One of the most distinctive - and defining - characteristics of early 20th century residential architecture in Chicago and a paragon, local sign or epitome of domesticality is the sunroom. These rooms are either at the front or back of a residential building, however, in this post we are going to address the front, as the rear sunroom is actually often just an enclosed back porch. They occur all the way from bungalows to high rises (though it may takes some sleuthing to determine this).
They were even noted at the time of construction as being noteworthy in the national, serious, architectural press. "Special attention should be called to the extensive use of the run parlor, sometimes taking the whole end of a room, or being added to the front and covering portions of the living room and dining room" (1) was written about the apartment houses of this area. Many apartment buildings have these "sun parlors" throughout the city, and without further ado, here are some examples.
Here is an earlier red brick example with colonial inspired brickwork, Dutch Colonial, in fact, with windows in the living room on either side of the sunroom. The brickwork is also heavily accented with varied soldier courses and rowlock courses along with limestone trim. The eyebrows above the first floor windows are particularly distinctive.
Next we have a similar version, also in red brick, but with the sunrooms pushed to the outside of the front of the building. This example is rather chaste, comparatively, when one looks at the previous example. The detailing, however, is quite typical of Chicago, with craftsman or prairie overtones. Even though this building has a symmetrical elevation, the plan becomes off center, with two different unit plans, one apartment will gain an extra bedroom (or larger living room or den) at the front.
Next up we have what is pretty much the prototypical Chicago apartment building; deep, dark reddish brick, sunrooms, sparing limestone trim with heavy brick ornamentation, metal cornicing and a symmetrical layout. This example is also exceptionally well maintained. It also have a nice "gable" above the front entry. A word, a quick note, should be said at this time about orientation. One would think that the sunroom would and should face south, if it could. But, as the if implies, this isn't always possible with the Chicago grid, though the majority of buildings face either east or west by virtue of the bulk of the city blocks being oriented north and south, but buildings, and hence, their sunrooms, can also face north.
Next we move on to another type of sunroom, the chamfered or "bay" sunroom. This generally called an 'octagon' in bungalow terminology, but I think that this would be more typically correct in a three-flat which is closer to a a bungalow (a close relative to be sure, planwise). This is a nice example of a fairly plainly decorated building which shows the chamfers very nicely. In this case, the lack of additional windows on the facade indicated that the sunroom and living room "run together" or really are one large, bayed room. The center windows indicate a front, rather than internal staircase as well.
Here is another, nearly identical example, except in a butter yellow brick, which also has slightly more exuberant decoration, such as the arched parapet wall, brick trim and stone 'quoins' below the first floor window sill.
Rather unusually there is an arched window at the upper stair landing; these are not terribly common in Chicago. Both likely in that they don't fit craftsman traditions to some extent, but more likely because of cost. Remember, most of these buildings were built speculatively for investors, either live-in or absentee, so cost was an issue, then as now, as would have been speed of construction, which was much longer then than now.
(1) The Architectural Forum, December 1919, "The Apartment Building for Moderate Rentals, Part II", Elisha Harris Janes, P. 194