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Project GuideResidential

Building a Swimming Pool?

Pool soils reports, foundation engineering, and what your contractor needs from the geotech before breaking ground.

Pool Engineering Prevents Expensive Problems

Swimming pools are engineered structures. The shell must resist hydrostatic pressure from groundwater, expansive soil pressure, and seismic loading. The deck must be properly supported to prevent settlement and cracking. And if you're building on a slope, the pool may need specialized retention systems.

Most jurisdictions in California require a geotechnical investigation for swimming pools — especially on hillside lots, in areas with expansive soil, or where shallow groundwater is present. The soils report provides foundation recommendations, drainage requirements, and design parameters your pool engineer uses to design a shell that won't crack, settle, or heave.

We've worked on pool projects ranging from simple flat-lot installations to complex infinity-edge pools on steep hillsides. The level of engineering varies significantly based on site conditions, but the goal is always the same: a pool that lasts decades without structural problems.

What You'll Need

Engineering deliverables for swimming pool projects:

Usually Required

🔩

Pool Soils Report

Geotechnical investigation specific to pool construction. Evaluates bearing capacity, expansion potential, groundwater depth, and drainage conditions. Provides foundation and backfill recommendations for the pool shell.

Included in Soils Report

💧

Groundwater Evaluation

Critical for pool design. If groundwater is above the pool bottom elevation, the shell must be designed as a tank to resist hydrostatic uplift. The report specifies required waterproofing and drainage measures.

If Grading

📐

Grading Plan (Hillside Pools)

Required when the pool involves significant cut/fill, retaining walls, or drainage modifications. Shows finished grades, pool elevation, deck slopes, and drainage flow to approved discharge points.

If On Slope

🪨

Slope Stability (Hillside Pools)

If the pool is on or near a slope, slope stability analysis verifies the hillside can support the pool structure and any required retaining walls. Determines setback requirements from slope face.

If Walls Required

🧱

Retaining Wall Parameters

Pools on slopes often require retaining walls for the pool terrace or deck area. The geotech report provides lateral earth pressure, bearing capacity, and drainage design parameters for these walls.

During Construction

🏗

Compaction Testing

During construction, we verify backfill around the pool shell and under the deck meets compaction specifications. Prevents future settlement and deck cracking.

Why Pool Failures Are So Visible

A cracked pool shell is expensive to repair and impossible to hide. Structural cracks from poor soil conditions, differential settlement from inadequate compaction, deck heaving from expansive soils — these aren't minor cosmetic issues. They're tens of thousands of dollars in demolition and reconstruction.

The most common pool problems we see: shells that crack because they weren't designed for expansive soil pressure, decks that settle or heave because the backfill wasn't properly compacted, and hillside pools that develop drainage problems because the grading wasn't engineered. All preventable with proper geotechnical engineering upfront.

90%

Of pool projects in expansive soil areas require specialized shell design to resist soil pressure

5 ft

Typical depth for pool geotechnical borings (must go below the pool bottom elevation)

95%

Minimum compaction required for backfill around pool shells and under decks

What to Expect

Proposal & Site Review

We review your pool plans (or site photos if plans aren't finalized) and determine investigation scope. Proposal includes borings, lab testing, and report.

Geotechnical Investigation

We drill borings at the pool location — typically to at least 5 feet below the proposed pool bottom. Soil samples are tested for strength, expansion, and permeability.

Pool Soils Report

We provide foundation recommendations for the pool shell, backfill specifications, drainage requirements, and waterproofing recommendations if groundwater is present.

Construction Testing

During pool construction, we verify backfill compaction around the shell and under the deck. Final report documents compliance with geotechnical recommendations.

Building Something Else?

ADU Engineering Guide

Engineering deliverables for ADU construction in California.

Read Guide →

Hillside Development Guide

Slope stability, specialized foundations, and hillside engineering requirements.

Read Guide →

Retaining Wall Engineering

When you need geotech for walls, and what's involved.

Read Guide →

Common Questions

In most California jurisdictions, yes — especially if you're in an area with expansive soils, on a slope, or in a high groundwater area. Even if not required by code, it's good insurance against future structural problems.

The pool shell must be designed as a tank to resist hydrostatic uplift (water pressure pushing up on the pool bottom). This typically requires thicker floors, additional reinforcement, and sometimes a permanent subdrain system.

Probably not. Pool reports require specific information — groundwater depth, backfill recommendations, and drainage design — that aren't typically included in a foundation investigation. A new investigation at the pool location is almost always required.

On flat lots with minimal grading, sometimes no. But if the pool involves significant cut/fill, retaining walls, or changes to drainage patterns, a grading plan is typically required.

Differential settlement causing pool shell cracks and deck separation. This happens when the backfill around the pool isn't properly compacted, or when expansive soils weren't accounted for in the design.

Ready to Get Your Swimming Pool Started?

Tell us about your swimming pool project and we'll send a proposal with every deliverable you need — scope, fee, and timeline.

Request a Proposal Talk to an Engineer