A variance may be granted by the Board of Adjustment if it concludes that strict enforcement of this regulation would result in practical difficulties or unnecessary hardships for the applicant and that, by granting the variance, the spirit of this regulation will be observed, public safety and welfare secured and substantial justice done. The strict application of the requirements of this regulation may be varied or adapted, in the case of exceptionally irregular, narrow, shallow or steep lots or other exceptional physical conditions, whereby such strict application would deprive the owner of the reasonable use of the land or building involved.