Q. I’ve lived in my association for a few years, and I thought I understood the condo concept, but I’m confused about this issue: I have to have my front door lock replaced, and the powers that be are telling me that once it is replaced, I will get a bill for it. How can this be fair? I don’t own the door and I can’t take the lock with me when I leave. The association claims windows, doors, etc., to be our responsibility. What am I paying that monthly assessment for, if expenses like this aren’t covered?

                                           —Locked Up

A. “This is a good question. Unit owner and board responsibility for repairs and maintenance obligations are set forth in the condominium’s master deed and declaration of trust or bylaws. In general, without reading your condominium documents, unit owners are responsible to maintain and repair their units and the board is responsible to maintain and repair the condominium’s common elements,” says Michael W. Merrill, partner in the Merrill & McGeary law firm in Boston. “You indicate unit windows and doors in your condominium are unit owner responsibility which is fairly standard.

“Notwithstanding that unit windows and doors are unit owner responsibility for maintenance and repair, the exterior appearance of the windows and doors must be uniform in appearance and no changes to the windows and doors can be made without the approval of the board. I am not sure why your front door lock has to be changed, perhaps because it does not match the appearance of the other front door locks or because the condominium is replacing and rekeying the locks for security purposes? If so, in either case, the trustees would have the authority to require the installation of a new lock on your door. Since the new lock is a repair to a unit element, the cost of the repair is borne by the unit owner.

“Pursuant to the declaration of trust or bylaws of your condominium, your monthly common charges are to pay for common expenses and not for unit owner expenses. For that reason, the trustees will not pay the expense to install the new door lock from common funds.”