· by Michael Blair, Nashville's Concrete
On ground that stays put, choosing between poured concrete and pavers is mostly a matter of looks. Clay soils can swell as they take on water and shrink as they dry, and the USGS swelling clays map of the conterminous United States charts how widely those clays occur. Where the ground under a patio moves, the way each surface copes with that movement is the comparison worth making, and it is the first thing we look at before we price a new patio.
How do pavers and a slab cope when the ground shifts?
Pavers are separate units laid over a compacted base, so when the ground under them shifts they can shift with it. The usual sign is a dip or a ridge rather than a break, and a settled patch can be lifted, the base corrected underneath and the same pavers relaid.
A poured slab is one rigid piece. If the ground moves far enough it can crack, and a crack does not close up again on its own. We cut control joints so that when a slab does crack, it cracks along a line we chose, and our post on where control joints go explains how we space them.
Cost, up front and later
We would rather not put a single number on the gap between the two, because it moves with the job. The EPA’s page on cool pavements lists what drives the cost of any pavement, among them the region, the contractor, the time of year, the materials chosen, how easy the site is to reach, the soils underneath and the size of the project. Stamped concrete adds a pattern, color and a sealer to the same slab, and our concrete guide walks through what goes into a concrete price around here.
The later costs differ in kind. Expect a paver patio to need its joint sand topped up, weeds kept out of the joints and the odd settled unit reset. A plain slab asks little until it cracks, while a stamped or colored one also needs its sealer renewed on the schedule the sealer’s maker gives, which our post on stamped concrete upkeep covers.
- Concrete: one continuous slab, and a crack once opened stays
- Pavers: separate units that can be lifted and relaid
- Stamped concrete: a patterned slab with a sealer to keep up
- Both: start with a compacted base and water directed away from it
Are pavers easier to repair than concrete?
This is where pavers have a real advantage. A stained, chipped or settled area can be lifted and reset or replaced, and if spare pavers from the same batch were kept, the new ones can be hard to pick out.
In our experience a patch in a slab rarely matches the concrete around it. That matters more on a patio you sit and look at than on a driveway you park on. When a slab has sunk in one piece rather than cracked, lifting it may be an option, as our post on lifting versus replacing a slab explains, and broken sections fall under concrete repair and replacement.
Which suits which job
For a driveway we pour concrete, and our driveway page covers the base under it and the tie-in at the street. A mismatched patch is less of a worry there than on a patio.
For patios and pool surrounds, repairability favors pavers, and heat comes down to color more than to material. The EPA’s cool pavements chapter puts the peak summertime surface temperature of conventional concrete and asphalt at 120 to 150°F, and Lawrence Berkeley National Laboratory’s Heat Island Group shows a light stretch of pavement about 30°F cooler than a dark one beside it. By Berkeley Lab’s figures new concrete reflects 30 to 50 percent of sunlight, falling to 20 to 35 percent as tire marks and grease darken it.
The EPA notes that brick and block pavers come in colors and finishes made to reflect more sunlight, and concrete can be lightened too: the same chapter reports a 2007 study that measured almost 60 percent reflectance for cement with slag against about 35 percent for a conventional mix. A light paver or a light slab will be the cooler one under bare feet, and a dark version of either the hotter. If you are weighing the two for your yard, send us the size and the spot and we will price the concrete side.
Sources
- USGS, Swelling Clays Map of the Conterminous United States (I-1940), 1989 — Swelling clays mapped across the lower 48
- U.S. EPA, Using Cool Pavements to Reduce Heat Islands — What drives the cost of any pavement: region, contractor, season, materials, site access, soils, project size
- U.S. EPA, Reducing Urban Heat Islands: Compendium of Strategies, Cool Pavements chapter — Conventional concrete and asphalt peak at 120–150°F; pavers come in colors and finishes made to reflect more sunlight; 2007 study, about 60 percent reflectance for cement with slag against about 35 percent for a conventional mix
- Lawrence Berkeley National Laboratory, Heat Island Group, Cool Pavements — Light pavement about 30°F cooler than dark; new concrete reflects 30–50 percent of sunlight, aged 20–35 percent
FAQ
Poured Concrete or Pavers for a Patio — questions
Do pavers need more maintenance than concrete?
Somewhat, and of a different kind. Pavers want joint sand topped up, weeds kept out of the joints and the odd unit reset. A plain slab asks little until it cracks, and a stamped or colored one also needs its sealer renewed on the schedule its maker gives. Neither is maintenance free; pavers are the easier of the two to put right.
Which is better on Middle Tennessee clay?
Pavers cope with ground movement more gracefully, because a settled section can be lifted and reset, where a cracked slab stays cracked. Either one does better on a compacted stone base with water directed away from it, and on clay we put more of our effort into that base than into the surface.
Do pavers get hot in summer?
They can, and color matters more than the material. Light pavers or light concrete stay cooler than dark ones, and Lawrence Berkeley National Laboratory shows a light stretch of pavement about 30 degrees Fahrenheit cooler than a dark one. New concrete is fairly reflective, though it darkens as it ages. Around a pool, pick the lightest color you can live with.
Is a concrete patio cheaper than pavers?
It depends on the job, so we will not quote one gap between them. The EPA lists what drives any pavement’s price: the region, the contractor, the season, the materials, site access, the soil underneath and the project’s size. Later costs differ as well, with joint sand and resets for pavers and sealer for a stamped slab.