|January 16th, 2016|
The first problem is land. Houses in Somerville are expensive because the land is expensive: the land is typically  worth more than the building on it. Specifically, for the median 1, 2, or 3 family Somerville house, 55% of the value is land and only 45% is the building:
So if your land costs $350k and your structure is worth $300k, then getting your structure down to $50k or even $0 is not going to bring the total cost below $350k. Plus this area is already built up, so you can't just choose to buy a plot without the house on it and get it cheaper.
Tiny houses don't need much land, though, and existing plots generally have extra space, so can we put the houses next to other houses? There are a few tiny houses in Somerville sharing plots with larger houses:
Unfortunately, all of these date back at least 50 years and are grandfathered in: the town is not going to let you build more of them. Which is kind of sad, seeing as the existing ones are cute and seem like a good use of space.
What happens if you just go ahead and put a tiny house on an existing plot as an additional house? There's a conflict in Hadley MA over that right now. Sarah Hastings built a 190 square-foot house as part of her senior thesis. After graduation she found someone willing to rent her some space on their property, and moved her house there. Once the zoning enforcement officer found out about it, though, he issued her landlords a violation notice. Hastings went before the zoning board of appeals last week, who affirmed that the house was not legal under the town's existing bylaws. Since Hastings wants to change the bylaws to allow houses like this, though, the board decided to delay enforcement and let her stay where she is until she's had a chance to present her proposed bylaw change at the next Town Meeting.
I'm really conflicted about this case. It seems very likely to me that if, instead of being a recent college graduate with a hand-built wheeled house we had someone who was living in a trailer because they couldn't afford anything else, the zoning board and the rest of the town would be much less accomodating. On the other hand, we really need to bring down the cost of housing, and one way to do that is to relax zoning regulations so people can build more. Having a sympathetic challenger is basically required if the town is going to approve a change here; anyone else would be dismissed out of hand.
So I'm hoping Hastings is able to convince the town to pass a bylaw that will allow her house and others. And if you're thinking of trying to do the same in Somerville let me know!
 All this data comes from the Somerville assessors database, which has a valuation for each lot in the city broken down into the land value and the improvements (buildings) value. I pulled out the 9783 plots that are classified as "SING FAMLY," "TWO FAMILY," or "THREE FAM MDL-01". Raw data: improvements-land-classification.txt.