Start with one version of your plan
Give each supplier the same drawing and description, including external dimensions, doors, rooflight, facade and finishes. Add photographs of the house and access. Ask for deviations to be identified separately so alternatives do not quietly change your comparison.
Seven questions for a complete comparison
| Question | What to look for |
|---|---|
| 1. Which dimensions apply? | External dimensions, internal height and the same drawing revision. |
| 2. What do foundations include? | Investigation, foundation type and site-specific work. |
| 3. Who handles the opening? | Structural design, temporary works and making good. |
| 4. What does finished mean? | Specific flooring, wall, ceiling and service finishes. |
| 5. How are transport and crane arranged? | Access, setup and any additional costs. |
| 6. Which amounts may change? | Allowances, exclusions and rules for additional work. |
| 7. Who hands over and resolves defects? | A named party, handover list and aftercare agreements. |
Do not equate fixed prices with allowances
An allowance reserves money for work not fully defined. Ask what it is based on and how differences are settled. A low total with unclear allowances offers different certainty from a fully specified fixed price. Compare those differences before ranking totals.
Record changes before the work changes
Different doors or an extra socket can affect production, services or finishes. Before work, request a description, price and schedule impact. Keep the confirmed change with the quotation so the agreed result remains clear at handover.