Factors that make Zakaat compulsory

Zakaat on One's House

Q: We have Alhamdullillah two houses. One we are using to live and the other we are receiving rent from it and also my father's shop is there in this house...how should we pay zakaat on it?  As far as I know there is no zakaat on the house we are living in. Please provide me with the details.

Value of zakaatable goods

Q: I own a textile mill. I first import the yarn from which the material is manufactured. I supply certain companies material at the manufacturing cost plus ten percent profit. I also wholesale fabric at the wholesale price which is approximately my cost plus twenty percent. I am also a retailer and supply the public at the retail price. When calculating my zakaat, which market am I obligated to take into consideration? Should I evaluate my wealth in accordance to the retailer’s market, wholesaler’s market, or the manufacturer’s market?