Renovation of Terrace

I'm one of the Owner of a Stand Alone Apartment consisting of 9 Owners in Total...Our Apartment doesn't have any registered Flat Owners Association or any Official Committee.. We amongst ourselves created a Common Fund for maintaining the Apartment Expenses and we ourselves decide who will collect the fund etc.. I'm having my flat on the Top Floor and above that is the Terrace, and in my part of the Terrace there is always water logging especially in Monsoons... the other sides of the Terrace is quite good...The water logging in my part of the Terrace is seriously damaging my Flat...including all the Walls with severe damp issue and Furniture's as well electrical switches are getting damaged as well... I have informed all of the owners about this,, but there is no unity or cooperation....and they are not allowing me to take the money for the renovation from the Conmon fund as well as raising objection if I repair the terrace on my own also.... What legal steps can I take in this regard... Kindly let me know... Thank you