HomeMy WebLinkAbout2005-10-17 Correspondence City of Iowa City
MEMORANDUM
Date: October 17, 2005
To: City Council
From: Karen Howard -Associate Planner
RE: Proposed Zoning Code -issues and questions raised at public hearings
Over the last several weeks Council members have requested the following
additional information regarding the proposed changes to the City's zoning code.
Lot Size and Zero Lot Line Options
The cost of land has a great influence on the cost of housing in a market. As
mentioned before, one of the ways that Iowa City can provide opportunities for lower
cost housing is to reduce the amount of land required for each dwelling unit.
Attached is a table that summarizes the zoning regulations in Iowa City, Coralville,
and North Liberty. These three cities comprise the "housing market" .for the greater
Iowa City 'area. As you can see from the table, in all instances for every type of
housing - single family homes, zero lot line dwellings, duplexes, townhouses, and
apartments - Iowa City allows smaller lot sizes, smaller lot widths, and higher
densities than Coralville or North Liberty. In addition, there are opportunities to mix
duplexes and zero lot lines within single family neighborhoods in Iowa City, while
duplexes and zero-lot lines are excluded from single family zones in Coralville and
North Liberty. With regard to apartments, Iowa City allows densities double that of
either of the neighboring cities.
A second point to remember is that most undeveloped land within Iowa citY's growth
boundary has not yet been zoned for development. In other words, developers have
the opportunity to request the zoning that they need to achieve the type of housing
that they wish to build. The attached list entitled, "What the proposed changes mean
for residential development in Iowa City," describes the wide variety of choices
available to builders in the new code. It is not that the Planning and Zoning
Commission dislikes certain house plans or designs, as suggested by the Land
Development Council, but rather that each house should be placed on an
appropriately sized lot in a manner that protects the shared spaces along
neighborhood streets, and provides room for street trees and on-street parking.
Cost of "Design Standards"
A third topic of discussion has been the "design standards" for duplexes and
townhouses and whether they will significantly increase the cost of these housing
types. The Council requested an estimate of the cost of providing trim around doors,
windows, and roof eaves; the cost of complying with the requirement that the front
October 17, 2005
Page 2
entrance be emphasized with one of the following: a canopy, transom and side light
windows, or a porch. Estimated cost per unit: approximately $40.00 per window or
door for trim; $600 - $2500 for the front entrance depending on the developer's
choice of front entry feature; and approximately $2 per linear foot for trim around the
eaves. There is no requirement for frieze boards. Attached is an illustration of a
new duplex recently constructed in Longfellow Manor for the Iowa City Housing.
Authority. This duplex exceeds the standards proposed in the new code.
According to Iowa City Housing Authority the cost of the trim on this duplex was
approximately $1050.00 per unit. The Longfellow duplex units each contain 3
bedrooms, 2-baths, and approximately 1,250 square of floor area. As mentioned
this building actually exceeds the proposed code requirements. The trim material
used is fiber cement board rather than vinyl, and the units also include frieze board
trim. The cost of the trim amounted to less than 1% (0.73%) of the total cost of
construction.
The experience of many non-profit housing developers is that providing a minimal
amount on design results in a positive return on investment, increased equity to
home owners, and helps these more affordable housing types blend into single
family neighborhoods. The attached article about Springfield, Missouri's affordable
housing design guidelines provides a case in point. If you would like more
information about the Springfield, Missouri program or other research on non-profit
housing providers, let us know and we can provide this information to you.
With regard to market-rate housing, these requirements will only add cost to the
units in cases where the market would not otherwise haVe.provided such design
elements. Trim around windows, doorways, and eaves, and front entry features are
fairly standard on most market-rate zero lot lines and townhouses.
Alley Bonus Options
A final item of discussion on cost is whether new allowances in the code for
narrower home lots will actually result in a cost savings if an alley is required. There
were complaints from the Land Development Council that our comparison of costs
was misleading because it made the comparison using the proposed minimum lot
widths rather the current lot widths. Therefore, we have redone the alley
comparisons accordingly and have also included information about the savings on
land cost that was not included last time. I used Steve Gordon's estimate that raw
land costs approximately $25,000 per acre. As you can see from this analysis,
taking advantage of the density bonus option by providing alleys results in lower
per lot cost in both the RS-5 and RS-12 Zones. The "bonus" in these examples is
very apparent. The cost per lot for providing alleys in the RS-8 example shows that
even when there is relatively small difference in lot width (45 feet versus 40 feet with
an alley), the addition of an alley only amounts to about $400 per lot in additional
cost once you take into account the savings on land and infrastructure. In the end,
the market will decide whether the savings on land and infrastructure costs, plus the
benefits of providing more room along the street for street trees, front yard
October 17, 2005
Page 3
landscaping, uninterrupted sidewalks, and on-street parking, is worth the cost of an
alley, because the bonus density provisions are just an option, not a
requirement.
The attached illustrations give an idea what a street frontage would be like with 30-
foot wide, 40-foot wide, and 45-foot wide single family home lots. Since we currently
do not allow single family homes on lots narrower than 45 feet wide and there are
currently very few single family homes built on lots 45 feet wide, the effects of
garage placement on these lots should be carefully considered. The effect of front-
loaded garages on the public street frontage is apparent in these illustrations. Once
lots get to about 55-feet to 60-feet wide, it is quite easy to fit 2-car, front-loaded
garages on the lot and still have room for street trees and on-street parking.
Insurance for nonconforming properties
The Council requested information regarding the cost of insuring non-conforming
properties, Based on information from insurance agents, standard insurance policies
include an allowance of 10 to 15% to cover additional costs (if any) for complying with
changes to codes. A property owner may purchase an additional endorsement if they
believe it is necessary.
The implication behind the remarks made at the public hearing about nonconformities
seems to be that we will be creating more nonconforming properties if the proposed
code is adopted. To the contrary, there are actually many ways that the Commission
tried to decrease nonconformities or create new flexibility for nonconforming properties.
For example:
· Single Family houses are never considered nonconforming uses.
· All existing conforming duplexes will remain conforming with the new code.
· With the new code reducing lot sizes and reducing minimum setbacks will likely
bring many older properties into compliance with the code.
· Since the proposed code reduces the number of parking spaces required for
many commercial uses, currently nonconforming commercial parking areas may
become conforming, making it easier for older commercial areas to
accommodate new businesses over time.
· New provisions were added to the code to create more flexibility and allowances
for non~;onforming situations.
Changing the density formulas for multi-family development
The Council has requested an analysis of the implications of Mark McCallum's
proposed changes to the density formulas for apartment development. He
proposes to increase the allowed density for properties that contain apartments
with 3 or fewer bedrooms. The consequences of changing the density formulas
for apartment development are likely to be far-reaching and will vary based on
the current mix of apartments in a particular area. We ran a quick computer
October 17, 2005
Page 4
listing of all rental apartments in the city. Of the more than 15,000 rental units in
the City, approximately 36% are 1-bedroom, 43% are 2-bedroom, 15% are 3-
bedroom, 4% are 4-bedroom, and 2% contain 5+ bedrooms. So, while there may
be some recent projects close to downtown that have included dorm-like 4- and
5-bedroom apartments, the data indicates that that these units are not very
prevalent in the City as a whole.
For areas that already have a preponderance of 1-, 2-, and 3-bedroom
apartments, the changes will encourage property owners to add apartments or
redevelop their properties with additional apartments, thus increasing the overall
number of people living in that particular area of the city. More analysis will need
to be done to figure out the apartment mix and distribution in specific areas of the
City. From that information we would be able to determine the consequences
(both intended and unintended) from proposed changes to the density formulas.
If the Council wishes to pursue this issue, staff suggests that you direct the
Planning and Zoning Commission to .conduct the necessary research and
analysis and solicit input from the public and interested stakeholders.
Bonus provisions for accessible apartments
The Council has indicated some interest in pursuing density bonuses for small
accessible apartments (less than 3-bedrooms). The PRM Zone already contains
bonus provisions for efficiency and 1-bedroom apartments. The areas zoned
PRM consist largely of new buildings that are required to have accessible units.
Unfortunately, the market has not responded to the bonus provisions for smaller
apartments, even though they have been in the code for a number of years.
Without further research, it is difficult to determine why these have not been
successful. With the proposed.increase in the parking requirements in the PRM
Zc~ne, we may see a change in the mix of apartment sizes. We can certainly add
similar provisions to other multi-family zones, but without further analysis, the
results may be disappointing. If the Council wishes to pursue this issue, staff
suggests .that further research be done to determine what kinds of bonuses will
be necessary to actually encourage additional accessible units and to determine
the potential impacts of these bonuses, similar to the issue above.
Summary of Zoning Regulations in the Greater Iowa City Area
Iowa City Iowa City Coralville North Liberty
(Proposed Zoning Code) (Current Zoning Code)
Min. Lot Size 3,000 sq ft Min. Lot Size 5,000 sq ft Min. Lot Size 5,000 sq ft Min. Lot 5,000 sq ft
Single Family Size
(Smallest Lot Allowed)
Min. Lot 30 feet Min. Lot Width 45 ft Min. lot width 50 ft Min. lot 60 ft
Width width
Duplexes, Zero Lot Lines & Duplexes allowed in all single Duplexes and zero lot lines Duplexes, zero lot lines, Duplexes, zero lot lines,
Townhouses family zones allowed in RS-8 & RS-12, but and townhouses are no__~t and townhouses are no___~t
(allowance in Single Family not in RS-5 allowed in single family allowed in single family
Zones) Zero Lot Lines allowed in all zones, zones
single family zones Townhouses allowed in
RS-8 and RS-12, but are
Townhouses allowed in RS- impractical to build due to
12 Zone required lot width
Min. Lot Size 3,000 sq. ft. Min. Lot Size 5,000 sq ft Min. Lot Size 3,000 sq ft
Townhouses No allowance for
(smallest lot allowed) Min. Lot 20 feet Min. Lot Width 45 feet Min. Lot 30 feet townhouses, unless built
Width Width as a multi-family
building.
Minimum lot size: 5,000 sq ft Minimum lot size: 5,000 sq ft Minimum lot size: Minimum lot size:
Multi-Family Residential 8,000 sq feet 21,780 sq ft
(highest density allowed) 1 unit per 875 sq ft of lot area 1 unit per 875 sq ft of lot area
(about 50 units per acre) (about 50 units per acre) 1 unit per 1800 sq ft of lot 1 unit per 2000 sq ft of
In CB-5 & CB-10 density only In CB-5 & CB-10 density only area lot area
limited by FAR limited by FAR (about 24 units, per acre) (about 22 units per acre)
What the proposed changes mean for residential development in Iowa City?
· In the RS-5 zone, if you want to build single family houses where the garage takes up more
than 50% of the width of the home, you must build them on lots at least 70 feet wide.
· Coralville: minimum lot width - 80 feet.
· North Liberty: minimum lot width - 70 feet
· Proposed Iowa City Code:
o If garage standard is met, allowed to build on lots as narrow as (~0 feet.
o If alley access is provided, allowed to build on lots as narrow as 50 feet.
· In the RS-8 zone, if you want to build single family houses where the garage takes up more
than 50% of the width of the home, you must build them on lots at least (~0 feet wide.
· Coralville: minimum lot width - 50 feet
· North Liberty: minimum lot width - 60 feet
· Proposed Iowa City Code:
o If garage standard is met, allowed to build on lots as narrow as 45 feet.
o If alley access is provided, allowed to build on lots as narrow as 40 feet.
· In the RS-12 Zone, if you want to build single family houses where the garage takes up
more than 50% of the width of the home, you must build them on lots at least 60 feet wide.
· Coralville does not have an equivalent zoning district.
· North Liberty does not have an equivalent zoning district.
· Proposed Iowa City Code:
o If garage standard is met, allowed to build on lots as narrow as 45 feet.
o If alley access is provided, allowed to build on lots as narrow as 30 feet.
· If~you want to build duplexes on interior lots (non-corner lots) in a single family zone, you
can build them in the RS-12 Zone.
· Coratville and North Liberty do not allow duplexes in any single family zone.
· If you want to build duplexes on corner lots in a single family zone, you can build them in the
RS-5, RS-8, and RS-12 Zones.
· Coralville and North Liberty do not allow duplexes in any single family zone.
· If you want to build duplexes or zero lot line dwellings you must put trim around the
windows, doors and roof eaves and must emphasize the front entrance with a canopy,
porch, or transom and sidelight windows.
· If you want to build townhouses, you must put trim around the windows, doors and roof
eaves and must emphasize the front entrance with a canopy, porch, or transom and
sidelight windows. If four or more units are attached in a row, you must make some
distinction between the adjacent units to prevent monotony.
· Note townhouse development is not currently feasible without going through a
planned development rezoning process.
New allowances in the proposed zoning code that increase opportunities for affordable
housing:
If alley access is provided, · Single family homes are allowed on lots as narrow as 50 feet wide in the RS-5 Zone.
· Single family homes are allowed on lots as narrow as 40 feet wide in the RS-8 Zone.
· Single family homes are allowed on lots as narrow as 30 feet wide in the RS-12 Zone.
· Townhouses allowed on lots as small as 3,000 sq ft With lot widths as narrow as 20 feet.
· Duplexes allowed in the RS-5 Zone on corner lots.
Single family development that will be unaffected by the new zoning code:
· If you are building single family homes in the RS-5 Zone on lots 70 feet or greater in width,
you will be unaffected by the changes to the zoning code.
o 78% of new single family home lots platted in the last 10 years have been greater
than 70 feet in width.
· If you are building single family homes in the RS-8 Zone on lots 60 feet or greater in width,
you will be unaffected by the changes to the zoning code.
/T'~. WEST ELEW,.TION d:::z:zz!~::s::Zl_Z ....
"'-..L/ ',/¢-,'-o' ~ NORTH ELEVATION I
~, ROOF PLAN
;%'T". ',, TfPICAL WALL SECTION ""'LU/ ¢' ~o' /'5% EAST ELEVATION
D Evolution of Quality Affordable Housing Design:
The Springfield, Missouri Way
~ Across America, ¢omn~urlities are taking Ul) the d~al- to the character of the surrounding neighborhoods. The
,~- lenge of developing affordable housing. In some result has been affordable taousing units that clearly
~ instances, this has meant trading design aesthetics stand out from the crowd.., but for all the wrong
o Jar rapid construction arm lower costs. Places like reasons. Residenis cxt)ressed (:onccrn that these units
~ Springfield, Missouri have. taken a more balanced would lower their l)rol]erty values and increase rental
-, apt)roach by instituting design guidelines that cio a develol~rnent/renter l)Ol)ulation.
better iob of blending affordable housing inlo the
'-+ existing community aesthetic. In the process, they're Homes constu~cted
--' prior to the c~dop-
~ achieving a positive return on tt~eir investment tion of'design
through pride of ownership and increased equity, guidelines flo little
to promote inter-
Like many communities across America, Springfield, action between
with a population of over 150,000, is a HUD entitle- Dui/ding occupc~nt.s
ment recipient. Assisting Iow- to rnoderat¢-income and the surround-
families with housing needs is a significant part of the lng neighborhood,
City's Consolidated Plan. Programs developed in the
mid 198Os provide Iow to 0 percent interest-deferred
loans for the rehabilitation of existing owner-occupied
units, as well as for the rehabilitation of existing
affordable rental housing units and construction of
new affordable rental units.
Tt~ese activities target specific census tracts contain-
ing a high percentage of substandard housing stock
and Iow- to moderat¢~income residents. Springfield's
low-interest loan programs provide funding to address
the most essential deferred maintenance issues, while
meeting basic code compliance requirements and pro-
viding for decent, safe, and sanitary housing.
Because Springfield's affordable housing programs More recent design-driven homes incorporate elements, such as
front porches
have resulted in underutilized lots or dilapidated invit/n_q end engaging streetscape.
houses being rel}laced with new and rehabilitated
housing stock, they have traditionally enjoyed broad In the fall of 2002, the Springfield City Council
comrnunity support. The common perception has been responded by authorizing the use of basic design
that any new housing stock was good for the neigh- guidelines-the Residential Infill and Rehabilitation
borhood, regardless of how it looked. As Springfield Guideh'nes (ForSingle-Fomily and Duplex Development).
has evolved, so too have community expectations. The purl}OS¢ of these basic Guidelines is to promote
As more affordable housing units have been con- the rehabilitation and design of single-family residential
structed, an increasing number of residents t~ave come and duplex developments located within established
to question wiq¢tt~er these Lll'~itS are truly a benefit to neighborhoods in a manner that's compatible with
tt~¢ community as a whole. Many of the questions being surroundin§ sinflie-family housing styles, and to
asked are based on the relative quality of design in promote specific design elements that are beneficial
comparison to other single- and multi-family homes in to the health of affected neighborhoods.
the area. In an effort to meet the objective of provid- Since implementing the Guidelines, the City has con-
ing affordable housing, the City's loan programs were tinued to use its Iow-interest loan programs to fund
funding infill rental housing that was often inexpensive, several owner-occupied rehabilitation projects and
contemporary in style, cheap to build, and insensitive the construction of new rental housing units. These
continued on page 3
2
Evolution of Quality Affordable Housing Design
single-family and dui]lex projects incorporate tracli- and parcels for (re)development that are in close
tional designs that are compatible with the surround- proximity to City-funded affordable housing projects.
lng housing styles. In addition, the Guictelines reguire Further, citizens who previously called on a routine
the incorporation of clesign elements, such as front basis to complain about neighborhood conditions have
porches, thus promoting a streetscape that encourages now contacted City sLaff to thank them for remov-
pedestrian activity and interaction. At a recent open lng a blight and saving their neighborhood. Reneweci
house, responses fi'om neighbors, neighborhood orga- interest in infill development in distressed areas is
nizations, developers, and City Building Department now at an all-time high.
staff exceeded all expectations of acceptance. While For developers of affordable housing, the ClUeS-
not eliminating resistance altogether, use of the tions are always the same- how much will design
Guidelines has shrunk the NIMBY (Not In My Back requirements add to project costs, and why should
Yard) banner that's often raised in response to afford- they spend more if rent amounts stay the same? The
able housing down to the size of a postcard, preliminary results of Springfield's completed projects
During and following the construction of these new reveal that if design-related costs increase project
design-driven units, the City has received requests costs at all, they typically add no more than 2 to
from other developers interested in acquiring houses 3 percent to the overall cost. However, the earned
Evolution of Quality Affordable Housing Design
value in terms of increased property value and equity regardless of whether the properties are rented or
is approximately 5 percent over contemporary infill owner occupied. In addition, the sense of neighbor-
construction styles, providing an instant 2.5 percent hood pride associated with quality infill is something
(or better) gain in property equity. In addition, that only those directly affected by it are able to
tenants of these developments seem to be taking describe. Indeed, it is becoming increasingly common
nquch more pride in their housing, which equals for residents surrounding City-funded affordable
fewer associated overhead costs, housing projects to tell City staff that they are very
Springfield has found that there are many ways to proud of what is happening on "their" street, and
they often invite others to stop by for a look. And
measure design value. First, good design promotes
neighborhood unity through continued growth, while there has yet to be any hard data to support
Evolution of Quality Affordable Housing Design
Spriagfield's design subjective observation, surrounding property values
guidelines require may soon be on the rise. One thing that's obvious to
traditional building both the developers and owners who have first-hand
~ form to be maintained
during city-funded experience in the marriage of affordable and high
rehabilitation, as quality design is the renewed sense of pride in their
shown at left.
properties. It is not uncommon to hear developers
, say they are very proud to own affordable housin9
property funded through the City of Springfield's
Loan Programs, and to play an active role in making
NIMBYism a thing of the past. []
Here is the same home as F E B R U A R Y O~
it appeared prior to
rehabilitation.
Benefit/Cost Analysis for alley construction in new subdivisions
Comparison 1:RS-5 zone with and without alleys
Without alleys - minimum lot width 60 feet With Alleys - minimum lot width 50 feet
minimum lot size = 8,000 sq ft minimum lot size = 6,000 sq ft
Overall size = 550x240 = 132,000 sq fl = 3+ acres Overall size = 550x240 = 132,000 sq ft = 3+ acres
28 120 120 28 28 110 20 110 28
Total number of lots possible = 16 Total number of lots possible = 20
Street paving = 28'x(550' +240') = 22,120 sq ft Street paving = 28'x(550' +240') = 22,120 sq ft
Alley paving = 0 Alley paving = 16'x550' = 8,800 sq ft
Total paving = 22,120 sq ft Total paving = 30r920 sq ft
IPavin9 per lot = 1,382.50 sq ft I IPaving per lot = 1,546 sq ft J
Street cost = 2,458 x $25.69 = $63,140 Street cost: 2,458 x $2569 = $63,140
22,12Osq ft *lsq yd/9sq ft = 2458 sq yd 22,120sq ft *lsq yd/9sq ft = 2458 sq yd
Alley cost = 0 Alley cost = 978x$25.69 $25,125
8,80Osq ft*lsq yd/gsq ft = 978 sq yd
Sewer construction costs = $11,550 Sewer construction costs = $11,550
Water line extension costs = $8,250 Water tine extension costs = $8,250
Electricity extension costs = 0 Electricity extension costs = 0
Natural gas extension costs = 0 Natural gas extension costs = 0
Cable and media extension costs = Cable and media extension costs =
Total Infrastructure cost = $82 940 Total Infrastructure cost = $108~065
IInfrastructure cost per lot = $5,184 Ilnfrastructure cost per lot = $5,403t
Per lot alley cost = $1,256
Raw land cost for a 550x240 block= $75,240 Raw land cost = $75,240
Raw land cost for street ROW $.70(790' x 50') ~ $22,515 Raw land cost for street ROW $.70(790' x 50') $22,515
Total raw land cost = $97,755 Total raw land cost = $97,755
Number of lots = 16 Number of lots = 20
Raw land cost per lot = $6,110 Raw land cost per lot = $4,888
Land + infrastructure cost per lot = ' $ii,294 Land + infrastructure cost per lot = : $10;291
Paving per lot is equal to half the width of all streets plus half the width of the alley, multiplied by the width of the lot.
It does not incorporate paving for driveways.
All streets are 28' wide. All local streets are 7" thick. Alleys are paved 16' wide and 7" thick. Sanitary sewer
extensions are assumed to by 8". Water main extensions are assumed to be 6" PVC. Water and sewer extension
assumes one line per block.
Paving price was obtained from the average bidding contract data for the state of Iowa, 2003. Local streets average
$25.69/sq yard. Water and sewer extension prices are averages received from an area engineering company. Non-
compacted 8" sanitary sewer extensions average $21 per linear foot, while 6" water main extensions average
$15/foot. For a 550' long block, the costs are $11,550 for sewer and $8,250 for water.
Land cost is estimated at $25,000 per acre or about $0.57 per square foot.
Comparison 2:RS-8 zone with and without alleys
Without alleys- minimum lot width 45 feet With alleys - minimum lot width 40 feet
minimum lot size = 5,000 sq ft minimum lot size = 4,000 sq ft
Overall size = 550x240 = 132,000 sq ft = 3+ acres Overall size = 550x240 = 132,000 sq ft = 3+ acres
28 120 120 28 28 110 20 110 28
Total number of lots possible = 24 Total number of lots possible = 26
Street paving = 28'x(550' +240') = 22,120 sq ft Street paving = 28'x(550' +240') = 22,120 sq ft
Alley paving = 0 Alley paving = 16'x550' = 8,800 sq ft
Total paving = 22,120 sq ft Total paving = 30~920 sq ft
I Paving per lot = 922 sq. ft. I I Paving per lot = 1,189 sq ft I
Street cost = 2,458 x $25.69 = $63,140 Street cost = 2,458 x $25.69 = $63,140
22,12osq ft *lsq yd/9sq ff = 2458 sq yd 22,120sq fl *lsq yd/gsq ft = 2458 sq yd
Alley cost = $0 Alley cost = 978x$25.69 $25,125
8,8OOsq ft*lsq yd/9sq ff = 978 sq yd
Sewer construction costs = $11,550 Sewer construction costs = $11,550
Water line extension costs = $8,250 Water line extension costs = $8,250
Electricity extension costs = 0 Electricity extension costs = 0
Natural gas extension costs = 0 Natural gas extension costs = 0
Cable and media extension costs = Cable and media extension costs =
Total Infrastructure cost = $82,940 Total Infrastructure cost = $108 065
Ilnfrastructure cost per lot = $3~4561 Ilnfrastructure cost per lot = $4,156
Per lot alley cost = $966
Raw land cost = $75,240 Raw land cost = $75,240
Raw land cost for street ROW $.70(790' x 50') $22,515 Raw land cost for street ROW $.70(790' x 50') $22,515
Total raw land cost = $97,755 Total raw land cost = $97,755
Number of lots = 24 Number of lots = 26
Raw land cost per lot = $4,073 Raw land cost per lot = $3,760
Land + infrastructure cost per lot = i$~i$~9 Land + infrastructure cost per lot = $~i§~6
Paving per lot is equal to half the width of all streets plus half the width of the alley, multiplied by the width of the lot.
It does not incorporate paving for driveways.
All streets are 28' wide. All local streets are 7" thick. Alleys are paved 16' wide and 7" thick. Sanitary sewer
extensions are assumed to by 8". Water main extensions are assumed to be 6" PVC. Water and sewer extension
assumes one line per block.
Paving price was obtained from the average bidding contract data for the state of Iowa, 2003. Local streets average
$25.69/sq yard. Water and sewer extension prices are averages received from an area engineering company. Non-
compacted 8" sanitary sewer extensions average $21 per linear foot, while 6" water main extensions average
$15/foot.
Land cost is estimated at $25,000 per acre or about $0.57 per square foot.
Comparison 3:RS-12 zone with and without alleys
Without alleys- minimum lot width 45 feet With alleys - minimum lot width 30 feet
Overall size = 550x240 = 132,000 sq fl = 3+ acres Overall size = 550x240 = 132,000 sq ft = 3+ acres
28 120 120 28 28 110 20 110 28
Total number of lots possible = 24 Total number of lots possible = 36
Street paving = 28'x(550' +240') = 22,120 sq ft Street paving = 28'x(550' +240') = 22,120 sq ft
Alley paving = 0 Alley paving = 16'x550' = 8,800 sq ft
Total paving = 22,120 sq ft Total paving = 30,920 sq fl
IPaving per lot = 922 sq ft I IPaving per lot = 859 sq ft
Street cost = 2,458 x $25.69 = $63,140 Street cost = 2,458 x $25.69 = $63,140
22,120sq fl *lsq yd/gsq fl = 2458 sq yd 22.120sq fl *lsq yd/9sq fl = 2458 sq yd
Alley cost = $0 Alley cost = 978x$25.69 $25,125
8,800sq fl*lsq yd/9sq ft = 978 sq yd
Sewer construction costs = $11,550 Sewer construction costs = $11,550
Water line extension costs = $8,250 Water line extension costs = $8,250
Electricity extension costs = 0 Electricity extension costs = 0
Natural gas extension costs = 0 Natural gas extension costs = 0
Cable and media extension costs = Cable and media extension costs =
Total Infrastructure cost = $82,940 Total Infrastructure cost = $108,065
Ilnfrastructure cost per lot = $3,456J Ilnfrastructure cost per lot = $3,002J
Per lot alley cost = $698
Raw land cost = $75,240 Raw land cost = $75,240
Raw land cost for street ROW $.70(790' x 50') $22,515 Raw land cost for street ROW $.70(790' x 50') $22,515
Total raw land cost = , $97,755 Total raw land cost = $97,755
Number of lots = 24 Number of lots = 36
Raw land cost per lot = $4,073 Raw land cost per lot = $2,715
Land + infrastructure cost per lot = $7,529 Land + infrastructure cost per lot = $5,717
Paving per lot is equal to half the width of all streets plus half the width of the alley, multiplied by the width of the lot.
It does not incorporate paving for driveways.
All streets are 281 wide. All local streets are 7" thick. Alleys are paved 16' wide and 7" thick. Sanitary sewer
extensions are assumed to by 8". Water main extensions are assumed to be 6" PVC. Water and sewer extension
assumes one line per block.
Paving price was obtained from the average bidding contract data for the state of Iowa, 2003. Local streets average
$25.69/sq yard Water and sewer extension prices are averages received from an area engineering company. Non-
compacted 8" sanitary sewer extensions average $21 per linear foot, while 6" water main extensions average
$15/foot.
Land cost is estimated at $25,000 per acre or about $057 per square foot.
30' m,n. lot.
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40' min. Ioi;wi
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