Habitat for Humanity of Greater Lowell is building four homes on Rock Street in Lowell and is seeking local families interested in purchasing the affordable, three-bedroom, 1.5-bath duplexes. Each home is roughly 1,200 square feet and is expected to be completed in December 2013. To apply, families must meet Habitat for Humanity’s income guidelines, which range from $21,800 to $36,300 for a two-member household to $31,600 to $52,650 for a six-member household. The organization is holding information sessions in Billerica and Lowell. Those interested in being considered must attend one of three informational meetings to get an application: at 10:30 a.m. to noon Feb. 23 at Habitat for Humanity ReStore, 257 Boston Road in Billerica; 6 to 7:30 p.m. on Feb. 25 at the Merrimack Valley Housing Partnership, in the Pollard Exchange Building, 67 Middle St., Lowell; and 6 to 7:30 p.m. on Feb. 28 at Community Teamwork Inc., 155 Merrimack St., Lowell. For more information, contact Habitat for Humanity, 978 692-0927.