The housing appeals board may, in cases of extreme hardship to owner-occupants or tenants of dwellings, provide for deferral of the effective date of orders of abatement. Any deferral of the effective date of an order of abatement under this section shall terminate upon any sale or transfer of the dwelling by the owner-occupant but shall not terminate upon the sale or transfer of the dwelling if the dwelling is occupied by a tenant other than the owner-occupant.