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Repairing Decks and Railings

Updated: Jun. 30, 2017

Expert fixes for common problems

FH04APR_DECKRE_01-2Family Handyman
Easy fixes for common deck problems like rotten boards, wobbly railings and loose nails. Plus, see how to stiffen a bouncy, wobbly deck

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A full day

Replace broken deck boards

Photo 1: Cut out the bad board

Draw a square line on the decking to one side of a joist below. Cut the deck board with a jigsaw. Pull the decking nails with a cat’s paw.

Photo 2: Add cleats to support the new board

Predrill three clearance holes in two 16-in. treated wood cleats. Apply construction adhesive, hold each cleat tight to neighboring deck boards, and screw one to the joists at each end of the repair.

Photo 3: Install the new board

Cut the replacement board to length. Then tap it into place with a hammer and a wood block. Predrill pilot holes and drive a pair of 2-1/2-in. deck screws (or galvanized nails) into each cleat. Fasten at all other joists as well.

You don’t have to let a split, rotted or otherwise ugly deck board ruin the appearance of your deck. Simply replace it and in a year or so the replacement will blend right in.

You usually don’t have to replace an entire board. Just make sure to cut out a piece that spans at least three joists. The remainder should be at least that long. And don’t hesitate to cut out a little extra to keep adjacent decking joints staggered for better appearance.

The most difficult part is cutting out the damaged section cleanly (Photo 1). Don’t try to cut directly over a joist. Instead, cut to one side and screw on a cleat to support the new decking. It’s a fairly hefty cut for a jigsaw, so use a sharp, stiff blade to keep your cuts as straight and smooth as possible.

Predrill screw holes in the cleats so they pull tight to the joists (Photo 2). Also pull up on them so they butt tightly against the decking on each side as you screw them in.

Cut the new deck board from matching material, both in thickness and wood type. It’ll look different initially, but it’ll blend in after a year or so, especially if you clean and reseal or stain your deck. Cut the new deck board to fit snugly, then screw or nail it into place (Photo 3).

Strengthen wobbly posts

Photo 1: Drill bolt holes

Drill two 1/2-in. holes through the post and framing. Offset the holes to prevent splitting the post. Angle the hole to avoid joist hangers.

Photo 2: Drive in the carriage bolts

Tap in 1/2-in. carriage bolts, shim if necessary to plumb the post, and install washers and nuts. Tighten the nuts until the bolt heads are set flush to the post.

You don’t have to live with loose, wobbly railing posts when a couple of bolts will make them safe and solid. Measure the thickness of the post/framing assembly, add 1 in. and buy 1/2-in. diameter galvanized carriage bolts that length (plus a nut and washer for each) from any hardware store or home center.

Drill the 1/2-in. clearance holes well apart, one about 1-1/2 in. from the top of the framing and one about 1-1/2 in. up from the bottom of the post (Photo 1). You may have to angle the holes slightly to avoid joists, framing anchors or other obstructions. If your drill bit isn’t long enough to go through the post and framing, get a long spade bit. Versions up to 16 in. long are available at home centers and hardware stores.

Most posts are held fairly plumb by the railing, but check them anyway with a level and tap in shims to straighten them if necessary. Don’t over-tighten the bolts; the heads will sink deep into soft wood without much effort.

Stiffen a bouncy deck

Photo 1: Tap in snug-fitting blocks

Snap lines for blocks every 3 to 4 ft. along the joist span. Measure and cut the blocks to fit tightly. Tap them into place in a staggered pattern.

Photo 2: Nail blocks in place

Square each block to the joist and drive three 16d galvanized box nails through the joists into each end of the block. Repeat for each row.

A deck that bounces when you walk across it won’t feel strong and solid, even if it meets structural requirements. The cause is usually long joist spans between beams or between a beam and the house.

To stiffen a deck, you have to be able to get to the framing underneath. You can add another beam, along with posts, to support the joists. However, this is a big job. We recommend that you first add rows of solid blocking every 3 to 4 ft. along the span (Photo 1). Run the first row down the middle of the span, check the deck for bounce, then add rows to further reduce it.

Use treated lumber blocking that’s the same size as the joists (usually 2×8 or 2×10). Install the blocking in rows along a chalk line snapped at a right angle to the joists. You’ll have to measure and cut each block separately to get a snug fit, since the joists are never exactly the same distance apart. Staggering the blocking in a step pattern (Photo 2) allows you to easily drive nails from both sides, rather than having to toenail.

Replace loose, popped nails

Photo 1: Start with a diagonal cutter

Grab slightly protruding nails directly under the head with a diagonal cutter. Roll the cutter back onto thin blocking to pry the nail up slightly.

Photo 2: Yank the nail with cat’s paw

Tap the claw of a cat’s paw under the nailhead and lever the nail up. Finish pulling with a hammer or pry bar. Protect the deck board with a shim or thin block.

Photo 3: Replace the nail with a screw

Stand on the deck board to hold it down. Then drive a 2-1/2 in. deck screw down into the old nail hole. Set the screwhead flush to the surface.

Decking swells and shrinks as it goes through repeated cycles of wet and dry seasons. This frequently causes nails to loosen and pop up above the deck boards. You can drive them down again, but chances are that’s only a short-term solution. They’ll probably pop up again after a few years. The long-term solution is to remove the popped nails and replace them with deck screws.

The trick is to pull the old nails without marring the decking. Always use a block under your prying tool (Photos 1 and 2). And work on tough-to-get-out nails using several steps. A diagonal cutter works well for nails that only protrude slightly (Photo 1). The slim jaws can slip under the head. You’ll only raise the nail a slight amount, so you may have to repeat this process two or three times. Once the nailhead is high enough, you can grip it with a cat’s paw or hammer claw without marring the deck board (Photo 2). Be sure to use thin wood blocks to protect the decking. Minor dents will disappear when the wood swells after the next rain.

There’s no need to drill a pilot hole if you send the screw down the old nail hole. However, one drawback of screws is that their heads are larger than nailheads and can be unsightly. We recommend that you buy deck screws in a color that most closely matches the aged decking.

Solutions For Stubborn Nails

If the head breaks off a stubborn nail and you can’t get it with a pry bar, try pulling it with locking pliers. Grip the nail tip and roll the pliers over to get it going. If the nail shank breaks off, don’t worry. Just drill a pilot hole beside the nail and drive a screw. The screwhead will cover the nail.

Take out the sway with an angle brace

Photo 1: Add diagonal bracing

Cut and nail a treated 2×4 diagonally from corner to corner under your deck. Drive two 16d galvanized nails at each joist.

Some otherwise solid decks tend to sway or wobble as you walk across them, especially decks resting on tall posts 4 or more feet above the ground. Angle-bracing the posts is one good solution to this problem, but the braces often look tacky. Instead, install an angle brace underneath your deck. It’s a virtually invisible fix that all but eliminates sway.

If your longest 2×4 doesn’t span the entire distance, don’t worry. Add a second one starting from the other corner and run it back alongside the first, nailing it to at least two of the same joists. Have a helper hold the 2×4 in place while you drive the first nails. Driving 16d galvanized nails upward will give your hammer arm a workout!

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Cat's paw
  • Caulk gun
  • Chalk line
  • Circular saw
  • Corded drill
  • Drill bit set
  • Hammer
  • Jigsaw
  • Pliers
  • Safety glasses
  • Square
  • Tape measure

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.

  • 2x4s
  • 2x8s or 2x10's
  • Carriage bolts
  • Construction adhesive
  • Deck boards
  • Deck screws
  • Nails