Hi everyone,
and thanks for rewarding my news-post with this active discussion. The speculations made here are very nice. Especially for the insignifcant ammount a housing weighs. You are all completely right on that, but the article was not ment as a late April fool.
In fact I got the idea of writing and researching the news after talking to a housing manufacturer. So it's not made up. My research revealed the illustrated increase in the stock market. Even though housing manufacturers use only little compared to other industries they might run into a supply problem. Spoken in economic terms they might even more easily run into a supply problem, than if they would consume more aluminium compared to other industries.
The fact that they need so little gives them less buyer power than other industries. If they cannot benefit from the purchase of related companies in a group they might not even get the metal at all. I experienced the same situation when I was a productmanager for ISDN-Telephones. They needed the same components as Nokia and Erricsson during the cell-phone market boom. The fact that we did not buy as much as Siemens or Nokia resulted in a situation of not getting any products out for several month on the "less interesting" corded-phone market. In the end smaller companies (as the one I worked for) had to buy from the big ones at ridiculus prices. For computer chips of a certain kind that was up to 10 times of the list-price. You should expect that housing companies are not in the position of buying as cheap as on the stock market.
Another fact you should consider is that Subal, Seacam, Sealux, Hugyfot... machine their housing (and sometimes also the ports) from a solid block that weighs much more than the housing itself. *** I just read that this was already mentioned above.
sidenote: your comments are also warmly welcome under the article 
http://www.digideep.com/english/info/html/1282/