Railings: Define your deck style and guard your safety

Composite black railings

This article on railings is one in a series starting with ​​planning and building a deck. In this 3rd installment you will learn when railings are required, what building codes are important, the types of railings available, some railing terminology and finally we will take you through the steps of building a wood railing.

There are many types of railings to choose from, the more traditional, low cost wood railings to the fancier aluminum, composite, glass or any combination of these products. 

It is difficult to drive a city block without seeing a railing code infraction. These railings not only detract from the house but provide a significant safety hazard. Let’s do it right the first time. Why not contact your local deck designer for some free advice here!

As we mentioned before, a deck project can be quite overwhelming, the easy home renovation planner tool that is part of your free quinju.com subscription will help ensure you are on top of things at all times by collecting everything and anything about your project in one place it is like having your home renovation binder in your pocket anytime, anywhere!

stone faux railing posts

Articles on covered porches and stairs will be next in this series, so register now!

The 5 most common code questions related to deck railings!

Understanding these code questions means you are 90% of the way to having a code compatible railing. Not all decks require railings, however if you choose to install a railing it must comply with code.

Interpretation of national codes differ greatly by region, make sure you check with your local building department for their requirements.

1. What determines if I need a railing? The height between your deck surface and the common grade, determines if a railing is required.

diagram showng railing dimensionng

a. North of the 49th parallel (Canada eh!) more than a 24” elevation change between grade and deck surface requires a railing.

b. South of the 49th parallel generally a railing is required when there is 30” or more between deck surface and grade.

2. What height must a railing be? In both Canada and the United States, if railings are required or you choose to install one, railings must be 36” tall with the exception of the state of California where 42” railings are required. In Canada if a deck is above 5’10” then a 42” railing is required.

Understand, there is a difference and you should always check with your local building department.

3. What is the 4” Rule? A 4” sphere shall not be able to pass through any portion of the railing (guard). The 4” rule is common to a majority of building codes across North America and is a safety mechanism for kids. There is an exception to the 4” rule around stairs but we will deal with that in future articles. Another child safety requirement is that balusters often called pickets cannot be installed in a way that provides a climbing apparatus. A horizontal baluster looks like a child’s playground so climbing is inevitable.

4. How is a handrail different than a railing? Handrails are designed for grasping when navigating stairs and may be required when there are more than 3 risers in a set of stairs. Railings or guards are designed as a barrier to prevent falls from one level to another. Grasping of a handrail typically has codes limiting handrail dimensions and profiles. Again check local code as there may be different interpretations.

composite black cap rail

5. Why does the building code focus on Post attachment? Generally the guard rail design must be able to withstand load to restrain people during an accidental fall against the railing. Most codes limit the distance between posts to 6’ to meet the requirement to restrain people during accidental trips.

Manufactured railings go through substantial testing and qualifications to meet standards, it is critical to read and understand the INSTALLATION instructions provided by manufacturers.

Often building departments, at time of inspection, want to see the manufacturer’s installation specifications so make sure you follow them and keep them for inspection. Read about how you can go beyond what is required by building codes!

Codes in a nut shell

1. Building codes may be based on National Codes but regional interpretations do apply, seek details from your local building department before starting your project.

2. Read and comply with installation instructions of manufactured railings.

3. Railings and hand railings are taken seriously by building departments, do it right!

4. Measurements to remember;

a. United States- 30” from grade 36” high (exception California 42”)

b. Canada- 24” from grade 36” high (exception when above 5’10” it is 42”)

4 parts to all railing systems

Each element of a guard rail is part of the overall assembly which is designed to protect you and your guests.

1. Posts- Structural element that needs to support 200-225lbs of load. Attachment to the deck is critical. Guard rail post brackets are an engineered angle bracket installed to the joist with carriage bolts running to front side of post, these brackets are a must, in getting proper connection of wood railing posts

Often composite railings use a 4X4 wooden post with a sleeve to match the railing system.

Glass railing www.quinju.com

A preferred way to install safe posts is to install them inside the fascia board sandwiched between blocking. This install technique requires more planning as posts need to be installed prior to decking, but provides a much stronger post connection.

2. Balusters- Need to withstand force and need to be spaced to stop a 4” sphere from passing through.

3. Top and Bottom Rail- These horizontal pieces provide a framing and attachment point for balusters. The bottom rails needs to be within 4” of the deck surface.

4. Railing Cap- Railing Caps are the finish element to a railing they provide structural support to all the elements and make a great place to sit a drink.

Wooden Railing, made safe and easy!

Local code requires a 36” high railing on the deck we framed in the previous article as it is 29” from finished grade.

As a recap the deck was built with 2X6 joists 16”O.C. with a 2X8 fascia board. The deck boards used were 5/4 board or 1-1/4” thick. These dimensions are important to determine the cut length of the posts.

Post length Calculation;

Required height - Top rail + Deck boards + Joists= Post length

36” - 1.5” + 1.25” + 5.5” = 41.25”

Cut all posts to 41-1/4”. Give the posts a quick sanding to remove any rough areas.

Blocking for post installation was installed during framing, quick recap;

Where posts were going to be installed (every 6’-0” max.) a piece of 2x6” blocking cut to 14-1/2” was installed between joists, 3-1/2” from the inside face of the fascia board. A second 3-1/2” long block was installed perpendicular to fascia and parallel to joist.

You have basically created a structural pocket for the post and provided backing for deck board installation.

how to install deck railing posts

Slip the cut and sanded deck posts into the pocket flush to the bottom of the joist. Use a level, clamp in place before drilling holes. Pilot holes need to be snug to the shaft of the carriage bolt for proper post installation.

A good technique is to use 2 long Carriage bolts and install them through the fascia board and blocking secured in place with washers and bolts.

Local code requirements should have been investigated during the planning stages.

Time to install the top and bottom rail.

Notching of posts is not a good idea and placing screws at an angle to secure the rail only permits water penetration, we like to use metal 2x4 hangers. Black decorative hangers are found at most building supply stores, they work and look great.

bottom rail of deck rail

Install the hangers so there is less than 4” from the bottom of the hanger to the deck surface. Using a block of post material works great to set a good height well within code requirements.

Measure the distance between the inside plate of hangers, accuracy is important here! Prior to securing the rails take the time to give them a light sanding removing rough edges.

The Balusters we use on this project are simple 2X2’s. Measure the distance between top and bottom edges of the rails for baluster cut length. A 30 degree cut on the bottom edge, if not at time of purchase, adds a finished look.

The Baluster will be secured with two screws top and bottom. Pilot holes with countersink will help to eliminate cracking when securing balusters. Take the time to do a brush sand prior to install. An assembly line with a friend help makes this process quick.

Mark center less ¾” between posts on the top and bottom rail. Install the first baluster flush to the top rail and on the top and bottom line. Install all other balusters working towards each post. A 2x4 spacer works well to set balusters well within code requirements of 4”.

The rail cap is not required by code, but adds a decorative finish to a railing and ties all members together for improved strength. 12’ lengths of 2x6 are used to span over two sections of railing that were set 6’-0 apart. The rail cap is screwed down into the top of posts and into top rail through countersunk holes. A high quality exterior wood filler is applied to fasteners or any blemish where water could penetrate the wood. Sanding the rail cap is important to protect hands from splinters.

Guards on stairs follow a similar process however remember that guards are not necessarily handrails, this topic is covered in the next article on stairs and handrails here.

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One Thought to “Railings: Define your deck style and guard your safety”

  1. It made me chuckle how it was mentioned how railing caps make a great place to sit a drink. It’s so true, though. I think that getting the right type of railing for decking can make a good difference.


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