Residential zoning alone does not establish that a planned home can be permitted, reached and served. For small builders, land investors and agents, buildable lot due diligence means checking whether access rights, site constraints, wastewater options, utilities and recorded restrictions can accommodate the proposed home. Those conditions need to work together on the same parcel.

1. Confirm the parcel and proposed home

Obtain the deed, recorded subdivision plat and permit history. Ask planning staff whether the parcel is a legally recognized lot for development and whether your proposed home meets applicable use, setback, height and lot-coverage rules. Identify overlays, prior approval conditions and any discretionary approvals still needed.

Philadelphia’s development checklist, revised September 2019, illustrates why these reviews are separate: it distinguishes zoning, water/sewer connection review and building permits, and says zoning approval does not approve final driveway layout or design. This example is specific to Philadelphia; obtain your jurisdiction’s current checklist.

Use staff responses to identify the zoning and permitting path, recording which answers are preliminary guidance and which are formal decisions.

2. Verify access rights and recorded restrictions

A visible driveway does not establish your legal right to use every segment. Obtain a title commitment or preliminary title report and the underlying recorded access documents. Napa County’s landlocked-parcel guidance recommends a title report identifying deeded or court-ordered access rights.

Have a surveyor compare the described route with the driveway. Check which parcel benefits, permitted uses, width and maintenance obligations. Ask the road authority about entrance approval and the fire authority about emergency access; an easement alone does not answer those design questions.

Also obtain covenants, plat notes, conservation restrictions and utility easements. EPA’s property-review guidance explains that easements and restrictive covenants can limit intended use. Read their terms rather than relying on their labels in a title report.

3. Test the building envelope against all constraints

The building envelope is the portion of the lot where the proposed structure can fit after applying relevant constraints. Commission a concept site plan using surveyed boundaries and appropriate topographic information. Show the home, driveway, grading, drainage, utilities and wastewater facilities alongside applicable setbacks and easements.

Use flood and wetland records to identify questions that need further review:

• Flood records: Use FEMA’s Map Service Center to identify the effective map panel and date. Review applicable amendments, revisions and revalidations; FEMA’s map-search guidance explains how to find these records and distinguish effective, historic and preliminary products. For an August 8, 2026 assessment, retain products effective by that date and label pending changes separately.
• Flood risk: Ask the local floodplain administrator about development requirements, and investigate site drainage. A mapped low-risk designation still carries flood risk.
• Wetlands: The National Wetlands Inventory mapper does not establish regulatory wetland boundaries or jurisdiction. Ask the relevant agencies whether field delineation, buffers or permits are needed.

Hypothetical example: Assume a lot’s front setback pushes the house rearward, a utility easement occupies one side, and a wetland buffer and septic area constrain the rear. Each might appear manageable separately; together they could leave no suitable home-and-driveway layout. Resolve their locations on one plan before accepting the proposed envelope.

4. Establish septic feasibility beyond a soil map

For a proposed septic system, start with USDA’s Web Soil Survey to identify potential limitations. The agency explains that soil map units can contain multiple component soils, with information collected at varying map scales. A mapped suitability rating does not establish conditions at the proposed drainfield.

Obtain the site evaluation and wastewater approval required by the responsible authority. EPA says septic permits come from local permitting authorities; system selection depends on soil, slope, lot size, home size or occupancy, regulations and budget.

Confirm that the approved design capacity fits the planned home, locate any required replacement area, and check approval expiration or transfer conditions. For an alternative system, request installation and ongoing operating costs. Be explicit about whether the evidence is preliminary testing, design approval or permission to install.

5. Get utility capacity, connection terms and costs in writing

A nearby utility line does not establish that your project can connect on acceptable terms. Seattle Public Utilities’ construction guidance illustrates why: projects can require main extensions, and preliminary charge estimates are distinct from final invoiced charges.

For water, sewer and electricity, request a response tied to the parcel and proposed demand. Ask for the connection point, available capacity, required extensions or upgrades, easements, fees, owner-paid work and expected service date. Identify conditions and expiration dates, and ask whether any capacity is actually reserved.

For a private well, ask the responsible authority what permits and evidence of yield and water quality are needed. Carry service work and remaining uncertainty into the site and construction cost budget.

6. Make unresolved evidence a purchase contingency

Set an acceptable project cost and schedule before committing to a land purchase. Negotiate contingencies around specific deliverables:

• Satisfactory title, access and restriction review.
• A concept layout resolving survey and environmental constraints.
• Acceptable wastewater approval and water-supply evidence.
• Written utility requirements and a supportable site-work estimate.
• Required approvals, or a clearly documented remaining approval process.

Specify investigation access, deadlines, document delivery, extension provisions and termination rights with a local real-estate attorney. Use qualified survey, engineering and wastewater professionals for technical findings.

For a purchase priced on near-term construction, a useful decision threshold is whether every material unresolved item has a responsible party, a feasible resolution and a budgeted cost. If an item lacks those, seek more investigation time or evaluate the land as speculative.