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Guide to building a deck railing. Here we describe choices among types of deck railings, followed by explanation of how to build & connect the railing posts. Once our railing support posts are in place we describe how to attach the railing to the posts. Companion articles explain how to make or buy and install balusters to enclose the railing and how to make and install guardrails and handrails along stairs.
This article series describes construction details for decks and porches, including deck structure, floors, ledger boards, guardrails, stairs and railings.
From most vantage points, a deck’s railing is its most visible feature. While you may feel justifiably proud of the top-quality decking you bought and installed, it is the railing that will create the first impression of your deck for neighbors and passersby.
Yet, while railings are a significant visual component, they exist for the purest of functions— they keep people from falling off the deck, The need to build railings that can perform their safety duty necessarily restricts the design options that are available, but it certainly does not eliminate them.
You should focus on designing and building safe railings that will complement your deck while standing up to the bumps and bruises that are bound to come their way.
Watch out: building a deck guardrail or stair handrail that is not safe, not securely fastened, or not graspable is dangerous and can contribute to a deck or stair fall and serious injury. At the end of this article we provide additional technical references on stair and guardrail safety and codes.
Deck railings are generally made up of posts, rails, and balusters. But there are many potential variations on this basic theme. One decision you must make in planning for railings is what material or materials you will use. Then you need to consider how your building code will limit your choices.
Even where code issues are not relevant, it is still necessary to view with great caution any trade-offs between safety and aesthetics.
A railing on a low deck that is not likely to be used by children might call for a very different design choice than one on a high deck that is attached to a house where there are young children. But in all cases the design/build project must comply with building codes about guardrail and handrail location, placement, and strength.
Watch out: I inspected a property with a high deck and no railings whatsoever. The owner did not want to obstruct the view, and the local building official approved this non-compliant structure. Everything was fine until there was an injury. Having local permission from someone who was un-trained or inattentive did not prevent an injury nor its consequences. The code inspector decided he could exclude the deck from code compliance because it was "free-standing" and not attached to the structure. The subsequent eight foot fall was not ameliorated by this point of view.
The components of wood railings are usually readily available. You can even find decorative balusters, if that suits your fancy. You may need to visit a variety of stores and do some research online to see what is available to you.
Wood railings are the traditional choice for wood decks. They are affordable, easy to build, and time-tested.
Balusters can be attached directly to the rim or end joist. Railings are also often built with flat cap rails covering the post tops. Another, less rustic look can be created with railing sections installed between posts, with the post tops decorated by caps or with designs cut into them.
Manufacturers of composite decking products are increasingly offering matching railing components. Solid composites can be found in standard railing sizes and can be cut and installed much like wood. Some extruded tubular products allow you to snake wiring runs through the railing to supply lights.
PVC railing systems are also available from a number of manufacturers. The glossy, smooth surface is not likely to be mistaken for wood, but with the growing popularity of vinyl siding and composite decking, a PVC railing can look right at home on many decks. A PVC railing is bought and assembled as a system; you can find components sized to match conventional railings, such as 4 x 4 posts, 2x2 balusters, and more.
Similar systems are available in formulations other than PVC, including urethane foam, fiberglass, and other plastics.
Other Railing Materials
If you want to maximize the view from your deck, it is hard to beat clear acrylic or tempered glass panels like those shown here. Some manufacturers offer a post-and-railing system that can accommodate clear panels, matching balusters, or a combination of both. Stainless-steel cable is also great for viewing the scenery, although some building codes prohibit the use of such horizontal railing systems.
Railing posts are usually made from 4 x 4s, although you can use 6 x 6s if you prefer a heftier appearance. Decorative milled posts are available, but you can also install regular posts and cut your own decorative pattern, or add a separate cap or finial.
Space the posts no more than 6 feet apart; a 4- or 5-foot spacing will create an even stronger railing.
While operating within these guidelines, make an effort to keep the posts equally spaced along each side.
Posts should be bolted, not nailed, to the deck. To create a trimmer profile, railing posts are often notched to
fit over the decking and joist. This practice does weaken the post connection, however, and is prohibited by some building codes.
If you like the notched approach but are restricted by code, you may be able to notch 1 1/2 inches off 6 x 6 posts, but check with your building inspector before doing so.
Plan to keep a 2-inch gap between the house and the end post, which will make it easier to paint or replace the siding at a later date.
Railing posts need to be attached to the rim joist and the end joists, and the method varies slightly for the two types of joists. Blocking is often necessary at post locations to strengthen the structure; use joist stock for the blocking. Plan to use two ½ inch carriage bolts to attach each post unless your code says otherwise. Note that if access to the bottom of the deck will be difficult, you should plan to add the blocking before installing the decking.
Solid posts can be attached most easily to the outside of the joists. This approach allows you to finish the decking before having to worry about posts. But many people do not like the appearance of bulky posts hanging off the sides of their deck. With a little more planning, you can install solid posts inside the joists.
You will need to do so before installing all of the decking (and you may want to do it before installing any of the decking). Notched posts are usually attached to the outside of the joist, with the 1 ½ inch notch resting against the side of the joist and on top of the decking.
Properly planned and built, notched posts can produce a strong and attractive railing. The notch permits the post to be moved in closer to the deck by having the unnotched portion rest on top of the decking above the joist. Begin by cutting all posts to length, then follow the steps below for each one.
From the bottom of each railing post, measure up the joist depth plus the decking thickness, subtract 1/2 inch, and make a mark across the post.
Set your circular saw to cut exactly 1 1/2 inches deep. Make a series of closely spaced cuts between the line marked in Step 1 and the post bottom. You can also make these cuts on a table saw or radial arm saw.
With a hammer; knock out the pieces of cut wood. Use a chisel to clean out the notch. Work carefully to create a notch that is squarely cut and the same depth throughout; avoid gouging out too much with the chisel.
The exposed bottom edge of the post will look better if it is beveled. You can make this cut with a circular saw, with the blade tilted to make a 45-degree cut, but it will be easier to make a clean, accurate cut on a power miter saw.
The strength of the railing is determined first and foremost by the connection of the post to the deck frame. If the posts are plumb and evenly spaced, installing the rails and balusters will also proceed much more smoothly. For most railing styles, it is best to attach all the posts before assembling the rest of the railing.
The procedures for attaching posts are similar regardless of whether they are notched or solid, or going on the inside or outside of the joists. Be sure to add any needed blocking.
If the posts are going on the inside, however, you can skip the first step at right. Cut and support decking to fit around the posts.
If your decking overhangs the edge, you need to cut a notch so that the post can rest against the joist. For 4 x 4 posts, cut the notch about 3 3/4 inches wide, leaving a 1/2-inch gap between the decking on both sides. A jigsaw is the best tool for this job.
if you are using notched posts, set the post in place with the top of the notched portion resting on the decking. With solid posts, you will have better luck having a helper hold the post in place. Use a level to ensure that the post is plumb. Drill pilot holes for each bolt, using a bit the same size or just slightly larger than the bolt diameter. To minimize the chances of splitting, do not locate the top bolt directly over the bottom one; instead, set each off-center just a bit.
Slide the carriage bolts through the pilot holes. Next, reach beneath the deck and behind the joist to place washers on the bolts, then tighten the nuts on the bolts using a socket wrench or an adjustable wrench.
Installing the Rails Between Deck Posts or Stairway Posts
The easiest way to install rails is to attach them on edge to the inside faces of the posts. Unless your deck is particularly long, you can probably accomplish this with a single board for each rail. A top rail and bottom rail are sufficient, but you may prefer to add a cap rail, which provides a flat surface along the top of the railing.
Somewhat more involved are rails installed on flat between the posts. Rails can be toenailed to the posts or attached with metal brackets designed for the job. This technique allows you to create decorative post tops and attach milled balusters between the rails, but keep in mind that the flat rails are not nearly as secure (when stepped on, for example) as rails set on edge.
Although it requires a bit of work, you can create a stronger connection by placing the rails in dadoes cut into the posts. Alternatively, you can install rails on flat, with a flat cap rail.
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