The housebuilder has traded on an even more junior market, OFEX, since 2001, but decided further expansion was necessary.
Carl Turpin, chief executive, said: "We've been on OFEX for nearly three years and felt that we had exhausted it. We had the option to have a venture capitalist [to back the company], but we did not find that too palatable."
A venture capitalist would look to leave the company after making a profit from its sale.
Hampshire-based specialist brick maker Michelmersh will list at the end of this month. It hopes to raise £6m at first. Its market value should be about £24m.