Excavation depth, subgrade condition, aggregate selection, lift thickness and compaction determine whether a patio stays level.
What to account for
Remove organic soil and unsuitable fill rather than compacting over it.
Use geotextile only for a defined separation or stabilization purpose, not as a cure for drainage.
Compact in controlled lifts with equipment appropriate to the material and access.
Questions to settle before work begins
- Is the subgrade firm and consistent?
- Where will excavated material go?
- How will compaction quality be checked around edges and utilities?
Common planning failures
- Building over roots or topsoil
- Compacting saturated material
- Using one deep loose layer instead of compacted lifts
Compare options on the same basis
Write down the intended use, site limits, maintenance expectations and approval assumptions before comparing products or quotations. Use the same dimensions and performance requirements for every option. A useful comparison notes what supports the work, how water leaves, what must remain accessible, which components carry safety functions, and what the owner will need to inspect or renew later.
Before materials are ordered
Confirm final elevations, transitions, clearances and product availability. Review the current installation instructions for every proprietary component and check that the planned base, framing, fasteners, finishes and accessories are compatible. Record any allowance or unresolved condition in writing so it does not quietly become an expensive change after excavation or demolition begins.
Keep a project record
Save the site measurements, product names, installation manuals, approved drawings, permit and inspection records, photos of concealed work, contractor changes and warranty documents. Add photographs before surfaces or trim conceal drainage, flashing, connectors, wiring or foundations. These records make later maintenance, repairs and ownership changes much easier.
Know when to stop
Pause the project when structural framing cannot be identified, soil or drainage conditions are uncertain, utilities may be affected, a safety barrier is involved, or the planned work conflicts with product instructions. Ask the relevant building authority, engineer, licensed trade or manufacturer for project-specific direction. Restrict use immediately if an existing elevated structure moves, a guard is loose, stairs are unstable or significant decay is visible.
Relevant primary sources
Use the version and requirements accepted by your local authority.