HomeMy WebLinkAbout07-03-25 Public Comment - E. Bonnett - Public Comment_ New UDC Plate Height DefinitionFrom:Erik Bonnett
To:Bozeman Public Comment
Subject:[EXTERNAL][Possible Scam Fraud]Public Comment: New UDC Plate Height Definition
Date:Thursday, July 3, 2025 2:22:37 PM
Attachments:ANALYSIS OF BOZEMAN UDC REVISED HEIGHT LIMITS - 250623.pdf
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This comment is addressed to Planning Staff and Members of the Community DevelopmentBoard.
Please see the attached letter and drawing file.
Thank you,
Erik Bonnett
Architect, AIAHe, Him, His
www.studiocohab.com
p. 651.336.0394
Staff and Community Development Board,
Thank you for your service to our city and work on improving the UDC to beƩer suit the needs
of our community.
During your June 2nd meeƟng, Staff made a presentaƟon on various mass and scale tools that
could be used in the new UDC. The presentaƟon included several 3D illustraƟons showing how
staff intends to implement and interpret Plate Height limits. In the public comment that
followed, I noted that the interpretaƟon of Plate Height as illustrated by staff was problemaƟc in
how it treated the variety of roof forms. The following pages illustrate those problems along
with a proposed soluƟon.
Plate height is not included in the DefiniƟons secƟon of the October 29th, 2024 public
engagement UDC draŌ. I strongly recommend including a definiƟon if you conƟnue to propose
using Plate Height instead of total Building Height to regulate mass and scale in the proposed R-
A and R-B zones.
Defining plate height is not straighƞorward. In common usage, plate height is where the wall
framing meets the roof framing or roof trusses. However, complexiƟes arise given many
residenƟal roof forms do not meet the ceiling at a uniform elevaƟon around the whole building.
For instance, ceilings oŌen slope. SomeƟmes a gable is asymmetrical, with one horizontal plate
higher than the other. Which point are we measuring from? And more importantly, what are the
implicaƟons of how we measure?
Staff appeared to interpret that plate height was measured from the lowest point on most roof
forms, but would be measured on the high side of a monopitch/shed roof. The result of doing so
would be that monopitch/shed roofs would be essenƟally unbuildable in 2-story configuraƟons.
The aƩached drawings show a 600 square foot ADU over a two car garage. That is essenƟally
the smallest 2-story structure likely to be built. Even with such a small structure, a shed roof –
measured to the high side – would exceed the 25’ plate height limit, and therefore not be
permiƩed. Meanwhile a gambrel or mansard roof atop a 25’ plate would be allowed to reach
40’ tall with a third story or perhaps more with an aƫc. This approach arbitrarily preferences
gambrel and mansard roof forms over other more common roof forms. In fact, a similar
loophole in regulaƟon is what led to the original development of mansard roof forms in Europe.
Instead, roof forms should be treated more uniformly, especially the most common
configuraƟons: gable, flat, and shed roofs.
To achieve uniform treatment of all roof forms, I suggest defining plate height as “the lowest
intersecƟon of the ceiling and wall on the second level in R-A and on the third level in R-B.”
Certain roof forms will be a bit higher than others in certain parts of a building, but overall the
results will be much more uniform and will not contain the same huge mansard loophole.
Though with any plate-based massing limit, mansard roofs will be the largest building form
allowed. It is also worth noƟng that this definiƟon for R-B assumes that the Community
Development Board and/or the City Commission will direct staff to restore the right to full 3-
story construcƟon in R-B in the new UDC, as is currently allowed under the current UDC.
Thank you for considering this feedback,
Erik BonneƩ, AIA
Gambrel Roof Height
40' -O"
Third Floor
25' -0"
r·• Second Floor
.j 14'-0" --
----
□ �
,_
(-9 ·\1 Gambrel Gable Roof - Right Elevation"'---) 1/8" = 1 '-0"
1-. Gambrel Roof Height .._-; 40' -O" ------
_]_ I _I l I I _]_ _I I_: c:�1 : I : I_ I :-, , I : I ,-i=:�L. 1: I, c·�1: I I_ �I' I I_ _I I I
Third Floor
25' -O"
Second Floor
14' -0"
(;;\ Gambrel Gable Roof -Left Elevation
\ .J 1/8" = 1'-0"___ _/
r-,1\ Gambrel Roof Height •:7 40' -0" ------
Third Floor
25' -0"
Second Floor
14' -O"
/; /; /; /;
-
(;�\, Gambrel Gable Roof -Backyard elevation
\ ) 1/8" = 1'-0" - /
Gambrel Roof Height
40' -0"
(.. Third Floor
._; 25' -0"
------
'
□
Second Floor
14' -0"
(;;·\, Gambrel Gable Roof -Alley elevation\ ___ ) 1/8" = 1 '-0"
D
,--- -,-
□ I\
\ I\
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--1--1-+-I-+, __
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DD
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UDC Top Plate Max Height
25' -0"
--
UDC Top Plate Max Height
25' -O"
UDC Top Plate Max Height
25' -0"
--
UDC Top Plate Max Height--
25' -0"
--
_,,, c•
.-",, ,_.
-----,c•
(-�
Gable Roof Height.. 29' -6" --
--
(�
Top Plate --•-18' - 8"
� 2nd Floor
1 0' -7"
(�'\ Gable Roof -Right Elevation\. ____ ./ 1/8" = 1 '-0"
r--. Gable Roof Height 1111") 29'-6" --
r·• Top Plate1111") 18'-8"
� 2nd Floor___,, 1 O' -7"
(�--\ Gable Roof -Left Elevation\ .J 1/8" = 1 '-0" ·--
� Gable Roof Height
�
(-.
291 -611
Top Plate
18' -8"
2nd Floor
10' -711
--
--
(r-;-\, Gable Roof -Backyard elevationi 1/8"-1'0" , _____ ./ - -
r--. Gable Roof Height1111") --29' -6"
--
r·•Top Plate1111") --18' -8"
( .. 2nd Floor1111") --10' -7"
(-;,., Gable Roof -Alley elevation
\ / 1/8" = 1'-0" '----·
I _JLJ
-
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CJ
c::::J
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I 11· □
--
!II I III I
□
UDC Top Plate Max Height----251 -011
UDC Top Plate Max Height .-.\----
--
25' -0" c•
�
UDC Top Plate Max Height --\--25•_0 .. c•
UDC Top Plate Max Height .-'\
25' -0" CIJ
lf-------------,11 ' I :]
' Cs
•'---•""./·_T_o_p_Plat_e _Pe_ r New UDC -NO_T_A_LLO_W_E_D __
'----26' -311 --__..--:: ----------------------------------__ ,,----_______---:.--- -
Top Plate
18' -8"�
-
-
2nd Floor
10' -T'
✓----' ', Shed Roof -Right Elevation1,_ 1 / 1/8" = 1'-0"
1·-· Top Plate•7 18' -8"
2nd Floor
101 -711
(-;-·\ Shed Roof -Left Elevation\ ) 1/8" = 1'-0"
□
-t D
,---
UDC Top Plate Max Height .-,.
--25'-0" a,
UDC Top Plate Max Height �'---25'-0" J
.,r·.-•"'1--T_o_p _Plate Per New U DC -N OT'__.':A":L�L�O'.,:';W�E�D�:;::::::::;::::;:=a==;;:::,::;::::::::;:::;:=a==:,:=a=:;:::::::,::::=====:,:::,:s===:='l-U 26'-3" --UDC Top Plate Max Height .---.
r• Top Plate•:J 18' -8"
1• 2nd Floor•7 10' -7"
I:·;,, Shed Roof -Backyard elevation• / 1/8" = 1'-0"
"-, __ ,J
Top Plate
18' -
8
11
2nd Floor
10' -7"
(-�-\, Shed Roof -Alley elevation
\ // 1/8" = 1 '-0" "------
c::::J
II I I I I
-
CJ □
--H-t-' II II I I IHIIH--I II oc"ll=====i DD
II
c::::J
/
-----25'-0" CJ,
UDC Top Plate Max Height .-,-25'-0" (JI/
ANALYSIS OF
BOZEMAN UDC
REVISED HIGHT
LIMITS
s T u D 0 co+hab
ARCHITECT:
ERIK BONNETT
914 W BOZEMAN, BABCOCK MT 59715ST.
EmPhone: ail: Erik@studi651.336.0394
ocohab.com
No. Description Date
Sheet Title:
ELEVATIONS FOR
THREE DESIGNS
Project Number
Drawn By
Date
2307ADU
M.B & E.B
6/20/2025
NOT FOR CONSTRUCTION
A0.2
6/23/2025 1 :43:38 PM