Ellen sent two questions into our "Ask Us Anything" page, so here's here second question and our answer. Be sure to go back and see her first question concerning piers and load bearing walls, if you haven't read that post, yet.
Question
Should a contractor ALWAYS be able to find bedrock if they drill
in helical or steel piers?
Answer
Dear Ellen, another great question.
No, a contractor will not always find "bedrock" when installing Helical Piers or Steel piers, especially in the DFW Metroplex.
For starters, "bedrock" has a specific geological definition and is not found here in our area. This is why the contractor should make the effort to terminate their piers into "load bearing strata". The definition of load bearing strata can be a little subjective but it can also get technical. The main components of the definition, at least for my company, are: the pier should be at least 15' deep and should encounter a strata which produces enough resistance to support two times the weight of the structure it will carry.
Since any type of "rock" in this area of Texas can be at depths from 2 to 100 feet, affordability becomes a factor for the home owner. We have pushed our steel piers as deep as 98' in order to reach a strata that would not allow further advancement of the piers. This is where the helical piers come to the rescue of the budget.
The helical pier is designed to be installed at low speed and high torque until it bears into a strata which produces sufficient resistance to meet our criteria and then it is terminated. Sort of like when you screw a screw into a piece of lumber and the progress is easy until the screw reaches a harder layer of the wood and halts the process.
For example, where a thick bed of sand stone lies 85' deep and the steel pier would have to be driven that deep, the helical may only need to be advanced 35' deep to find a good strata for support. This is why my company has kept a database of the depths we have driven our steel piers on past jobs. When we are called to provide an estimate for a home owner, we can pull up past jobs nearest to their property and get a good idea where "load bearing strata" is and use that information to help advise the customer.
Again, feel free to forward any other questions you have and I will do my best to get you answers.
Sincerely,
Alan Ardoin.
Get more information by visiting www.AceFoundation.com.
Posts
This is intriguing because the strange bedrock has been a major cause for the need of foundation repair orem lately. I can only imagine what it would do for steel peers.
ReplyDeleteThe key is recognizing the problem early. In Fort Wayne, IN, this question comes up frequently. It's important to have a professional do the foundation repair. Be sure to shop around!
ReplyDeleteThanks, Ellen, for asking such a great question. I was wondering the same thing about always being able to find bedrock. I didn't know it wasn't found in this area. Thanks for clearing that up!
ReplyDeleteBrooke Bowen | http://hdfoundationrepair.com/foundation-repair-fort-worth/
98 feet is an incredible depth to steady the underpinning of a home. There are some desert areas where the hard-pan dirt is so much like cement that you don't even need a foundation. Bridging a gap between building and bedrock of a hundred feet of sand sounds like a fun challenge to stabilizing a building.
ReplyDeletePaul | budgetreblocking.com.au
Cool ! Thanks for the post.
ReplyDeletedrywall repair