppingstone or two between the two paved areas.
Q: Can I glue pavers over the steps?
A: Yes. If your patio includes steps, you must cover the treads in order to maintain the height of the steps. Or you can completely cover the steps if you like. Just be sure to leave a gap of at least 1/2 in. between the pavers on the steps and those on the patio to allow for movement.
Q: Do I have to use paver bricks?
A: You can cover the field with any type of paving product: natural or manufactured flagstone, pavers of any size or shape. But paver bricks are best for the border because they provide a flat, even surface for screeding (see Photo 4).