This is a drum I'm going to keep beating. Yes zoning is an issue, but fixing that isn't a panacea. Build social housing that appeals to a variety of income levels then rent it out at a cost which covers a high standard of maintenance and upkeep (require that they be revenue-neutral in the bill, even). Aside from the upfront costs of construction, that gets you affordable high quality housing without any long term budget impact while relieving some of the pressure driving up costs for private rentals in the neighborhood. Hell, you could probably even distribute the construction costs over, say, 30 years and still beat market rates even with interest.