Start with geometry and drainage
Roof slope, deck, drainage, transitions, rooftop equipment, ventilation, fire and wind requirements, and the existing assembly determine which systems are appropriate. A mixed-use or multifamily property may need both systems on different areas.
TPO scope questions
- Existing membrane and attachment method
- Deck and insulation condition
- Drainage, penetrations, curbs, edges, and transitions
- Membrane, reinforcement, attachment, flashing, and warranty requirements
- Tear-off, recover, moisture investigation, and disposal assumptions
Asphalt-shingle scope questions
- Required slope and underlayment
- Deck repairs and ventilation
- Ice-barrier, valley, wall, chimney, and penetration details
- Shingle system, accessories, fastening, and warranty requirements
- Flashing replacement versus reuse
Avoid generic cost-per-square-foot comparisons. Tear-off, wet insulation, deck repair, access, staging, drainage, details, and warranty scope can change project cost materially. Compare proposals against the same documented assembly and assumptions.
Plan transitions as their own details
Where low-slope and shingle roofs meet, the transition is often more important than either field material. Require drawings or clearly written details for membrane termination, step flashing, counterflashing, wall interfaces, drainage paths, and sequencing.
Use manufacturer documents for the exact system
Performance and warranty terms vary by product and assembly. Require bidders to identify current manufacturer specifications and verify that the proposed contractor, system, details, and inspections qualify for the offered warranty.
Need a mixed-roof condition record?
Document each roof area and transition before asking contractors to price the work.
Plan a Property Assessment