The reason for this assumption stems from the fact that frequently the two terms are cited with the opposite meaning. Normally, the under shelves do not have a particular finish, (I honed it sandblasted) as being placed at a certain height would not be appreciable.
Are often painted in tone with the other decorative elements.
The realization of concrete under shelves provides for the formation of a mold, (negative or matrix), from which can then derive the finished piece (positive).
The price of each individual under a shelf in cement therefore depends largely on the number of pieces to produce, but also by the presence or absence of “curls” undercut or decorations such as leaves and various convoluted that complicate the realization of the mold.
The under shelves concrete cheapest among those exposed are indicated by the code MEN 001-003-005-007-008-011.
Often under shelves in cement have a single decorative function, in these cases may also be applied after laying the balcony.
Other times may be structural support to the shelf above it, in these cases a large part of the shelf under the concrete is incorporated into the wall.