Start with roof shape, slope and building use
Map steep and low-slope areas, valleys, dormers, walls, penetrations and additions before comparing products. A material suited to one simple plane may require different detailing at another part of the same building. Note occupied uses, attic configuration, access and whether appearance restrictions or strata approvals apply. This baseline keeps the conversation focused on the actual roof rather than a generic list of product advantages. Ask every bidder to state which areas and transitions their proposed system covers.
Ask complete questions about asphalt systems
For an asphalt proposal, record the exact product, underlayment, eave and valley protection, starter, ridge treatment, ventilation components and flashing approach. Confirm how existing layers are removed and how deck findings are handled. Product literature can describe coverage conditions, but it does not predict the life of a particular installation. Compare colour and profile only after the water-shedding layers, transition details and workmanship documentation are clear. Keep current manufacturer documents for the exact proposed line in the estimate file.
Examine metal profiles, fastening and transitions
Metal roofing is not one system. Ask whether the proposal is standing seam, exposed fastener or another profile, then request the fastening, trim and penetration details relevant to that system. Discuss snow movement, runoff concentration, expansion, corrosion compatibility and connections to gutters or lower roofs where they affect the property. Do not convert marketing language into a maintenance-free or lifetime promise. Compare substrate preparation, ventilation implications and repair access alongside the visible panels.
Treat low-slope areas as separate assemblies
Low-slope roofs and flat sections require their own membrane, drainage, flashing and penetration questions. Record the proposed membrane type, substrate preparation, insulation or cover-board scope, seam approach and treatment at parapets, drains and scuppers. Ask how trapped moisture or unsuitable existing material will be addressed if found. A small low-slope addition should not disappear inside a steep-roof price because its installation and drainage details can be materially different.
Compare maintenance and future repair access
Ask what routine observations and maintenance the proposed system expects, which components remain exposed to service and how future penetrations should be handled. Consider safe access to gutters, drains, rooftop equipment and transition points. BC Housing's maintenance guidance reinforces that roofs need ongoing observation rather than being forgotten after installation. Compare the availability of replacement components and the documentation needed for future service, without assuming that current product availability or coverage terms will remain unchanged indefinitely.
Normalize price, upgrades and warranty documents
Put each option into the same schedule: removal, deck allowances, membranes, flashings, ventilation, drainage coordination, protection, cleanup, taxes and closeout. List optional upgrades separately so a higher total does not look like the same scope at a different price. Request the actual product and workmanship documents that are being offered, note owner obligations and confirm who registers any coverage. Avoid summaries that promise outcomes not contained in the written terms.
Record why the selected system fits this property
Complete a short decision note linking the selected option to the roof geometry, known condition, transition details, maintenance plan, budget and unresolved risks. State which evidence came from site observation, which came from product literature and which questions still need confirmation. Include permit or authority checks where relevant to the final scope. This record is more useful than declaring one material universally best because it explains the property-specific trade-offs to future owners or decision-makers.