West Virginia
http://www.contractors-license.org/wv/wv.htm
All contractors and subcontractors must be licensed if the work performed is $2,500.00 or more. Plumbers and HVAC contractors must be certified.
License search: http://www.wvlabor.com/newwebsite/Pages/contractor_searchNEW.cfm
Plumber certification search: http://www.wvlabor.com/newwebsite/Pages/plumber_searchNEW.cfm
HVAC certification search: http://www.wvlabor.com/newwebsite/Pages/plumber_searchNEW.cfm