Va. Code § 19.2-396
An inspection, testing or collection of samples for testing pursuant to such warrant may not be made in the absence of the owner, custodian or possessor of the particular place, things or persons unless specifically authorized by the issuing judge upon a showing that such authority is reasonably necessary to effectuate the purpose of the law or regulation being enforced. An entry pursuant to this warrant shall not be made forcibly, except that the issuing judge may expressly authorize a forcible entry where facts are shown sufficient to create a reasonable suspicion of an immediate threat to public health or safety, or where facts are shown establishing that reasonable attempts to serve a previous warrant have been unsuccessful. In the case of entry into a dwelling, prior consent must be sought and refused and notice that a warrant has been issued must be given at least twenty-four hours before the warrant is executed, unless the issuing judge finds that failure to seek consent is justified and that there is a reasonable suspicion of an immediate threat to public health or safety.
Va. Code § 19.2-396