10.125 Mandatory Landscape Requirements

(a) Single family and duplex uses (4/06 revisions).

(1) General. 
Except as provided in Section 51A-10.127, a lot containing a single family or duplex use established after May 29, 1994, must comply with this subsection before the final inspection of any building on the lot.  The lot must have at least three trees with a caliper equal to or exceeding two inches.  At least two of these trees must be located in the front yard.  The trees must be species listed in Section 51A-10.134(b).  The trees may be located in the public right-of-way if all private licensing requirements of the city code and charter are met.
  • Revise required trees for new single family and duplex uses to be based on zoning.  
  • Discussion:  The concept has been discussed of landscape tree requirements being based on lot types by zoning.  Example:

                                    (a)        R-1Ac(A) through R-10(A):  5 trees required (minimum 3 large)

                                    (b)        R -7.5(A): 3 trees required (minimum 2 large trees) – at least two trees in front yard (CURRENT ORDINANCE)

                                    (c)        R-5(A):  2 trees required (minimum 2 large trees) – at least one tree in front yard

                                    (d)        D(A):  2 trees required (minimum 2 large trees) – at least one tree in front yard

                                    (e)        TH-1(A) through TH-3(A):  1 tree required (large or small species)

                                    (f)         CH:  1 tree required (large or small species)


Another possible consideration would be to require trees based on a percentage of canopy coverage.  Example:  A lot may require 38% canopy coverage.  Trees would be planted on the lot to meet this goal.


(2) Shared access development.

(A) Single family districts.  Shared access developments in single family districts must comply with the following requirements: 
(i) Three trees with a caliper equal to or exceeding two inches are required for each individual lot in the shared access development.  One of the three required trees per lot may be located on the individual lot, but at least two trees per individual lot must be located in the front yard of the shared access development, where all of the property in the shared access development is considered to be one lot ("shared trees").  
(ii) If there is more than one front yard to the shared access development, where all of the property in the shared access development is considered to be one lot, the shared trees must be evenly distributed within those front yards. 

(iii) The trees must be species listed in Section 51A-10.134(b).  The trees may be located in the public right-of-way if all private licensing requirements of the city code and charter are met.

(B) Districts other than single family districts.  Shared access developments in districts other than single family districts must comply with the following requirements:

(i) A minimum of 20 percent of the shared access development must be designated as landscape area.  Permeable pavement does not count as landscape area.

(ii) One site tree must be provided for every 4,000 square feet within the shared access development.  Every site tree must have a planting area of at least 25 square feet.  The trunk of any site tree must be located at least two-and-one-half feet from any pavement.  Site trees must be species listed in Section 51A-10.134.  

(iii) In addition to any site trees, one large canopy street tree must be provided for every 25 feet of street frontage, excluding shared access points, with a minimum of two street trees required.  Street trees may be located within the front yard or parkway if all private licensing requirements of the city code and charter are met.  In this subparagraph, parkway means the portion of a street right-of-way between the projected street curb and the front lot line or corner side lot line.  If the director determines that a large canopy tree would interfere with utility lines, a substitute street tree from a species listed in Section 51A-10.134 may be provided.

  • Discussion:  'Districts other than single family districts' was created in the 2003 amendments.  It is the only portion of Article X that requires a percentage landscape area for a development.  It also established the standard to allow the building official to permit a change of tree size and species when a tree is placed in conflict with a utility.  



(b)     Other uses.  Lots containing a use other than single family or duplex must comply with the following requirements:
See List of Arborist Recommended Shrubs for specific uses.


          (1)     Perimeter landscape buffer strip.  A landscape buffer strip must be provided along the entire length of the portion of the perimeter of the lot where a residential adjacency exists, exclusive of driveways and accessways at points of ingress and egress to and from the lot. The buffer strip must be at least 10 feet wide, except that:
               (A)     any portion of the buffer strip adjacent to public street frontage need not exceed 10 percent of the lot depth; and
               (B)     any portion of the buffer strip in the front yard and adjacent to the side lot line need not exceed 10 percent of the lot width.
  • Revise to allow the building official the authority to approve an alternative plan when a landscape buffer strip is in conflict with utilities or other site restrictions.
  • Discussion:  The perimeter landscape buffer is a carryover of the original Chapter 51 Article X.  It establishes a 'cushion' between non-residential uses from the residential districts.  The buffer for the rear yard is always a minimum of 10 feet wide.  A reduction of the buffer to 10% of the lot width can be established to a buffer strip adjacent to the side lot line that is also in the front yard.  The rest of the side yard is 10 feet.  Example:  A 60'-wide lot would only require a 6'-wide (10%) buffer on each side with adjacency IN THE FRONT YARD.  The buffer would expand from 6' to 10' in the side yard and around to the rear yard. When a screening fence (zoning) is required, the plant buffer group planting requirement is reduced to the taller trees.  When there is no screening required, additional plant group options are provided in (b)(7).
 
Mandatory 10' wide buffer separating the non-residential use from the residential adjacency.  The plant buffer group is one large canopy tree due to the presence of the zoning required screening fence. If there was no fence requirement, the buffer group would be changed in this case to one large canopy tree and one large non-canopy tree (see below). 


         (2)     Screening of off-street loading spaces.
               (A)     All off-street loading spaces on a lot with residential adjacency must be screened from that residential adjacency.
               (B)     In all districts except CS and industrial districts, all off-street loading spaces on a lot must be screened from all public streets adjacent to that lot.
               (C)     The screening required under Subparagraphs (A) and (B) must be at least six feet in height measured from the horizontal plane passing through the nearest point of the off-street loading space and may be provided by using any of the methods for providing screening described in Section 51A-4.602(b)(3).


        (3)     Site trees.  
               (A)     One tree having a caliper of at least two inches must be provided for each 4,000 square feet of lot area, or fraction thereof, with a minimum of four trees being provided, except for industrial uses in IM and IR districts, where one tree having a caliper of at least two inches must be provided for each 6,000 square feet of lot area, or fraction thereof, with a minimum of four trees being provided. 
               (B)     Existing trees that are determined by the building official to be healthy may be used to satisfy the site tree requirement, in accordance with the tree credit chart below:

CALIPER OF RETAINED TREE                          NUMBER OF SITE TREES CREDIT /RETAINED TREES
Less than 2 inches                               0
2 inches or more but less than 8 inches               1
8 inches or more but less than 14 inches                       2
14 inches or more but less than 20 inches               4
20 inches or more but less than 26 inches               8
26 inches or more and less than 32 inches               10
32 inches or more but less than 38 inches               18
38 inches or more                                     20

  • Revise to require all site trees must be located at least 4 feet from any pavement
  • Discussion:  In order to quantify all appropriate trees on the property for landscaping, protected or otherwise, it is suggested, by ordinance, to count existing trees that are not protected by species to be allowed as one site tree credit, as approved by the building official, and only if the tree is not an invasive tree. Any tree considered as a site tree must be fully protected under 51A-10.136 and identified on a landscape submission.  Trees not identified on a landscape plan will not be counted.  The tree must also conform to the standards and guidelines for a healthy and safe tree listed in the Technical Manual in order to be counted.  See the Health and Safety Protocols attachment on this page.
  • Helpful Tools:  Area Calculator Using A Map , City of Dallas Zoning Website , Dallas Central Appraisal District 

          (4)      Street trees.  
A large tree must be provided for each 50 feet of frontage, with a minimum of two trees being provided.  These trees must be located within 30 feet of the projected street curb.  The trees may be located in the public right-of-way provided that all private licensing requirements of the city code and charter are met.  For purposes of this paragraph, "projected street curb" means the future location of the street curb consistent with the city thoroughfare plan as determined by the director of public works and transportation.
  • Revise to allow the building official the authority to approve a substitute tree when a conflict with utilities exists.
  • Revise to allow the building official the authority to approve an alternative site location when a conflict with utilities exists.
  • Discussion:  Recommendation is to allow for the building official to approve an alternative location for street trees when in conflict with overhead or underground utilities. Also, it is suggested that a small tree size could be approved to avoid utility conflicts.   The conditions would be limited to reasons other than self-imposed restrictions.  Additional discussion had been to expand the tree planting zone to 50' from back of curb.  
  • Suggested Reading:  Tree Space Design, Structural Soil, Silva Cell Tree and Stormwater System, Rootwell

  
        (5)     Parking lot trees.
               (A)     No required parking space may be located more than 120 feet from the trunk of a large canopy tree.   No parking space in excess of required parking may be located more than 100 feet from the trunk of a large canopy tree, and the tree must be located in a landscape area of a minimum of 120 square feet.  Each tree required by this subparagraph must have a caliper of at least two inches and may not be planted closer than two and one-half feet to the paved portion of the parking lot.
               (B)     An industrial use in an IM or IR district need not comply with Subparagraph (A) if it provides at least one tree meeting the requirements for street trees in Paragraph (4) for each 25 feet of frontage.
Each required parking space must be within 120 feet radius of the trunks of large canopy trees on the lot.
  • Revise to require no parking space be located more than 50 feet from the trunk of a large canopy tree.  Parking lot trees must have a caliper of at least 3 inches.
  • Discussion:  The UFAC conditions recommend a 50' radius with minimum large canopy tree sizes of 3" caliper.  No paving could be within 4 feet of the tree. Typically, trees would be planted in planting corridors (perhaps along bioswales) rather than small islands.



          (6)     Minimum sizes.  Except as provided in Subsections (a), (b)(3), and (b)(5) of this section, plant materials used to satisfy the requirements of this division must comply with the following minimum size requirements at the time of installation:
               (A)     Large trees must have a minimum caliper of three inches, or a minimum height of six feet, depending on the standard measuring technique for the species.
               (B)     Small trees must have a minimum height of six feet.
               (C)     Large evergreen shrubs must have a minimum height of three feet.
For purposes of this paragraph, "height" is measured from the top of the root ball or, if the plant is in a container, from the soil level in the container.
  • Discussion:  Item 6(C) modifies the 'screening' requirement of 51A-4.602 to require the plant at three feet in height at time of planting.

          (7)     Buffer plant materials.
               (A)     If a fence with a buffer strip is required along any part of the perimeter of a lot, the buffer strip must contain either one large canopy tree or two large non-canopy trees at a minimum average density of one large canopy tree or two large non-canopy trees for each 50 linear feet of the buffer strip, with new trees spaced no less than 25 feet apart.
               (B)      In all other cases, a landscape buffer strip provided to comply with this section or Section 51A-10.126 must contain one of the following groups of plant materials at a minimum average density of one group for each 50 linear feet of the buffer strip:
               (i)     One large canopy tree and one large non-canopy tree.
               (ii)     One large canopy tree and three small trees.
               (iii)     One large canopy tree and three large evergreen shrubs.
               (iv)     One large canopy tree, two small trees, and one large evergreen shrub.
               (v)     One large canopy tree, one small tree, and two large evergreen shrubs.
               (iv)     Two large non-canopy trees.  (Ord. Nos. 19455; 19786; 20496; 22053; 24731; 25155)
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Philip Erwin,
Jul 26, 2011, 10:07 AM
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