Patio blocks go down in layers: base, sand, then blocks set in a running bond or similar pattern
Patio block installation starts with a compacted gravel base, a leveling layer of sand, and then the blocks themselves, set in a staggered pattern so joints don't line up. The whole job takes a weekend for a small patio if the ground is already level. If you're starting from bare soil, add a day for excavation and base prep. Most blocks are 12 inches by 12 inches or 12 by 24 inches, weigh 30 to 50 pounds each, and sit on top of each other without mortar—the sand between them lets them settle slightly and move with frost.
The most common mistake is skipping the base layer or making it too thin. Blocks will sink unevenly, crack, or shift if they sit directly on soil or on less than 4 inches of compacted gravel. The second mistake is not sloping the surface slightly so water runs off instead of pooling.
Key Takeaways
- Dig out the patio area 5 to 6 inches deep, compact 4 inches of gravel base, then add 1 inch of sand and level it before laying blocks.
- Slope the finished surface about 1/8 inch per foot away from your house so water drains and doesn't pool under the blocks.
- Lay blocks in a running bond pattern (like bricks in a wall) so the joints are staggered, which distributes weight more evenly than a grid.
- Tap each block down with a rubber mallet as you go, checking level frequently with a 4-foot level, and fill joints with polymeric sand after the patio is complete.
- The entire job—base, sand, and blocks—takes one to two days for a 10-by-12-foot patio if you work alone.
Measure the area and mark the edges
Measure the length and width of the space where your patio will go. Mark the edges with chalk, spray paint, or string lines tied to stakes. Include a 1-foot buffer on all sides if you plan to add a border or edging—this gives you room to work and keeps blocks from shifting outward.
Check the slope of the ground by laying a long straight board (a 2-by-4 works) across the area and placing a level on top. If the ground is already sloped away from your house, note how much. If it's flat or slopes toward your house, you'll need to create slope during the sand-leveling step.
Excavate and compact the base layer
Dig out the marked area to a depth of 5 to 6 inches. Remove all grass, roots, and loose soil. The bottom should be firm—step on it and it should not compress further under your weight. If the soil is very soft or clay-heavy, dig an extra inch and add a layer of landscape fabric to prevent weeds from growing up through the patio later.
Spread 4 inches of crushed gravel or crushed stone over the excavated area. Do not use river rock or smooth pea gravel—these don't compact. Use a hand tamper or a plate compactor (which you can rent from most tool rental shops for $40 to $60 per day) to compress the gravel in 2-inch layers. Compact the first 2 inches, then add the second 2 inches and compact again. The base should feel rock-solid and not shift when you walk on it.
Add and level the sand layer
Spread 1 inch of coarse sand (also called concrete sand or mason sand) evenly over the compacted gravel. Do not use fine play sand—it compacts too much and doesn't drain. Rake the sand smooth, then use a long straight board laid across the area to check that it's level. If you need slope for drainage, tilt the board slightly away from your house—about 1/8 inch per foot is enough to shed water without being noticeable.
Use a level on top of the board to confirm the slope. If one end of the board is higher than the other, add or remove sand under the low end until the board sits at the angle you want. This step matters more than any other—blocks laid on an uneven sand bed will rock and settle unevenly over time.
Lay the blocks in a running bond pattern
Start at one corner, usually the one closest to your house or the lowest point of the slope. Lay the first block in place and tap it down gently with a rubber mallet until it sits firmly in the sand. Check that it's level in both directions using a 4-foot level. Adjust by adding or removing sand underneath if needed.
Lay the second block next to the first, leaving a gap of about 1/8 inch (roughly the thickness of a pencil). Tap it down and check level. For a running bond pattern, the second row starts with a half block (or a full block offset by half its length) so that the joints in the second row fall in the middle of the blocks in the first row. This staggered pattern is stronger than a grid because weight is distributed across more joints.
Continue laying blocks row by row, checking level every few blocks. If a block sits higher than its neighbors, tap it down more. If it sits lower, lift it out, add a pinch of sand underneath, and reset it. Work in sections of 10 to 15 blocks at a time so you can step back and see if the surface is staying level.
Cut blocks to fit edges and corners
When you reach the edge of the patio, you'll need to cut blocks to fit. Mark the cut line on the block with a pencil. Use a circular saw with a masonry blade, a wet saw (which you can rent), or a hand-held masonry chisel and hammer. A wet saw is cleanest and fastest but requires water and electricity. A circular saw is loud and creates dust—wear a dust mask and eye protection. A chisel works but is slow and the cut is rougher.
Make the cut on a stable surface, not while the block is in place. Test-fit the cut piece before tapping it into the sand. If it's too tight, trim a bit more. If it's loose, it will rock—remove it and add sand until it sits snug.
Fill joints with polymeric sand
Once all blocks are laid and level, sweep polymeric sand (also called polymeric joint sand or poly sand) into the gaps between blocks. This sand contains a binder that hardens when wet, locking the blocks together and preventing weeds from growing in the joints. Spread the sand across the patio surface and sweep it into the gaps, working diagonally so you don't pull sand out of joints you've already filled.
After the joints are full, mist the entire patio lightly with a garden hose set to a fine spray. Do not flood it—the sand should darken slightly as it absorbs water, but water should not pool on the surface. Let it dry for 24 hours before walking on it heavily. The polymeric sand will harden as it dries, and the patio will be ready to use.
Frequently Asked Questions
Do I need to use edging around the patio?
Edging is optional but helpful. Plastic or metal edging strips nailed to stakes around the perimeter keep blocks from shifting outward over time, especially if the patio gets heavy foot traffic. If you skip edging, the outer blocks may creep outward by an inch or two over a few years, but the patio will still be usable.
Can I install patio blocks on top of existing concrete?
Yes, but the concrete must be clean, level, and not cracked. Sweep it thoroughly, then lay 1 inch of sand on top and level it. The blocks will sit on the sand instead of the concrete. If the concrete is cracked or uneven, the blocks will rock—in that case, remove the concrete or grind it level first.
What if my patio is on a slope and I can't level it?
Use a stepped design instead. Divide the slope into two or three flat sections, each one step down from the last. Build a small retaining wall or use a row of taller edging blocks to hold back the upper section, then lay blocks on each flat area. This looks intentional and drains better than trying to force blocks onto a steep slope.
How long do patio blocks last?
Concrete patio blocks typically last 15 to 20 years in most climates. In areas with freeze-thaw cycles, they may crack after 10 to 15 years as water seeps into small pores and expands when it freezes. Natural stone blocks like flagstone or bluestone last longer, often 25 to 30 years, but cost more upfront.
Can I remove and reset blocks if I make a mistake?
Yes. Lift out the block, scrape away the old sand, add fresh sand, and reset it. If you need to move several blocks, work from the edge inward so you don't destabilize blocks you've already set. The sand layer is forgiving—you can adjust blocks multiple times before the patio is complete.