Commercial flat roof replacement options: EPDM / Reinforced EPDM vs. others

[Pradeep Ranganathan]

We recently purchased a 12-unit multifamily apartment complex, and the pre-purchase inspection revealed that the 80 ft. x 50 ft. roof needs immediate replacement. We're currently reviewing proposals for the roof replacement and are leaning towards an EPDM roof with insulation underneath. We've received quotes ranging from $30,000 to $75,000. The higher bids include creating a slight slope using varying thicknesses of insulation under the membrane.

We've encountered a few different options in the quotes:

Reinforced EPDM vs. 60 mil membrane: One roofer suggested reinforced EPDM for superior puncture resistance, while others argue that upgrading from a 45 mil to a 60 mil membrane is sufficient for occasional foot traffic (for inspections), falling debris, and hail.

Attachment methods: Some roofers propose mechanical attachment (especially for reinforced EPDM), while others prefer an adhesive method.

We're seeking advice from anyone with experience in EPDM roof installations. How should we navigate these different options? We're currently considering an adhesive install with a 60 mil membrane and insulation, but we're unsure if the price increase for reinforced EPDM is worthwhile.