Renovation & construction
Unit mix: how many homes to build and of what type
The unit mix must reflect demand, planning constraints, floor efficiency and the price of each type; the maximum unit count is not always the best outcome.
Set the unit mix according to demand, planning restrictions, floor efficiency and the price of each type of home. Maximising the number of units does not necessarily produce the best outcome.
Treat the design decision as a testable hypothesis
Consider architecture alongside the market and cost. The scheme must fit within permitted development, serve a defined buyer and remain buildable within budget. An attractive plan without structural, engineering and commercial checks is still a sketch.
Compare each iteration with the brief: saleable area, shared space, vertical circulation, parking, accessibility, energy efficiency and operation. Check the economic effect against the full-budget structure. A change should proceed when the team documents its cost and benefit, not because a new drawing looks more persuasive.
Build scenarios around decisions
Base-case assumptions need evidence about the target buyer, depth of demand and efficiency of plans and common areas. A downside case changes a specific driver — volume, cost, time or access to capital — rather than applying one arbitrary reduction to profit. Density, accessibility and parking restrictions should trigger a recalculation.
If the programme lengthens, add financing costs, site management and possible shifts in sales. If area falls, recalculate revenue, unit types, common space and affected costs. Keep the causal relationship visible.
Set a condition for proceeding
Identify the next hard-to-reverse step — signing, issuing construction documents, ordering equipment or handing over to buyers — and the evidence needed before it. If the condition fails, follow a preselected alternative involving the product, price, contract, reserve or timetable. The related DNPI financing check provides direction, not a substitute for site-specific records.
An example without invented numbers
One information pack appears complete but does not establish the efficiency of the plans and common space. Another contains fewer presentation materials, yet primary documents support the buyer and demand assumptions and trace density, accessibility and parking constraints to cost and timing. Use the second in the base model; leave the first conditional on further proof.
Red flag: if all profit depends on a narrow buyer type, the product is too concentrated. Pause before the next commitment, obtain a targeted opinion and update the model. This does not automatically mean abandoning the scheme. A retention, guarantee or exit right must be negotiated in the contract; the team cannot create it unilaterally.
Brief the next design version
The architect records the selected option, rejected alternatives and effects on area and cost. The cost consultant and commercial team use the same plan version. If the buyer hypothesis or planning condition changes, revise the brief before issuing the next set of documents rather than rewriting past economics.
