Three proposals for the same rubber roof can look nearly identical on the first page and be completely different underneath. The membrane, the insulation, the way seams are joined and what happens at the drains all affect how long the roof lasts. Asking the right questions up front makes the bids comparable and shows you who really understands your building.
Questions about the roofing system
Start with the materials. Ask what thickness of EPDM is proposed and why. Thicker sheets cost more but resist punctures and weathering better. Then ask how it will be attached:
- Fully adhered with bonding adhesive
- Mechanically fastened with plates and screws
- Ballasted with stone or pavers
Each method suits different buildings and wind exposures. Ask how seams will be spliced, whether primer and seam tape will be used, and how flashings around curbs, pipes and walls will be detailed. A good answer is specific, not vague. If a crew member cannot explain how they flash a drain or an inside corner, treat that as a warning sign rather than a minor detail.
It is also fair to ask whether they considered other membranes. Some low-slope roofs are better served by TPO or PVC sheets, for example over restaurants that vent grease onto the roof. A contractor who explains why rubber fits your building, rather than offering it by default, is thinking about your roof.
Questions about your building
The roof you see is only the top layer. Ask whether they plan to take core samples or run a moisture survey to find wet insulation. Ask how many existing layers are on the roof and whether a tear-off is needed. Find out how they will handle any ponding: tapered insulation, added drains, or crickets behind curbs.
When you talk with EPDM roofing contractors Minneapolis winters should come up too. Ask how they schedule around cold weather, what temperature limits apply to the adhesives they use, and how they protect an open roof if snow arrives mid-project.
Questions about paperwork
A clear written scope protects both sides. Make sure the proposal lists:
- Removal and disposal of old materials
- Insulation type and thickness
- Membrane brand, thickness and attachment method
- Flashing and edge metal details
- Cleanup and protection of landscaping or parking areas
Minneapolis requires a permit for reroofing, so ask who will pull it; check with the city if you are unsure what applies to your property. Request a certificate of insurance before work begins, and ask what manufacturer and workmanship warranties are offered, in writing, and whether the manufacturer warranty must be registered after installation.
Comparing the answers
Lay the proposals side by side and compare line by line. A lower price that leaves out insulation replacement or flashing work is not a real saving. Pay attention to who asked questions about your building, took measurements and explained trade-offs clearly.
The best choice is usually the one whose answers were most specific. That level of detail during the bid tends to carry through into the work on your roof.