Suds pressure zones

The BC Canada plumbing code talks about a "Suds pressure zone" can someone tell me if this applys to a single family, one story home ?. I think I need a better diagram/understanding of this code item / requirement. In my case I will have a sanitary drain pipe which will be coming out from the street on an inclined horizontal and then vertical up to fixtures on the main floor. There is no full basement and only a 4 foot crawlspace. Thanks