Just need to stat under the occupancy limit.Also keep in mind basement needs to be livable square footage, ie have egress and proper ceiling height. 

For example, this can be adding square footage, adding an extra unit, or adding a pool in a STR market/luxury market.  

Every room occupied for sleeping purposes by one person shall contain at least seventy (70) square feet of habitable room area and every room occupied for sleeping purposes by two (2) people shall contain at least fifty (50) square feet of habitable room area for each person.

Multi-family properties many times provide a better return per square foot than single family, which would be to your advantage as well.As long as you're mindful of the reinvestment requirements and purchase at least as much as you sold and use all of the proceeds, you shouldn't have any issues with this strategy.

I'd suggest taking a free course like that provided by Pete Reese at Land Conquest to get your feet wet and take some action. 

Quote from @Nicolas Tow: I recently purchased a 3,125 square foot empty lot in the 27th ward area of Humboldt Park Chicago and I was wondering how difficult it is to re zone from RS-3 to RS3.5 or RT 4.

.)- All in Cost = Cost to build * Square foot  - Sales Price = All in Cost + (All in cost * 20%)* Covers contractor and soft cost on either fee based or cost+- Profit = (Sales price - (Sales Price * 7%))* - All in Cost   accounts for agent fees and closing cost- Initial List Price = Sales price + 10%      A buffer to test market absorption- Break Even being All in cost, point where everyone is paid except me. - List price is to test the market absorption at "x" price. 250k land + build.

Purchase price: $140,000 in Nov. 2005 Sale price: $175,000 in July 20071872 square foot single family home with no garage.

A week into the job he was still demoing an 1100 square foot row home in Philly. 

I went on Zillow and found this 1900 square foot house with 2 bed, 1 bath and a nice floorplan in the listing.