Posted by Jonathan Maguire on Thu, Apr 08, 2010
This post will help describe how a helical pier works. Helical piers are used for foundation repair projects as well as new construction projects in poor soils. A helical pier is a round or square metal shaft with flights or helixes. What is a flight? It’s a steel plate welded onto the main shaft of a helical anchor (see picture). These plates are generally 3/8-1/2″ in thickness and have a pitch of 3″. This pitch allows the helical anchor to advance into the soil 3″ per revolution or 4 revolutions per foot.
How many flights or helixes are needed? Great question and there is no definitive answer for all applications. On a standard residential project where the loading is 10-30,000 lbs, one-two plates will work (each plate can handle between 20-25,000 lbs/ea depending on the manufacturer). Adding flights can increase the surface area that is made with soil and multiple flights decrease the loading required on each flight. We have found that adding flights can also help us install the product better as you have two or more flights pulling a helical into a the ground instead of just one single.
In part two of this blog, I’ll give some insight into how adding flights helps, and what are the limiting factors of helical pier capacities.
Posted by Jonathan Maguire on Fri, Mar 19, 2010
In 2003 there were 20 helical or resistance pier manufacturers, 4 of them were considered “Major”. The top two companies were AB Chance and Atlas Systems (where we received our name). In 2009 there were over 50 manufactures of piers, with AB Chance topping the list followed by Earth Contact Products then Dixie, RamJack, DriveRite, etc.
As you can see, there has been a LOT of manufacturers enter into the business in the last few years. Many of these manufacturers are making helical and resistance piers from their own shop or “basement”. The top companies – and ones with the longest history have licensed engineers behind all their designs, a full fledged manufacturing facility, and quality control. The smaller guys are making a few piers - and while some of these 2nd tier or 3rd tier manufacturers may have engineers that help design, there is no way to compete with the larger companies in quality control, manufacturing and oversight. When you are supplying multiple thousands of piers (sometimes tens of thousands of piers), your quality has to be top notch. You cannot afford product failures, you cannot afford for a 3rd party engineer or inspector to question your products. There is just too much riding on them.
Why does this matter? Atlas Piers of Atlanta only purchases from platinum manufacturers. We have too much at stake to trust a lesser manufacturer. So when you have someone look at making foundation repairs to your structure ask which helical pier or resistance pier manufacturer they install. Piers may seem like a commodity, but there are vast differences.