Increased requirements respecting lot area, frontage, width,
yard and similar dimensions provided in this bylaw or amendments thereto,
shall be subject to the exceptions provided in MGL c. 40A, § 6
and shall not apply to a lot for single- and two-family residential
use which at the time of the recording or endorsement, whichever occurs
sooner, was not held in common ownership with adjoining land, conformed
to the then-existing requirements and had less than the proposed requirement
but had at least 5,000 square feet of area and 50 feet of frontage.