Hardscape Construction and Materials
What the exam tests
Hardscape Construction and Materials tests your ability to build paving, walls, steps, edging, and decks that stay flat, drain, and hold up in Hawaii's salt, sun, and termite pressure. Expect questions on base preparation, compaction, reinforcement, jointing, retaining-wall drainage, tolerances, ADA access, and material selection.
Core rules
- Build from the subgrade up: compacted subgrade, geotextile where fines migrate, graded aggregate base, bedding layer, and surface. For vehicular pavers, base depth is engineered, not guessed.
- Compact base in lifts to the specified density (commonly 95% modified Proctor) and test if required.
- Slope paving 1–2% away from buildings; provide positive drainage. ADA accessible routes have tighter cross-slope limits (generally 1:48, or about 2.08%).
- Retaining walls need a drained backfill, filter fabric, weep holes or drainage pipe, and proper batter. Walls over a threshold height usually need engineering and permits.
- In coastal Hawaii, specify corrosion-resistant fasteners and avoid mild steel in soil or salt spray; use stainless, hot-dip galvanized, or approved composites. Termite-resistant detailing matters for wood.
Worked example
A 12 ft × 20 ft paver patio is to sit against a house on a 6% slope. Reasoning: set the patio finished floor at least 6 in below the siding or door threshold; slope the patio 1.5% away from the house, so fall over 12 ft is about 2.2 in. Excavate for 4 in compacted base, 1 in bedding sand, and 2.375 in pavers; add edge restraint on the downhill side; discharge to a splash block or dry well, not the neighbor's lot. Confirm the slope still meets the door threshold and does not create a trip hazard.
Traps
- Skipping geotextile or compacting base in one thick lift.
- Assuming pavers are waterproof; water moves through joints.
- Using mortar to set flexible pavers.
- Forgetting edge restraint, so the field spreads.
- Ignoring ADA cross slope on walkways.
- Detailing retaining walls without drainage, causing failure by hydrostatic pressure.