Homes in Historic Districts are subject to rules and regulations not found in areas not designated as Historic Districts.
Check the building permit history on your home to see if there is any un-permitted work or open permits. Ignorance of un-permitted work is not an excuse. Do your best to educate yourself on your property to avoid any costly problems. If you are aware of the potential problems before close of escrow, you can negotiate with the seller.
If anything is newer but there is no permit or Certificate of Appropriateness (C of A) for the work, it may be problematic for you in the future. For example, if you purchase a home with vinyl windows that were installed without a permit or C of A, and you apply for a permit and C of A for an addition, it may be made a condition of approval for your addition that you replace the windows with a more appropriate type and that any new windows you propose be the appropriate type as well.
If replacement is necessary, it must be the same as what you are replacing (wood windows replaced with wood windows). Both a building permit and a Certificate of Appropriateness are required for any work in a Historic District.
Changes cannot be made to the front elevations of a home. Additions are subject to review by the Cultural Heritage Commission. Fees for reviews are charged based on the size and scope of the project. Sizes of additions must be compatible in scale and massing to surrounding properties. For example, if no other homes in the immediate area have a second story addition, you most likely will not be allowed to add a second story to your home.
Additions in excess of 50% of the original home are held to a higher scrutiny. Setbacks on properties are held to a higher standard as well, in order to maintain the massing on the lots. If your are considering purchasing a home in a Historic District with the plan of doing a large addition, check with Development Services and reference the California Heights Ordinance. You may not be able to do the project you want and it is better to know prior to purchasing the property. Knowledge is power, especially in this instance.
Hardscape must be appropriate to the architectural style of the home.