Topsoil vs Fill Dirt: What Each One Is For and How to Layer Them

Topsoil vs fill dirt comes down to one job each: fill dirt raises and shapes the ground, and topsoil is the thin living layer on top that grows grass and plants. Fill goes in first and gets compacted in thin layers, then 4 to 6 inches of topsoil goes over it.

What is the difference between topsoil and fill dirt?

Fill dirt is subsoil with little organic matter, used to raise grade and fill low spots because it compacts and stays put. Topsoil is the dark, organic top layer that grows grass and plants. Put fill down first in thin compacted lifts, then finish with 4 to 6 inches of settled topsoil.

What topsoil is

Topsoil is the dark upper layer of natural soil, where most of the roots, organic matter and soil life are. It holds water and nutrients, and it’s loose enough for roots to grow through. That’s exactly what you want under a lawn or a garden bed, and exactly what you don’t want under anything that needs to stay put.

Bagged or bulk topsoil from a yard varies a lot. Some is stripped from farm fields, some is blended with compost or sand, and some is mostly subsoil with a little dark color. Look at it before you buy.

What fill dirt is, and how structural fill differs

Fill dirt is soil from below the topsoil layer, usually dug out of a foundation, pond or road cut. It’s mostly mineral (clay, silt, sand, gravel, rock) with little organic matter. That’s why it compacts and stays put. Quality ranges from good clean subsoil to a mix of clay chunks, rock and junk.

Structural fill is fill that has been specified, placed and tested to hold a load. The International Residential Code says fill soils that support footings and foundations must be designed, installed and tested in accordance with accepted engineering practice. In practice that means a known material, placed in lifts at the right moisture and checked for density.

Clean fill is a legal term, not a soil type. It means fill free of contamination and trash. More on that below.

	Topsoil	Fill dirt	Structural fill
What it is	Upper soil layer, dark, organic	Subsoil from excavation	Selected soil or stone, engineered
Organic matter	High	Low	Little to none
Compacts well	No, it stays spongy	Often, if moisture is right	Yes, it’s tested for it
Good for	Lawns, beds, the top 4 to 6 in	Raising grade, filling holes	Under footings, slabs, heavy loads
Bad for	Deep fill, under patios or slabs	Growing grass by itself	Overkill for lawns and beds

Why topsoil makes bad fill

People use topsoil as fill because it’s easy to find and looks nice. It causes three problems:

• It settles. Organic matter is soft and compressible, and it slowly decomposes. A low spot filled deep with topsoil tends to sink again, and you end up filling it twice.
• It won’t compact to a firm base. You can’t build a stable subgrade for a patio, walk or shed out of spongy soil. Our patio bases go on firm, compacted subgrade, never on topsoil.
• It’s a waste of good soil. Good topsoil usually costs more than fill dirt. Burying 2 feet of it where roots will never reach is money in the ground for no reason.

The building code says the same thing in its own way. Fill under a concrete floor must be free of vegetation and foreign material and compacted, and unless approved it can’t be deeper than 24 inches of clean sand or gravel, or 8 inches of earth. Roots, sod and buried debris rot and leave voids.

How to layer fill and topsoil

The right order is the same for a low corner of the yard or a whole lot.

1. Strip the existing topsoil and pile it to the side. Penn State’s lawn establishment guide has you rough grade the subsoil first and put stockpiled topsoil back at the end.
2. Remove roots, stumps, rocks and debris from the area you’re filling.
3. Place fill in thin lifts and compact each one. Road builders work this way too: Ohio DOT spreads embankment in loose lifts no more than 8 inches thick, and 6 inches near walls and structures where big rollers can’t reach. With a walk-behind compactor at home, thinner is better.
4. Set the subgrade low by the depth of topsoil you’ll add, shaped to the final slope. Penn State suggests a gentle 1 to 4 percent slope away from the house where you can (a 1 to 4 foot drop per 100 feet). Right next to the foundation, the IRC asks for more: at least 6 inches of fall in the first 10 feet, so check what your local code adopts.
5. Spread topsoil 4 to 6 inches deep, measured settled. Penn State calls for at least 4 to 6 inches of good topsoil for quality turf, ideally working the first 2 inches into the top 2 to 3 inches of subsoil so there’s no hard line between layers.

Don’t skip that mixing step. Penn State notes it reduces subsoil compaction and improves drainage where the two layers meet.

Related: Sod calculator: square feet, rolls, pallets and the topsoil for a 4 to 6 in. prep layer

For bigger grade changes, see our guide to leveling a sloped backyard. If water is the reason you’re filling, fix the cause first: our article on whether you need a French drain covers when regrading alone will do it.

Leveling part of a hillside with the soil you already have? Our step-by-step guide to landscaping and leveling a sloped backyard shows how to balance cut and fill and when the edges need a wall.

Clean fill dirt: what the rules usually say

“Clean fill” is regulated at the state level, so the exact rules depend on where you live. Pennsylvania is a good example of how it works. The state DEP says the use of uncontaminated soil, rock, stone, gravel, brick and block, concrete and used asphalt as clean fill doesn’t require a permit. DEP also has a general permit for what it calls “regulated fill,” and it publishes a Certification of Clean Fill form.

What that means for you:

• Free fill isn’t always free. Fill from a demolition site, an old industrial lot or a fuel spill area can carry contamination you inherit when it’s on your property.
• Ask where it came from. A reputable excavator or supplier can tell you the source site.
• Check for trash in the load. Wire, plastic, wood and chunks of drywall are signs the fill was never screened.

Outside Pennsylvania, check your state environmental agency’s fill rules. Definitions and permit thresholds differ from state to state.

Screened vs unscreened topsoil, and how to order

Screened topsoil has been run through a screen to remove stones, roots and clods. It spreads evenly and is the right choice for seeding a lawn or filling beds. Unscreened topsoil comes as dug, with rocks and roots. It costs less and works for rough grading where you’ll rake out debris anyway. Penn State recommends removing stones larger than 2 inches before seeding, so if you buy unscreened, plan to rake.

Before you order:

• Get a soil test. Penn State recommends testing before establishment so you know how much lime, fertilizer and organic matter to add. Bought topsoil isn’t automatically good soil.
• Look at the pile. Good topsoil is dark, crumbly and smells earthy. Gray, sticky or sour-smelling soil is a warning sign.
• Order for settled depth. Penn State’s 4 to 6 inches is a firmed depth. Loose soil settles, so order a bit more than the math says.
• Do the volume math. Square feet × depth in feet ÷ 27 = cubic yards. At 4 inches, 1,000 square feet takes about 12.3 cubic yards; at 6 inches, about 18.5. Our mulch and topsoil calculator runs it for you.

Fill dirt vs topsoil cost per yard

Fill dirt is the cheap layer and topsoil is the expensive one, which is one more reason not to bury topsoil where roots will never reach it. Here’s what two national cost guides report per cubic yard. Local prices swing with distance from the pit or yard, so call your supplier for a real number.

Material	HomeGuide	Angi (2024 data)
Fill dirt	$5 to $25 per cu yd	$5 to $15 per cu yd
Screened or clean fill	$8 to $25 per cu yd, plus $15 to $60 delivery	$8 to $15 per cu yd
Engineered or structural fill	$10 to $30 per cu yd	$10 to $30 per cu yd
Bulk topsoil	$10 to $50 per cu yd	$12 to $55 per cu yd
Screened topsoil	$20 to $30 per cu yd on orders of 15 cu yd or more	About $20 per cu yd
Organic compost	$20 to $50 per cu yd	Not listed

Delivery changes the math. HomeGuide puts a dump truck load of fill dirt at $150 to $400 delivered, and a 10 to 15 cubic yard load of topsoil at $150 to $500. Angi says haulers charge $7 to $55 per cubic yard to deliver, depending on truck size and material weight. HomeGuide also notes some suppliers quote soil and delivery as one per-yard price and others quote them separately, so compare quotes the same way. The money-saving move is the same as the building move: use fill for the depth and buy topsoil only for the top 4 to 6 inches.

Soil varies a lot by region. Our article on soil types in Pennsylvania shows how much the ground can change from one valley to the next, which is why you shouldn’t assume the fill on your site will behave like the fill on your neighbor’s.

Filling low spots in a lawn: topsoil, fill or sand?

A shallow dip in a lawn you want to keep doesn’t need fill dirt. It needs topsoil, a little at a time, so you don’t bury the grass. Clemson’s Home and Garden Information Center says to topdress no more than 1/2 inch at a time, because a thicker layer can stunt the turf. University of Maryland Extension puts it at about 1/4 to 3/4 inch of topsoil or compost before you smother the grass crowns.

• Shallow dip, grass still alive: spread topsoil 1/2 inch or less and rake it down between the blades. Clemson says to do it during the growing season and repeat light passes rather than one heavy one.
• Sand only on sandy soil. Clemson says sand should only be used to topdress when the native soil is sandy; otherwise use topsoil.
• Deep hole or rut: too deep to topdress. Maryland Extension’s fix is to remove the sod, regrade the soil and replant. That’s a small version of the layering above: firm mineral fill for the bulk, topsoil on top, then the turf.
• Low spot that holds water: figure out why before you fill it. Filling a wet spot without fixing the slope usually just moves the puddle.

If the low spot is wet, start with our yard drainage guide. It covers when regrading is enough and when the water needs a drain.

When to call a pro

Topdressing a lawn or filling a garden bed is an easy DIY job. Bring in an excavator or engineer when:

• You’re filling under a slab, garage, addition or footing (that’s structural fill territory, and the code wants it engineered)
• The fill will be more than a foot or two deep over a large area
• You’re filling against a foundation or retaining wall, where heavy compaction can push on the structure
• The low area holds water, which usually means drainage needs fixing before any dirt arrives

If you’re reshaping a yard, a grading plan saves a lot of guessing about how much fill goes where. Our yard grading plans come with the Full Yard plan ($895), which includes a grading and drainage concept that shows where the water should go before your excavator starts. For dig work near a house, our article on foundation digging explains how site prep for slabs and footings is handled.

Frequently Asked Questions

Can I use topsoil as fill dirt?

Only for the top few inches where you want grass or plants to grow. Used deeper, topsoil stays soft, compresses and settles as its organic matter breaks down.

What is clean fill dirt?

Clean fill is fill free of contamination and trash. Pennsylvania’s list, for example, is uncontaminated soil, rock, stone, gravel, brick, block, concrete and used asphalt; other states set their own rules.

How deep should topsoil be for a new lawn?

Penn State Extension recommends at least 4 to 6 inches of good topsoil, measured after it’s firmed or settled. Working the first 2 inches into the subsoil below helps drainage and rooting.

Is screened topsoil worth it?

For seeding a lawn or filling planting beds, yes, because it spreads evenly and has no rocks or roots to rake out. For rough grading that will get more soil on top, unscreened is usually fine.

Can fill dirt go under a patio or shed?

Firm, compacted mineral fill can, with the right gravel base on top. Under a house’s concrete floor slab, the IRC limits fill to 24 inches of clean sand or gravel or 8 inches of earth unless the building official approves more.

Can grass grow in fill dirt?

Not well on its own. Fill dirt has little organic matter, so seed struggles in it. Penn State Extension calls for at least 4 to 6 inches of good topsoil, firmed or settled, for quality turf, and recommends a soil test first so you know what lime and fertilizer to add.

Can you put topsoil directly over fill dirt?

Yes, that’s the right order. Compact the fill in thin lifts, shape it to the final slope, then spread topsoil on top. Penn State recommends working 2 inches of the topsoil into the upper 2 to 3 inches of subsoil so there’s no hard line between the layers.

How much topsoil do I need?

Multiply square feet by depth in feet and divide by 27 to get cubic yards. At 4 inches, 1,000 square feet takes about 12.3 cubic yards; at 6 inches, about 18.5. Order a little extra, because loose soil settles to a shallower depth.

Do I need to call 811 before grading or bringing in fill?

If the job involves digging, yes. Pennsylvania law requires notice to PA One Call (811) at least 3 and no more than 10 business days before excavation work begins, and the state PUC says that applies to homeowners as well as contractors. Call even for a small job.

Is fill dirt cheaper than topsoil?

Yes, usually by about half. HomeGuide lists fill dirt at $5 to $25 per cubic yard and bulk topsoil at $10 to $50. That’s why you build the depth with fill and buy topsoil only for the top 4 to 6 inches.

What should I use to fill low spots in my lawn?

For a shallow dip, topsoil spread no more than 1/2 inch at a time and raked down between the grass blades, per Clemson’s Home and Garden Information Center. For a deeper hole or rut, University of Maryland Extension says to remove the sod, regrade the soil and replant.

Can I use sand to level my lawn?

Only if your native soil is sandy. Clemson’s Home and Garden Information Center says to topdress with topsoil instead on soil that isn’t sandy, so a clay or silt lawn should get topsoil.

Sources: Penn State Extension, Lawn Establishment; 2021 International Residential Code, R506.2.1 Fill; 2021 International Residential Code, R401.2 Requirements; 2021 International Residential Code, R401.3 Drainage; Ohio DOT Construction and Material Specifications (2008), Item 203 Roadway Excavation and Embankment; Pennsylvania DEP, Construction Waste (management as clean fill); Pennsylvania PUC, PA One Call – 811; 73 P.S. § 180(2.1), Underground Utility Line Protection Law (excavator duties); HomeGuide, Fill Dirt, Sand and Topsoil Delivery Cost; Angi, How Much Will Fill, Topsoil and Sand Cost (2024 data); Clemson Home and Garden Information Center, Topdressing a Home Lawn; University of Maryland Extension, Improving a Struggling Lawn and Repairing Damage

Written and reviewed by Thayne Muthler, owner of Muthler Landscaping & Construction. How we check facts: editorial policy.