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Hardscape and Site Work Glossary

The words our crews, suppliers, engineers and inspectors use every day, in plain English. If a quote, a wall design or a building inspector throws a term at you that you do not know, look it up here. Where we have written a full article on a term, the definition links to it.

Jump to: 0-9 | A | B | C | D | E | F | G | H | I | J | L | M | N | O | P | R | S | T | U | V | W

0-9

28-day strength: The compressive strength a concrete mix is designed to reach at 28 days of age, which is the age most strength requirements are written for. Concrete keeps gaining strength after that, but 28 days is the benchmark. More: how long concrete takes to cure.
2A modified: Pennsylvania’s most common modified aggregate: PennDOT 2A crushed stone with fines blended in so it packs into a dense, well-graded base. It is the go-to base stone under patios, walks and driveways around here. More: crushed stone sizes.
57 stone: Clean, open-graded crushed stone (AASHTO No. 57, a blend of No. 5 and No. 7 sizes) with no fines, so water moves through it freely. We use it around drain pipe, behind walls and as clean base where drainage matters more than compaction. More: 57 stone vs crusher run.
811 call: The free national call-before-you-dig number that sends utility companies out to mark buried lines. In Pennsylvania it routes to PA One Call, and homeowners and contractors must call at least three business days before digging. More: 811 dig laws by state.

A

Aggregate: Crushed stone, gravel or sand used as base, fill or as an ingredient in concrete. It is sold by size and gradation, and the right one depends on whether the job needs drainage or compaction. More: crushed stone sizes.
Air-entrained concrete: Concrete with an admixture that puts microscopic air bubbles into the paste, giving freezing water room to expand. In a freeze-thaw climate like central PA, any exterior slab should be air-entrained. More: concrete driveways.
Angle of repose: The steepest angle a pile or slope of loose material will hold before it slides. It is why excavation sides get sloped or benched and why spoil piles need room.
As-built: A drawing or survey that shows what was actually built, including changes made in the field. Handy later for finding drain lines, sleeves and wire runs.
ASTM C1372: The ASTM standard specification for segmental retaining wall units, the dry-stacked concrete block used in most modern landscape walls. More: segmental retaining walls.
ASTM C33: The ASTM standard specification for the fine aggregate (sand) and coarse aggregate (stone) used in concrete.
ASTM C936: The ASTM standard specification for solid concrete interlocking paving units, the spec quality concrete pavers are made to. More: paver brands compared.
ASTM D448: The ASTM classification of aggregate sizes for road and bridge construction. Size numbers like 57 and 8 that you hear at the quarry come from this system. More: crushed stone sizes.

B

Backfill: Material placed behind a wall or into a trench or foundation hole after the work is in. Behind a retaining wall it should be clean drainage stone near the block and compactable soil beyond. More: retaining wall drainage.
Base course: The compacted layer of crushed stone that carries the load under pavers, slabs or a driveway. Most paver failures trace back to a base that was too thin or not compacted. More: how deep a paver base should be.
Batter: The backward lean built into a retaining wall face so it tilts into the hill it holds. Most segmental block builds it in automatically through a lip or pin. More: retaining wall batter.
Bearing capacity: How much load a soil can support without settling or shearing. Soft clay and fill have less than undisturbed ground. More: Pennsylvania soil types.
Bedding sand: The thin, screeded layer of coarse, washed sand that pavers are set on. It is a leveling layer, not structure, so it is kept thin and never used to make up for a low base. More: building a paver patio.
Bench (excavation): A level step cut into a slope or trench wall. Benching keeps excavation sides stable and gives new fill a flat surface to key into.
Benchmark: A fixed reference point with a known elevation that all grades on a job are measured from. More: measuring your yard.
Berm: A raised mound of soil used to direct water, block a view or add height to plantings. More: landscaping a slope.
Bluestone: A dense sandstone quarried in Pennsylvania and New York and cut into flagging, treads and coping. It comes in thermal (flamed flat) and natural cleft (split) finishes. More: thermal vs natural cleft bluestone.
Bond beam: A course of block filled solid with grout and reinforcing steel that ties a masonry wall together, usually at the top.
Bond pattern: The layout pavers or block are laid in, such as running bond, herringbone or basketweave. Some patterns lock together better under traffic than others. More: paver patterns.
Border course: The row of pavers set around the edge of a field, often in a contrasting color or a soldier course. It frames the patio and gives the cut field pieces something to butt against. More: paver patterns.
Borrow: Soil brought in from somewhere else to make up a fill. Also called borrow fill. More: topsoil vs fill dirt.
Broom finish: A textured concrete surface made by dragging a broom across fresh concrete. It gives traction on walks and driveways. More: concrete driveways.

C

Cap (wall cap): The finished top course on a retaining or seat wall, usually glued down with concrete adhesive and set with a slight overhang. More: retaining wall caps.
Catch basin: A box set at a low spot with a grate on top that collects surface water and sends it into a buried pipe. More: catch basin vs French drain.
Chip stone: Small, clean crushed stone used in permeable paver joints and as a setting bed. More: crushed stone sizes.
Clay: The finest soil particle size. Clay holds water, drains slowly and swells and shrinks, so it makes poor base and needs drainage planning around it. More: Pennsylvania soil types.
Clean stone: Crushed stone washed or screened so it has no fines. It drains well but does not lock together like a dense-graded base. More: 57 stone vs crusher run.
Cleanout: A capped riser in a drain or downspout line that gives access to flush or snake the pipe. More: how to bury a downspout.
Compaction: Packing soil or stone tighter with a plate compactor, roller or jumping jack so it will not settle later. It is done in thin lifts, never all at once. More: how deep a paver base should be.
Compressive strength: How much crushing load concrete can carry, reported in pounds per square inch (psi) and usually specified at 28 days. More: driveway load capacity.
Concrete adhesive: A construction adhesive rated for masonry, used to glue caps and the top courses of a wall. More: retaining wall caps.
Construction joint: A planned stopping place where one concrete pour ends and the next begins.
Contour line: A line on a plan connecting points at the same elevation. Close lines mean steep ground. More: drawing a landscape plan.
Control joint: A groove tooled or saw-cut into a slab so it cracks along a straight line instead of at random. The NRMCA rule of thumb is a maximum spacing of 24 to 36 times the slab thickness, cut at least a quarter of the way through. More: concrete patio thickness.
Coping: Stone or precast units that cap the top of a wall, step or pool edge, often with an overhang. More: retaining wall caps.
Course: One horizontal row of block, brick or stone in a wall. More: counting wall block.
Cross slope: The side-to-side pitch built into a patio, walk or driveway so water runs off instead of sitting. More: how much slope a patio needs.
Crusher run: Crushed stone sold straight off the crusher with everything from the top size down to dust mixed in. It compacts hard, which is why it is used as base. More: 57 stone vs crusher run.
Cubic yard: The unit soil, stone, mulch and concrete are ordered in: a cube one yard on each side. More: what a yard of gravel weighs.
Curing: Keeping fresh concrete moist and warm enough so it can gain strength. Curing is different from drying, and how well it is done shows up in the surface for years. More: how long concrete takes to cure.
Curtain drain: A gravel-filled trench with perforated pipe placed uphill of a house or yard to catch groundwater before it reaches the problem area. More: French drain or regrading.
Cut and fill: Moving soil from high spots (cut) to low spots (fill) to reach a planned grade. A balanced job moves as little dirt off or on site as possible. More: land grading basics.

D

Daylight drain: A drain pipe that runs out of the ground to an open outlet downhill, where water can leave by gravity. When there is enough fall, it is the simplest outlet for a drain. More: retaining wall drainage.
Deadman: A tieback anchored into the soil behind a timber wall, a perpendicular timber with a crosspiece buried in the slope that keeps the wall from tipping. More: timber vs block walls.
Dense-graded aggregate: Stone with a full range of particle sizes, from coarse down to fines, so the small pieces fill the gaps between the big ones and it compacts tight. 2A and crusher run are dense-graded. More: crushed stone sizes.
Downspout extension: Pipe that carries roof water away from the foundation, above or below ground, to where it can drain off safely. More: downspout extension length.
Drain tile: Perforated pipe laid in stone to collect and carry groundwater. The name comes from the clay tile it used to be made of. More: French drain or regrading.
Drainage aggregate: Clean stone placed directly behind retaining wall block so water can drop to the drain pipe instead of building pressure. More: retaining wall drainage.
Dry well: A buried pit or chamber that collects stormwater and lets it soak into the ground. It only works where the soil can take the water. More: dry well vs French drain.

E

Easement: A recorded right for someone else, usually a utility or neighbor, to use part of your property. You often cannot build walls or patios inside one. More: when you need a surveyor.
Edge restraint: The plastic, metal or concrete edging that holds the outside row of pavers in place. Without it, pavers creep outward and joints open. More: paver edging and edge restraints.
Efflorescence: The white, chalky haze that can show up on new pavers or block as salts come to the surface with moisture. It is cosmetic and usually fades on its own or cleans off. More: efflorescence on pavers.
Elevation: The height of a point relative to a fixed reference, like the house floor or a benchmark. More: measuring your yard.
Erosion and sediment control plan: A written plan for keeping soil on site during earthwork using silt fence, stabilized entrances and fast seeding. In Pennsylvania, 25 Pa. Code 102.4 requires one when earth disturbance reaches 5,000 square feet or more. More: excavation cost.
Excavation: Digging out soil to make room for a base, footing, foundation or utility. Depth and what you hit determine the cost. More: excavation cost.
Expansion joint: A flexible strip placed between concrete and another structure, or between pours, so each can move. In flatwork it usually means an isolation joint.

F

Fall: The vertical drop over a run of pipe, swale or surface that makes water flow. No fall, no flow. More: how to bury a downspout.
Filter fabric: A non-woven geotextile that lets water through but keeps soil out, used to wrap drain stone and keep it from clogging. More: landscape fabric under gravel.
Fines: The dust-sized particles in crushed stone or soil. Fines help base compact but block water in drainage stone. More: 57 stone vs crusher run.
Finish grade: The final surface of the ground after topsoil, ready for seed, sod or plantings. More: land grading basics.
Flagstone: Flat, irregular slabs of natural stone used for patios, walks and stepping stones. More: flagstone vs pavers.
Flatwork: Any horizontal concrete: slabs, sidewalks, patios and driveways. More: concrete driveways.
Float: To smooth and level fresh concrete after screeding, with a bull float or hand float, before finishing.
Footing: The widened base at the bottom of a wall, column or foundation that spreads its weight into the soil. Structural footings go below the frost line. More: foundation digging.
Freeze-thaw cycle: Each time the ground or a surface freezes and thaws. Many cycles a winter is what wears down concrete and opens joints. More: salt and ice melt on pavers.
French drain: A trench of clean stone and perforated pipe that collects groundwater and carries it to an outlet. More: French drain or regrading.
Frost heave: Ground lifting when water in the soil freezes and forms ice lenses. It cracks slabs, pops pavers and tips walls that sit on wet, fine soil. More: pavers heaving in winter.
Frost line: The depth the ground is expected to freeze in a given area. Local building codes set how deep footings must go to sit below it. More: frost line depth by state.

G

Geogrid: A plastic or polyester mesh laid in layers between wall courses and stretched back into the backfill. It ties the soil to the wall so they act as one mass. More: when a wall needs geogrid.
Geotextile: Any engineered fabric used in soil work. Woven fabric separates and stabilizes, non-woven fabric filters water. More: landscape fabric under gravel.
Grade: The ground surface and its elevation, or the act of shaping it. Positive grade means the ground slopes away from the house. More: land grading basics.
Grade stake: A stake marked with a target elevation or cut and fill depth so the operator knows how much to dig or fill.
Gravity wall: A retaining wall that holds back soil with its own weight and batter, without geogrid or tiebacks. More: segmental retaining walls.
Groundwater: Water held in the soil and rock below the surface. A high water table or a spring changes how a site has to be drained. More: underground springs.
Guard: The code term for a guardrail. Under IRC R312.1, guards are required on open-sided walking surfaces more than 30 inches above the floor or grade below, measured within 36 inches horizontally of the edge. More: fences on retaining walls.

H

Hardpan: A dense, compacted soil layer that water and roots cannot get through easily. It is a common reason a yard stays wet. More: why a yard holds water.
Hardscape: The built, non-living parts of a landscape: patios, walls, walks, steps and edging. More: hardscape design.
Herringbone: A paver pattern laid in a zigzag at 45 or 90 degrees. It interlocks well and holds up under vehicle traffic. More: paver patterns.
Hydrostatic pressure: Pressure from water trapped in soil, pushing on a wall or foundation. It is the force that topples walls with no drainage. More: why retaining walls fail.

I

Ice melt: Salts and chemicals spread to melt ice. Some types are much harder on concrete and pavers than others. More: salt and ice melt on pavers.
Interlock: How pavers transfer load to each other through the sand in the joints and tight edges, so the surface acts as one piece. More: building a paver patio.
Isolation joint: A joint that separates a slab from a fixed object like a foundation, column or step so each can move without cracking the other. More: concrete patio thickness.

J

Joint sand: Sand swept into the gaps between pavers to lock them together. It can be regular sand or polymeric sand. More: polymeric sand vs regular sand.

L

Leveling pad: The compacted base of crushed stone under the first course of a retaining wall. If it is not flat and solid, nothing above it will be. More: retaining wall base depth.
Lift: One layer of fill or base placed and compacted before the next goes on. Thin lifts compact. Thick ones do not. More: how deep a paver base should be.
Loam: Soil with a balanced mix of sand, silt and clay. Good for growing, poor as structural base. More: topsoil vs fill dirt.

M

Mason sand: A fine, uniform washed sand used in mortar. Too fine for paver bedding. More: polymeric sand vs regular sand.
Modified stone: Crushed stone that has fines blended in so it compacts. In PA it usually means 2A. More: crushed stone sizes.
Mortar: A mix of cement, lime, sand and water that bonds brick, block or stone in a mortared wall.
Mortared wall: A wall where stone or block is set in mortar on a concrete footing, as opposed to dry-stacked. More: timber vs block walls.

N

Natural cleft: Stone split along its natural layers, leaving a textured, uneven face. More: thermal vs natural cleft bluestone.
Non-woven fabric: A felt-like geotextile that lets water through while filtering soil, used to wrap drains. More: landscape fabric under gravel.

O

Open-graded aggregate: Stone that is mostly one size with few fines, leaving voids that water flows through. 57 stone is open-graded. More: 57 stone vs crusher run.
Outlet: Where a drain releases its water: a daylight end, pop-up emitter, storm drain or dry well. More: how to bury a downspout.
Overexcavation: Digging past the planned depth to remove soft or unsuitable soil, then rebuilding with compacted stone. More: foundation digging.

P

Paver: A precast concrete, clay or porcelain unit laid on a sand and stone base to make patios, walks and driveways. More: paver brands compared.
Pedestal system: Adjustable supports that hold porcelain or stone pavers up off a roof or slab. More: porcelain pavers.
Perc test: A percolation test that measures how fast water soaks into the soil. It tells you if a dry well or infiltration system will work. More: dry well vs French drain.
Perforated pipe: Drain pipe with holes or slots that let groundwater in, used in French drains and wall drains. More: retaining wall drainage.
Permeable pavers: Pavers with wider joints filled with clean chip stone over an open-graded base, so rain soaks through instead of running off.
Pins (wall pins): Fiberglass or plastic pins that tie some wall block courses together and set the setback. More: Versa-Lok Standard.
Plan view: A drawing looking straight down on the site, showing layout and dimensions. More: drawing a landscape plan.
Plate compactor: The vibrating machine used to compact base stone and to seat pavers into the bedding sand. More: building a paver patio.
Polymeric sand: Joint sand mixed with binders that harden when wetted, locking joints and slowing weeds and washout. More: polymeric sand vs regular sand.
Pop-up emitter: A spring-loaded cap at the end of a buried downspout or drain line that lifts to let water out, then closes. More: how to bury a downspout.
Porcelain paver: A thin, kiln-fired paver that is dense and stain resistant, set on pedestals, sand or a concrete slab. More: porcelain pavers.
Positive drainage: Grading that moves water away from buildings and walls instead of toward them. More: land grading basics.
Proctor test: The lab test that finds the maximum density a soil can be compacted to and the moisture content that gets it there. ASTM D698 is the standard effort version and ASTM D1557 the modified effort version.
PSI: Pounds per square inch. For concrete, it is how compressive strength is reported, and most requirements are set at an age of 28 days. More: concrete driveway thickness.

R

Rain garden: A shallow planted basin that catches runoff from roofs or paving and lets it soak in. More: rain garden sizing.
Rebar: Steel reinforcing bar placed in concrete to hold cracks tight and carry tension. Bars are called by number, and bigger numbers are thicker bars. More: rebar vs wire mesh.
Retaining wall: Any wall that holds back soil to create a level area on a slope. More: retaining wall design.
Riprap: Large, loose rock placed on slopes, ditches or outlets to stop erosion where water runs fast.
Riser: The vertical face of a step. Also a pipe that comes up out of the ground, like a cleanout.
Rough grade: The shaped ground before topsoil goes down, set slightly below finish grade. More: land grading basics.
Running bond: A paver or block pattern where each row is offset by half a unit, like brick. More: paver patterns.
Runoff: Rainwater that flows over the surface instead of soaking in, mostly from roofs, paving and saturated soil. More: why a yard holds water.

S

Saw cut: A joint or cut made with a concrete or paver saw. Control joints are often saw cut the day after a pour. More: concrete patio thickness.
Scale (drawing): The ratio between a drawing and real life, such as one inch on paper standing for a set number of feet. More: drawing a landscape plan.
Screed: To strike off sand or fresh concrete flat using a straight board or pipe rails. Also the tool used to do it. More: building a paver patio.
Sealer: A coating applied to pavers or concrete to deepen color, repel stains or harden joint sand. More: sealing pavers.
Seat wall: A low freestanding wall built at sitting height, usually capped, around a patio or fire pit. More: seat wall dimensions.
Section (drawing): A drawing that slices through a wall, patio or drain to show the layers and depths underneath. More: drawing a landscape plan.
Segmental retaining wall: A dry-stacked wall of interlocking concrete block that relies on weight, batter and sometimes geogrid instead of mortar. Often shortened to SRW. More: segmental retaining walls.
Setback (wall): How far each course of block steps back from the one below, which creates the wall’s batter. More: retaining wall batter.
Setback (zoning): The minimum distance a structure must sit from a property line, road or stream under local zoning rules. More: when you need a surveyor.
Silt fence: A short fabric fence staked along the downhill side of a dig to catch soil before it washes off site.
Site plan: A scaled drawing of the property showing buildings, property lines, utilities and the proposed work. More: drawing a landscape plan.
Sleeve: A pipe laid under paving or through a wall before it is built so wires or water lines can pass through later.
Slump: A field test of how stiff or soupy fresh concrete is, measured by how much a cone of concrete sags.
Soldier course: A row of pavers or brick set side by side with the long edge facing out, usually as a border. More: paver patterns.
Spoil: Excavated soil piled on site, to be reused, hauled off or spread. More: excavation cost.
Spot elevation: A single marked elevation on a plan, usually at corners, doors and drains. More: drawing a landscape plan.
Stepping (wall base): Dropping a retaining wall’s base in level steps to follow a sloped grade. More: retaining wall base depth.
Stringline: A tight line pulled between stakes to set straight edges and elevations during layout. More: building a paver patio.
Subbase: A layer of stone below the base course on heavier-duty jobs, used to bridge weak soil. More: gravel driveway base depth.
Subgrade: The native or filled soil the base sits on. If it is soft or wet, it has to be fixed before base goes down. More: how deep a paver base should be.
Sump pump: A pump in a basement pit that pushes groundwater out of the house through a discharge line. More: sump pump discharge ideas.
Surcharge: Any extra load above or behind a wall, like a driveway, building, pool or slope. Surcharges add pressure the wall has to be designed for. More: retaining walls over 4 feet.
Swale: A shallow, grassed channel graded into the yard to carry surface water to a safe spot. More: swale vs French drain.

T

Takeoff: Measuring a plan or site to list quantities of material and labor for an estimate. More: estimating a paver patio.
Terrace: A level step of ground made by building a series of shorter walls instead of one tall one. More: terraced backyards.
Thermal finish: A stone surface flamed with a torch to make it flat with a fine texture, common on bluestone. More: thermal vs natural cleft bluestone.
Topsoil: The dark, organic top layer of soil that grows lawns and plants. It is stripped before base work and replaced at the end. More: topsoil vs fill dirt.
Tread: The horizontal part of a step that you stand on.
Trench drain: A narrow channel drain with a grate set flush in paving to catch water across a driveway or garage door. More: water running into a garage.

U

Unbalanced fill: The difference in soil height between the high side and low side of a wall. It is the height that matters for wall design and permits. More: retaining walls over 4 feet.
Uniform Construction Code (UCC): Pennsylvania’s statewide building code law, which adopts the International Codes and sets when permits and inspections are required. More: permits under the PA UCC.
Utility locate: The paint and flags utility companies put down after an 811 call to show where buried lines are. More: 811 dig laws by state.

V

Vapor barrier: A plastic sheet under an interior slab that slows moisture coming up from the ground. More: pole barn and garage pads.

W

Wall drain: The perforated pipe at the base of a retaining wall, in clean stone, that carries water out to daylight. More: retaining wall drainage.
Water table: The level below which the ground is saturated. It rises in wet seasons. More: underground springs.
Weep hole: An opening at the base of a mortared or concrete wall that lets trapped water out. More: retaining wall drainage.
Welded wire mesh: A grid of light steel wire placed in slabs to hold shrinkage cracks tight. It only works if it ends up inside the slab, not lying on the ground under it. More: rebar vs wire mesh.
Woven fabric: A strong, flat geotextile used under base to separate it from soft soil and spread the load. More: landscape fabric under gravel.

Want help putting these terms to work? See our topic guides, run the numbers with our free calculators, or, in central PA, get a quote from our crew.

Sources: NRMCA, CIP 6: Joints in Concrete Slabs on Grade; NRMCA, CIP 35: Testing Compressive Strength of Concrete; PCA, Joints: what type are used and where; ICC, 2021 International Residential Code, Section R312.1 Guards; PA Public Utility Commission, PA One Call; 25 Pa. Code 102.4, Erosion and sediment control requirements; Penn State Center for Dirt and Gravel Road Studies, DSA Handbook Appendix F (aggregates); ASTM C33; ASTM C936; ASTM C1372; ASTM D448; ASTM D698; ASTM D1557.