It can take an underwriter 5 to 10 days to underwrite your mortgage application. However, if there are conditions attached to your approval such as a need to complete a home inspection or an appraisal which can create delays. Further delays may arise if your approval is re-conditioned to give you time to fix any issues with the home before you can get final approval. A full approval on your mortgage typically takes about 25 days if conditions need to be satisfied or an appraisal is required.