Good question. If hot tubs are permitted at your association under the covenants, conditions & restrictions as a matter of course but the manufacturer of the new roof will not warrant its membrane if there is a hot tub upon it, the solution would be that you can have a hot tub on your roof but you waive any replacement costs paid by the homeowner's association for the roof as a common area maintence item for your particular unit.Meaning, if you are the unit's property owner, any future problems with the roof would be paid by you out of pocket and would not be covered under the warranty of the manufacturer of the roofing components. If you sell the unit, you need to disclose this fact to the new owner in writing before close of escrow.