Washington · Concrete flatwork guide
How to build a concrete flatwork in Washington
Driveways, walks, aprons and steps with joints and finish. Driveways, walks and steps live or die on base prep and joint spacing. Concrete arrives on the truck's clock, so the plan matters more than the muscle.
Typical cost
$2,442–$3,878
Time
2 days plus cure
Skill
Intermediate
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Permits & code in Washington
Flatwork over 200 sq ft typically needs a permit, and anything touching the public sidewalk or curb needs a separate right-of-way permit. Frost line here is 18". Seismic bracing requirements apply to sheds and garages in the western half of the state.
State-level rules only — cities and HOAs frequently add stricter requirements. Always confirm with your local building department before you dig.
What most people get wrong
- Pouring on uncompacted base. Compact in 3" lifts or the slab settles and cracks along the low spots.
- Forgetting drainage pitch. Level flatwork against a house sends water into the foundation.
- Cutting control joints too late or too shallow — the slab cracks where it wants instead of where you planned.
The 5-step concrete flatwork plan
- Step 1Confirm site and permit pathLocate property lines, call 811 for utility marking, and check whether your city/HOA needs approval before you break ground.
- Step 2Order materialsUse the shopping list from our planner. Confirm delivery vs pickup — bulk lumber and concrete are usually cheaper delivered.
- Step 3Lay out and prep the siteBatter boards, string lines, level the base. Getting this right saves days later.
- Step 4Frame the structureFollow the cut list. Check for square with the 3-4-5 method every few pieces. Fasten with the right structural screws.
- Step 5Finish and inspectSand, stain/seal, and (if required) schedule your final inspection before backfilling or closing anything up.
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