Site readiness: what an assumptions register should actually contain

Every early development model is built on assumptions. That is not a flaw; it is the nature of working before the facts exist. The failure is not making assumptions — it is losing track of which numbers are proven and which are still borrowed.

An assumptions register fixes that. It is a single maintained document that names each unproven input and states what would settle it.

The six fields that make a register useful

1. 01The assumption, written as a specific claim rather than a topic — not "utilities", but "12-inch water main in the adjacent right of way has capacity for the planned unit count".
2. 02Status: proven by document, partially supported, or unverified.
3. 03The evidence that would settle it — the exact document, letter, report or approval.
4. 04The responsible person, by name, inside your team or your consultant group.
5. 05The date it will be confirmed, tied to the decision it blocks.
6. 06The consequence if it is wrong, in cost, schedule or yield — and whether the contingency covers it.

What the register has to cover on a development site

• Control: the instrument, its deadlines, extension rights and assignment rights.
• Title: easements, access, setbacks, restrictions and anything that reduces buildable area.
• Zoning and approvals: the current classification, the path being relied on, and the real calendar for hearings and plats.
• Utilities: water, wastewater, power, gas and telecommunications capacity, the service provider, and who pays to extend.
• Physical site: survey, topography, geotechnical findings, floodplain, drainage and detention.
• Environmental: recognised environmental conditions, wetlands, tree and habitat constraints.
• Yield: units or square feet actually achievable after setbacks, detention, parking and open space.
• Cost: hard cost basis and its date, soft cost and fee schedule, impact and tap fees, offsite and infrastructure cost.
• Schedule: approval duration, procurement lead times, construction duration and seasonal constraints.
• Revenue: rent or price comparables, absorption, concessions and exit assumptions.
• Capital: loan terms being assumed, equity requirement, interest reserve and carry duration.

How to tell a real register from a disclaimer

A real register changes. Entries move from unverified to proven, dates get met or get moved with a reason, and consequences get priced. If a register has not changed since it was created, nobody is working it — and the assumptions have simply become the plan.

A second test: pick the three assumptions with the largest cost consequence and ask who owns each of them and what document settles them. If those answers are not immediate, the register exists on paper only.

Illustration only, not a Threefold engagement: a site model assumes detention can be handled on a corner of the parcel. Once topography and drainage are confirmed, detention takes land the unit count depended on. The assumption was reasonable; not tracking it as an assumption is what made it expensive.

Where the register belongs in the decision

Before you go non-refundable, the register should be the agenda for the decision meeting. Every unverified line with a consequence larger than the contingency is a reason to extend, to reprice, or to walk — and saying so early is far cheaper than saying it later.