In 2010 Portland, Oregon made it cheap and easy for people to build ADUs (Accessory Dwelling Units — also known as “granny flats”, “in-law apartments”, “carriage houses”, etc — small secondary dwellings that are on an existing property), and to nobody’s surprise, the tiny homes boomed. This kind of housing adds density without changing neighborhood character, lets people live lighter on the land, and helps makes housing affordable both for the renters, and the homeowners who now have a rental income that was impossible before. And they do it all without any public subsidy.
Boulder can do this too.
Arvada has a permissive ADU ordinance and I have taken advantage to build a carriage house on the alley behind my home in Olde Town. It’s all I hoped for and more: A way to further virtuous policy aims like quality affordable housing and higher density near transit (while respecting the historic fabric of the neighborhood), plus it’s good for me personally. I am more likely to be able to age in place; it provides added income; and the unit is a key part of my retirement plan. Best of all, it’s successful! Many people of all strips vie to rent, whenever it becomes available, and tenants really like living in it.