FixItCity.com

Outdoor & exterior

How to fix a loose deck board

A deck board that rocks or a nail head sticking up is a trip hazard, but usually an easy fix. While you are down there, check for rot, because that is the part that matters most.

Updated · 7 min read

  • DifficultyEasy
  • Time30 minutes to 2 hours
  • If you need helpHandyman

Wood decks move. Boards soak up rain, dry out in the sun, and swell and shrink with the seasons. Over the years that motion works nails loose, so you get a board that wobbles underfoot or a nail head sticking up, ready to catch a bare foot.

Fixing a loose board is usually simple: pull the old nails and drive deck screws, which grip much better. The more important job is checking why the board came loose. If the wood under it is rotten, a screw will not help, and rot in the wrong place can make a deck unsafe.

Plan on about 30 minutes to re-screw a few boards, or an hour or two to replace one.

What you'll need

Shopping links may earn us a small commission at no cost to you. Disclosure.

See the toolbox for our recommended starter tools.

First, check for rot

Before you add a single screw, find out whether the wood is still sound.

  1. Probe the loose board. Push a flathead screwdriver into the board near the loose fasteners and at the ends, where rot often starts. This Old House says that if the screwdriver sinks in more than about 1/4 inch, or the wood feels spongy or crumbles rather than splintering, it is likely rotten.
  2. Look underneath. If you can safely see under the deck, probe the joist the board sits on, especially the top edge. Fine Homebuilding suggests probing joists, beams, posts and the ledger, mainly where wood stays damp.
  3. Decide. Solid board and solid joist: re-screw it. Rotten board, solid joist: replace the board. Soft joist, post or ledger: stop and call a pro.

Replace popped nails with screws

  1. Pull the old nails. Work a cat's paw under the nail head and lever it out. Set a scrap of wood under the tool so you do not dent the board next to it.
  2. Drill pilot holes. Next to the old nail hole, drill a small pilot hole through the deck board. This keeps the board from splitting, especially near the ends.
  3. Drive the screws. Drive a deck screw through the board into the center of the joist, so the head sits just flush with the surface. Use two screws at each joist, as the other boards do.
  4. Check the rest. Walk the deck and look for other raised nails or wobbly boards. Fixing them all at once saves you another afternoon.

Replace a rotten or split board

  1. Remove the old board. Pull the nails or back out the screws. Pry the board up gently, using scrap wood to protect the boards beside it.
  2. Inspect the joists. With the board off, you have a clear view. Probe the tops of the joists. If they are soft, stop here and call a pro.
  3. Cut the new board. Measure, cut it to length, and treat the cut ends with an end-cut sealer if it is pressure-treated wood.
  4. Match the gaps. Set the new board with the same gap as its neighbors so water can drain.
  5. Fasten it. Drill pilot holes near the ends and drive two deck screws into each joist.

Composite decking

Composite boards often use special screws with color-matched plugs or hidden clips. Trex says to install a replacement the same way the original was fastened, and to follow its installation manual for screw placement and gaps. Using the wrong fasteners can cause problems with the boards, so check the maker's instructions and your warranty before you start.

When to call a pro

Stop and call for help if you find:

  • Soft, rotten or cracked joists, beams or posts.
  • A ledger board (the board fastened to the house) that is rotted, held with nails only, or pulling away. Fine Homebuilding notes ledgers must be bolted or screwed to the house.
  • Railings or balusters that wobble when you push on them.
  • Rusty or missing hardware such as joist hangers.
  • Sagging, bouncing or swaying, or stairs that feel loose.
  • Holes or sawdust that suggest insects.

Codes and permits vary by city and county, and structural deck repairs often need one. Renters should report deck problems to the landlord rather than fixing them. A handyman can handle boards and small repairs. For structural work, look for a licensed deck builder or contractor. Not sure? Try the fix-or-call quiz.

Keep it from happening again

  • Walk your deck each spring and fall, probing board ends and joists. Add it to your fall maintenance checklist.
  • Keep the gaps between boards clear of leaves and dirt so water drains.
  • Clean and reseal wood decks as the stain or sealer maker recommends.
  • Keep planters and furniture from trapping water on the boards.

Common questions

Should I just pound the popped nails back in?

That works for a little while, but nails that have backed out once usually do it again. Pull them and drive exterior deck screws instead, which hold much better as the wood swells and shrinks.

What kind of screws should I use on a deck?

Use screws made for outdoor decks and rated for pressure-treated lumber, such as stainless steel or coated deck screws. Fine Homebuilding notes these resist corrosion better than plain galvanized screws in treated wood. For composite decking, use the fasteners the decking maker specifies.

How can I tell if a deck board is rotten?

Push a flathead screwdriver into the wood, especially at board ends and near fasteners. This Old House says that if it slides in more than about 1/4 inch, or the wood feels spongy or crumbles instead of splintering, it is likely rotten.

Do I need a permit to fix my deck?

Swapping a board or two usually does not, but rules vary by city and county. Replacing joists, posts, the ledger or railings, or rebuilding a deck often does. Call your local building department if you are unsure.

Sources

Related