When you are required to have one
Under the 2018 IRC, which Pocatello has adopted, a guard goes on any open side where the surface is more than 30 inches above the floor or grade within three feet horizontally of the edge. A ground-level platform under that height can be an open edge. A walkout deck, six to nine feet up, is guarded on every open side, and the stairs are guarded too.
On the flat deck the top of the guard is at least 36 inches above the walking surface. Along the stairs the 2018 IRC measures from the line of the nosings and the minimum is 34 inches. A handrail is a separate piece: graspable, and set between 34 and 38 inches. People use one word for both. The inspector does not. Openings in the guard have to be tight enough that a 4-inch sphere cannot pass. On stairs the code allows a slightly larger sphere in specific places. Build to the adopted code and let the inspection confirm it, especially if a local amendment is in play on a covered deck.
Where railings actually fail here
The balusters are what you notice. The failure is usually the post. A guard has to resist a person falling against the top rail — the IRC design load is a 200-pound concentrated force at that rail, from any direction. Screws driven down through the decking boards into the joist ends will not carry that. The post needs to be bolted through the rim joist, so the push goes into the frame.
Two details show up on older Pocatello decks. The post is face-screwed to the outer joist and nothing more. Or the post is notched so it hangs on the rim, which cuts away the section of wood that has to resist the push. Either one feels acceptable the day it is built. A few seasons of weather, or one person stumbling, and the rail moves in your hand. A railing you can shift by pushing is a repair, particularly on an elevated deck. How to tell that from a cosmetic problem.
Wood, composite, aluminum, cable
The structure is the post connection. The infill is a price and a maintenance choice.
- Wood is the budget guard and the one that matches a pressure-treated deck. It weathers in this sun the way the deck boards do, and it wants the same finish schedule. About $30–$50 per linear foot installed.
- Composite matches a composite deck and drops the staining. It is bulkier than metal, so it blocks more of a view. About $45–$90 per linear foot, overlapping aluminum.
- Aluminum is a thin metal frame, usually black, bronze, or white. It takes the sun well in a dry climate and it keeps the view. Same broad band as composite, about $45–$90 per linear foot.
- Cable is the view railing, which is why it comes up on the Bench and on canyon lots. The posts and the anchors are the cost, and the cables have to be tensioned tight enough to pass the 4-inch sphere, then re-tensioned later when they relax. About $60–$120 per linear foot. Horizontal runs are easier for a child to climb. Ask the inspecting department before you commit to cable on a family deck.
Those are regional installed ranges from Idaho and Treasure Valley price guides, for planning. A Pocatello bid in writing replaces them. A raised 12 by 16 with the house side open is about 44 feet of guard before you add the stair rail. Near the middle of the bands, that stretch is roughly $1,800 in wood and $3,000 in composite or aluminum. The stair rail on a walkout is additional footage, and it is easy for a low bid to leave it vague. Where railing sits in the whole deck budget.
A composite deck with a wood guard and a composite top rail is a common way to keep the expensive line short. It is a reasonable save if you will maintain the wood. It is a poor save if the reason you bought composite was to stop maintaining a finish.
Replacing a railing on an old deck
If the deck is level, the posts are plumb, and the ledger is solid, a new guard on the existing frame is a straightforward project. The new posts still have to bolt through solid rim material. While the old rail is off, probe the rim. Soft wood means the frame needs a repair before a new rail is worth fastening to it.
Surface railing replacement is often outside the permit requirement. Once posts, rim, joists, or the ledger are being replaced, you are in structural work and a permit generally applies. The line between the two.
Common questions
How tall does a deck railing have to be in Pocatello?
Pocatello builds under the 2018 IRC. A guard is required where the drop is more than 30 inches, measured within three feet of the edge. On the deck itself the guard is at least 36 inches high. Beside the stairs it is measured from the nosing, and the 2018 IRC minimum there is 34 inches. Openings have to stop a 4-inch sphere. The inspector is who measures it.
Can I replace just the railing?
Often, and it is the right job when the frame is level and solid and the posts or the balusters are what failed. Feel the rim joist the posts connect to. If that wood is soft, the railing job has become a framing repair. Push the existing rail hard before you price it as a surface project.
Are cable railings allowed?
The 4-inch sphere rule still applies, so the cables have to be tensioned and they have to stay tensioned. Horizontal cables are easier to climb than vertical balusters. Departments differ on whether they care. Ask the office that will inspect the deck — Pocatello, Chubbuck, or Inkom — before you buy a cable kit for a deck children use.
What does a deck railing cost in Pocatello?
For planning, wood guards run about $30 to $50 per linear foot installed, composite or aluminum about $45 to $90, and cable about $60 to $120. Those are regional installed ranges from Idaho and Treasure Valley price guides, and a written local bid replaces them. A raised 12 by 16 with three open sides is about 44 feet of guard before the stairs.