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What Are Crawl Space Jacks?

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Crawl space maintenance can be challenging. It’s crucial to keep your crawl space clean and dry, but moisture can easily accumulate inside it if it is not taken care of properly. This can cause sagging floors when moisture seeps into the foundation from poor drainage. Once the water or moisture reaches the wooden beams and subfloors, it can weaken them. Professionals often use crawl space jacks to stabilize and strengthen these weakened floors.

Crawl Space Jacks: Defined

Professionals use crawl space support jacks in homes with elevated foundations, which are homes with crawl spaces. These jacks are placed throughout the crawl space to help support the foundation — each adjustable brace can support up to 50,000 pounds. Crawl space jacks sit directly under girders, which support the floor joists and floor above the crawl space.

You might hear someone refer to crawl space jacks as crawl space jack posts. These are the same thing — floor jacks for crawl spaces. Crawl space jacks have four components that help provide this support:

  1. Bottom plate: The bottom plate attaches to a concrete post.
  2. Pipe: This pipe houses the threaded rod. The size of the pipe determines the load capacity.
  3. Spindle with a threaded metal rod: A nut welded to the spindle helps lower or raise the top plate.
  4. Top plate: The top plate attaches to the girder beam via screws or nails.

What Are Crawl Space Jacks Used for?

Crawl space support jacks help address problems with your home’s foundation. They either add support for the floors or prepare your home for foundation repairs. A floor joist system provides weight-bearing support to hold up everything inside your home. If your floors are sagging, a floor joist jack or crawl space jack can provide additional support.

A few signs you’re experiencing foundation problems include:

  • Sagging floors
  • Tight windows or doors
  • Foundation cracks
  • Wall cracks
  • Uneven floors
  • Issues with your crawl space

How Are Crawl Space Jacks Installed?

HydroHelp911’s process for installing crawl space jacks is as follows:

  1. Preparation: A system designer reviews the design with you before installation. Once you approve it, our installers map out the location of each jack and dig a hole. They fill the holes with an engineer approved filling such as #57 or #67 stone.
  2. Precast footing: Installers place a concrete base over the filled holes. The concrete base is the foundation for the jack post, and the engineered fill base supports it.
  3. Jack post cutting: Our team measures and cuts the steel jack posts to length.
  4. Assembly and tightening: Our professional installers assemble each jack post. They secure the top plate to the girder beams and install sister girders if needed. After assembly, the installers tighten each jack until the floors are level or supported.

Crawl Space Support Jack FAQs

Do you have a few more questions about how crawl space jacks work? Check out these frequently asked questions regarding crawl space support jacks:


Foundation jacks can be permanent or temporary. If professionals use crawl space jacks to repair your foundation, they’re not permanent — once they complete the repairs, they’ll remove the jacks. However, the jacks can be permanent if your foundation needs permanent support, instead of other repairs.


If the foundation jacks are permanent, they’ll last for many years. Some permanent foundation jacks can last for the rest of your home’s life. In temporary cases, the installation team will remove them as soon as the repairs are complete, so that will depend on the project’s timeline.


Crawl space supports are an excellent option if your home’s flooring system don’t have the proper support. Many houses require more support for their joists and girders, and crawl space supports can do the job. To determine whether you need crawl space jacks, consult a professional team who can tell you more about the situation and the best solutions.


Your home’s entire structure could crumble if the flooring system fails without additional support. If your floor is uneven, the weight of your house is unevenly distributed. This causes extra pressure in an area that can’t handle it.

If you fail to repair your crawl space, it can result in the stack effect, causing higher energy bills. The stack effect explains how air enters your home — warm air from outside seeps into the foundation, rises and enters your home. Because colder air is dense, it pushes out the warm air during the winter. Your crawl space provides about half of the air inside your home, meaning the stack effect can drastically impact your home’s indoor temperature.

Uneven flooring causes gaps to form, exposing your crawl space. These gaps provide an access point for air to enter your home. In the summer, your air conditioner must work harder to keep your home cool as the warm air enters it. During winter, cold air enters your home and interferes with your heating system. As a result, your heating and cooling systems have to work harder and your energy bills increase.

With the help of crawl space support jacks, you can ensure your home has crucial foundational support and your crawl space is more insulated, keeping high energy costs at bay.

Call HydroHelp911 for a Free Inspection

HydroHelp911 helps homeowners in North Carolina repair their foundations and solve moisture problems. We offer many services, including crawl space jack installation and foundation repairs. Our knowledge, training and experience provide us with the tools we need to solve your problems.

With over 10 years of experience, we’ve earned more than 125 five-star reviews. Our customers trust us because we treat them like family, working hard to find the right solution every single time. Fill out our online contact form today or call us at 704-741-9737 to get in touch.

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