15-0227 v3.0/RurAL Cap Housing - Muldoon/Living Transect & FAR Question for Building Addition


Hello ILFI,

For our LBC project up here in Anchorage, Alaska, we would like to confirm:

  1. That we have considered ourselves in the correct Transect and
  2. That our FAR calculations are correct.

Project History/Background:

Currently on site, there is an existing building which consists of housing for low income families in the south end and an old depleted restaurant on the north end. This restaurant is not used, deemed structurally unsound. Our project is to demolish and recycle this north end of the building and replace it with new housing for low income families. This addition will be placed in the exact footprint of the existing restaurant. The old restaurant is two stories high; the new housing addition will be three stories high of housing units. The existing south end of the building will be left as is. There will be no upgrading or updating of any systems, no use of its systems, spaces or strucutre. Please refer to the attached plan for further details.

  1. Living Transect: We have decided that our project is located in an L4 General Urban Zone. The population of Anchorage consists of 291,826 residents. Our project is located on the Eastern most side of Anchorage at 207 Muldoon Road, Anchorage, Alaska 99504. Amongst the existing developments, one can find Auto Repair Shops, Clothing Alteration Shops, Mexican Food Restaurants, Hardware Stores, Pancake Houses, Gas Stations, Pizza Restaurants, Post Office, local Paris Bakery & Cafe, RadioShack, along with many residential developments.
  2. The Project Area for our site has calculated out to be 83,296 sf (this is the entire property including disturbed areas of the site). This new addition will be three stories high totaling 21,000 sf. The existing south end of the building that will not be affected is 19,917 sf. Since we have the existing building on-site, that is not part of our addition project, we have some questions regarding the tabulation of our FAR. 

If we calculate the entire building area (existing and new addition) with the entire site area:

  • Total building area including addition and south end (aka site gross building) = 40,917 sf
  • Total Site area = 83,296 sf
  • 40,917 / 83,296 sf = 0.49; 30% of site to be Urban Ag
  • 30% x 83,296 = 24,988 sf to be Urban Ag


If we calculate just the new building area (excluding the existing building area) with the site area (excluding the existing building area) then we have the following:

  • 21,000 sf – new addition
  • 63,379 sf – site area (excluding the existing building area)
  • 21,000 / 63,379 = .33
  • 0.33 FAR would require 30% Urban Ag (like above)
  • 30% x 63,379 = 19,014sf to be Urban Ag


However, if we use (or can we use?) the Proportional Floor Area Ratio (FAR), then I assume the following calculation:

  • 40,917 / 83,296 = 0.49 (FAR calculation for entire building and entire site)
  • 21,000 sf is the new bldg sf and that is (21,000 / 40,917 = 0.51) 51% of the Gross Building Area.
  • 51% of the required Urban Ag (24,988 sf x 0.51) is 12,744 sf
  • Can we use this Proportional Floor Area Ratio (FAR)?

Thank you for your time and feedback. We are excited to hear back from you.


The Institute agrees that your project is located in Transect L4, General Urban Zone.

Your team may define a Project Area that is smaller than your site boundary, as long as the Project Area encompasses all areas disturbed by construction and utilities conveyance, and used for materials staging. See the Place Petal Handbook (PPH p5).

Once you have defined your Project Area that will clarify if the existing building factors into your FAR and Urban Agriculture calculation.  If the existing buildling is included in the Project Area, you may use the first proposed calculation (the entire new & existing building area) or the proportional calculation.  If the existing building is not in the Project Area, you should use the second calculation (only the new building area) for your FAR calculation. 

Post ID 2697

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