How to Jack Up a Deck

How to Jack Up a Deck
Written By
Keith Dooley
Keith Dooley
Published: Feb 6, 2011
Updated: Nov 20, 2021
1 minute read

Jacking up the deck and shimming the post can resolve deck sag problems.

Things You Will Need

  • Two-by-four lumber
  • Car jack
  • Wood or masonry (for use as shim under support post)
  1. Access the area under the deck. Identify the area of the deck that is sagging and locate the support post that needs to be shimmed.

  2. Place a short length of two-by-four lumber on the ground beside the support post as support for the jack.

  3. Position a car jack on the two-by-four or use a bottle jack.

  4. Raise the jack so it contacts the wooden floor joist supporting the decking. Continue raising the jack until the deck is no longer sagging.

  5. Place a wood or masonry shim under the deck support post so it will once again support the deck securely. Use treated wood or thin masonry stepping stones as a shim under the support post.

  6. Lower the jack so pressure is once again placed on the support post. Determine if the deck is still sagging and add another shim under the post if necessary.

The Drip Cap

  • A deck can be a focal point of outdoor activity or a quiet place of rest for many homeowners.
  • Place a wood or masonry shim under the deck support post so it will once again support the deck securely.

Photo Credits

Jupiterimages/BananaStock/Getty Images

Jupiterimages/BananaStock/Getty Images

Keith Dooley

Keith Dooley has a degree in outdoor education and sports management. He has worked as an assistant athletic director, head coach and assistant coach in various sports including football, softball and golf. Dooley has worked for various…

Sponsored
HomeSteady Logo

HomeSteady is the ultimate guide for all your household needs, from cleaning and HVAC to electrical, DIY and maintenance.

Property of TechnologyAdvice. © 2026 TechnologyAdvice. All Rights Reserved

Advertiser Disclosure: Some of the products that appear on this site are from companies from which TechnologyAdvice receives compensation. This compensation may impact how and where products appear on this site including, for example, the order in which they appear. TechnologyAdvice does not include all companies or all types of products available in the marketplace.