I have been trying to install house builder with no success, Im on a mac with sketch up 8. I downloaded the Housebuilder extension from the link provided and my mac must unzip files for me as I have yet to see a .zip file show up when I download the link. I compressed the folder that was downloaded and changed the .zip to a .rbz file. I added the .rbz file to sketch up by using the preferences - extensions - install extensions method and it says the installation is complete, but I don't see an option to choose the Housebuilder extension.