Once the property owner posts the property, it becomes illegal to carry a firearm onto the property. This does not come from the firearms laws, but the laws rgarding trespass.
The property owner has made entry onto the property conditional. Violating that condition constitutes trespass - the illegal entry onto or remaining on private property when not authorized/invited to do so.
§ 18.2-23. Conspiring to trespass or commit larceny.
A. If any person shall conspire, confederate or combine with another or others in the Commonwealth to go upon or remain upon the lands, buildings or premises of another, or any part, portion or area thereof, having knowledge that any of them have been forbidden, either orally or in writing, to do so by the owner, lessee, custodian or other person lawfully in charge thereof, or having knowledge that any of them have been forbidden to do so by a sign or signs posted on such lands, buildings, premises or part, portion or area thereof at a place or places where it or they may reasonably be seen, he shall be deemed guilty of a Class 3 misdemeanor.
B. If any person shall conspire, confederate or combine with another or others in the Commonwealth to commit larceny or counsel, assist, aid or abet another in the performance of a larceny, where the aggregate value of the goods or merchandise involved is more than $200, he is guilty of a felony punishable by confinement in a state correctional facility for not less than one year nor more than 20 years. The willful concealment of goods or merchandise of any store or other mercantile establishment, while still on the premises thereof, shall be prima facie evidence of an intent to convert and defraud the owner thereof out of the value of the goods or merchandise. A violation of this subsection constitutes a separate and distinct felony.
C. Jurisdiction for the trial of any person charged under this section shall be in the county or city wherein any part of such conspiracy is planned, or in the county or city wherein any act is done toward the consummation of such plan or conspiracy.
(Code 1950, § 18.1-15.1; 1960, cc. 99, 358; 1975, cc. 14, 15; 2003, c. 831.)stay safe.§ 18.2-119. Trespass after having been forbidden to do so; penalties.
If any person without authority of law goes upon or remains upon the lands, buildings or premises of another, or any portion or area thereof, after having been forbidden to do so, either orally or in writing, by the owner, lessee, custodian or other person lawfully in charge thereof, or after having been forbidden to do so by a sign or signs posted by such persons or by the holder of any easement or other right-of-way authorized by the instrument creating such interest to post such signs on such lands, structures, premises or portion or area thereof at a place or places where it or they may be reasonably seen, or if any person, whether he is the owner, tenant or otherwise entitled to the use of such land, building or premises, goes upon, or remains upon such land, building or premises after having been prohibited from doing so by a court of competent jurisdiction by an order issued pursuant to §§ 16.1-253, 16.1-253.1, 16.1-253.4, 16.1-278.2 through 16.1-278.6, 16.1-278.8, 16.1-278.14, 16.1-278.15, 16.1-279.1, 19.2-152.8, 19.2-152.9 or § 19.2-152.10 or an ex parte order issued pursuant to § 20-103, and after having been served with such order, he shall be guilty of a Class 1 misdemeanor. This section shall not be construed to affect in any way the provisions of §§ 18.2-132 through 18.2-136.
(Code 1950, § 18.1-173; 1960, c. 358; 1975, cc. 14, 15; 1982, c. 169; 1987, cc. 625, 705; 1991, c. 534; 1998, cc. 569, 684.)