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HomeMy WebLinkAbout08-04-25 Public Comment - T. Minge - UDC Mass & Scale ToolsFrom:Tammy Minge To:Bozeman Public Comment Subject:[EXTERNAL]UDC Mass & Scale Tools Date:Monday, August 4, 2025 2:00:15 AM Attachments:UDC-mass & scale tools.pdf CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe. See attached comments on RA & RB mass & scale tools per Chris Saunders questions. Regards, Tammy -- Tammy Minge Licensed Architect/Master Certified Green Professional Frog Rock Design, PLLCP.O. Box 6216 Bozeman, MT 59771406.581.0527 1 P.O. Box 6216, Bozeman MT 59771 * Tel: (406) 581 0527 *minge@frogrockdesign.com R E S I D E N T I A L A R C H I T E C T U R E August 3, 2025 Attn: Chris Saunders & City Commissioners Design Professional response on Mass and Scale Tools: Saunders-Q. Based on your experience are the heights allowed in the zoning districts of the Current Code workable, or could better design and more functional outcomes be achieved with modest adjustments in some districts? If so, how and what? For RA and RB I would not want to see maximum heights increased from the current code. In the current code the heights are linked to the roof pitch to help with massing and scale which has been an effective tool. Less than 3:12 roof pitch for R1/R2 is 28’/30’. Greater than 3:12 roof pitch is 40 for R1 & R2. R3 is 36’ and 46’ respectively per the above roof pitches. Lower overall heights will encourage breaking down the lengths of the building façade to accomplish typical gable roof forms which will create smaller massing and scale even if you choose to increase density allowances. For RA I would recommend a maximum of 36’-38’ tall in conjunction with maximum wall height that does not allow for three stories (less than 25’). This height is tall enough for larger structures that look like single family residence and duplex/townhomes to be built in a reasonable fashion. (Most of my single-family homes up to 4-plexes today are two story and max out around 32’. Many subdivisions have a maximum of 28’). This same height works for 2 ½ stories. RB does not need to be much taller than RA to include more density. A three-story flat roof could be accomplished with a height of 32’ and a wall plate height of 32’. A low sloped roof could be accomplished with 46’ or less. Saunders-Q. Given typical building methods and the way wall plate is measured, will 25 feet be a readily achievable standard in RA? FROG ROCK D e s i g n, LLP 2 P.O. Box 6216, Bozeman MT 59771 * Tel: (406) 581 0527 * minge@frogrockdesign.com Yes, easily achievable. Could even be reduced to 21’ and have achievable (likely more affordable) construction. Typical 2-story construction on flat site is 20” to top of floor from grade with basement or crawl space below, 9’ plate height with 1-2’ floor space, 8 or 9’ upper level for a total of 21-22’ wall plate. You also have energy heels of 1’ at the trusses so that adds 1’ of height as part of the roof that is above the wall plate with a flat soffit (so really 26’). Luxury homes often have taller ceilings (10-12’), but this is more expensive to build, so if the goal is affordable housing this should not be encouraged. If these homes want taller ground floors they can put in dormers in the upper level with shorter sidewalls to keep the overall massing of the building the same as for a more affordable build without towering over the neighbors. For 2 ½” stories there is enough height in my above recommendation to add limited dormers per the proposed UDC for the extra ½ story. I measured some larger massing homes in the Bonton District for the following plate heights: • Story Mansion: 23.5’ sidewall • Large House (NW corner of Grand and Story): 25’ sidewall • Large House (SE corner of Grand and Story): 24.5’ sidewall These structures are all on corner lots with 15’ setbacks on two sides and 10’ or more side yards which is typical of the larger homes in the NCOD. The exception is the Story Mansion which sets back from all sides 25’ or more. Based on this, a 25’ wall plate with a 5’ setback will not fit with the current context of the existing RA neighborhoods within the NCOD. This is also true for new neighborhoods that want to look like lower density neighborhoods of the RA type. Is it appropriate to have a structure with the mass and scale of the Story Mansion land 5’ off the property line in RA zoning? The proposed UDC with a 25’ wall plate, 80 wall length and 40’ maximum building height could allow for this to happen in all RA neighborhoods. If the goal is to increase the density but to have the neighborhood to feel like a lower density neighborhood, I recommend using an angled setback, setback that relates to height for a 25’ wall plate or other tool in conjunction with the 21-25’ wall plate height. This becomes a factor as the lots are allowed to get narrower and density is increased as in the proposed UDC verses the current code (unintended consequences). Saunders-Q. To readily achieve three full floor stories in RB, what adjustments to wall plate height may be appropriate? 32’ would allow for three 10’ “stories” and the typical 20” start off grade for a standard foundation. Again, is this appropriate in all RB neighborhoods starting from a 5’ side yard setback. Are there other tools to address existing neighborhoods and is this desirable for new 3 P.O. Box 6216, Bozeman MT 59771 * Tel: (406) 581 0527 * minge@frogrockdesign.com neighborhoods? Should there be requirements for larger setbacks between structures of this height/wall plate? • Measured example - 3 story new 4-plex (SW corner of 8th and Alderson): has a 33.5’- 34.5’ wall plate with a 5’ tall landscape berm above sidewalk level. I would estimate the overall height is about 45’tall. It has 15’ setbacks on two sides as a corner lot and +/- 20’ setback from the house next to it for the driveway. Regards, Tammy Tammy Minge 715 S. Grand Ave. Licensed Architect