Renovating an HDFC coop usually has the same or similar procedures as any coop. Board approval is required. Some structural changes may not be allowed and certain appliances like washer/dryer may not be allowed
A restriction may be the language in the flip tax. If a portion of the profit is paid to the coop upon sale/transfer of shares some HDFC coops define profit as the difference between price paid and gross profit.
Some coops may allow a deduction for capital improvement or renovation. Some HDFC coops encourage renovations. The flip tax is defined in the certificate of incorporation, bylaws or offering plan.