Reprising this post because folks keep asking me about it via email, etc.

These thresholds fit a three story apartment building or mixed use building into the fire/life safety requirements of the International Building Code (IBC) and the accessibility requirements of the Fair Housing Act.

1. All ground floor units are accessible/adaptable (minimum one unit). 2. TYPE V wood frame construction with fire sprinklers. 3. When built with a single stair, upper stories are limited to four units each. (more than 4 units on a floor and two stair will be required separated by a rated corridor at least 1/2 the diagonal of the building floor plate in length --1/3 for buildings with fire sprinklers.) 4. 2nd floor units are limited in size to 125′ max. exiting distance from the furthest point inside the unit to the entry door. 5. 3rd floor units are limited in size to 125′ max. exiting distance from the furthest point inside the unit to the entry door. (3rd floor units can be two story units with internal stairs as long as the max. exiting distance of 125' is observed).

Code research and design by David Kim

A comment from Will Dowdy:

This is a good summary. It’s probably worth being explicit about that ground floor unit. If you don’t have a unit on the ground floor, the requirement for accessibility is shifted to the second floor of the building, which means that you’re stuck with an elevator. BIG problem. This design is an elegant solution.

It is important to understand the relative advantages a potential sites over other sites in the area, so here are some screening criteria for considering where to invest time and attention in a given city.

Where can you have the most impact while building a stable portfolio of income properties that will become more valuable with time, reinforcing their neighborhood? What projects present the best return on the inevitable brain damage and learning curve that doing this kind of work brings with it? What is the Return On Brain Damage (ROBD)? When it comes to picking sites and building types, Opportunity Cost is about trying to understand what else you could have done with your time, attention and other resources compared with committing to a particular piece of property. http://www.investopedia.com/terms/o/opportunitycost.asp

To be extra clear, I personally don't want to spend a minute pursuing numbers 4 - 6 when there are opportunities for 1 - 3 .

Which kind of building in what kind of location?

1.  Single story commercial, 2 and 3 story rental walk up mixed use and apartment buildings in locations with reasonable rents, and potential for catalytic upside and/or flywheel effect for the neighborhood.
2.  Two and Three story rental walk-up mixed use and apartment buildings in locations with reasonable rents, but no catalytic upside or flywheel effect.
3. Small houses and atypical building types for rent on infill parcels close to food and drink and transit (bungalow courts of small rental units and live/works are appealing to me).
4. Small houses, rowhouses, and live-works for sale.
5. Houses for sale in locations where appraisers will look to conventional subdivisions for comparable sales.
6. Multifamily in sprawling locations typical for conventional Garden Apartments

Here is a list for sorting sites that meet the first criteria for catalytic upside and potential flywheel. 

• Look for sites with the following:
• Proximity to Food and Drink.
• Your proposed buildings and site plan can be built as of right, with no discretionary approvals.
• Discretionary approvals needed, but room to build a brand and reputation as the preferred developer/builder.
• Chances for actually fixing the street on the horizon; public investment in correcting the streets looks sure to likely.

Watch out for Potential Deal Killers:

• Site constraints; topo, utilities.
• Proximity to a horrible big wide fast arterial street (Stroad).
• Level of Administrative Contamination; Excessive Minimum Parking, Fire Code Appendix D adopted.

Maybe we should construct a matrix for ranking sites, building types and tenure by their potential return on brain damage.