Renovation Between Tenants

My first tenants moved out near the beginning of the year. We renovated the house for a few months before a second set of tenants moved in within the same year. Can we claim that the house was a rental for 100% of the year per IRS rules? Will I be able to write off the expenses (either as expenses or add to basis of the house) on the improvements made during the time of renovation when there were no tenants?