To grant specific variances from the terms of this chapter where it is shown that unique physical circumstances applying to a lot cause hardship to the owner under this chapter and that the variance still will be in fundamental harmony with surrounding uses. The Board may reverse or affirm wholly or in part or may modify any order, requirement, decision, or determination appealed from and shall make such order, requirement, decision or determination as in its opinion ought to be made and to that end shall have all the powers of the Building Inspector. The concurring vote of four members of the Board shall be necessary to reverse any order, requirement, decision or determination appealed from or to decide in favor of the applicant on any matter on which it is required to pass or to effect a variance. The grounds for every such determination shall be stated and recorded.