Square footage is only one cost driver. Demolition method, site access, structural changes, utility relocation, ceiling height, waterproofing, custom fabrication, finish level, protection, and the number of construction phases can matter more. Two kitchens with the same footprint can have very different costs if one keeps its layout and the other removes a bearing wall, relocates plumbing, upgrades electrical service, and requires new flooring through adjacent rooms. A responsible estimate describes those differences instead of relying on a broad cost-per-foot promise.
Allowances should be specific enough to guide shopping. Cabinets, counters, plumbing fixtures, tile, hardware, appliances, lighting, flooring, and glass should not disappear into one generic materials number. When a final selection exceeds or falls below its allowance, the reconciliation should be visible. Owner-supplied products also need a clear boundary: who verifies dimensions, receives the item, inspects damage, stores it, provides missing parts, and carries schedule risk if it arrives late?
Existing construction always carries some uncertainty. Walls can conceal damaged framing, nonstandard alterations, old wiring, abandoned plumbing, or previous water intrusion. The team should identify what can be investigated before pricing and what can only be confirmed after demolition. A change process should require a description, supporting photographs when useful, a price, and a schedule effect before added work proceeds whenever practical. Contingency then becomes a planned response to real uncertainty, not permission for vague billing.