When getting a quote it’s important to know what you’re getting. What’s under the concrete? What’s the re-bar like in the concrete? What kind of concrete is used? We use road-base foundation under the concrete (crushed concrete and gravel). Many other companies use cushion sand, because it’s cheaper. The problem is that in time it will wash away. We use 3/8 inch rebar on 16 inch centers. Most other companies put it at 24 inches. The concrete we use is 3500 psi (standard is 3000).