Find the Best House Site on Your Wisconsin Land
A big wooded parcel, one house. Test every part of the property at once for slope, facing direction, winter sun, wetness and room for a pad, and see only the ground that passes them all.
Screen a property now
Select the parcel, pick the House site preset and run it. Matching ground turns green.
Open Find Matching Areas →Why one map at a time is not enough
A good house site is several things at once: gentle enough to build on without a tall retaining wall, facing the sun, out of the ground where water gathers, and big enough for the house, the garage and somewhere to turn a truck. A slope map shows the first, a sunlight map the second, a wetness map the third. Laying them over each other in your head is where site visits get wasted.
Find Matching Areas does the overlay for you. Every cell of the USGS 3DEP bare-earth model is tested against each condition, and a cell is green only when it passes every one.
The conditions
- Slope is at most… in degrees, from the terrain. Always on.
- It faces… north, east, south or west (each within 45° either side), or any way. Flat ground has no facing direction, so it only passes when any direction is allowed. Always on.
- Winter sun is at least… hours of direct sun on December 21, the shortest day, with shadows from terrain up to 1.86 mi away. Always on; set it to 0 to ignore sun.
- It isn't in the wettest… percent of the area, by the same topographic wetness index as the Wetness Map. Under More conditions.
- There's room for a square… of the width you set, with every cell inside it passing. A long thin strip can pass every other test and still have nowhere to put a house; this removes it. Under More conditions.
The presets
Start from one of these and change any number. They are sensible first guesses, not rules.
| Preset | Slope at most | Faces | Winter sun | Not in the wettest | Room for a square |
|---|---|---|---|---|---|
| House site | 12° | Any | 4 h or more | 20% | 60 ft |
| Solar panels | 20° | South | 5 h or more | Not tested | 15 ft |
| Orchard or vineyard | 15° | South | 4 h or more | 25% | 100 ft |
| Septic drainfield | 10° | Any | Not tested | 30% | 50 ft |
| Shed or shop | 5° | Any | Not tested | 20% | 30 ft |
Whatever the preset says, the slope your house can sit on depends on the foundation, the access and what your county requires. Ask your county planning department and your designer before you design to a number.
How to find a house site
- Select the property. Click the parcel, draw a box or polygon, or upload a boundary. Without a selection, Analyze this view uses the area on screen.
- Pick House site, or another preset, or set the three sentences yourself. Open More conditions for wetness and room to build.
- Choose Run analysis. Matching ground is green, everything else gray.
- Read What each condition leaves. It lists the ground remaining after each test in turn, in area and as a share. The condition that removes the most is highlighted: relax that one first if too little is left.
- Check the near misses. Tick Show ground that misses by one condition to color amber the ground that fails exactly one test.
- Use the best patch. Largest patches lists the five biggest matching patches. Use as area makes one of them the selected area for the next tool.
Then look at just that patch
Once a patch is the selected area, every tool runs on it alone.
A Wisconsin example
On a ridge-and-coulee parcel in the Driftless Area, around Blue Mounds or in the hills along the Kickapoo, the gentle ground is usually on the ridge tops and in the valley bottoms, with steep wooded sides between. The slope test alone keeps both. Add winter sun and the valley floor can drop out, because the valley walls shade it in December; add the wetness test and the low ground beside the creek goes too. What is left is often a few patches on the ridge tops and shoulders.
On flatter glacial ground, in the Kettle Moraine or across central Wisconsin, slope rarely rules much out. There the wetness test and room for a pad do most of the work, removing the kettles and low swales where water stands in spring.
What it cannot tell you
The result is terrain only. It does not know about zoning, shoreland rules, setbacks, access from the road, utilities, soils, septic suitability, flood hazard or ground stability. Check septic rules with your county sanitary department and Wisconsin DSPS, flood hazard on the FEMA flood maps, and the rest with your county planning department. Winter sun counts the shape of the land, not the trees on it.
About the data
Ground elevations come from the USGS 3D Elevation Program (3DEP) seamless bare-earth model, with elevations above NAVD 88. Source cells are 3.3 ft per pixel in the finest work units, with about 9.8 ft per pixel and 33 ft per pixel sources elsewhere. USGS elevation data is public domain. Lidar coverage and source dates vary across Wisconsin. Check your site against the USGS 3DEP work-unit index; an unavailable lookup means coverage is unknown. Areas up to 7.5 miles per side can be searched; larger areas are sampled more coarsely. More from the USGS 3D Elevation Program and Wisconsin elevation resources.
Frequently asked questions
How do I find the best place to build on my land?
Select the property, open Find Matching Areas and pick the House site preset. The tool tests every part of the parcel for slope, facing direction, winter sun, wetness and room for a square pad, and colors the ground that passes every test green. Those patches are the places worth walking first.
Are the preset numbers rules?
No. They are starting points, and the panel says so. Your county, your designer and the way you intend to build decide what slope and pad size actually work. Change any number after picking a preset.
Nothing came up green. What now?
Look at What each condition leaves. The condition that removes the most ground is highlighted; relax that one first. Turning on Show ground that misses by one condition colors amber the ground that fails only one test, which shows where a small change in a number gains the most.
Does it account for trees shading the site?
No. Winter sun is modeled on bare ground for December 21, with shadows from terrain up to 1.86 mi away. A patch behind a stand of pines can still show as sunny. Check the aerial basemap, or clear trees in your head before you trust a sunny result in the woods.
Does it check zoning, setbacks or septic suitability?
No. It is terrain only. Zoning, shoreland rules, setbacks, access, utilities, septic approval, flood hazard and ground stability are checked with the county and the right professionals. The tool finds the ground worth asking them about.
How big an area can I search?
Areas up to 7.5 miles per side. Larger areas are sampled more coarsely, so small pads can disappear; select a smaller area, such as one parcel, for detail.
Related guides
- Slope maps for building on sloping land — what the slope numbers mean for a site.
- Terrain checks before buying rural land — the full pre-offer pass.
- Find wet ground with the topographic wetness index — the wetness test on its own.