HomeMy WebLinkAboutA020 - Motion directing staff on text amendments to Chapter 31 of the Ames Municipal Code Regarding Historic PreservationITEM #:21
DEPT:P&H
February 24, 2026
Staff Report
REQUEST FROM THE HISTORIC PRESERVATION COMMISSION REGARDING
WINDOWS AND INFILL OF OPENINGS
BACKGROUND:
On December 16, 2025, City Council referred to staff two zoning text amendment requests
from the Ames Historic Preservation Commission (HPC) (see Attachment). The requests
pertain to Double Pane Windows and Infill of Openings:
Double Pane Windows:
The first requested change includes explicitly stating that double pane windows are
allowed as an acceptable window type to increase energy efficiency of historic
structures and including definitions for Double Pane Windows, Multi-Pane Windows,
and Muntin Bar. Currently, Chapter 31 does not explicitly allow or disallow double pane
windows, nor are there added definitions for clarity when referencing window details.
The current regulations applied by staff focus on use of historic materials for windows
and do not address multi-pane window types. Staff's understanding is that the current
window design criteria and guidelines would still apply. However, the change would essentially
allow for double pane windows without consideration of the of the standard of repair of existing
versus replacement.
Staff researched the requested changes and provided the initial findings to the HPC in October
before the Commission formulated its recommendations. The communities that staff consulted
with, Iowa City and Dubuque, did not have historic preservation guideline language regarding
double pane windows; instead, they prioritized the retention and repair of original windows, as
well as non-invasive weatherization techniques to increase energy efficiency versus
replacement.
It is staff’s understanding that the HPC requests are not intended to alter the existing historic
requirements, but to allow increased energy efficiency when they otherwise meet the historic
material and profile requirements of an appropriate window. The structure, form and materials
should be sensitively treated to preserve the building’s character. Depending on how the
double pane window language is written, the priority of historic character vs. modern window
design will be defined.
Infill of Openings:
The second request is to amend Chapter 31 to provide clear guidance related to when,
or whether, to allow for the infill of window openings. An example of this issue would be
someone wanting to fill in a window as part of remodeling project of a room.
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The request to address this issue follows the Commission’s review of a Certificate of
Appropriateness where the Commission found that Chapter 31 does not provide standards or
guidance on window removal or infill to make an adequate decision. There was a mixed
history of whether to approve or deny such requests as precedence for the decision.
Before making this request, the HPC considered language from other cities, and believes that
addressing the issue directly would be appropriate to assist homeowners with understanding
what alterations would be permissible. The Commission requests to add specific window
infill language stating when window removal or infill is appropriate, as well as
specifying that any window infill must be architecturally consistent with the historical
structure.
Staff also reviewed language from Iowa City related to how infill of openings may be
permitted by the HPC and reviewed this with the HPC in October.
OPTIONS:
Option 1. Direct staff to prepare a Text Amendment to allow double pane windows in
historic districts as well as add and revise definitions to add clarity on Double Pane
Windows, Multi Pane Windows, and Muntin Bar.
Council could amend Chapter 31 to explicitly allow double pane windows and improve or add
definitions. During a text amendment process final language and guidance regarding how to
apply it would be developed.
Option 2. Direct staff to prepare a Text Amendment to add code language regarding the
removal and infill of windows.
This option would provide clear guidelines to Chapter 31 regarding the removal or infill of
windows. The HPC has reviewed several applications for window infill over the years and has
a mixed history of approving or denying applications. The request looks to provide language
that would provide a consistent approach and determination. During a text amendment
process final language and guidance on the removal or infill of windows with the limits of
meeting the historic materials and character defining feature requirements would be
developed.
The intent is to apply guidance allowing window infill to side and rear facades, but not front
facades. Infill could be approved on an historic side or rear façade if it met the guidelines.
Option 3. Direct staff to prepare a Text Amendment to allow double pane windows AND
address removal and infill of windows.
Council could amend Chapter 31 to allow the requested changes from both Option 1 and
Option 2.
Option 4. Make No Changes at This Time
If the Council is satisfied with City standards within Chapter 31, Historic Preservation Districts ,
or finds the requests to allow alterations that would negatively impact the historic district, no
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change is required.
Under this option, the Historic Preservation Commission will continue to review applications on
a case-by-case basis and only allow changes that will not be harmful to the historic character
of the district. Window changeouts would be subject to the current standards, and if they are
met could still allow for new double pane windows. Infill of openings is less clear regarding
whether it is permitted, but based on past practice it could be considered by the HPC without
well defined standards.
STAFF COMMENTS:
Enhanced energy efficiency and reviewing Chapter 31 are designated Historic Preservation
Commission tasks from its 2025 Work Plan. Through Commission research and applying the
existing guidelines when reviewing Certificate of Appropriateness applications, the HPC has
identified areas of desired improvement.
The existing guidelines do not explicitly disallow or allow double pane windows, nor do they
provide the Commission, or staff, with clear direction regarding window removal and infill. If
double pane windows were allowed, the added definitions would provide increased clarity
regarding the differing window features to ensure there is no confusion by the new term within
the code.
While increasing energy efficiency and identifying areas of improvement within the Code are
important goals of the Commission, all historic structure alteration shall maintain the existing
historic character whenever possible. However, staff has not found in its initial research that
allowing double-pane windows is a recommended alteration to a historic structure because it
may modify the original character. This issue will be subject to more review of language if the
text amendment is initiated.
The removal or infill of windows was allowed by other communities when specific criteria had
been met relating to the location of the window. The HPC informed staff that its intent is not to
provide guidelines or language that would directly conflict with the goal to preserve, but to
allow alterations that may help improve a structure when it is appropriate to do so.
A representative of the HPC will be present to discuss the proposal with the City Council at the
February 24 meeting.
If City Council decides to proceed with any text amendment, two steps must be
decided. The first is to decide what level of input from the public is necessary before
adopting new standards. As a text amendment, no specific public notice is required other
than a published newspaper notice. Staff believes that at a minimum, a mailing to all
properties in the Old Town Historic District prior to review by the HPC of final text would be
expected. Council could also direct that a neighborhood meeting be held prior to presenting
final text amendment language to the HPC.
The second issue is the timing of starting the text amendment process. Council will
have also seen the proposed HPC workplan for the upcoming year before making a
decision regarding this request. Council could determine to proceed with the text
amendment process in May, or wait to review it in relation to other P&H workplan priorities at
an upcoming Council meeting on April 14.
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ATTACHMENT(S):
2025-12-04 HPC Memorandum to City Council.pdf
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MEMORANDUM
TO: Ames City Council
FROM: Historic Preservation Commission
SUBJECT: Chapter 31 Revision Support
DATE: December 4, 2025
The Historic Preservation Commission (HPC) respectfully requests the City Council to authorize
the Planning and Housing Department staff to draft proposed revisions to Chapter 31 of the
Municipal Code relating to energy efficiency and window infill.
Energy Efficiency
As part of HPC’s 2025 Work Plan, we sought to review Chapter 31 and consider changes to
“allow exterior materials on historic structures that would meet the standards and be energy
efficient,” in accordance with Goal #3 of the Ames Comprehensive Historic Preservation Plan
(ACHPP). We created a subcommittee and identified potential revisions pertaining to energy
efficiency, outlined below.
Our proposed changes concern the explicit allowance of double-layer insulated glass (also
known as double-pane glass) for windows. While the code doesn't explicitly prohibit these items,
we believe the code should explicitly allow these items to eliminate any ambiguity. We propose
the following additions be made to Section 31.13(13):
● That double-layer insulated glazing is explicitly permitted in windows. An item (k) can
be added that reads as follows (or similar):
○ (k) Windows containing double-layer insulated glazing (also known as
double-pane glass) shall be permitted.
We note that the inclusion of "double-pane glass" in the suggestion above may create confusion
with the meaning of the word "pane," which is used throughout Section 31.14 to refer to the
glass in a window sash (see Section 31.14(1)(c)(vii) for a description of Colonial Revival
windows having a "multi-pane sash"). Because "multi-pane” and “double-pane” mean different
things, we want to provide clarity and consistency between the Design Guidelines and the
Design Criteria. We therefore propose the following changes:
● Revise the definition of “muntin bar” in Section 31.2(22) to be as follows (or similar):
○ Muntin Bar: a strip dividing a single window sash or casement into a grid system
of smaller panes of glass, called “lights” or “lites.”
● Add items (33) and (34) to Section 31.2 to provide definitions for “double-pane” and
“multi-pane” windows as follows (or similar):
○ (33) Double-Pane Windows: Windows containing two layers of glass, separated
by a space to reduce heat transfer and provide insulation (also known as
double-layer insulated glazing)
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○ (34) Multi-Pane Windows: Windows wherein a sash or casement is divided by
muntin bars into multiple panes or “lights,” creating a grid system of smaller
panes of glass
● Revise the description for windows under the Queen Anne Design Criteria in Section
31.14(1)(b)(vii) to be as follows (revision italicized):
○ (vii) Windows Vertical emphasis. Double hung. Window sash with single
undivided pane. Trim 4" to 6".
Window Infill
One of the duties of the HPC is to review Certificates of Appropriateness (COAs) for new
construction, alteration, demolition, or relocation of contributing structures in the Old Town
Historic Preservation District. In the past year, we encountered a COA application for which
Chapter 31 provided inadequate direction. This COA concerned the removal and infill of a
window on a contributing structure, and we found that the code lacked any provisions to help
guide our decision.
It is for this reason that we are seeking Planning staff support to draft language pertaining to
window removal and infill. In our research, we found that the Iowa City Historic Preservation
Handbook provides guidelines for when a window is to be relocated or removed/infilled, and we
wish to establish similar language in the Ames Municipal Code.
It is possible that the revision could be a single line provision under “windows” in Section
31.13(13), but it is paramount that the infill of a removed window be consistent with the
architectural style, and we want to ensure that the language that is added is done thoughtfully
and thoroughly. The assistance we are requesting from staff may warrant a review of other
cities’ Historic Preservation code sections or discussions with their planning staff and HPCs to
understand how they handle such alterations.
With this in mind, we request that the City Council authorize adding the following to the Planning
and Housing Department’s work plan for 2026:
● Research Assistance: Review other cities’ historic preservation ordinances and
information available from the National Alliance of Preservation Commissions (or other
preservation organizations) that pertain to window removal and infill.
● Draft Sample Provision(s): Research and propose sample language from these
resources to use in drafting revisions to Section 31.13(13)
In summary, we believe that revising provisions in Chapter 31 to include energy efficient
materials and to address window removal and infill will improve the regulatory efficiency of the
historic preservation ordinance and provide residents with more clarity with respect to alterations
to their historic structures. With the help of City Planning staff, we hope to complete this project
by the end of calendar year 2026.
Thank you for your consideration and support.
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