Run Buildable Area Analysis

This page walks through the steps to run the Buildable Area Analysis on all parcels on a project.

The Buildable Area Analysis can only be run on parcels/site boundaries that have been saved to a project. Don't have parcels saved to the project yet? Add them via one of these methods first.

Open the Buildable Area Analysis form

  • From a project, go to the Parcels tab

  • Click the See Actions button

  • Select Project Tasks

  • Select Project Buildable Area Analysis

This will bring up the Buildable Area Analysis form.

Apply desired hazard settings

In the Buildable Area Analysis form, toggle on the desired hazard settings for analysis, input hazard parameters (e.g. max slope %), and customize setbacks. Save time in the future by saving a template.

Skip any settings that aren't relevant.

Parcel Boundary Setback

Apply an internal setback from the parcel boundary line to ensure that you're not building right up to the edge of a property (follow local municipal guidelines for exact setback distance).

  • Input parcel boundary setback (commonly about 25-50 ft)

Slope

Automatically analyze high slope areas and mark as 'not buildable'.

  • Toggle on the Slope setting

  • Input a max slope %. (Anything above that slope % will be marked as not being buildable due to high slope; 10% is a fairly common cutoff).

  • (Optional) Input desired setback

Flood

Automatically analyze known 100-year, 500-year, and regulatory flood zones.

  • Toggle on Flood setting

  • (Optional) Input desired setback for each flood zone

Can you build on 500-year flood zone? If so, uncheck the checkbox on the right-side of that 500-year flood setting.This will display known 500-year flood zones on the constraint map but will still consider the area 'buildable'.

Wetlands

Automatically analyze wetlands on the property and mark them as hazards.

  • Toggle on Wetlands setting

  • (Optional) Input desired setback for wetlands

Trees

Automatically analyze areas with tree cover as 'not buildable'. This step analyzes 30mx30m tiles for tree cover density of each tile. Only tiles within a parcel that exceed the tree density % (as set below) will be marked as not buildable due to tree cover.

  • Toggle on Trees

  • Adjust tree density threshold, if desired

  • (Optional) Input desired setback for wetlands

If the project is in an area where land with heavy tree cover is still usable, then skip this setting.

Bedrock Depth

Automatically analyze and flag areas with shallow bedrock as hazards.

  • Toggle on Bedrock setting

  • Input minimum bedrock depth (ft.)

  • (Optional) Input desired setback for bedrock

Infrastructure

Automatically mark roads, buildings, transmission lines, railways, airport runways, and oil/gas wells as hazards and apply custom exclusion area setbacks around each.

  • Toggle on Infrastructure setting

  • (Optional) Input desired setback for wetlands

Critical Habitats

Automatically mark U.S. Fish & Wildlife designated Critical Habitats as hazards/exclusion areas.

  • Toggle on Critical Habitats setting

  • (Optional) Input desired setback for Critical Habitats

Public Lands

Automatically mark public/fee manager lands as hazards and apply desired setbacks.

  • Toggle on Public Lands setting

  • (Optional) Input desired setback for Public Lands

(Optional) Input advanced settings to configure final buildable area polygons requirements

Use these settings to help get a more realistic final calculated buildable acreage / constraint map. Input criteria to help filter out small, isolated sections that are too small for practical siting purposes.

Ex.: If a 1 acre section of a parcel was not in a hazard or a setback, then it would technically be marked as being 'buildable', but in practice, if that buildable area is not connected to a larger buildable section, it shouldn't count towards the total buildable acreage.

  • Scroll up to the top of the Buildable Area Analyis form

  • Click on the 2nd tab called Buildable Area Settings

Min Size Buildable Area

  • Input minimum contiguous buildable area size allowed

    • Depending on the size of the parcels on the project, it's best to set this much LOWER than the total desired acreage. Goal is to remove no-brainer sections that are too small -- not over-automate out sections that would still be usable.

    • Start with 2-3 acres for projects with smaller parcels; for projects with larger parcels, try starting with 5-10 acres.

Sliver Removal

Long skinny sections of buildable area (slivers) are often not a good fit for siting projects. Remove these 'slivers' of buildable area to get a more accurate final buildable acreage calculation.

  • Choose sliver removal setting level:

    • Regular - uses 40 m. in diameter circle to check for sliver width; anywhere that the circle doesn't fit will be marked as too small to be buildable)

    • Aggressive - uses 100 m. in diameter circle to check for sliver width; anywhere that the circle doesn't fit will be marked as too small to be buildable)

Run the analysis

Once desired inputs and settings have been configured, hit 'Run' at the bottom of the Buildable Area Analysis form to start running the analysis.

In the background, each of the layers will be reviewed, hazards analyzed, setbacks added and buildable area calculations run.

Track the progress of the buildable area analysis in the notifications on the project window:

No need to keep the project up while you're waiting for the analysis to finish processing! This task runs in the background even if you close the project window. Turn on the constraint maps when you reload the project: Map toolbar > Drawings > Load all drawings.

On the project map, the parcel constraint maps will load in as they complete.