How Do You Replace Rotted Deck Boards, and What Does It Cost?

by the Berry team · Updated October 20, 2026

If you have a wood deck, replacing a few rotted or cracked boards is a manageable DIY job that often costs $15-$80 per board in materials, or about $300-$800 for a few boards with a contractor. Before you replace boards, check the joists, posts, and the ledger board where the deck attaches to the house, because rot there is a safety problem, not a cosmetic one.

What deck repairs cost

Ranges are typical US prices. Composite and tropical hardwood boards cost more than pressure-treated pine.

Repair	When it fits	DIY cost	Pro cost
Replace a pressure-treated deck board	One board is cracked, soft, or splintering, and the joists below are solid.	DIY$15-$40 per board	Pro$300-$800 for a few boards
Replace a composite deck board	If you have composite decking: a cracked, scorched, or damaged board.	DIY$40-$80 per board, if you can match it	Pro$300-$900 for a few boards
Flip a weathered board	The top is worn or cupped but the wood is sound. The underside is often in good shape.	DIY$0-$20 for new screws	Pro$150-$400
Sister or replace a rotted joist	A screwdriver sinks into the joist, often at the top edge under board seams.	DIY$30-$100 per joist, if you are experienced	Pro$300-$1,500
Clean and seal or stain	Slows weathering and water absorption. Typically every 2 to 3 years for wood decks.	DIY$100-$300 in materials	Pro$800-$2,000 for a typical deck
Repair a ledger or post problem	The deck pulls away from the house, posts are rotted at the base, or the deck sways.	DIYNot a DIY job	Pro$1,000-$4,000+, more if the deck needs rebuilding

Ranges are typical US prices and vary with your region, your home, and the season. A pro quote for your exact job beats any range.

Rot or just weathering?

Gray, rough, or slightly cracked boards are usually just weathered, and cleaning and sealing will help them. Rot is different. Push a screwdriver into the wood: if it sinks in easily, the wood is soft and spongy, or it breaks off in wet chunks, that board has rot.

Check board ends and seams. Rot usually starts where boards butt together and water sits.
Check under planters and mats. Anything that holds water against the wood speeds up rot.
Check the joists. Look from below with a flashlight. Probe the top edges of joists under board seams.
Check the posts at the ground. Posts rot where they meet soil or concrete. See fence post rot for the same pattern.
Check the ledger board. Where the deck attaches to the house. Look for gaps, rust streaks, soft wood, or missing flashing above it.

How to replace a deck board

Remove the fasteners. Back out the screws, or pry up nails with a cat's paw or flat bar. If the board is rotted, it may come up in pieces.
Check the joists underneath while the board is off. Replace or sister any that are soft before going further.
Cut the new board to length. If it does not span the whole run, make sure each end lands on the center of a joist.
Match the gap. Use a nail or spacer to keep the same gap as the neighboring boards for drainage.
Fasten it with two exterior deck screws at each joist. Pre-drill near the ends to avoid splitting.
Seal the cut ends of pressure-treated lumber with an end-cut preservative.

When it is a safety issue

Deck boards carry people, but the joists, beams, posts, and ledger carry the deck. A rotted board can make you trip. A rotted ledger or post can let the deck fall. If the deck feels bouncy or sways, has gaps where it meets the house, or has soft posts, stop using it for gatherings until a contractor or inspector looks at it.

The ledger board is the most common failure point. It should be bolted to the house, not just nailed, and covered with flashing so water runs away from the joint. If you see rust streaks, gaps, or soft wood there, get it checked.

Making boards last

Sweep leaves and debris off regularly, especially in fall.
Clean and reseal wood decks every 2 to 3 years, or when water stops beading on the surface.
Move planters and furniture periodically, and use planter stands that let air under them.
Keep gutters and downspouts from dumping water onto the deck. See gutter cleaning.

When to call a pro

The ledger board is soft, gapping, or pulling away from the house.
Posts are rotted at the base, or the deck sways or bounces.
Several joists are rotted, not just one.
Railings are loose. Railings carry a lot of force if someone leans or falls on them.
The deck is high off the ground, where a structural failure would be serious.

What makes it worse if you wait

Rot spreads from boards into joists and from joists into beams, turning a board swap into a framing repair.
A soft board can break under someone's foot.
Rot at the ledger or posts can lead to a collapse, especially with a crowd on the deck.
Water getting behind a failing ledger can rot the house framing it is attached to.

Common questions

How much does it cost to replace deck boards?

Materials often run $15-$40 per pressure-treated board and $40-$80 per composite board. A contractor typically charges about $300-$800 to replace a few boards, more if joists underneath need repair.

Can I replace just one deck board?

Yes. Remove the screws or nails, check the joists below, cut the new board so its ends land on joists, keep the same gap as the neighbors, and screw it down. The new board will look different until it weathers.

How do I know if my deck is rotted?

Push a screwdriver into the wood. If it sinks in easily, the wood feels spongy, or it breaks off in wet chunks, it is rotted. Check board ends, joist tops, posts near the ground, and the ledger where the deck meets the house.

How often should a wood deck be sealed?

Every 2 to 3 years for most wood decks, or when water stops beading up on the surface. Decks in full sun or harsh climates may need it more often.

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