Ask the listing agent for the name of the contractor they used to winterize the property in the first place.
It should cost you between $200 and $300 total - $100-$150 to de-winterize the property just before the home inspection and the same to re-winterize the property immediately after the home inspection.
On a related note, your Buyer's Agent should know the answer to these types of questions so check with them in the future.
Hope that helps
Check with http://www.hbav.com/
Home builders association of Virginia.
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