You’re not sure how or when it happened, but you’re now the sad owner of a saggy deck.
It might be that just one section is sagging, or maybe the entire deck is looking warped.
Whichever situation you find yourself in, one thing’s for certain — it’s time to restore your outdoor living space back to its original glory.
In this article, you’ll discover the factors that could be causing the issue in the first place and four possible solutions for how to fix a sagging deck.
Table of Contents
- Is There a Difference Between a Sinking and a Sagging Deck?
- What Are Some Issues That May Cause Sagging in a Deck?
- 4 Possible Solutions for How To Fix a Sagging Deck
- Frequently Asked Questions on How To Fix a Sagging Deck
- Three Rivers Custom Decks Can Build a Sturdy, Reliable, and Beautiful Deck for Your Portland Area Home
Is There a Difference Between a Sinking and a Sagging Deck?
Yes. There is a difference, however, the problems of sinking and sagging are often related.
If the frame or footings are built on soil that isn’t compacted, the weight of the deck can cause it to sink into the ground and become less stable. Whether your deck is sinking or sagging, consider adding support posts to the existing deck first. If this does not work, your team of trusted professionals can help you find a different solution to this common problem.
A sagging deck may be related to issues such as:
- Expanding or contracting lumber
- Rotting wood; or
- Improper weatherproofing
What Are Some Issues That May Cause Sagging in a Deck?
Sagging decks may be caused by a variety of issues ranging from:
- Unstable deck footings
- Poor choice of lumber; or
- A sagging frame
If it was built properly and the problems aren’t too bad, it’s usually a fairly simple process to fix and reinforce a deck. For those that are in especially poor shape, however, it may be necessary to call a reputable company like Three Rivers Custom Decks to replace the deck in its entirety.
At Three River Custom Decks, we specialize in making even the most complicated deck projects look easy. Whether you opt for a waterproof deck or a hardscape surface, our talented design team will create an outdoor space you’ll be proud to call home.
The Deck Footings Not Being Stable
The most common reason for a sagging deck is related to footings settling down into the dirt. They may be just beginning to sink or have already settled. If this is the case, the deck can be outfitted with temporary support and the supporting posts replaced to bring it back to level.
The Type of Lumber Used
If the deck is sagging due to issues with the lumber, it can get a little more complicated. In this scenario, you may have to replace an entire beam or several joists.
The sagging may be caused by the boards or materials that make up the deck’s framing. Sometimes the builder may have used softwood, like hemlock. We find this to be a common problem in the Portland area. The issue is that hemlock (or another softer type of wood) can expand and contract. If a joist shrinks more than the one next to it, you’ll be left with little waves that look like sagging.
At Three Rivers Custom Decks, we use laser technology to ensure that the top of the surface the deck will be going on is completely flat. We also frame with Douglas fir, which is a dense, stable lumber, so you won’t have to worry about dealing with shrinking and swelling.
A Sagging Frame
If you put off maintaining your deck for too long, you may discover that the boards have begun to warp and sag. This can occur when your deck is not properly weatherproofed. You’ll need to act promptly if your decking planks begin to warp and flex for any reason.
If you notice sagging in the frame of your deck, you’ll want to take action as soon as possible by following these steps:
- Stay off the deck.
- Never test the integrity of a deck whose frame appears to be compromised by yourself.
- Call a professional to look at the deck. They’ll be able to determine whether it can be repaired or if you’d be better off opting for replacement.
4 Possible Solutions for How To Fix a Sagging Deck
Fixing a sagging deck the right way can be complicated, and it’s important for decks to be safe and up-to-code. For this reason, we don’t recommend doing a DIY deck fix. However, here are a few ideas of solutions a professional might implement to fix the problem.
If you decide your deck is damaged beyond repair, consider contacting Three Rivers Custom Decks for a free quote for the installation of a new deck.
#1: Check and Repair Loosened Ledgers
A ledger deck support is created from a long, horizontal pressure-treated board that’s directly connected to your home. It is then attached to each floor joist by a metal hanger. Generally, when a deck collapses, it is either due to a ledger that was incorrectly attached to the house or that has been compromised by corrosion.
To keep water from seeping behind the ledger and causing damage, a continuous metal flashing should be installed that runs down the entire length of the ledger. It’s also critical for the flashing to continue to run behind the siding so that it overlaps the upper edge of the ledger. If this is missing from your home, it can be easily added.
You’ll also need to confirm the ledger is not simply fastened to the plywood sheathing. Rather, it should be securely attached to all sides of the house with lag screws or carriage bolts spaced in 16 to 24-inch increments. A badly damaged ledger should be replaced.
#2: Align Any Cracked Piers
The majority of raised decks are built on vertical wood pillars or piers that extend down into concrete-filled holes or rest on concrete piers.
Double-check the condition of the concrete to be sure it’s free of cracks and crumbling. It is also wise to measure the diameter of each pier to ensure it is three times the post’s width.
The most common supports for an on-grade deck built near the ground include poured concrete piers, concrete blocks, or bricks. You can easily determine the condition of the piers by using a flashlight to look underneath the deck. If any of the supports have broken, shifted, or sunk into the dirt, you’ll need to jack up the deck to make any needed repairs.
#3: Fix Sagging Joists
The beams and ledger board provide support for the floor joists and are typically spaced sixteen inches apart. Metal joist hangers are used to hold the ends in place.
Joists that have suffered water, insect damage, or breakage should be replaced. As you’re checking the integrity of joists, pay particular attention to splitting or rotting joist ends and joists that are excessively bowed or have begun to sag.
Follow these steps to fix a sagging deck joist:
- Remove the blocking from the joist.
- Remove the hardware from the joist hangers.
- Straighten the board by snapping a line and using a circular saw and a straightedge to cut the board.
- Smooth the board with a power planer or jointer.
#4: Cross-Braced Joists
A critical thing to keep in mind when jacking up a sagging deck is that you generally can’t apply jacks under two or three joists and expect it to be enough to lift the entire deck. Instead, you’ll need to install cross braces (two-by-fours work well) on the bottom of the joists spanning the length of the deck. Space the jacks at the same interval as the other supports.
Frequently Asked Questions on How To Fix a Sagging Deck
How Do I Fix My Sagging Deck?
It depends on what’s causing the problem. In some cases, adding new support posts or tightening up loose connections can help bring the deck back to level. If the issue is deeper — like unstable footings, rotted framing, or soft lumber — you’ll need a more thorough repair. The best thing you can do is have a professional take a look so you know exactly what’s going on before making any changes.
How Much Does It Cost To Fix a Sagging Deck?
That really depends on the extent of the problem. Small repairs, like replacing a few joists or securing loose boards, can be fairly affordable. But if the damage involves the structure itself — such as the frame or footings — the price will be higher. Every deck is a little different, which is why it’s best to get an inspection and a quote from a professional before deciding on the next step.
Contact Three River Custom Decks today for a free inspection and no-obligation consultation.
How To Stop a Deck From Sinking?
The key is a solid foundation. If your deck’s footings were built on soil that wasn’t compacted well or if water collects around the base, the ground can shift over time and cause the deck to sink. Keeping the area underneath well-drained and checking the supports once in a while can help prevent problems. If you notice sinking starting, it’s best to call a professional before it gets worse.
Should a Deck Shake When You Walk on It?
No, a sturdy deck should always feel solid, even when you are walking on it. If you notice some movement, it might be a sign that something in the structure isn’t doing its job anymore. Loose fasteners, weak joists, damaged materials, or aging connections could all be to blame. Even if the deck still looks fine, it’s always a good idea to have it inspected by professionals to make sure it’s safe to use.
Three Rivers Custom Decks Can Build a Sturdy, Reliable, and Beautiful Deck for Your Portland Area Home
Three Rivers Customs Decks is the Portland deck specialist.
Our team is committed to customer satisfaction — our #1 goal is creating a custom deck that you love and perfectly suits your purposes.
Whether you choose a beautiful natural wood, PVC, or composite option, we use only the highest-quality deck materials. Our services include:
- Outdoor living spaces
- Stairs; and
- Railings
Three Rivers Customs Deck’s crews are trained to work with you as the project unfolds to ensure the final result exceeds your expectations.
Discover the difference for yourself. Contact us today for your free, no-obligation quote.