The costs included in the claim relate only to preservation or rehabilitation work done to any of the following: a.
(a)#
The exterior of the historic property.
(b)#
The interior of a window sash if work is done to the exterior of the window sash.
(c)#
Structural elements of the historic property.
(d)#
The heating or ventilating systems.
(e)#
Electrical or plumbing systems, but not electrical or plumbing fixtures.