How to Replace Porch and Deck Railings

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How to replace deck and porch railings with composite, PVC, or wood railings and balusters.

Replacing the railing on your porch not only improves the safety and functionality, but it can also add to your home’s curb appeal. Consult with your local building and code department for specific rules and requirements for your location. Chances are you will need a permit and final inspection. A visit to local home centers and lumber yard showrooms will show you what is available and common in your area.

Porch and deck railings are required in most towns on any deck higher than 36", 24" in some places, above grade. Most building codes specify criteria for deck railings by characteristic and performance rather than material. The balusters should be close enough so that a 4" diameter ball cannot be pushed through the railing at any point. This prevents children from getting their heads caught in the railing. Consider these factors when purchasing railing material.


Take measurements of the old railings, and compare them to code requirements in your area. Use the information as you shop for new railings. Remove the old railings and any posts you plan to replace. If your railings are connected to structural support posts on a covered porch, you'll need to brace the roof with temporary supports, usually 4 x 4 posts or 2x8 joists can be used on an angle as long as they are securely staked to the ground. You may also need to replace or repair damaged wood on the porch decking or posts after you remove the old railings.

Measure the distance between posts on the porch or deck. Add about 4 inches to this length for cutting and adjustments.


You may want to consider man-made materials such as composites when shopping for new railings and posts. They are practically maintenance free and will not require periodic painting and sealing like wood railings. Some PVC and composite posts are actually covers for 4 x 4 pressure treated posts. Other post covers and railing assemblies are aluminum or steel.

PVC Deck Railing and Posts

Post and Rail Installation

Post Installation

If the old posts were attached to the porch framing, drill holes for 1/2 inch carriage bolts and install with washers and nuts. For concrete porches, you'll need a hammer drill, concrete lag bolts or bolts and anchors with appropriate mounting brackets. Keep the posts plumb during installation by checking frequently with a level.

Post sleeves slip right over 4 x 4 posts. Cut them to the right size, set them over the post and secure with supplied, color-matched screws. The post sleeve will probably wobble a little once installed; keep it level as you secure it with the screws.

If replacing wood posts that go through the decking remove the old post and bolt the new post to the floor joists of the porch or deck. It may be necessary to remove some decking to access the joists if there is no access from below. Use carriage bolts or lag bolts to secure the posts.

Railing Installation

Measure for the new upper and lower railings, cut and install railing brackets or "L" brackets and screws. The bottom opening between the lower rail and porch and the height of the upper rail must meet code requirements. Measure, mark and install both railings to stay within those requirements.

Typical Composite Railing Assembly

Baluster Installation

Install balusters with an even spacing or 4 inches maximum between the balusters. Calculate number of balusters and cut two blocks to match the spacing. The space on each end will probably be less than 4 inches, align the balusters so that you have equal spacing on each end. For example, if you have 7 inches of space left after all the balusters are installed; make each space 3 ½ inches, not 4 inches and 3 inches. Use the blocks to space the balusters during installation. Drill pilot holes and attach each baluster with two screws, one at the top and one at the bottom.

Calculating Spacing

To obtain an even spacing pattern take the width of one baluster and add 3-1/2 inches to it. Divide this number into the distance between the two posts, and round it to the nearest whole number. This is the number of balusters. Divide the distance between the two posts by the number of balusters, and you have the center-to-center spacing of each baluster. Simply subtract the width of the baluster from this number for the space in between balusters.

Railing Kits

Assemble railings and balusters prior to installation. Cut upper and lower rails equally on both ends by cutting half of the amount off each end. Round tubular balusters install over small balls screwed into the railings. Others fit into holes along the upper and lower rails.

Install the railing kits using blocks to hold the railing up. Drill pilot holes for the screws, and attach the rails to the posts with brackets. A long extension for your screwdriver bits will help drive those hard to get at screws in with the least amount of trouble.

Adding New Posts

If your deck or porch has a longer span than the railing kit you purchased, you will have to add an additional post. You may also want to add new posts to change the look of the porch or add structural integrity.

Mark Cut lines on the Porch Floor for a New Post

Measure the distance between existing porch roof supports or posts to determine if the porch railing stock will span the distance. If wooden railings are not long enough, center cut lines dimensioned for a new post halfway between the porch supports.

Create a New Opening for the Post

Drill a starter hole for a jigsaw blade within cut lines marked for the new railing post. Cut precisely along the rectangular cut lines with a jigsaw. Insert the post into the hole and rest it on a leveled brick or concrete paver placed on the ground.

Attach the Railing Post to Porch

Bore pilot holes into the framing with a right-angled drill, working from a position beneath the porch. Insert lag screws to attach the new post to the porch floor joists. Snug the lag screws with a socket wrench.

Making a Baluster and Railing with Wood Components

After cutting the top and lower railing, space balusters according to building code along the bottom porch railing. Lay out the pieces on a flat surface and screw through the underside of the bottom wooden railing into the center of the positioned balusters.

Set the bottom railing and baluster assembly upright and position the top railing after marking baluster positions. Adjust the balusters as necessary on the marks and drive two nails through the railing into each baluster to stop it from rotating.

Screwing railing assembly to posts

Secure porch railing units to posts with stainless steel or epoxy coated screws. First, position the piece of railing between posts, ensuring that it is level and doesn't bind. Drill angled pilot holes from each side of the rails and drive in screws.

Remove excess length from the new post top with a handsaw. Add a decorative cap and finial to top the new post and match any existing stair railing posts. Prime and paint the porch railings and the new post.


Deck Material Buying Guide