Freeze the basis of comparison
A quotation for an earlier design and one for a revised layout are not competing prices for the same job. Record the drawing number, revision and date sent to each contractor. If the design changes during pricing, issue the change consistently before comparing the responses.
Use a bill of quantities, or BOQ, to organise measurable work. A useful line item identifies the work, its quantity, its unit and the specification used for pricing. Separate an allowance from a measured quantity so they are not mistaken for equivalent commitments.
Look inside each line item
For stone work, for example, check the area being measured, material description, thickness, finish, edge treatment and installation scope. Ask whether preparation, wastage, transport or handling are included. Two identical-looking line totals can cover different work.
For joinery, distinguish the carcass, shutters, finish, hardware and installation. For lighting, establish whether the quote includes only fixtures or also wiring, controls and fitting. Use the same questions for every bidder.
Make uncertainty visible
Keep a comparison column for exclusions, provisional items and unanswered questions. A blank entry is an unresolved scope question, not a zero cost. Record the contractor's clarification against the relevant line rather than relying on a verbal understanding.
Compare the schedule and responsibilities too. Identify who supplies drawings, who confirms dimensions, and which selections have to be made before an order. A quote is easier to evaluate when its assumptions are explicit.
A simple comparison sheet
- Drawing revision and date of quotation.
- Item, specification, quantity and unit.
- Quoted rate and extended amount.
- Included work, exclusions and provisional allowances.
- Clarification received, responsible person and decision status.
Keep design changes separate
When a room, finish or quantity changes, record the changed scope alongside the previous version. That gives the project team a basis for discussing the impact. This guide does not provide market rates or approve a contractor's invoice.