Can you legally be fined by a condo association for not letting them in your house for an attic inspection?

Yes.

Read your governing documents to determine the association's process for accessing limited common areas -- such as your deck, your dedicated garage, your attic -- only accessible through your unit. Generally, notice is required unless in case of emergency, when no notice is required.

By refusing access, you hamper the association's ability to do its job, which is to protect, preserve and maintain the real estate assets that all owners own in common. Usually, this means roofs, exterior walls, doors, utility delivery systems behind the walls and so forth.

It is entirely appropriate that you pay a fine, because by denying access, you have cost all owners additional expenses to perform the work required.