Before you compare two lots, build a parcel evidence sheet
Two lots can have the same area and zoning label and still need very different investigations. One may have a clear boundary and an unresolved sewer connection. The other may have good utility records but a narrow access route. A useful first comparison records what supports each conclusion and what would change it.
Start with one sheet per property. Put the parcel number and jurisdiction at the top, then work through the questions below. Leave an unresolved field blank or mark it unknown. Giving it a plausible number makes the comparison harder to correct later.
Match the records to the land
Save the parcel number, county, address, and the date you looked them up. Check that the selected outline is the property you mean to investigate. If an address returns several parcels, keep them separate until you know which land belongs in the proposal.
Record the permitting jurisdiction explicitly. King County's own property research guidance starts with jurisdiction and zoning, and directs its permitting research toward land outside city limits. A parcel's presence in a county database is not enough to choose the applicable city or county standards.
Keep the reported lot area next to its source. If a listing, assessor record and survey show different areas, record the disagreement. Do not average them. The useful question is which area the proposed calculation is meant to use.
Write down the proposal before reading the limits
“What can I build?” becomes easier to investigate when it has a first sketch behind it. For example:
Keep the existing house and investigate one detached dwelling at the rear. Assume access along the east side. Existing house dimensions and the access width still need confirmation.
That is a hypothetical proposal, not a statement that this arrangement is allowed. It identifies the questions a zoning label cannot answer on its own: whether the housing form is available, how the existing house counts, which setbacks apply, and whether the intended access can work.
Record each important rule with a link and section number. Keep the rule separate from the fact that makes it apply. A conditional allowance needs evidence for its condition; copying the larger number alone loses that requirement.
Use a worksheet that leads to an action
| Question | Record to keep | Next action if unresolved |
|---|---|---|
| Which land is included? | Parcel IDs, jurisdiction and selected outline | Resolve mismatched parcels or boundaries before combining areas. |
| Which rules apply to the proposal? | Zoning designation, overlays, cited sections and relevant dates | Ask the jurisdiction a question about the specific housing form and condition. |
| What space can the proposal use? | Dimensions, retained buildings and the source of each measurement | Have the needed boundaries and site features measured. |
| What could affect placement? | Relevant hazard, water, tree or other mapped evidence, with layer names | Identify the site investigation or record needed for the particular uncertainty. |
| How would people and services reach it? | Proposed access, utility provider and available records | Ask the provider or appropriate reviewer about that connection or route. |
| What recorded rights need review? | Relevant title documents, surveys and easement references | Ask the title professional and surveyor how they affect this layout. |
This is a working research sheet. Add a row when the proposal introduces another material question. For an existing house, that might be the dimensions of an addition. For a sloping site, it might be the location and height of a retaining wall.
Decide what to investigate next
Consider two hypothetical properties. Both have enough apparent open space for the first sketch. On Lot A, the proposed building sits close to a mapped parcel line. On Lot B, the building location has room, but the intended sewer connection is unconfirmed.
For Lot A, refining interior room sizes would leave the central uncertainty untouched. The next useful evidence concerns the boundary and the space beside it. For Lot B, a provider response about the proposed connection may change the layout more than another round of floor-area arithmetic.
Write the question narrowly: “Can this proposed connection serve the rear building?” is easier to resolve than “Are utilities available?” Attach the parcel ID and sketch, and record who answered, when, and what their answer actually covers. An unanswered question stays open.
Carry the evidence into design
Before handing the sheet to a designer, make sure every major assumption can be traced to a record, a measurement, or a named open question. Include the original links and any conflicting figures. A screenshot without a layer name or date is difficult to revisit.
LotFactor can help assemble available parcel facts, mapped evidence and supported scenario estimates. Keep the source references alongside the result, then use this worksheet to decide which questions need a record check, site measurement or professional response.
For a numerical example of how area limits interact, read FAR, lot coverage, and the footprint that actually fits. If a layer returns nothing, use How to read a blank constraint map before marking that question closed.
Sources checked . The worksheet and property examples are illustrative; they do not describe an actual LotFactor customer or a permit decision.