Details have been revealed of the long-delayed new home for the Treaty of Waitangi.

The document is being moved 200m down the road from its current home at Archives New Zealand to a permanent exhibition within Wellington's National Library to be known as He Tohu.

He Tohu has a number of meanings, such as - signs, signatures, marks and symbols.

The exhibition,will open early next year and will feature the 1835 Declaration of Independence of the United Tribes of New Zealand, the 1840 Treaty of Waitangi and the 1893 Women's Suffrage Petition.

The documents will be housed in environmentally controlled display cases to protect them.

The government has been forced to defend costs and delays in the $6.7 million project, which was meant to happen in 2013.