If you notice that something is wrong on your deck, but the exterior part seems okay, try to check its foundation for other problems.

Over time, due to different weather conditions, the deck joist will gradually degrade and might not handle to support the deck.

Thinking about replacing deck joists is already a hassle but, do you really need to replace it or do something else to prolong their lifespan? In this blog, we will talk about the signs for deck joists replacement, alternative solutions to fix the joists, and other related guidelines.

How Long Does Wood Joists Last?

On average, the lifespan of high-quality joists and deck foundations can last more than a decade depending on the weather patterns in your area and how well you maintain it.

Signs for Deck Joists Replacement

If you want to replace the deck joists, it is necessary to replace other parts as well to maintain the overall quality of your deck and prolong its lifespan. Old materials that have mildews or molds on it can transfer to the new materials, causing the overall deck components to degrade faster.

Here are the signs you should look at to determine if you need to replace the joists of your deck:

If you experience different weather patterns in your area, expect that your wooden materials will be worn out faster than usual. If you saw small decay spots all over your deck, replace all the joists as soon as possible so it won’t spread out and affect other parts of the deck.

Check if other components are also rotting, especially the deck foundation. The moisture and water vapor from the ground can easily transfer to any wooden beams and support columns. Over time, it will cause other components including the joists and the ledger to rot.

The most typical installation problem with LP SmartSide is the missing paint at the sliced edge, butt joint, and cut edge just above the roof and window. This issue might not concern other homeowners, but you need to remember that all sides need to be painted for moisture protection. Moreover, the manufacturer recommends that all visible surfaces be primed and painted for better security.

Another problem you might encounter is the fasteners being easily overdriven, causing deep siding puncture. Not only is it unattractive, but it also traps moisture over time.

Splitting planks are a sign of damaged joists. Woods will tend to split over time if subjected to frequent temperature changes. Consider replacing all the cracked joists once you notice the problem to avoid any incidents that might happen in the future.

Deck with soft and weak joists can be easily noticed if there are sunken parts of the floor and if the foundation materials are shifted. An unsteady deck due to damaged joists may cause incidents if not replaced as soon as possible.

You may also check if any of the joists need to be replaced by inspecting them thoroughly. You can examine the joists from a crawlspace or an unfinished basement to inspect them without pulling up the floor. Look for any signs of damage in the floor joists beneath (find out how to enhance floor joists) the sagging area.

If the foundation of the deck is damaged, it is advisable to replace all the major structural parts to protect the deck’s integrity and maintain its durability.

The durability and structure of the deck are important to support and hold the outdoor furniture properly. If you want to replace certain parts of the deck such as the ledger, you may need to replace the foundation and the joist with a type of material that can support the new component’s weight.

Look for wood crumbs and dark-colored areas on your joists. Decaying wood is eaten by the termites and if not removed immediately, termites can build a colony on your deck and make the situation even worse.

Check the deck for electrical wires or pipes near the joists. Cuts in the joists created to accommodate other structural elements may weaken the deck joists even when placed properly.

Alternative Solutions

You don’t have to spend hundreds of dollars to replace all the joists because of minor complications. Here are other actions you can do to save your deck.

1. Repair or Replace Selected joists

You can save a lot of time and money by repairing the damaged parts rather than replacing all the deck joists. If you noticed a small movement on the floorboard of the deck, try replacing the boards and some deck joists and tightening their fit. You can replace your joists with redwood or wood composites for better durability. If there is no major structural damage on your deck, consider doing this step. 

2. Remove and Install New Fasteners

Remove corroded nails and other damaged metallic fasteners on your deck to avoid the rust to transfer to other components.

3. Sistering

If some joists are damaged but are in good form, “sistering” can be used to repair the joists. Sistering involves the process of installing a temporary beam across the damaged joists and the floor frame is jack-up from below.

Guide for Deck Joists Replacement

Consider changing the material of your joist and switch to more durable material such as wood composites and other pressure-treated woods. If you’re hesitant to replace all the deck joists, ask a professional to further examine the existing deck structure so they can thoroughly inspect the sturdiness of the joists. They can suggest alternative solutions and recommendations so you would know the estimated cost of the overall construction.

Replacing a floor joist should be done by a professional, especially if the joist is not easily accessible from a basement or crawlspace because you might need to remove portions of the floor and subfloor to reach each troublesome joist. If you can access the joist from the basement easily and think you can remove and replace it yourself, wear protective clothing and install a good work light.

How to Protect Your Deck Joists?

1. Add a deck ledger flashing. This material will stop the moisture to spread on the ledger and the joists, preventing further complications.

2. Plan the construction of your outdoor space thoroughly. The joist’s structural integrity will degrade if it was cut or drilled incorrectly to install wires, pipes, or ducts beneath the floor. Plumbers, electricians, HVAC specialists, as well as homeowners, are known to cut more portions out of joists than is necessary, leaving the joists prone to structural failure.

3.  Proper maintenance. Inspect each component of the deck at least once a year to determine the issue before it spreads out to other parts. Washing the deck with mild detergent is an effective and safe way to clear the debris from the deck.

4. Weatherproofing the deck. Adding seals and painting the materials will prolong the durability of your deck and will help to prevent mildews. 

5. Avoid putting materials on the deck that absorbs or have moisture. Do not put plants on any wooden components and avoid putting water pipes on the deck to protect it from moisture build-up, insect problems, and fungi infestations.

That’s the end of our guide about deck joists replacement. We hope that this blog will help you to decide whether you should replace the deck joists or repair them instead. Remember, if major structural members are damaged, don’t hesitate to replace all the deck components.

Editorial Contributors
avatar for Matt Greenfield

Matt Greenfield

Matt Greenfield is an experienced writer specializing in home improvement topics. He has a passion for educating and empowering homeowners to make informed decisions about their properties. Matt's writing focuses on a range of topics, including windows, flooring, HVAC, and construction materials. With a background in construction and home renovation, Matt is well-versed in the latest trends and techniques in the industry. His articles offer practical advice and expert insights that help readers tackle their home improvement projects with confidence. Whether you're a DIY enthusiast or a seasoned professional, Matt's writing is sure to provide valuable guidance and inspiration.

Learn More