In a speech to the National House Building Council, Emma Reynolds said that assembling "an army of smaller firms and custom builders" would be key to the delivering of the party’s pledge to build "at least" 200,000 new homes a year by 2020.
Reynolds said that while big volume housebuilders had an essential role to play in doubling housing starts from the 117,110 figure she cited for 2013, she said "greater competition and diversity" in the market was needed.
"We know that one of the key barriers for small and custom builders is access to land," she said.
"Too often a huge emphasis is placed on large land sites by local and national government ignoring smaller sites," she said.
"The next Labour government will require local authorities to include a higher proportion of small sites in their five-year land supply.
"Second, we will give guaranteed access to public land to smaller firms and custom builders.
"We will ensure that any public land given over for housebuilding will have a proportion dedicated for this purpose."
Adding to shadow chancellor Ed Balls’ November commitment of future government funding to aid the development of additional new towns and garden cities, Reynolds promised the the party would ensure that "a proportion" of the homes would be built by smaller firms and custom builders.
She added that Labour would ask every local authority in the country to create a new waiting list for people to register their interest in a custom-build, co-operative build or community land trust plot.
Reynolds also said that a future Labour government would offer greater transparency on the ownership of development sites.
"Where communities want to expand and build the homes for their children and grandchildren, they should know where land in their local area is available," she said.
"So we will increase transparency in the land market by ensuring that developers register the land they own or have options on."