Ah I took the wrong stat from that article, that was national (and quarterly)
So the actual WA number is about 5000 per quarter http://www.perthnow.com.au/business/housing-starts-will-stay-soft-in-2011/story-e6frg2ru-1225970924814
That makes 20,000 per year. over 5 years, 100,000. Time 2.6, and that gives accomodation for 260,000 people.
So, looks like with my conservative assumption of 300,000 immigrants we wouldn't quite have enough. But, as the article you referenced used 150,000 as it's panic by-line, we should be ok. Whew!
(and again, the 5,000 per quarter is low, as they are crying in the reference about how it is very low...of course because of low demand!)
