As to every insurance contract insuring any dwelling or other building and written in the name of less than all of the joint owners or tenants in common, with or without survivorship, if such joint tenants or tenants in common are husband and wife, it shall not be a defense against liability under the policy that all the joint owners or tenants in common were not named as the insured therein, nor will the amount due in event of loss be diminished on such account unless, by special endorsement of the policy, the insurer’s liability is limited to the interest of the named insured.