Does an engineer incur sin by supervising construction funded by a usurious loan, or by providing consultations regarding it, whether for a fee or gratuitously? And is this considered an encouragement of usury? What about drawing maps and writing reports that facilitate obtaining loan disbursements?

It is permissible for a civil engineer to design, plan, and supervise the construction of a house, even if the homeowners' money was obtained through an unlawful usurious loan, provided that the design and planning occurred after they obtained the usurious loan. This is because the engineer receives money for his effort and labor, and he has no connection to the usurious loan.

However, if the engineer designs or plans the house for the purpose of obtaining a usurious loan, then his action is forbidden, because he is cooperating in sin and aggression.