The houses do not "have elements".
The signs on the cusp of the house determines the house's nature as to quality and element.
As you probably already know, houses are divided into quadratures and triads, which correspond to the qualities and elements of the signs.
Analogous to the qualities (modes) are the Angular, Suceedent and Cadent houses.
Corresponding to the elements the houses are grouped into triads, which are:
The 1st, 5th and 9th...."Fire Houses"
The 4th, 8th and 12th ..."Water Houses"
The 7th, 11th and 3rd..."Air Houses"
The 10th, 2nd and 6th..."Earth Houses"
The references to the elements are analogs. Houses are concerned with affairs, circumstances, events, the goings-on in your world. Signs are fields that color whatever is contained within them. Houses do not "have elements" per se, but have similarities, run in parallel (the triads) with the elements that correspond to the signs. Thus the Earth houses are primarily concerned with "earthly affairs"... work and profession, honor and notoriety, money and possessions, health of the physical organism... those things that sustain us and improve our position in the world. In this sense they are "Earthy".
We also have Fiery or Watery, Earthy or Airy planets, analogs of the elements...but, as with the houses, not the same.
If, for example, there were 5 planets in the Water Houses (4, 8, 12) we would expect some form of emphasis on the types of affairs symbolized by these houses. These affairs would come to prominence, be of vital interest in the life. You can see that two of the houses in this triad are "unfortunate" and the remaining house (4) is the Dark House, the tomb, the final outcome, the House of the Midnight Sun.
In my own chart there are 7 planets in Fixed signs and Suceedent houses. There are 6 planets in houses originating at the IC, the Water houses, and these planets are in the Air element. If we combine these factors according to whether they belong to house or sign, we find that the Suceedent Water house and the Fixed Air sign are preponderant. This says the 8th House, Aquarius. My 8th is populated by Sun, in Aquarius, and others...so the outstanding house and sign in the chart is the 8th - Aquarius. In this way we can find a focal point in the chart, if there is one -- not all charts provide this powerful type of pointing -- that tells us about the "overtone" of the life as well as pointing to house and sign that tend to produce key events and circumstances in the life.
The preponderant sign describes the coloration, the quality or nature of these events of 8th house nature.
At the same time this preponderance enhances the power of Saturn (or Uranus, or both...depending on how you use rulerships). The planet ruling a preponderant sign/house grows in influence in the whole life because that planet disposes the affairs indicated, which themselves play a preponderant role in the life. We are now aware of the important role played by Saturn, and thus when we examine his condition and aspects we understand what his function in the personality-life is.
