A garden without paths is a garden you walk across. A garden with the right paths is a garden you walk through. That distinction — between crossing and experiencing — is the difference between a collection of planted beds and a designed landscape. Paths define movement, create rhythm, connect spaces, and establish the visual framework that holds the garden together. A well-placed, well-built path transforms a yard from a flat plane into a journey.
But choosing path material is one of the more confusing decisions in garden design, because every option has real trade-offs and the "best" material depends entirely on your specific situation. Gravel is cheap and drains beautifully but migrates into beds and hurts bare feet. Mulch is soft and natural but decomposes and needs annual refreshing. Natural stone is gorgeous and permanent but expensive and heavy to install. Brick has a timeless aesthetic but can become slippery and uneven over time. Stepping stones are charming for low-traffic paths but impractical for wheelbarrows and mobility devices.
This guide provides an honest comparison of the five most common garden path materials, covering cost, installation difficulty, drainage performance, maintenance requirements, accessibility, aesthetics, durability, and weed prevention. By the end, you will know which material fits your budget, your garden style, and your practical needs — because a path you love the look of but hate to maintain is a path you will eventually rip out. For step-by-step construction details once you have chosen your material, see our complete guide on how to build a garden path.
Gravel Paths
Gravel is the most popular garden path material in the country, and for good reason — it is affordable, drains perfectly, installs quickly, and looks at home in virtually any garden style from formal courtyard to casual cottage. The satisfying crunch underfoot, the way it reflects light, and its neutral color palette make gravel a versatile foundation for garden paths of any width and length.
Cost: Gravel is the least expensive hard path material. Pea gravel — rounded stones roughly three-eighths to three-quarters of an inch in diameter — costs two to four dollars per square foot installed, including a base layer of compacted crushed stone. For a three-foot-wide path, that translates to roughly six to twelve dollars per linear foot. Crusher run or decomposed granite, which compact more firmly than pea gravel, cost slightly more — three to five dollars per square foot. Buying gravel by the ton from a landscape supply yard is significantly cheaper than buying it in bags from a home center; a ton of pea gravel covers roughly eighty square feet at two inches deep and costs sixty to one hundred dollars delivered.
Installation: Gravel paths are a straightforward DIY project. Excavate the path area to a depth of four to six inches. Lay landscape fabric over the compacted subgrade to suppress weeds (not eliminate them permanently, but significantly reduce them). Add a two-inch base of compacted crusher run or road base for stability. Top with two to three inches of your finish gravel. Edge the path with steel edging, stone, brick, or landscape timbers to contain the gravel and prevent it from migrating into adjacent beds and lawn. The edging step is critical — gravel without edging spreads everywhere, creating a maintenance headache that never ends.
Drainage: Excellent. Gravel is essentially self-draining — water falls between the stones and passes into the ground beneath. You will never have standing water on a properly graded gravel path, and paths shed water quickly even during heavy rain. This makes gravel an excellent choice for paths in low-lying areas, rain gardens, and climates with heavy precipitation.
Maintenance: Moderate. Gravel paths need raking two to three times per season to redistribute stones that have been kicked or washed into ruts and thin spots. Weeds will grow through gravel over time despite landscape fabric — pulling them is an ongoing task, though much less effort than weeding an unmulched path. Every three to five years, you will need to add a fresh layer of gravel to replace what has compacted, migrated, or sunk into the base. Pea gravel specifically requires more frequent maintenance than angular gravel because the round stones roll and migrate more easily.
Accessibility: Poor to moderate. Loose gravel is difficult for wheelchairs, walkers, and strollers because the surface is unstable and wheels sink into it. Compacted decomposed granite or crusher run is significantly better — these angular materials lock together to form a firm, relatively smooth surface that most mobility devices can navigate. If accessibility is a priority, choose compacted decomposed granite over pea gravel, and maintain the surface to prevent ruts and soft spots. For a complete guide to accessible garden design, see our wheelchair-accessibility guide.
Aesthetics: Gravel works in nearly every garden style. Pea gravel in warm tones (tan, gold, brown) suits cottage and Mediterranean gardens. Gray crushed stone complements modern and minimalist designs. White marble chips brighten shade gardens and formal spaces. Decomposed granite in warm earth tones blends naturally with Southwestern and drought-tolerant landscapes. The visual neutrality of gravel lets the plants and structures around it take center stage.
Durability: Moderate. Individual stones do not break down, but the path surface degrades over time through compaction, migration, and organic accumulation. A well-maintained gravel path lasts indefinitely with periodic gravel additions. A neglected gravel path disappears into the ground within five to ten years as soil works up through the fabric and gravel sinks into the subgrade.
Weed prevention: Moderate. Landscape fabric beneath the gravel significantly reduces weed growth in the first few years. Over time, organic debris — leaves, pollen, decomposing matter — accumulates on top of the fabric and between the stones, creating a thin layer of soil-like material that seeds germinate in. Annual weeding and occasional raking to distribute fresh gravel keep weeds manageable but do not eliminate them permanently.
Wood Mulch Paths
Wood mulch — including shredded bark, wood chips, and arborist chips — is the most natural-looking path material and the softest underfoot. Mulch paths feel like walking through a forest floor, which makes them the perfect choice for informal, naturalistic, and woodland-style gardens. They are also the most affordable option and the easiest to install.
Cost: Wood mulch is the cheapest path material, often free. Arborist chips — the mixed wood and leaf material produced by tree-trimming crews — are available at no cost in many areas if you contact local tree services. Bagged shredded bark mulch from a garden center costs three to five dollars per two-cubic-foot bag, which covers about six square feet at four inches deep. Bulk mulch from a landscape supply yard costs fifteen to thirty-five dollars per cubic yard, which covers roughly eighty square feet at four inches deep. For a three-foot-wide path, mulch costs two to five dollars per linear foot — the lowest of any path material.
Installation: Mulch paths are the simplest to install. Excavate two to three inches if desired (not strictly necessary), lay landscape fabric or cardboard as a weed barrier, and spread four inches of mulch. Edge with logs, stones, or commercial edging to keep mulch from spreading into beds. The entire installation for a thirty-foot path can be completed in under two hours by one person. No tools beyond a shovel, wheelbarrow, and rake are required.
Drainage: Good. Mulch absorbs some water but allows excess to drain through to the soil below. Mulch paths handle moderate rain well but can become soggy in areas with persistent standing water or heavy clay soil with poor drainage. In very wet areas, a gravel base beneath the mulch improves drainage significantly.
Maintenance: High. Mulch decomposes — that is its nature as an organic material, and it is also its primary drawback as a path surface. Wood mulch paths need replenishing annually, with a fresh two-inch layer added each spring to maintain depth and appearance. The decomposed bottom layer of mulch turns into soil, which is excellent for the ecosystem but means your path is slowly sinking into the ground. You will also need to weed regularly, as mulch paths are particularly hospitable to weed seeds — the decomposing mulch provides a perfect germination medium. Raking the path surface smooth after heavy rain or foot traffic keeps it looking tidy.
Accessibility: Poor. Soft, loose mulch is one of the most difficult surfaces for wheelchairs, walkers, canes, and strollers. The uneven, yielding surface creates resistance and instability. Even able-bodied people in heels or dress shoes find mulch paths challenging. If any garden user has mobility limitations, mulch is not an appropriate material for primary paths.
Aesthetics: Mulch paths have a warm, natural, informal appearance that blends seamlessly into woodland gardens, cottage gardens, and naturalistic landscapes. The brown, fibrous texture looks organic and inviting. Dyed mulch (red, black, brown) is available but often looks artificial and out of place in a garden setting — natural, undyed wood mulch is more visually harmonious. As mulch ages and weathers, its color matures from bright to dark brown, which most gardeners find attractive.
Durability: Low. A mulch path is a temporary surface that must be continuously renewed. Expect to add new mulch every year and completely rebuild the path every three to five years as the lower layers decompose entirely. In high-traffic areas, mulch compacts and thins faster than in low-traffic areas. Heavy use — daily wheelbarrow traffic, for example — can wear through a mulch path to bare ground within a single season unless the path is thick and well-maintained.
Weed prevention: Poor to moderate. Fresh, deep mulch (four inches or more) suppresses weeds effectively for the first several months. As the mulch decomposes and thins, weed seeds that land on the surface find easy germination in the moist, organic material. Annual refreshing helps, but mulch paths are never weed-free for long. Cardboard or landscape fabric beneath the mulch provides a secondary barrier that extends weed-free time but eventually breaks down as well.
Natural Stone Paths
Natural stone — flagstone, slate, limestone, sandstone, and other quarried or field-collected stone — is the premium garden path material. It is permanent, beautiful, and carries an inherent authority that lesser materials cannot match. A stone path says the garden was designed, not just planted, and it ages with a patina that improves rather than degrades over decades.
Cost: Natural stone is the most expensive common path material. Flagstone typically costs six to twelve dollars per square foot for the stone alone, with installation adding another five to fifteen dollars per square foot depending on whether stones are dry-laid on a gravel base or mortared onto a concrete pad. For a three-foot-wide path, expect thirty to seventy-five dollars per linear foot fully installed. Field stone (uncut, irregular shapes) is cheaper than sawn flagstone but requires more skill to lay well. Regional stone — whatever is quarried locally — is always less expensive than imported stone because shipping heavy stone is extremely costly.
Installation: Moderate to difficult. Dry-laid flagstone on a compacted gravel base is achievable by a handy DIYer but requires careful leveling, fitting, and patience. Each stone must be individually placed and adjusted so the surface is level and stable. Mortar-set stone on a concrete base is a professional-level project that requires forms, concrete pouring, mortar mixing, and stone-setting skills. Either method requires significant physical labor because stone is heavy — a single two-inch-thick flagstone piece two feet square weighs roughly fifty pounds.
Drainage: Variable. Dry-laid stone with gravel-filled joints drains well — water passes through the joints and into the gravel base below. Mortar-set stone on concrete drains poorly because the solid surface sheds water rather than absorbing it — proper grading to direct runoff away from beds and foundations is essential. In cold climates, mortar-set stone paths are subject to frost heaving that can crack mortar joints, while dry-laid paths flex with freeze-thaw cycles without damage.
Maintenance: Low. Natural stone is essentially permanent and requires very little ongoing care. Sweep or blow off debris periodically. Pull weeds from joints in dry-laid paths once or twice per season, or apply polymeric sand to joints to inhibit weed growth. Reset any stones that shift or settle — which happens occasionally in dry-laid installations, especially in the first year. Mortar-set paths may need joint repair every five to ten years as mortar cracks and deteriorates. Beyond that, stone asks nothing of you. It does not decompose, fade, or need replacing.
Accessibility: Good to excellent, if properly installed. Flat, well-fitted flagstone with narrow, filled joints provides a firm, smooth, stable surface suitable for wheelchairs, walkers, and strollers. The surface must be level — lippage (height differences between adjacent stones) greater than a quarter inch creates a tripping hazard and a barrier for wheelchair wheels. Rough, irregular stone with wide, uneven joints is less accessible. If accessibility matters, choose sawn flagstone with consistent thickness and fill joints with polymeric sand or fine gravel for a smooth, continuous surface.
Aesthetics: Natural stone is universally regarded as the most attractive garden path material. The color variation, natural texture, and irregular shapes of stone complement every garden style. Blue-gray slate suits formal and contemporary gardens. Warm sandstone and limestone suit cottage and Mediterranean styles. Irregular fieldstone suits rustic and woodland gardens. Stone also develops a beautiful patina over time — lichen and moss colonize the surface, edges soften, and the stone settles into the landscape as if it has always been there.
Durability: Excellent. Natural stone lasts essentially forever in a garden context. Flagstone, slate, and granite are measured in decades and centuries, not years. Even softer stones like sandstone and limestone, which erode slowly in wet climates, will outlast the gardener, the house, and probably the neighborhood. The only durability concern is cracking from heavy point loads or frost heaving of mortar joints, both of which are repairable.
Weed prevention: Good in mortar-set installations, moderate in dry-laid. Mortar-filled joints eliminate weed space entirely until the mortar cracks. Dry-laid joints filled with gravel or polymeric sand resist weeds effectively but not permanently — over time, organic material accumulates in joints and provides a germination medium. Regular sweeping and occasional re-sanding of joints keeps weeds minimal. Compared to gravel and mulch, stone paths are significantly less weedy because the impermeable stone surface itself covers most of the ground area.
Brick Paths
Brick is the classic garden path material, used in formal and cottage gardens for centuries. It carries associations with old gardens, established estates, and timeless design that no other manufactured material can match. A brick path installed today will look contemporary; the same brick path in twenty years will look like it has been there since the house was built.
Cost: Moderate to high. Standard clay brick pavers cost three to six dollars per square foot for the brick alone. Reclaimed antique brick costs more — five to ten dollars per square foot — but has an aged, weathered appearance that new brick takes years to develop. Installation on a compacted gravel base with sand setting bed adds three to eight dollars per square foot for professional installation, or save significantly by doing it yourself. Total cost for a three-foot-wide path runs eighteen to forty-two dollars per linear foot professionally installed. DIY installation cuts cost roughly in half.
Installation: Moderate. Brick-on-sand installation is a popular and achievable DIY project. Excavate six to eight inches deep, add and compact a four-inch gravel base, add and screed a one-inch sand setting bed, lay bricks in your chosen pattern (running bond, herringbone, and basket weave are the most common), cut bricks to fit edges and curves, install edge restraints, and sweep polymeric sand into the joints. The process is straightforward but time-consuming and physically demanding because you are moving, leveling, and fitting hundreds of individual bricks. A thirty-foot path at three feet wide contains roughly five hundred standard bricks — that is a lot of bending, placing, and adjusting.
Drainage: Moderate. Brick-on-sand with sand-filled joints allows some water to percolate through the joints, but the drainage rate is slower than gravel or mulch. Properly graded brick paths shed water to the sides rather than absorbing it. In high-rainfall areas, ensure the gravel base beneath the brick extends to freely draining soil to prevent water from pooling under the path and causing frost heaving or settlement.
Maintenance: Low to moderate. Brick itself requires almost no maintenance — it does not rot, fade significantly, or need sealing. The primary maintenance issues are weeds in joints (pull regularly or use polymeric sand), moss and algae growth in shady or damp conditions (which can be slippery and may need periodic scrubbing or pressure washing), and occasional settling or shifting of individual bricks that need to be lifted, re-leveled, and replaced. In cold climates, freeze-thaw cycles can cause heaving — bricks may shift out of alignment and need resetting every few years. Edge restraints that loosen over time need periodic tightening or replacement.
Accessibility: Good. A well-laid brick path with tight joints and a level surface is firm, stable, and suitable for wheelchairs and walkers. The small unit size of bricks means the surface has many joints, which can create a slightly rough texture compared to large flagstones, but this is manageable if joints are filled flush with the surface. The primary accessibility concern is brick that has shifted or heaved to create uneven surfaces — regular maintenance to reset displaced bricks keeps the path safe and navigable.
Aesthetics: Brick is warm, inviting, and versatile. Red brick is traditional and fits cottage, colonial, and farmhouse styles. Gray and brown bricks suit contemporary and modern gardens. Laying patterns dramatically affect the visual character — running bond (offset rows) is classic and directional, herringbone is dynamic and formal, and basket weave is casual and chunky. Brick blends naturally with most house styles because houses are often built with similar materials. An old brick path with moss between the joints and a weathered patina is one of the most beautiful features a garden can possess.
Durability: Good to excellent. Quality clay pavers rated for outdoor and freeze-thaw use last fifty to one hundred years or more. The key word is quality — cheap, soft brick (like interior face brick or non-paver-rated brick) absorbs water, spalls in freeze-thaw cycles, and deteriorates within a few years. Always use brick specifically rated as a paver for garden path construction. Reclaimed antique brick that has already survived a century in a building is almost certainly durable enough for a path.
Weed prevention: Good. Tightly laid brick with polymeric sand joints resists weeds well. The solid surface of the brick itself covers most of the ground area, and polymeric sand hardens in joints to create a nearly impermeable barrier. Over time, joints may need re-sanding as the polymeric material degrades, but the maintenance interval is typically three to five years. Compared to gravel and mulch, brick paths are significantly less weedy.
Stepping Stone Paths
Stepping stones — individual flat stones, concrete pavers, or precast rounds placed at regular intervals with plants, mulch, or gravel between them — are the most informal and least expensive hard path material. They suggest a path without constructing a full surface, which gives them a light, casual, garden-integrated character that a continuous path cannot match.
Cost: Low to moderate. Natural flagstone steppers cost three to eight dollars each depending on size and type. Precast concrete steppers cost two to five dollars each. You need roughly three steppers per linear foot for a comfortable walking stride (placing them about twelve to sixteen inches apart center to center). Total cost per linear foot runs six to twenty-four dollars, depending on the stone type — comparable to gravel but less than brick or continuous flagstone.
Installation: Easy. For each stone, excavate a hole slightly larger than the stone and slightly deeper than the stone's thickness. Set the stone on a one-inch bed of sand or crusher dust. Level the stone by adding or removing sand beneath it. The top of the stone should be at or slightly above the surrounding ground level. That is it. No base construction, no edging, no joint filling. A twelve-stone stepping path can be installed in under an hour. The hardest part is getting the stones evenly spaced for a natural walking stride — pace out the path first and mark each stone location with spray paint.
Drainage: Excellent. Stepping stones have more open ground than covered ground, so drainage is essentially the same as unpaved ground. Water falls between the stones and absorbs into the soil normally. This makes stepping stones appropriate for any drainage condition and any climate.
Maintenance: Low to moderate. The stones themselves need no maintenance. The spaces between stones, however, need regular attention — weeding if left bare, mowing or trimming if planted with ground cover, and raking if filled with gravel or mulch. Planting between stones with creeping thyme, chamomile, or Irish moss creates a beautiful, low-maintenance living carpet that suppresses weeds once established but requires weeding during establishment and occasional trimming to keep plants from covering the stones. Stones may shift or sink over time and need re-leveling, but this is a ten-minute task.
Accessibility: Poor. Stepping stone paths are inherently inaccessible for wheelchairs, walkers, strollers, and many people with balance or mobility issues. The gaps between stones create an uneven, discontinuous surface that requires stepping accuracy and balance at every stride. Stepping stone paths are appropriate only as secondary, decorative paths in gardens where the primary paths are continuous, firm surfaces. Never use stepping stones as the only path to a garden area that all users need to reach.
Aesthetics: Charming, informal, and garden-integrated. Stepping stones placed through a lawn, a bed of low plants, or a groundcover planting have a natural, inviting quality that more structured paths lack. They suggest that the garden came first and the path was added gently afterward, which gives them an established, relaxed character. Round stones, irregular flagstone, and reclaimed materials like salvaged granite or antique millstones all work as stepping stones and each creates a distinct visual character.
Durability: Excellent for the stones themselves, variable for the infill. Natural stone steppers are permanent. Concrete steppers last decades. The spaces between stones, however, require the ongoing attention mentioned above. A stepping stone path through bare soil looks good for about one season before weeds take over the spaces. A stepping stone path through established ground cover looks good indefinitely with occasional maintenance.
Weed prevention: Poor in bare-ground installations, good in planted installations. Bare ground between stones is essentially unmulched garden soil — weeds will colonize it aggressively. Dense ground cover plantings between stones outcompete most weeds once established. Gravel fill between stones provides moderate weed suppression, similar to a standard gravel path but with less total area to manage.
Quick Comparison Table
This summary compares all five materials across the key decision factors at a glance.
Gravel: Cost — Low ($6-12/linear foot). Installation — Easy. Drainage — Excellent. Maintenance — Moderate. Accessibility — Poor (pea gravel) to Moderate (compacted DG). Durability — Moderate. Weed resistance — Moderate.
Wood Mulch: Cost — Very low ($2-5/linear foot). Installation — Very easy. Drainage — Good. Maintenance — High (annual replenishing). Accessibility — Poor. Durability — Low (1-2 years between full refreshes). Weed resistance — Poor to moderate.
Natural Stone: Cost — High ($30-75/linear foot installed). Installation — Moderate to difficult. Drainage — Variable (good if dry-laid, poor if mortared). Maintenance — Low. Accessibility — Good to excellent (if flat and level). Durability — Excellent. Weed resistance — Good.
Brick: Cost — Moderate to high ($18-42/linear foot installed). Installation — Moderate. Drainage — Moderate. Maintenance — Low to moderate. Accessibility — Good. Durability — Good to excellent. Weed resistance — Good.
Stepping Stones: Cost — Low to moderate ($6-24/linear foot). Installation — Easy. Drainage — Excellent. Maintenance — Low to moderate. Accessibility — Poor. Durability — Excellent (stones) / Variable (infill). Weed resistance — Poor to good (depends on infill).
How to Choose: Matching Material to Situation
Choose gravel if you want a budget-friendly, all-purpose path material that drains well and looks good in most garden styles. Best for main garden paths, utility routes, and areas where drainage is critical. Avoid for areas where wheelchair or stroller access is needed unless you use compacted decomposed granite.
Choose wood mulch if you want the most natural look at the lowest cost and you are willing to replenish annually. Best for informal, woodland, and naturalistic gardens. Best for secondary paths with light foot traffic. Avoid for high-traffic routes, wheelchair-accessible paths, or areas where you want a permanent surface.
Choose natural stone if you want a permanent, low-maintenance, premium path and are willing to invest the higher upfront cost. Best for primary garden paths, entryways, and formal garden rooms where the path is a design feature, not just a functional surface. Choose dry-laid for flexibility and drainage; mortared for a cleaner, more formal finish.
Choose brick if you want a warm, traditional aesthetic with good durability and moderate cost. Best for cottage gardens, formal gardens, and paths adjacent to brick or stone buildings. A strong DIY option for homeowners willing to invest weekend time. Avoid in heavy shade where moss makes the surface slippery unless you commit to periodic cleaning.
Choose stepping stones if you want a light, informal, garden-integrated path for low traffic. Best for secondary routes through planted beds, across lawns, and through ground cover plantings. Avoid as the sole path material for any route that needs to be wheelchair-accessible or that carries heavy foot or equipment traffic.
Many of the best gardens use multiple path materials in a hierarchy: natural stone or brick for the main paths from the house to primary garden areas, gravel for secondary paths between beds and to the compost area, and stepping stones for tertiary paths through ornamental plantings. This layered approach matches material cost and formality to traffic level and visibility, stretching the budget while putting the best materials where they matter most.
Frequently Asked Questions
What is the most wheelchair-accessible garden path material?
Natural stone flagging — sawn to uniform thickness, laid with tight joints filled with polymeric sand on a compacted gravel base — provides the firmest, smoothest, most accessible surface for wheelchairs and walkers. Brick pavers are a close second. Compacted decomposed granite is a more affordable option that provides adequate wheelchair access if maintained to prevent ruts and soft spots. The key for any accessible path is a firm, stable, level surface with no gaps, lips, or soft areas greater than a quarter inch. Path width should be at least four feet, and five feet is preferred for comfortable wheelchair maneuvering.
How do I prevent weeds in gravel paths?
Start with landscape fabric beneath the gravel — this is the single most effective weed-prevention measure. Use a commercial-grade woven fabric, not cheap black plastic, which deteriorates quickly and does not allow water through. Top with three to four inches of gravel. Maintain the gravel depth by adding fresh gravel as needed — thin spots where the fabric is exposed or nearly exposed are where weeds establish first. If weeds appear, pull them when they are small. Avoid herbicides in garden paths where drift or runoff could damage adjacent plantings. Occasional flaming with a propane weed torch is effective for gravel paths without chemical concerns.
Can I combine different path materials in one garden?
Yes, and doing so is one of the best strategies for balancing budget and aesthetics. Use your most expensive, most attractive material for the main paths that are most visible — from the house to the patio, the patio to the main garden area. Use a mid-range material like gravel for secondary paths between beds and to utility areas. Use mulch or stepping stones for informal, low-traffic tertiary paths through ornamental areas. The key is consistency within each zone — do not mix materials randomly. Each path type should be consistent in material, width, and edging within its traffic tier.
How wide should a garden path be?
Main paths (house to garden, primary circulation): minimum three feet, preferably four feet. Secondary paths (between beds, to compost): minimum two feet, preferably three feet. Tertiary paths (through ornamental plantings): eighteen to twenty-four inches. For wheelchair access, four feet minimum throughout, five feet preferred, with level rest areas at least five feet square every fifty feet. These widths assume the path is clear of overhanging plants — prune anything that encroaches on the path width, because effective path width is measured between the plants, not between the edges.
What path material is best for a slope?
On gentle slopes, compacted gravel or compacted decomposed granite with perpendicular timber or stone water bars every six to eight feet to divert runoff is the most practical solution. On moderate slopes, steps with stone or brick treads and gravel or mulch landings manage the grade change safely. Loose gravel and mulch both wash downhill on slopes — the steeper the slope, the more critical it is to use compacted materials and install cross-path water management. Natural stone steps are the most durable and attractive option for significant grade changes and are worth the investment on a slope where cheaper materials will constantly migrate and need replacement.