The bulk plane is really a series of planes which limit the allowable volume of space the building can occupy. As with the height limitations, the bulk plane requirements are separated into limits for the front 65% of the lot and the rear 35%. The purpose of the bulk plane is to allow adjacent neighbors access to sunlight and to maintain privacy. Because of the sunlight requirement, the planes follow the length of the property and slope inward at a 45 degree angle. Typically the vertical leg is 17′ in front and 10′ in the rear and is horizontally located above the property line. The top plane is determined by the building height limitation. To learn more, see the bulk plane drawings in this section, page 13.1-16, and figure 13.1-21.

Because the bulk plane can cause acrimony between neighbors, especially in cases like ours with city infill projects, the measurement requirements are very detailed. The information below is spread over several chapter 13 pages.

1. Base plane .. The base plane is an imaginary horizontal bottom plane from which the vertical legs of the bulk planes are measured.
   1. The vertical position of the front base plane is determined by an average of the vertical spot elevations, shown on the survey, at the face of the house (not the porch) plane which intersects the property line.
   2. As an example, if the west spot elevation is 94.00 and the east spot elevation is 96.00, the front and back edges of the base plane are at elevation 95.00. The rear base plane is the same except that the vertical spot elevations are taken at the rear property corners. To learn more, see page 13.1-2.
2. Side wall height .. Depending on the chart shown on page 5.3-5, the side wall is typically 17′ in the front and 10′ in the rear. Page 13.1-16 shows some very specific rules of measurement, but 17′-10′ is ok for our purposes.
3. 3. Height .. The height of the bulk plane is shown on page 5.3-5 but for our purposes is typically 30′ in front and 17′ in the rear. See page 13.1-12 to learn more.

Please let me know if you have any questions regarding the above.

Allowable height is separated into limits for the front 65% of the lot and the rear 35%. Most Denver lots are 125′, so these limits apply to the front 81.25′ and the rear 43.75′. As generally stated in the zoning code, the purpose of this distinction is to provide privacy in the back yards of these houses. The allowable height in the rear of the lot is lower to restrict overlook views by adjacent neighbors.

The heights are stated in two ways:

1. Maximum allowable stories .. 2.5 stories for the front and 1 story for the rear.
   1. There is a huge amount of detail in chapter 13 but basically:
      1. The basement doesn’t count as a story unless it’s height from adjacent grade is fairly high.
      2. Likewise, a ½ story is rigidly defined.
      3. Experience shows it is possible to fit 2.5 stories in the front half of the lot, but ceiling heights can’t be over 8′-9′, the first floor must be reasonably close to grade, and the half story will have vaulted ceilings which need to start at 5′-6′ from the perimeter.
   2. A 2 ½ story house is inherently more economical per sf because the basement is smaller and a basement concrete foundation structure is more expensive than a frame structure. See the section on cost efficiency for more detail.
      1. Although a 2 ½ story house is more efficient from a cost viewpoint, it may not work the best for your life style. For instance, the upper level is separated from the second level. This means the bedrooms will be separated into two groups. Young children may need to be near the master and teenagers may need to be away from the master.
   3. For all these reasons, you may want a 2 story house instead. See the section on design efficiency for more detail.
   4. For that matter, you may want a 1 story house. See the section on design efficiency for more detail.
2. Allowable height in feet .. 30′ in the front and 17′ in the rear.
   1. This requirement is more straight forward than the 2 ½ story section, although they amount to the same thing.
   2. All the rationale above applies.

Please let me know if you have any questions regarding the above.

Normally, a survey is required when you are building a new construction project. A soil report is required when you are building a free-standing new construction project. A wastewater permit is needed for almost any building permit.

1. It only takes a week or two to get a wastewater permit, and the whole thing can be done on line.
   1. The main purpose of this permit is to determine if you need a new sewer line from your property to the main sewer line in the alley or the street.
   2. Normally it’s a good idea to replace an old sewer which runs under a new structure because, if you have to replace it later, you have to access the sewer line from inside your new building.
   3. If the sewer is not old or if you think it’s in good condition, you can have it “scooped”. This is a reasonably easy process where-in a company runs a camera down the sewer line to access its condition. Most of these companies will give you a written report which can locate any problems.
   4. If the existing sewer is outside your new structure, it may be unnecessary to replace it because you can always dig it up later.
   5. For almost all cases, it’s not required to dig the sewer inside the public street or alley because, again this can be done later and technically the sewer doesn’t belong to you. You shouldn’t decide to replace the sewer to the public way unless you can’t avoid it because, with construction and tap fees, this work can cost thousands.
   6. The permit is only $100 unless you have construction work.

Please let me know if you have any questions regarding the above.