The Thompson House is a center-hall double-pile house, a common building plan in the Greek Revival style. Each floor has four rooms, two on either side with a center hall. The staircase ascends to the second story from the front of the hall. The ceilings and the floors of the rooms are board, and the walls are plaster. The ceilings differ in heights for the two floors. The ceilings are ten feet on the first floor, and nine feet on the second floor. The hand-planed ceiling planks are original to the house and have been preserved. The house has pine floors throughout. Each of the rooms, except the hallways, is accented by the location of a fireplace with a wooden mantel. The interior rooms are approximately eighteen by eighteen feet square.
The first floor contains a front and back hall, parlor (northeast room), the northwest room, and two rear rooms. The front hall and two front rooms possess more high style Greek Revival trim.
The two southern rooms and the second story are decorated with less ornate vernacular interpretations of the Greek Revival. The trim in the front rooms and the hall is fluted and raised, and the remainder of the house has plain cornerblock trim. The parlor has a six-inch chair rail with cap and plaster wainscoting similar to the downstairs hall and staircase. The parlor mantel is the most ornate, with a fluted surround and fluted end blocks. The northwest room has deep baseboards with added trim at the top and paneled aprons under the windows. The mantels in the northwest room, and rear rooms all are simple post-and-lintel mantelpieces that are characteristic of the Greek Revival style. The mantels vary slightly in size of and the level of ornamentation. They all have raised triangular panel pilasters that are similar in design to urns.
All of the fireplaces on the first floor have soapstone fireboxes, which is a rare building material for houses of the area. The southwest room, used as a kitchen in recent years, has been altered by the addition of new counter tops and an island in the middle of the room. The southeast room has been divided by the addition of a laundry and bathroom.
Access to the second floor is from either an enclosed winder staircase in the parlor, or the primary open stringer staircase in the front hall. The first story balustrade is anchored with an octagonal chamfered newel post; a double octagonal chamfered newel posts sits at the top of the staircase. The balustrade consists of rectilinear balusters, and the open stringer has a wave pattern skirt board. The newel posts and balustrade are original and have been preserved. A closet is located under the staircase.
The second floor is very similar in layout to the first floor, with a central hall and two rooms to each side. As stated before, the second floor is trimmed in plain Greek Revival elements. The mantels are simple post-and-lintel mantelpieces, and the two in the rooms on the eastern side do not have soapstone fireboxes. The soapstone in the two fireboxes had been removed by prior owners in previous remodeling. The mantels are similar in design to the secondary Greek Revival-style mantels on the first floor. They lack the level of ornamentation as the first floor parlor mantel. The mantel in the northeast room has taller, Federal proportions, with a paneled frieze. The other three have raised triangular panel vertical supports that are similar in design to urns. The southeast room mantel has a shallow peaked frieze above the fireplace opening. The southwest room mantel has a shallow peaked panel set on the frieze below the shelf.
Two bathrooms have been added to this floor. One is in the southeast room and the other is between the two west rooms. The doors to the western rooms are original to the house and have corner-block surrounds. The doors to the east rooms are smaller and have plain surrounds. This indicates that the doorways were added later, maybe as late as the 1940s. At the south end of the hallway is a bathroom that appears from the architectural evidence to have always been a separate room. The original function of the room in unknown, but in the 1930s it was converted into a bathroom.
The millwork in the house exhibits Greek Revival style details. Architectural historian Howard
Major described the typical Greek-Revival interior as "marked by simple wall-surfaces with attention concentrated upon structural members and functional necessities, such as doorways, windows, fireplaces and the center-pieces of ceilings." The Thompson House's design elements are typical of this style. Baseboards downstairs are twelve inches tall and the profiles are typical
Greek-Revival: however, most public rooms have chair board and cornices, both of which are unusual for the Greek Revival period. They might be twentieth century additions. Both staircases have chair boards along one wall, and each of the downstairs rooms has a cornice and chair board. Chair boards are heavier in scale than the rest of the woodwork in the house (approximately a six-inch board with a cap). Cornices are cavetto or cyma reversa. Most of the interior doors are made of two vertical panels, which are slightly raised. Only the door to the closet below the staircase has flat panels. Set in the plaster in all the rooms and the halls are two inch wide beaded strips on at least one wall, some with projecting wood peg coat hooks.
Much of the interior's historic fabric remains intact. Of the eleven original doors in the house, nine remain. The two were replaced with more modem doors prior to the move. All the original doors are vertical two-panel pine doors. The five downstairs doors are larger and heavier with applied moldings because they are in the public space. The door between the parlor and the rear room retains its original lift latch hardware. The four original upstairs doors are simpler in design with no applied molding or planing on one side and a slightly raised, hand planed panel on the reverse. The original lock sets are on the two western room doors upstairs. The original dark finish appears on the inside of the second floor southwest room door. The finish also appears under some of the downstairs door hardware. Where additional doors were added and where original doors had been removed, they were replaced with similar pine, two-panel doors. Where no similar sized doors could be located, new doors have been made to replicate the original style.
Additionally, during the restoration, the craftsmen were able to save roughly fifty percent of the plaster. During the relocation, it was discovered that the vertical beams in the exterior walls of the house were marked with Roman numerals corresponding to identical markings on the sills.
These marks have been retained. The primary changes were the repairs to the chimneys mentioned above, the conversion of the southwest room on the first floor into a kitchen and the creation of a bath at the top of the staircase on the second floor.