Photo of a residential deck construction(C) Daniel Friedman Guardrailing Post Specifications
Requirements & codes for guardrail posts on decks & stairs

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Guard rail & handrail strength requirements & strength testing requirements specified in various building codes & standards. This article provides details about standards, requirements & testing procedures for handrailings & guardrailings in or on the exterior of buildings.

Our page top photo shows an odd guardrail along a tiny walking space - the DIY owner-installer never considered that someone (a housepainter) might actually need the railing to be secure and functional. The result was a serious injury.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Guardrail Post Requirements

Deck balusters eliminate need for guardrail posts (C) Daniel FriedmanQuestion: are posts required in guardrailings or not?

20187/05/30 Martin Alper said:

You post a photo of a deck where the rail is supported by the balusters only. No Posts. Do the codes allow this?

This Q&A were posted originally at DECK & PORCH GUARDRAILINGS

Reply: posts are not necessarily required in guardrailing construction: it depends

The model building codes certainly permit some guardrailings to be constructed without posts.

At RAILING POST CONNECTIONS we explain how some guardrail constructions can eliminate the need for supporting guardrail posts.

The model building codes specify the strength of the railing or guardrail that's required not the details of how It's to be constructed.

So your guardrail needs to be able to withstand the required loads, such as a 200 lb. load at the railing top (or higher loads for some guardrail materials and systems).

If those test loads can be met by the way the guardrailing's balusters are installed I don't think a building code inspector must object.

Reader follow-up:

Martin Alper said:

Then why all the time spent on post, especially 6 foot spacing versus 0 feet for balister supported rails.

Reply: Reasons for using posts when installing a guardrail


1. Guardrails built following instructions:

All guardrails, regardless of the system (wood balusters, steel balusters, wire cables, glass, plastic panes, etc) must be built following the instructions of the specific guardrail manufacturer - failing to do so may be unsafe as well as a code violation. Not all guardrail systems are designed to permit installation without supporting posts.

Reminder: IRC Table R301.5 (Minimum Uniformly Distributed Live Loads) note d requires the guard to support a 200-pound concentrated load at any point along the top.

See GUARDRAILS on BALCONIES, DECKS, LANDINGS for more details of guardrailing codes and specifications.

2. Some Manufactured Guardrail Systems Are Not Self-supporting

Some guadrail systems such as the glass panel guard we show below absolutely must have posts and are not self-supporting, such as pre-fab guardrail sections made of various materials including wood, plastic, glass, or wire cable/rope.

Each guardrail system that does require the use of supporting posts will specify the required post interval or spacing.

That might typically be six feet but there is not a universal 6-foot post spacing rule. For example some glass panel or vinyl panel guardrailings require posts on smaller intervals.

Glass guardrailing & glass stair guard (C) Daniel Friedman

3. Conventional post + wood-rail & baluster guardrail construction

Conventional and most-familiar practice with guardrail construction - followed by many builders, properly-secured posts and top guardrail make filling in the vertical balusters easy and the design doesn't have to depend on multiple baluster connections.

Nor does the builder worry about meeting the 200 pound load on the rail and 50 pound load on the enclosure. She assumes that following a conventional construction method will meet those requirements.

Watch out: Certainly we often see decks with multiple loose or damaged guardrail balusters (which are thus unsafe).

Simpson Strong Tie DTT2Z deck tension tie for throug-bolting a deck guardrail post to the floor joist - at cited in detail in this articleWatch out: even using posts spaced at proper 6 ft. (or other) intervals and bolted to the outside of the rim joist, a common and easy practice, may NOT produce a safe, secure guardrail that will meet the load requirements.

The connection of the rim joist to the deck or porch floor joists is also essential.

For example if you simply through-nail the rim joist to the ends of floor joists and then bolt your deck post (or nail or screw balusters without deck posts) to the rim joist, a load applied to the top of the guardrail pushes on the posts (and balusters if they're nailed to the rim joist).

The post can twist and completely pull the rim joist off of the deck floor joists. That's because the withdrawal force of the nails is not very great.

Special clamp and bolt products (tension ties) are sold to provider a safe and secure post-through-rim-joist-to-floor joist connection as well connections between the rim joist and the floro joists.

For an example of such connectors see

4. Local building code inspector may require posts:

Even when guardrail system manufacturers do not specify details about how posts shall be installed or secured to the structure, typically the instructions will say that the guardrail and posts (if included)

... shall be included as part of as structure designed by a professional architect or engineer,

or that the guardrail and posts

... shall be installed according to and comply with local building codes


... shall be installed as approved by the local buiding code official

Bottom line on posts for guardrails

Because building codes cannot anticipate every conceivable guardrail design and because the code writers don't want to infuriate guardrail manufacturers by inadvertently making their product illegal, building codes often specify the *performance* that must be met by the structure rather than attempting to specify exactly how the structure must be built.

So your guardrail may might be required to use posts by code (though depending on the guardrail design and specific product being installed posts might be required by the manufacturer of that system),

But your guardrail must meet the 200 pound top thrust load requirement. Higher strength requirements are specified for some guardrailing systems, such as plastic guards.

Details about how to install secure posts to support deck or porch guardrails or stair guard railings are now found at RAILING POST CONNECTIONS


Continue reading at GUARDRAIL & HANDRAIL STRENGTH or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see these

Guardrail / Railing Articles

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GUARDRAIL POST CODES & SPECS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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