You can get the certification online, quick, for a single family property. L&I doesn't inspect. However, if you have received a violation, it needs to be corrected. Someone from L&I has to come out the see that the violation has been cleared, then make his report. Then it takes a few days for the cleared violation information to get to the certification department. When that is the case, then allow at least a couple of weeks. Also, be sure that there are no current violations, such as missing smoke detectors, or you will have a new violation which will have to be corrected and visited by the inspector.