Flatwork Prep 101: Get Your Site Ready for a Perfect Pour

Philip Ellis • August 8, 2025

If you’re pouring a driveway, patio, shop slab, or sidewalk, the success of that concrete starts with what’s underneath it. Proper flatwork prep isn’t just about making the ground level—it’s about creating a compacted, stable, and graded surface that will support the concrete for years to come.

At Just Dig It, we’ve prepped hundreds of concrete jobs across Utah. We’ve seen what works, what doesn’t, and what happens when this crucial step is rushed or skipped altogether.

In this guide, we’ll walk you through everything you need to know about flatwork prep—from excavation and subgrade to compaction and cleanup—so your concrete pour goes off without a hitch.

Why Flatwork Prep Matters So Much

Concrete is only as strong as the base it sits on. Without a proper subgrade, even the best concrete can:

Crack due to settling or movement
Shift due to poor compaction or moisture
Develop uneven surfaces or drainage problems

Good prep ensures your flatwork stays level, drains correctly, and holds up under foot traffic, vehicles, or structures. It also makes life easier for your concrete crew—saving time, materials, and frustration.

What Is “Flatwork” in Construction?

Flatwork refers to any horizontal concrete surface, including:

Driveways
Sidewalks
Patios
Garage floors
Shop or shed pads
Walkways or utility slabs

Each of these needs a compact, level base to avoid cracking, sinking, or premature wear.

Step-by-Step Flatwork Prep Process

Step 1 – Site Evaluation

We walk the site and review the scope of the pour:

What are the dimensions?
What kind of concrete use is expected (foot traffic, cars, machinery)?
Are there slope or drainage concerns?
What’s the condition of the existing soil?

This helps determine how much excavation, fill, or grading is needed.

Step 2 – Excavation to Proper Depth

We remove any sod, soft topsoil, debris, or previous surface materials. Then we dig to the required depth—typically 4–8 inches below finish grade, depending on the concrete thickness and use case.

For high-load areas (like driveways or garages), deeper excavation may be needed to allow for gravel base and thicker concrete.

Step 3 – Grading and Shaping

Once excavated, we use skid steers, grading blades, and hand tools to:

Create a smooth, even subgrade
Ensure proper slope for drainage (usually 1–2% away from buildings)
Shape edges and transitions for formwork

At this stage, we check elevations against string lines or laser levels to confirm accuracy.

Step 4 – Base Material (If Needed)

Some projects require imported base material, especially if:

Native soil is soft or loose
You need better drainage
Your engineer or GC has called for it

We install and level gravel or road base, then compact it thoroughly using plate compactors or rollers.

Step 5 – Compaction Testing & Final Touches

Before the concrete crew arrives, we double-check:

Surface is solid and compact
Grade matches the pour plan
No soft spots or dips remain
Trenches (if needed) are cut for thickened edges or utilities

This prep ensures the slab goes in without unexpected delays or adjustments.

Tips for a Smooth Concrete Pour

1. Confirm Elevation and Drainage Slopes

Water should run away from the house, garage, or structure—never toward it.

2. Leave Access for Trucks and Tools

Your concrete team will need a clear path for the mixer, forms, and finish tools.

3. Coordinate With Your Concrete Contractor

If you’re not the one pouring, connect us with the flatwork crew. We’ll confirm their specs so everything lines up on pour day.

4. Don’t Skip the Compaction

Loose or uneven subgrades cause cracks and callbacks—something nobody wants.

Common Mistakes to Avoid

We’ve fixed plenty of jobs that were poorly prepped. Here are mistakes to avoid:

Skipping excavation over old material or sod
Assuming it’s “flat enough” without checking slopes
Underestimating traffic loads and using weak base material
Failing to compact layers properly
Letting weather conditions delay compaction or drainage

Getting it right the first time saves thousands in rework and repair.

Real-World Flatwork Prep Examples

We’ve prepped sites for:

Backyard patios with tricky access and soft topsoil
Large shop pads where drainage had to be graded across a wide slope
Driveways that required extra excavation to fix builder-grade subgrades
Retaining wall footings that doubled as walkways

Each job is different—but the fundamentals stay the same: dig, level, compact, clean, and prep for a perfect pour.

Work With Just Dig It for Your Concrete Prep