Torch down is not actually rubber. It is bitumin.

If you want a permanent roof use EPDM membrane.
It can be glued down or balasted, or even secured with flaps on the back side.
For smaller areas try Resource Conservation Technology, Baltimore, MD.
They can supply a turn key kit with all the materials and a factory seamed roof that uses hidden flaps at the seams to hold everything down.
Life span is at least 30 years.

Are they all speaking about the same roofing material?
Ron

I have an EPDM flat room on my garage - in MN. It lasted about 25 years. It does have a cedar deck over it - deck as in patio/deck - so it's protected from UV, etc. We had it replaced and the estimates varied widely - some were twice as much as others. I ended up having one of the less expensive people do the work and I think they did a good job - other than not being all that attentive to the details of putting the deck back on. I was just thankful to find someone who would do the whole thing - pull the deck off, replace the flat roof, put the deck back on.

The time had come to re-roof my condo and this is what I chose after getting bids and doing research about flat roofs.

Here is a link that might be useful: SPF foam roof