If your ancestors were in business they may appear in trade directories.
The private addresses of wealthier residents were often listed as well. However, not every house or building was listed, and house numbers may have changed since the trade directories were compiled.
Oldham Local Studies and Archives holds local directories from 1814.
The directories vary in content, listing by trade, address or surname. The Directories can be particularly useful for locating addresses, when trying to trace a family in the census returns.
Telephone directories at Oldham Local Studies and Archives:
1923, 1963, 1967, 1968, 1970, 1972, 1975, 1977, 1982, 1985, 1986, 1988, 1989, 1991, 1993, 1994, 1996, 1997, 1999, 2000 to present.