This I think is a second or third time this has been asked/addressed in NY Times.

http://realestateqa.blogs.nytimes.com/2008/07/04/building-repair-project-affects-use-of-a-terrace/

http://realestateqa.blogs.nytimes.com/2008/05/28/if-a-terrace-is-unusable-is-the-rent-reduced/

I guess some of the residents are not happy about the repair project. If everyone wanted a rent reduction based on the unusability of their terrace/balconies, how would it work financially. It is a zero-sum game, the maintainence payment pay for the running of the co-op, it does not generate a profit for any owner.

Here is an idea, we can give a $100 rebate per month to every resident, and charge everyone $100 per month additional maintainence to cover it.

Do some people feel that the board in not moving fast enough, or the contractor not doing the work as fast as possible.

let's take it one step further.... if we're all entitled to use the common areas of the building and are being denied the use, then we can all get a $100 rebate each month and all be charged $100 a month to cover the additional maintenance......