First establish a common basis for comparison
When several proposals arrive, check that they all use the same drawings, quantities and decisions. Record the date and revision used. If one quotation was prepared before a layout change, it should not be compared directly with another that already includes it.
Also define which parts of the work are settled and which still need investigation. An estimate based on assumptions can help move a project forward, provided those assumptions are identified. Problems arise when it is compared as though it were as fully defined as a detailed proposal.
Compare complete systems and intended results
In heating and cooling, the heat source is only one part of the system: distribution, emitters, insulation and controls all affect performance. The same applies to other trades. A list of brands or appliances does not, on its own, describe the installation the home will receive.
Prepare a table with one row per system and columns for its main elements. Mark what is included, excluded or awaiting clarification. Where an alternative is proposed, ask how it fits the project and what effect it has on the other work packages.
A checklist for each proposal
Use these questions to guide the comparison and request specific answers wherever the proposal leaves something unclear:
- Which items of equipment and accessories are identified, and by what model references or performance specifications?
- Which routes, quantities and distribution components have been allowed for?
- Are responsibilities assigned for power supplies, drains, controls and connections between systems?
- Are supports, insulation, penetrations, sealing and builders’ work included?
- Which tests, adjustments, operating explanations and documents form part of the handover?
Review exclusions and work that depends on others
An exclusion does not make a quotation unsuitable, but it must be included in the comparison. If another company will quote for that work, identify who will undertake it and on what basis. Leaving it unassigned makes it impossible to understand the actual overall scope.
Watch for phrases such as by the client, subject to site conditions or to be checked. Ask what information will allow the item to be defined and when it will be resolved. In refurbishment, concealed elements may need later inspection; that limitation should be described without pretending to have certainty that is not yet available.
Check the conditions for carrying out the work
Read the proposal alongside the construction sequence. Confirm which access routes, surfaces and services the installer needs to find available. Review how successive visits will be coordinated and what happens if a decision changes after work has been prepared or carried out.
Separate delivery lead time from the possible installation date and from commissioning. These are different milestones. Asking for that distinction helps you assess whether the proposal fits the builder’s programme and the project decisions still outstanding.
Resolve clarifications before awarding the work
Bring your questions together in a single document and keep the answers with each proposal. If a clarification changes the scope, request an updated version or an identifiable addendum. Avoid making the decision on the basis of scattered conversations that cannot later be linked to a particular item.
At Red Málaga, we define the scope by installation so it can be reviewed with the site team. A well-prepared comparison makes it clear what is being ordered and what remains outside the contract. The aim is a common basis, rather than a longer list of undefined items.
Check the units used in the quantities. An item priced per room may group together elements that another quotation lists separately. Before adding or excluding items, ask for an understandable comparison. This helps identify duplication and omissions without assuming that every formatting difference represents a real difference in service.
More common questions
Is the most detailed proposal always better?
Detail is useful when it describes a coherent scope that can be checked. You should also review assumptions, compatibility with the project and responsibility for connections and the final handover.
Sources and technical reading
Some source documents are available in Spanish.