Last Updated on September 27, 2026 by Umar Farooq
A concrete patio extension with pavers is a normal paver patio built tight against the edge of the old slab. Check that the slab is sound, dig the extension deeper than the slab (pavers, 1 inch of sand and at least 4 inches of compacted gravel), tamp the base hard against the slab edge without digging under it, and set the pavers 1/8 to 1/4 inch above the concrete so they settle flush when you compact them. Keep the same slope away from the house across both surfaces. Done that way, the slab acts as the edge restraint on one side, and the seam between old and new stays level. Concrete and pavers get along fine, provided nobody expects them to move the same way.
Is the old slab worth extending?
The extension will only ever be as flat as the slab it's butted against, so inspect it first:
- Hairline cracks are normal in concrete and don't matter here.
- A crack with one side higher than the other, a slab that rocks, or one that has sunk toward the house means the slab is moving. Pavers butted against a moving edge will show a step at the seam within a season or two.
- A slab that slopes toward the house needs fixing before anything is added to it. Water will follow the old fall into the new work.
Concrete Network's overview of patio extension options makes the same point from the concrete side: a damaged patio needs repair or resurfacing before it is extended. If the slab fails these checks, the honest options are to replace it with pavers or to cover it (see our guide to pavers over concrete).
Height is set by the slab, not the pavers
The slab's top edge is fixed, so every layer of the extension works back from it. A typical build under a 2 3/8-inch paver:
| Layer | Thickness |
|---|---|
| Paver | 2 3/8 in |
| Bedding sand, loose | 1 in |
| Compacted gravel base | 4 in minimum for foot traffic, more on wet or frost-prone soil |
| Dig below the slab top | about 7 3/8 in or more |
That usually means digging deeper than the slab itself, which is typically only a few inches thick. Dig right up to the slab's edge but not under it. The ground beneath the slab is holding it up, and undermining it is how a sound slab becomes a cracked one.
My firm view on this job: don't lay the pavers flush with the slab. Lay them a hair high. CMHA's guide specification for interlocking pavers allows pavers to sit 1/8 to 1/4 inch above final grade before compaction, because the plate pushes them down into the sand. Lay them flush with the concrete and they finish slightly below it, which is a lip that catches water, grit and toes. Set them proud, compact, and they settle level with the slab.
Base for a concrete patio extension with pavers
The part of the base most likely to fail is the strip against the slab, because a plate compactor can't reach right into the corner. There, in particular:
- Compact the soil in the bottom of the dig, including right against the slab edge.
- Place the gravel in thin lifts and compact each one. Along the slab, finish with a hand tamper so the stone is as dense at the seam as it is in the middle.
- Grade the base to the same slope as the slab, so the fall continues in one plane. A patio should drain away from the house; a slope that turns back toward the slab creates a trough along the seam.
- Screed an inch of loose concrete sand and don't walk on it. Lay pavers from the slab outward, so your first row is referenced to the concrete edge.
This Old House's patio extension tutorial uses a 6-inch crusher-run base, and it's worth copying on any soil that stays wet. The patio will be judged by the seam, and the seam is only as good as the gravel under it.
After laying, compact the pavers, sweep in joint sand, and compact again. Our guide to compacting pavers covers passes and the pad that keeps the plate from scuffing them.
Designing the seam between old and new
The practical question for most people is how to make pavers and concrete look like they belong together. There are three honest approaches:
- A contrast, on purpose. Don't try to match gray concrete with gray pavers; the slight mismatch looks like a mistake. Pick a paver that clearly differs and repeat a color from the house. Unilock's advice on adding pavers to an existing patio says to bring samples home and lay them beside the old patio before you choose.
- A border course along the seam. A soldier row of pavers laid along the slab edge turns the joint into a deliberate line and hides small differences in the slab edge. Carrying the border around the old slab too ties both together. Our guide to a concrete patio with paver border goes further.
- A change of level. Step the extension down one riser, or separate the two with a low seat wall. The new area reads as its own room, and the height doesn't need to match at all. Keep any step within the usual riser limits (no more than 7 3/4 inches in the IRC).
Pavers around three sides of a concrete patio
Wrapping pavers around a slab rather than extending one side follows the same rules on every edge, plus two:
- The slab's slope decides the paver slope. On the downhill side the pavers keep falling away. On the side edges they fall in the same direction the slab does.
- The outer paver edge needs its own restraint. The slab holds the inside edge; the outside edge needs edging spiked into the base, or the pavers creep toward the lawn.
(Pavers wrapped around a slab are a bit like a new frame on an old painting. People notice the frame first, so make it straight.)
Build to the slab, then sweep
A concrete patio extension with pavers works when the slab is sound, the base is dug deeper than the concrete and compacted hard against it, and the pavers go down a fraction high so they settle flush. Choose a contrasting color or a border to make the seam look planned. After that, the only visible difference between old and new should be the one you picked.
FAQ
Can you extend a concrete patio with pavers?
Yes. Build a standard paver patio against the slab edge: compacted gravel base, 1 inch of loose sand, pavers set slightly high so they settle flush, and edge restraint on the outer edges. The slab acts as the restraint on the side it touches.
How do you match the height of pavers to a concrete patio?
Work down from the slab's top edge. Dig for the paver thickness, 1 inch of sand and at least 4 inches of base, then set the pavers 1/8 to 1/4 inch above the slab. Compaction settles them level with the concrete.
What goes between a concrete patio and pavers?
Nothing special in most cases. The pavers butt tight to the slab edge and the joint gets the same joint sand as the rest. A soldier border along the slab makes the line look intentional.
Should pavers be flush with a concrete patio?
Flush after compaction, yes. Set them a fraction high before compacting, because the plate pushes them down into the sand. Pavers laid flush beforehand end up slightly low, leaving a lip at the seam.
