I've built lots of masonry pier foundations. I used to either stack cinder blocks or pour concrete into site-made wooden forms. Then, a few decades ago, the job got a lot easier with the invention of the Sonotube pier form, which is now an industry standard. In this article, I'll give some basic tips for working with tubes, along with some unusual ways of using them that I've learned over the years. Some Rules of Thumb Before laying out a run of piers, I determine the required diameter, the size and depth of the footing, and the spacing between the piers. After fixing several sagging decks, I've developed a few rules