Ask a Business Lawyer. Get Business Law Questions Answered ASAP.
Is this a commercial or residential lease?
What does your lease say about the landlord and your respective duties to repair (or make habitable)?
You can break the lease if the landlord won't repair in a timely manner. See: http://leg1.state.va.us/cgi-bin/legp504.exe?000+cod+55-248.21
Or, you can withhold rent, and then if the landlord gives you notice to pay or quit, you can pay the unpaid rent to the court escrow service and if you have proof that the landlord did not repair the building, that will be an affirmative defense against the unlawful detainer action. See http://leg1.state.va.us/cgi-bin/legp504.exe?000+cod+55-248.25.
Have a licensed, reputable roofing company come and give you a written estimate for the repairs. That way, you will have evidence of the existence of the damage from an objective third party.