Land Slope: How Steep Is Too Steep to Build On or Resell?

A parcel can look great in the listing photos and turn out to be a hillside. Slope decides where a house, a driveway, and a septic system can go, and that decides who will buy the land from you. Here is how to read it before you make an offer.

What Does Slope Mean on a Land Parcel?

Slope is how much the ground rises over a distance, written as a percent: rise divided by run, times 100.

If the ground climbs 10 feet over 100 feet of distance, that is a 10% slope. A 100% slope is a 45 degree angle, not a cliff. Most parcels are a mix: a flat spot near the road, a slope in the middle, maybe a ravine at the back. What matters is how much of the parcel is usable.

The ranges are slope math, not building rules. Your county sets the rules for building on steep ground.

How Do You Check the Slope of Land Before You Buy?

Use free topographic maps and the county GIS from your desk, then walk the land or get a survey if the deal depends on it.

1. Open a topographic map. The USGS National Map viewer shows contour lines. Lines close together mean steep ground; lines far apart mean flat ground.
2. Check the county GIS. Many counties publish contour or elevation layers with the parcel lines on top.
3. Draw an elevation profile. Mapping tools with an elevation profile let you trace a line across the parcel and see the rise and fall.
4. Find the building area. Mark the flattest spot near the access point. That is where a buyer will want the house, driveway, and septic.
5. Walk it or get a topo survey. Maps miss small drops, gullies, and rock. If your price depends on a building site, see it.

What Does Steep Land Do to Building, Septic, and Resale?

Steep ground costs more to build on, can limit septic, and shrinks the pool of buyers.

On a slope, a buyer pays for grading, retaining walls, and a longer driveway before the house goes up. Septic systems need a suitable spot too, so a steep parcel can run out of places for the drain field, which is why a perc test on the building area matters. Water also runs downhill, so the low end of a sloped parcel can stay wet. Check the wetlands and flood maps there.

Some buyers want slope: views, hunting land, and recreational tracts can sell fine on rolling or steep ground. Price the parcel on its usable acres and on who will actually buy it.

Do Lenders Lend on Steep Land?

We do when most of the parcel is usable. We pass when most of it is too steep to use.

We value land from comparable sales, with no appraisal, and steep or unusable sections lower our valuation. A parcel with good usable ground and a steep back section is fine. A parcel that is mostly too steep to build on or drive up is too hard to resell, so we pass on it, and you hear that on the first call. Our terms:

• $30,000 to $1,000,000, interest only, 14% on loans of $100,000 and up and 16% under $100,000, for 24 months
• Up to 65% of value (our own valuation, not an appraisal; closer to 50% of value in slower markets), never more than 80% of the price
• $600 closing fee, 2% exit fee at payoff, no points, no appraisal
• Business purpose loans to LLCs and corporations, on land of 2 acres or more

For the rest of what we check, see land loan requirements and how we value land without an appraisal.