False Promises: High Density will reduce Housing Cost

This page contains something very unusual in the planning field:
REAL DATA from REAL PROJECTS.
From: AFFORDABLE HOUSING COST STUDY, An Analysis of Housing Development Costs In Portland, Oregon, December 1997:

Over the last year and a half, the authors have gathered and analyzed housing cost information on nearly 70 housing projects built in the last four years. The projects range in size from single-family homes to multi-family projects of some 200 units. Staff interviewed developers and public officials, and conducted site visits to recently completed projects. The understanding we have gained and the results of our analysis are presented in this paper, and some of the principal findings are summarized below. The following figures represent total development costs, not just construction costs.

• The cost of developing housing, when measured per person housed or per square foot built, is lowest for single family residences. The cost is slightly higher for townhouses or small plexes, and increases significantly for multi-family and mixed-use developments.

• If housing development costs are calculated on a per-unit basis, on the other hand, multi-family projects are the most cost effective. Unit costs are lower because the majority of multi-family units are small studio or one-bedroom units.

Cost of Housing: All Developer Types

Single Family Plexes Multi Family Mixed Use
Per Person

$17,961

$20,407

$28,377

$31,488

Per Sq. Foot

$74

$77

$91

$96

• Housing development costs rise dramatically as building height and housing density increase.

Building Cost by Height & Density

HEIGHT

D E N S I T Y

FRAMING # of Stories Per SF Units per Acre Per SF
Wood

2 Story

$67

0-20

$62

3 Story

$85

21-50

$81

4-5 Story

$99

51-100

$95

Concrete

5-7 Story

$139

101-200

$104

200+ $125

Study Commissioned by Portland's Metro: We need higher land prices

If the public sector wants the private sector to build more densely it must do something to affect demand and supply conditions so that land prices increase...
from  (page 8) of  metrourbancentersreport.pdf  1.3meg PDF
 

Cost Premiums of High Density - Data from portland's Metro

Here is actual data from Portland's Metro, the regional planning agency

Metro Planning Department Slide

Calculating costs

$2,900,000 cost premium for 81 units

Premium per unit: $35,802

Premium per SqFt: $24.73

(Premium per unit=2.9e6/81=35,802)
(Total SqFt=12.9e6/110=117,273)
(Premium Per SqFt=2.9e6/117,273=24.73)

(54.7 units/acre)

$1,360,000 cost premium for 97 units

Premium per unit: $14,020

Premium per SqFt: $11.95

(Premium per unit=1.36e6/97=14,020)
(Total SqFt=14.8e6/130=113,846)
(Premium Per SqFt=1.36e6/113,846=25.47)

(51 units/acre)