Development Feasibility Analysis: FAR, Buildable Area, and Financial Viability for Architects

For an illustrative 1,000 m² site, 2,000 m² of counted floor area gives FAR 2.0. The controlling jurisdiction defines what floor area and lot area count. New York’s Zoning Handbook describes FAR in relation to the zoning lot; do not substitute gross internal area without checking the applicable definition. UK planning decisions do not generally reduce to one universal FAR table.

Draw height, access, servicing, setbacks and other applicable restrictions. Some constraints overlap or require interpretation; deducting their areas independently can double-count exclusions. A flood designation or heritage setting is not automatically a fixed no-build buffer. Record which boundaries are verified and which remain assumptions. A theoretical floor-area allowance can exceed what the practical envelope accommodates.

The inspected FAR interface has a fallback with default ratio assumptions. The cost interface also has a rough-order estimate fallback using cost factors. Treat such results as scenarios, not evidence of a site’s permitted density or tender cost. Replace defaults with documented local controls and project-specific quantities, dates, specification, currency and cost advice.

An appraisal should distinguish land, construction, abnormal works, professional fees, contributions, finance, contingency and receipts. State whether values include tax and whether figures share a valuation date. Leasing receipts cannot simply be added as though they were a sale value. Ask the appropriate cost and valuation advisers to review the assumptions.

Compare lower and higher cost, revenue and delivery-duration scenarios. Record which assumption changes the decision. Do not trim required accessibility, amenity or safety provision simply to make the arithmetic close. A positive residual under assumptions is not a guarantee of funding or a viable completed project.