Excel 2007 : Add space between characters and numbers in Microsoft Excel

I am doing data scrubbing where I have ~8000 addresses where only some contain the following "errors" in the string:

10847Elk Run Rd
11712Jefferson Ave
11801Coastal Hwy

I need a way to search for "numtext" and replace with "num text", regardless of how long the leading number or following Latin string is. The ideal function would add spaces where necessary and avoid those that are formatted correctly.

10847 Elk Run Rd
11712 Jefferson Ave
11801 Coastal Hwy

Please advise.