The reason builders keep shrinking product is affordability. With mortgage rates hovering a bit above 6 percent and only gradual easing expected, the buyer pool at 3,200 square feet is much thinner than the pool at 1,800, and a spec house only makes money if somebody can qualify for it.
On the physical math, attached units share a wall, a foundation run and often a roof line, and they split the land cost between two households. That's where the savings sit. What doesn't shrink is the expensive footage. Each unit still has a kitchen, still has two or three bathrooms, still has a furnace and a water heater and a panel. So your cost per square foot goes up even as your total cost per unit comes down. Don't be surprised if two 1,800 square foot units cost more in total hard dollars than one 3,200 square foot house while each individual sale price is far more achievable.
Thicket is right that the legal side is where the savings leak. Two-unit attached product needs a recorded party wall agreement or a small owners association, and whether your parcel can even carry two dwellings depends on the zoning, any minimum lot width, and whether your jurisdiction allows a subdivision or requires a condominium regime. Those rules are local and the documents need a land use attorney, so price that conversation before you pay for a redesign.
The question I'd ask your agent first is whether attached homes in that specific pocket appraise and sell, or whether the townhouse buyer in your market is all downtown. A product type that works statewide can be a slow sale three miles away.
