Give contractors the same work question and compare scope, investigation, junctions and exclusions. Comparing final totals alone is insufficient when the proposed work does not include the same components or address the same uncertainty.
Which starting points should be shared beforehand?
Prepare one short starting-point list identifying the roof area, reason for the work and available information. Distinguish established facts from matters still requiring investigation. Photographs, old drawings and repair records help when their relationship to the roof is clear. An estimated surface area should be labelled as an estimate.
Do not give one contractor a complete dossier and another only a photograph if you intend to compare their proposals meaningfully. Different input can produce different assumptions. You do not need to write a technical specification yourself; the aim is to give each assessor the same question and the same known limitations before they develop their own assessment.
Which components should be identifiable in each proposal?
Ask for a description of preparation, any removal, the proposed assembly and connections to retained components. Outlets, upstands, penetrations and edge finishing should not disappear behind a generic “roofing work” line. Identify which existing components will remain and which assessment supports that assumption.
Access and protection may also belong within the instruction. Ask which arrangements the contractor will organise and which decisions or agreements the client must provide. A quotation need not list every tool, but it should be sufficiently clear to establish later which result and work boundary were agreed. This clarity matters more than the number of pages in the document.
How should provisional items and unknown construction be handled?
Unknown components should remain visible as uncertainties. Ask what happens if investigation reveals a different assembly from the one anticipated. Who assesses the consequence, how is it recorded and when do you approve additional work? That process deserves attention before work begins, not only after a surprise appears.
Compare proposals together with their qualifications. A shorter list of exclusions may look attractive, but it does not prove uncertainties have disappeared. Replace vague wording with a concrete boundary or decision question. For an owners’ association, also identify who is authorised to consider a change within or beyond the original decision, rather than leaving that responsibility to whoever happens to be present.
What should be retained after comparison?
Keep the original proposals, clarifications and final choice together. Record why a method or work boundary was selected and which points still need confirmation before execution. A telephone explanation becomes transferable only when the relevant agreement is also identifiable in a written record.
Connect the selected scope to the handover information you expect. This might include photographs of important junctions and a description of departures from the proposal. Comparison then leads into a usable final dossier rather than ending with an isolated purchase decision. The local planner can structure starting points, but it does not assess quotations or choose an automatic winner based on price.
Worth asking
Frequently asked questions
Must every quotation be the same length?
No. Compare coverage and clarity, not page count. A concise proposal can still define precise work boundaries.
Do unknown components mean nothing can proceed?
Not necessarily. A separate investigation can be a sensible first instruction before selecting the work.
Does the planner calculate quotation amounts?
No. It organises the roof situation and open questions without pricing or technical ranking.