Drawing architectural plans for someone who builds with riba-based loans
Question

                I am a civil engineer working in an engineering firm. My job is to draw architectural plans and supervise them, whether these plans are for projects to be built with riba-based loans or otherwise. Does this work of mine come under the heading of riba or not? Because the state in which we live has suddenly opened the door to riba-based loans for that and there are very many such loans. Is my work riba-based on the basis that I take part in drawing the plans? Are the ones who sell cement, sand, gravel and iron, and all the workers involved in the project regarded as engaging in riba? Please answer, because I am very worried and this work is keeping me awake at night.
Praise be to Allah.If your work 
    involves drawing plans and supervising them, then it is permissible work so 
    long as you do not draw plans for buildings that will be used for evil 
    purposes, such as riba-based banks, bars, gambling halls and other places 
    that are used for sinful and immoral purposes, because in that case drawing 
    plans would come under the heading of helping in sin and increasing the 
    numbers of buildings used for evil. See question no. 
    82551. 
As for 
    drawing plans for permissible buildings, such as houses in which people will 
    live, there is nothing wrong with that, even if the owner is going to build 
    them with money that he has borrowed with riba, because you are not helping 
    him in his sin – which is borrowing money with riba – rather you are doing 
    permissible work for him and being paid for it. 
Among the 
    companions of the Prophet  (peace and blessings of Allaah be upon him) 
    were some who did work for pay for some of the Jews, doing permissible jobs 
    such as watering crops and so on. It is known that most of the Jews engage 
    in riba and consume people’s wealth unlawfully, as Allaah says 
    (interpretation of the meaning): 
“For the 
    wrongdoing of the Jews, We made unlawful for them certain good foods which 
    had been lawful for them — and for their hindering many from Allaah’s Way;
    
161. And 
    their taking of Riba  (usury) though they were forbidden from taking it and 
    their devouring of men’s substance wrongfully (bribery). And We have 
    prepared for the disbelievers among them a painful torment”
[al-Nisa’ 
    4:160-161]
The Prophet 
    himself  (peace and blessings of Allaah be upon him) dealt with the 
    Jews, buying and selling, and when the Messenger of Allaah  (peace and 
    blessings of Allaah be upon him) died, his shield was in pledge to a Jew for 
    some foodstuff that he had bought from him. Narrated by al-Bukhaari (2916). 
Hence it is 
    known that it is permissible to sell cement, sand and gravel to a person who 
    is going to use them to build permissible buildings, even if the owner is 
    one of those who engage in riba. 
We 
    appreciate your keenness to find out what is halaal. 
We ask Allaah to suffice us with that which is halaal so that you will have no need of that which is haraam, and to make us independent of means by His bounty. 
And Allaah knows best.