CSLB Landscaping (C-27) Trade — All Questions

Finished grade around a building should slope away from the foundation at approximately what minimum for the first several feet?

• a.Sloping the grade back toward the building
• b.About 5 percent, or 6 inches over 10 feet✓
• c.Flat, with no slope in any direction
• d.A 45-degree drop at the foundation

A common standard is to slope soil away from a foundation about 6 inches over the first 10 feet, roughly a 5 percent grade, to carry surface water away from the structure. Sloping toward the building or leaving it flat allows water to pond against the foundation. Positive drainage protects the structure from moisture damage.

A French drain is BEST described as what?

• a.A raised planter box built along the wall
• b.A surface concrete drainage channel or swale
• c.A type of segmental retaining wall
• d.A gravel-filled trench with perforated pipe✓

A French drain is a trench filled with gravel around a perforated pipe that intercepts subsurface and surface water and carries it to a discharge point. Water enters the pipe through the perforations and flows by gravity away from the problem area. It is used to relieve soggy soils and protect foundations.

Before placing concrete pavers on a driveway, a compacted aggregate base is installed mainly to do what?

• a.A stable, load-bearing, well-draining foundation✓
• b.The final wearing surface of the driveway
• c.A replacement for perimeter edge restraints
• d.Added color and texture at the paved surface

A compacted crushed-aggregate base spreads loads, resists settling, and drains water away from the pavers, forming the structural foundation of the pavement. Without proper base compaction, pavers rut and settle unevenly. A sand setting bed and edge restraints are added on top of this base.

Aggregate base under hardscape is best compacted in what manner?

• a.Only after the pavers have been placed
• b.In thin lifts, each compacted before the next✓
• c.By soaking it thoroughly with water only
• d.In one thick lift with no compaction at all

Base material should be placed and compacted in thin lifts, commonly around 3 to 4 inches, so the compactor can achieve full density throughout. Compacting one thick lift leaves the lower portion loose, causing later settlement. Layered compaction produces a stable, uniform base.

A segmental retaining wall over a certain height typically requires what to prevent failure?

• a.Engineered design, drainage, and geogrid✓
• b.No drainage of any kind behind the wall
• c.Only a decorative facing on the wall front
• d.A smooth clay backfill packed tight

Taller retaining walls carry large lateral soil loads and usually require engineered design, gravel backfill with a drain to relieve water pressure, and geogrid soil reinforcement. Without drainage, water pressure builds behind the wall and pushes it over. Many jurisdictions require permits and engineering above a set height, commonly 3 to 4 feet.

Weep holes or a drainage system behind a retaining wall serve what purpose?

• a.To relieve hydrostatic pressure behind the wall✓
• b.To hold more water in the backfill zone
• c.To increase the soil pressure on the wall
• d.To add decorative accents to the wall face

Weep holes and gravel drains allow water that collects behind a wall to drain out, relieving hydrostatic pressure that would otherwise push the wall over. Saturated soil greatly increases the load on a wall. Proper drainage is one of the most important factors in wall longevity.

A slope is described as 4:1. What does this mean?

• a.A 40 percent grade down the bank
• b.A vertical cliff with no run at all
• c.4 feet of run for every 1 foot of rise✓
• d.4 feet of rise for each 1 foot of run

A 4:1 slope means 4 units of horizontal distance for every 1 unit of vertical change, a gentle 25 percent grade. The first number is run and the second is rise in this common landscaping convention. Flatter ratios like 4:1 are more stable and easier to mow than steep ones like 2:1.

Managing stormwater runoff on a site with a bioswale accomplishes what?

• a.Slows runoff, filters pollutants, and promotes infiltration✓
• b.Prevents any water from infiltrating
• c.Raises the water table intentionally
• d.Concentrates runoff into a single fast channel

A bioswale is a shallow, vegetated channel that slows stormwater, filters out sediment and pollutants, and encourages water to soak into the ground. This reduces peak runoff and improves water quality leaving the site. Such low-impact designs are increasingly required for stormwater management.

A concrete slab for a patio typically includes control joints. What is their function?

• a.Planned weak points so cracks follow the joint✓
• b.Eliminating the need for a compacted stone base
• c.Increasing the water content of the slab
• d.Adding decorative color to the surface

Control joints are grooved or cut lines that create a deliberate weak plane, so as concrete shrinks and cracks, the cracks form neatly along the joint rather than randomly across the slab. They are usually spaced in feet roughly equal to two to three times the slab thickness in inches. They control, not eliminate, cracking.

Edge restraints installed around a paver patio serve what main purpose?

• a.To replace the compacted gravel base layer
• b.To keep pavers from spreading outward over time✓
• c.To change the color of the paver surface
• d.To provide seating around the patio edge

Edge restraints lock the perimeter pavers in place so the field of pavers cannot creep or spread apart under traffic. Without them, edges migrate and joints open up, leading to failure. They are a small but essential part of a durable paver installation.

A paved surface should be sloped for drainage at about what minimum cross slope?

• a.0 percent (dead level)
• b.10 to 15 percent
• c.Sloped toward the house
• d.About 1 to 2 percent✓

Paved surfaces such as patios and walkways are typically sloped about 1 to 2 percent, roughly 1/8 to 1/4 inch per foot, to shed water without being noticeably tilted. A dead-level surface ponds water, while too steep a slope is uncomfortable and unsafe. Water should always be directed away from structures.

A catch basin connected to underground drain pipe is used to do what?

• a.Collect surface water and pipe it away✓
• b.Store irrigation water for later reuse
• c.Support the base of a retaining wall
• d.Filter drinking water before use

A catch basin is a boxed inlet set at a low point that collects surface runoff and channels it into buried drain pipe leading to a safe discharge. A grate on top keeps out leaves and debris. It is a key part of a yard drainage system that prevents ponding.

When laying out a site from a plan, a builder's level or laser level is used primarily to establish what?

• a.Plant spacing across the planting beds
• b.Consistent elevations and grades✓
• c.Soil pH in the planting areas
• d.Water pressure at the meter

A builder's level, transit, or rotary laser establishes accurate reference elevations so grades, slopes, and drainage can be set consistently across a site. This ensures the finished landscape drains correctly and matches the plan. Accurate layout prevents costly grading errors.

Compaction of subgrade soil before hardscape is measured against what standard reference?

• a.A percentage of maximum dry density✓
• b.The number of compactor passes only
• c.The measured pH of the subgrade soil
• d.The color of the compacted soil

Compaction is specified as a percentage of a soil's maximum dry density determined by a laboratory Proctor test, commonly 90 to 95 percent for hardscape subgrade. Field testing verifies the soil reaches the required density. Adequate compaction prevents future settlement under pavement.

On expansive clay soils, hardscape and foundations are at risk because the soil does what?

• a.Stays perfectly stable in all conditions
• b.Turns to sand over time
• c.Swells when wet and shrinks when dry, causing movement✓
• d.Never holds water

Expansive clays contain minerals that absorb water and swell, then shrink as they dry, producing repeated ground movement that cracks slabs and walls. Managing moisture and using proper base and drainage details reduces this movement. Severe cases may need engineered foundations.

A dry-stack (mortarless) segmental block wall relies on what for stability?

• a.Steel beams set behind the block face
• b.A mortared concrete cap along the top
• c.Mortar placed between every block course
• d.Interlock, batter, and gravel backfill✓

Mortarless segmental walls gain stability from the interlocking block design, a slight backward lean (batter or setback), free-draining gravel backfill, and geogrid reinforcement layers in taller walls. There is no mortar, so drainage and reinforcement carry the loads. Proper base preparation is also critical.

Directing a downspout's discharge onto a splash block or into a pipe that carries it away from the house prevents what?

• a.Better interlock between the patio pavers
• b.A higher soil pH near the foundation
• c.Faster plant growth beside the house
• d.Erosion and ponding at the foundation✓

Concentrated roof runoff from a downspout can erode soil and saturate the ground against a foundation, leading to settlement and moisture intrusion. A splash block or piped extension moves that water away from the structure. This is a basic but important part of site drainage design.

Permeable pavers differ from standard pavers because they do what?

• a.They require no base course at all
• b.They are decorative only, not structural
• c.They block all water from passing through them
• d.They let stormwater soak through the joints✓

Permeable pavers are set with open, aggregate-filled joints over an open-graded stone base so rainwater infiltrates rather than running off. This reduces runoff volume and helps recharge groundwater, supporting stormwater regulations. They require a specially designed base to store and drain the water.

On a steep planted slope, which practice BEST controls erosion during establishment?

• a.Leaving the slope soil bare and exposed
• b.Frequent heavy flood irrigation
• c.Smooth compaction with no plants
• d.Blankets, mulch, and quick groundcover✓

Covering a slope with erosion-control blankets or netting, mulch, and fast-establishing groundcover protects the soil surface from rain impact and runoff until roots hold it. Bare or heavily flooded slopes erode and rill quickly. Vegetation and surface protection together stabilize the slope.

A retaining wall's footing or leveling pad should be placed on what?

• a.A layer of dry leaves and loose topsoil
• b.Compacted, level base at the proper depth✓
• c.Loose topsoil raked out smooth
• d.A single row of bricks laid flat

The base or leveling pad of a retaining wall must rest on compacted, level base material set at the correct depth so the wall does not settle or lean. A poor base is a leading cause of wall failure. Getting the first course level and solid is essential for the whole wall.

A C-27 licensee is asked to build a wood-framed pool house with a bathroom as part of a backyard landscape package. How should the licensee proceed?

• a.Subcontract it to contractors holding the appropriate classifications✓
• b.Build the structure and subcontract only the finish carpentry
• c.Build it if the total value stays under the landscape contract amount
• d.Build it, since it sits within the landscape area being developed

The landscaping classification covers landscape systems and features and the grading that supports them, not habitable structures with plumbing and electrical work, so those trades must be subcontracted to properly licensed contractors. Being inside the landscape area, keeping the framing in house, or comparing dollar values does not extend the classification.16 CCR §832.27

Which of the following is most clearly within the C-27 landscaping classification?

• a.Reroofing a detached garage that faces the new patio
• b.Installing a new subpanel to power landscape lighting
• c.Installing a residential swimming pool and its equipment
• d.Grading and preparing a yard for decorative treatment✓

Preparing and grading plots for horticultural and decorative treatment is expressly part of the landscaping classification. A new subpanel is electrical work, roofing is a separate specialty, and swimming pool construction has its own classification, so each of those must be held or subcontracted separately.16 CCR §832.27

A landscape contract includes low-voltage path lighting fed from an existing exterior receptacle. What is the correct division of work?

• a.An electrical contractor must install every part of a lighting system
• b.The landscape crew adds a new receptacle first, then the transformer
• c.The landscape crew may run 120-volt cable if it stays under 50 feet
• d.The landscape crew sets the transformer and low-voltage runs at that receptacle✓

Plugging a transformer into an existing code-compliant exterior receptacle and running the low-voltage cable is landscape work. Adding a new receptacle or running any new 120-volt cable is electrical work regardless of length. It is also not the case that an electrical contractor must perform the low-voltage portion once the supply already exists.

Finish grade at a house is being set. What is the standard target for surface drainage away from the foundation?

• a.A slight fall toward the wall, drained by a perimeter french drain
• b.A crown at the wall with equal falls in both directions
• c.A fall away from the wall over the first several feet of ground✓
• d.A level pad with a swale at the property line to collect water

Positive fall away from the wall in the first several feet is what keeps water out of the foundation, and every other detail is downstream of it. A level pad ponds against the wall. Sloping toward the wall and relying on a drain fails the moment that drain clogs. Crowning at the wall would require the wall to be the high point of the pad, which it is not.

A patio must drain across its surface to a lawn edge. What cross slope is normally specified?

• a.Zero, with drainage handled by joints between the pavers
• b.About five percent, to move water quickly off the surface
• c.About one quarter percent, so furniture sits level
• d.About one to two percent, roughly an eighth inch per foot✓

Roughly an eighth of an inch per foot moves water reliably without being noticeable underfoot or under furniture. A dead level surface ponds even on permeable paving. A quarter percent is inside construction tolerance and will pond in low spots. Five percent is steep enough to feel and would be uncomfortable for seating.

A grading plan describes a slope as 3:1. Which statement is correct?

• a.The slope rises three feet for each foot of horizontal run
• b.The slope is expressed as a three percent grade
• c.The slope runs three feet horizontally for each foot of fall✓
• d.The slope drops three inches per foot of run

Slope ratios are written horizontal to vertical, so 3:1 means three feet of run for every foot of rise or fall, which is about a 33 percent grade. Reversing the ratio would describe a very steep bank. It is not a three percent grade, and three inches per foot would be a 25 percent grade written differently.

Contour lines on a grading plan are drawn close together across one part of the site. What does that spacing indicate?

• a.The area is proposed for fill rather than cut
• b.The area drains toward the nearest catch basin
• c.The ground is nearly level in that area
• d.The ground is steep in that area✓

Contours mark equal elevations, so a short horizontal distance between them means elevation changes quickly and the ground is steep. Widely spaced contours indicate flat ground. Cut and fill are shown by comparing existing and proposed contours rather than by spacing alone, and drainage direction is read from the shape of the contours, not their closeness.

A designer wants to move surface runoff across a yard without a piped system. Which feature does that?

• a.A shallow vegetated swale graded toward the outlet✓
• b.A dry well set at the low corner of the yard
• c.A french drain laid level along the fence line
• d.A catch basin with a solid lid at the midpoint

A swale is a graded surface channel that carries and slows runoff on its way to an outlet, which is exactly the described need. A dry well stores and infiltrates at one point rather than conveying. A catch basin collects into a pipe. A level french drain has no fall and only intercepts subsurface water where it sits.

A new grading plan would send additional runoff onto the neighboring downhill lot. What is the contractor's obligation?

• a.Install a berm on the neighbor's side to contain the added flow
• b.Design the drainage to an approved outlet off the property✓
• c.Proceed if the neighbor gives verbal permission on site
• d.Proceed, since water naturally flows downhill between properties

Concentrating or increasing runoff onto adjacent property creates liability and usually violates local grading rules, so the work must be designed to an approved point of discharge. Natural flow does not license added flow. Verbal permission is not a substitute for a compliant design, and building anything on the neighbor's land is not the contractor's to do.

Perforated pipe is being installed in a gravel-filled trench to intercept subsurface water. How should it be laid?

• a.Holes down, in washed rock wrapped in filter fabric✓
• b.Holes up, bedded directly on native soil without gravel
• c.Holes to the sides, with the trench wrapped in plastic sheeting
• d.Holes up, so water enters only after the trench fills

Perforations face down so water entering the trench at any depth can get into the pipe immediately, and washed rock with filter fabric keeps fines from silting the system. Holes up delays entry until the trench floods. Plastic sheeting stops the very water the drain is meant to collect. Bedding on native soil without rock plugs the perforations.

What minimum fall is normally used on a landscape drain line so it does not silt up?

• a.About one quarter percent, roughly a thirty-second inch per foot
• b.About five percent, roughly five eighths inch per foot
• c.About one percent, roughly an eighth inch per foot✓
• d.No fall is needed because the pipe flows full under head

Roughly one percent keeps velocity high enough to carry silt through the line without being so steep that water outruns the solids. A quarter percent is too flat to self-clean at landscape flows. Five percent is far more fall than most yards can give and is unnecessary. A gravity drain that is laid flat will silt in.

Downspouts on a house currently discharge onto a planting bed near the foundation. What is the appropriate landscape correction?

• a.Install a dry well directly against the foundation wall
• b.Connect the downspouts to a pipe discharging away from the house✓
• c.Regrade the bed level so water spreads out instead of channeling
• d.Add six inches of mulch under each downspout to absorb the flow

Roof water is concentrated flow and belongs in a pipe that carries it well away from the foundation. Mulch cannot absorb a roof's worth of water. A level bed holds the water against the wall rather than moving it. A dry well set against the foundation deliberately puts infiltration exactly where it does the most harm.

A bioswale is specified on a commercial landscape. What is its main stormwater function?

• a.To slow runoff and filter it through soil and vegetation✓
• b.To provide a lined channel that speeds runoff off the site
• c.To separate irrigation runoff from roof runoff for metering
• d.To store runoff until it can be pumped to the storm drain

A bioswale slows water, lets it soak in, and filters pollutants through the planted soil profile before any overflow leaves the site. It is not a pumped storage basin, and a lined fast channel is the opposite of what it does. Metering separation is a plumbing arrangement, not a swale function.

Aggregate base is being placed for a paver patio. How should it be compacted?

• a.In lifts of about four to six inches at optimum moisture✓
• b.In one lift, wetted thoroughly and compacted from the center outward
• c.In lifts of about twelve inches at optimum moisture
• d.In one lift, compacted dry so the fines do not migrate

Compaction energy only reaches a limited depth, so base goes in lifts of roughly four to six inches at optimum moisture and each lift is compacted before the next. A single thick lift leaves the bottom loose regardless of direction of travel. Dry material will not densify. Twelve-inch lifts exceed what a plate compactor can reach.

Two crews compact the same base material at very different moisture levels and get different densities. What explains this?

• a.Drier material compacts to a higher density in every case
• b.Wetter material compacts to a higher density in every case
• c.Moisture affects only the finish, not the resulting density
• d.Every soil has an optimum moisture content for maximum density✓

Water lubricates particles up to a point and then occupies space that soil would otherwise fill, so each material has an optimum moisture at which density peaks. Wetter is not uniformly better, since saturated material pumps under the compactor. Drier is not uniformly better either, because friction blocks rearrangement. Density is directly affected.

A specification requires 90 percent relative compaction of the subgrade. What is that percentage measured against?

• a.The maximum dry density from a laboratory compaction test✓
• b.The in-place density of undisturbed soil elsewhere on the lot
• c.The percentage of the trench volume filled with backfill
• d.The density of the aggregate base placed over the subgrade

Relative compaction compares field density to the maximum dry density established for that soil in a laboratory test, which is why a sample goes to the lab before the specification means anything. Base density is a separate material. Undisturbed soil nearby is not a standard. The share of trench volume filled is not a density measure at all.

A crew must compact a narrow trench backfill in cohesive clay. Which equipment is best suited?

• a.A water jet, which settles the fill by saturation
• b.A rammer or jumping jack, which delivers impact into cohesive clay soil✓
• c.A vibratory plate compactor, which works granular material well
• d.A smooth drum roller, which covers the length quickly

Cohesive clay responds to impact rather than vibration, so a rammer is the right tool in a narrow trench. Plate compactors are designed for granular material. A drum roller cannot fit or reach the bottom of a trench. Jetting saturates the fill and produces settlement later rather than compaction now.

A paver walkway settles in ruts within one season while the adjacent driveway holds. What is the most likely cause?

• a.The joint sand was not swept in deeply enough
• b.The bedding sand layer was screeded too thin
• c.The base was too shallow or inadequately compacted✓
• d.The pavers were laid in a running bond instead of herringbone

Pavers ride on the base, so ruts and dips almost always trace back to base depth or compaction rather than to the surface course. Joint sand locks pavers together but carries no load. Pattern affects interlock under vehicles more than settlement. Bedding sand should be thin, and a thin screed is correct rather than a defect.

How does base thickness for a paver driveway compare with base thickness for a paver walkway?

• a.The walkway needs the thicker base because it lacks edge restraint
• b.The driveway needs a thicker base because it carries vehicle loads✓
• c.The driveway needs a thinner base because vehicles compact it further
• d.The two are the same because the pavers are the same thickness

Base thickness follows the load, so a drive carrying vehicles needs substantially more base than a pedestrian walk. Paver thickness alone does not set base depth. Walkways carry less load, and every paver field needs edge restraint regardless. Traffic does not usefully compact a base that was undersized to begin with.

Why is a herringbone pattern preferred for pavers in a driveway?

• a.It allows a thinner bedding sand layer to be used
• b.It resists creeping and shifting under turning vehicle loads✓
• c.It reduces the amount of joint sand the field requires
• d.It requires fewer cuts along the perimeter of the field

Herringbone interlocks in two directions, so braking and turning forces cannot push a line of pavers along a continuous joint. It generally requires more perimeter cuts, not fewer. Bedding sand depth is fixed by the screed regardless of pattern, and joint sand quantity varies little between patterns.

What is the correct thickness of the bedding sand layer under interlocking concrete pavers?

• a.About three inches, screeded and compacted before laying
• b.About two inches, screeded loose and left uncompacted
• c.About one inch, screeded loose and left uncompacted✓
• d.No bedding layer, with pavers set directly on the base

Roughly one inch of loose screeded sand is enough to seat the pavers and no more, because a thick sand layer behaves like an uncompacted base and lets the surface rut. Two or three inches is far too much. Compacting the sand before laying defeats its purpose. Setting pavers directly on base leaves no way to level the surface.

Edge restraint is being installed around a paver patio. What does it accomplish?

• a.It seals the field so water cannot enter the joints
• b.It carries the load at the perimeter where the base is thinnest
• c.It keeps perimeter pavers from spreading and losing interlock✓
• d.It provides a level reference for screeding the bedding sand

Without restraint the outer courses migrate outward, joints open, and the interlock that makes the whole field work is lost. Screed rails, not edge restraint, guide the sand. Restraint does not carry vertical load. It also does not seal the field, since paver systems are designed to shed water at the surface rather than to be watertight.

How does the base under permeable pavers differ from the base under standard pavers?

• a.It uses open-graded clean stone that stores and passes water✓
• b.It uses a fines-rich base compacted to a higher density
• c.It uses a thinner base because water does not sit on the surface
• d.It uses the same base with a perforated pipe added at the bottom

Permeable systems are built on open-graded washed stone with large voids so water can pass through and be stored before infiltrating. Adding a pipe to a dense base does not create that void space. The base is usually thicker rather than thinner because it doubles as a reservoir. Fines are exactly what must be kept out.

A permeable paver parking area stops draining after four years. What is the usual cause?

• a.Sediment has clogged the surface joints and must be removed✓
• b.The subgrade has consolidated under repeated vehicle loading
• c.The pavers have absorbed water and swelled against each other
• d.The joint stone has settled and reduced the void space

Permeable systems fail at the surface, where windblown fines and landscape debris seal the joints, and periodic vacuuming restores them. Joint stone settlement is minor by comparison. Subgrade consolidation would show as rutting rather than as ponding. Concrete pavers do not swell enough to close joints.

Control joints are tooled into a new concrete patio. What determines their spacing?

• a.They are placed wherever the pour is interrupted for the day
• b.They are spaced at a fixed twenty feet regardless of slab thickness
• c.They are placed at every change in the color of the finish
• d.Spaced in feet at two to three times the slab thickness in inches✓

A common rule spaces joints in feet at about two to three times the slab thickness in inches, so a four-inch slab gets joints around eight to twelve feet apart. A pause in the pour creates a cold joint, which is a different detail. Finish color is unrelated. A single fixed spacing ignores thickness entirely.

How deep should a control joint be cut or tooled in a concrete slab?

• a.About one half the slab thickness
• b.About one eighth inch regardless of thickness
• c.Through the full thickness of the slab
• d.About one quarter of the slab thickness✓

A joint about a quarter of the slab depth creates a weakened plane deep enough to direct the crack without cutting the slab apart. A full-depth cut makes separate slabs and severs any reinforcement. Half depth is deeper than needed and weakens the section. A shallow scratch will not control where the crack goes.

A new concrete walk will abut an existing building slab. Which joint belongs at that line?

• a.A doweled construction joint tying the two slabs together
• b.An isolation joint with compressible material full depth✓
• c.A tooled control joint matching the pattern of the walk
• d.A saw cut made the following day at the building face

The building and the walk move independently, so a full-depth isolation joint with compressible filler lets that happen without cracking either one. A control joint only guides shrinkage cracking within one slab. Doweling would tie the walk to the structure, which is the opposite of the intent. A late saw cut does not create separation.

A driver arrives with concrete that has been in the truck longer than expected and asks whether to add water. What is the correct answer?

• a.Add water only to the last third of the load being placed
• b.Do not add water beyond the design mix, since strength falls✓
• c.Add water and compensate by finishing the surface more heavily
• d.Add water freely, since workability governs the finish quality

Strength drops as the water to cement ratio rises, so adding water on site to restore workability trades durability for convenience. Limiting the addition to part of the load creates inconsistent concrete. Heavy finishing of a wet mix brings fines and water to the surface and produces a weak, dusting slab.

Why is a new concrete flatwork slab kept moist or covered for several days after placement?

• a.To allow cement hydration to continue and develop strength✓
• b.To prevent the aggregate from settling to the bottom
• c.To keep the surface soft enough for later saw cutting
• d.To keep the surface color uniform as the slab dries

Cement gains strength through hydration, which requires water, so curing keeps moisture in the slab while that reaction proceeds. Color uniformity is a finishing matter. Aggregate segregation happens during placement, not during curing. Saw cutting is timed to the concrete's set and is not the reason for curing.

A segmental retaining wall is planned at five feet exposed height on a residential lot. What should the contractor expect?

• a.A permit and an engineered design from the local jurisdiction✓
• b.No permit, since the wall retains only landscape soil
• c.No permit, since segmental walls are not structures
• d.A permit only if the wall is closer than five feet to the property line

Most California jurisdictions require a permit and engineered design once a retaining wall passes roughly four feet or carries a surcharge, and a five-foot wall is squarely in that range. Segmental construction does not exempt a wall, retaining landscape soil is still retaining, and proximity to a property line is a separate setback question.