Chloe Mei checking an open landing and stair baluster (C) Daniel Friedman Stair Baluster Codes Specs FAQs
Q&A on Building Code, Construction, & Safety of Stair & Guardrail Balusters

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Stair baluster safety & code specification FAQs.

This article series describes procedures for performing safety inspections of the balusters used on indoor or outdoor stairs, railings, landings.

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.

Questions & Answers About Balusters along Stair Guards, Balcony & Landing Rails

Deck balusters eliminate need for guardrail posts (C) Daniel Friedman

These questions and answers about proper design, installation, strength, and spacing of balusters that enclose guards along stairs, balconies, decks, etc. were posted originally at BALUSTERS, STAIR & RAILING - be sure to review that article as well.

On 2018-09-28 15:23:40.526828 by (mod) - guardrail strength - pounds of force

IBC 1607.7.1 Handrails and guards.

Handrail assemblies and guards shall be designed to resist a load of 50 pounds per linear foot (pound per foot) (0.73 kN/m) applied in any direction at the top and to transfer this load through the supports to the structure.

IBC 1607.7.1.1 Concentrated load.

Handrail assemblies and guards shall be able to resist a single concentrated load of 200 pounds (0.89kN), applied in any direction at any point along the top, and have attachment devices and supporting structure to transfer this loading to appropriate structural elements of the building.


On 2018-09-28 by David Scott

Pounds of resistance against a handrail allowed.

On 2018-09-28 by (mod) - example of building code on guard rail baluster spacing


Depending on the codes that apply where you live, balusters should be spaced from 4" apart.

In an interesting refinement that I quote below, some officials want balusters on an outdoor deck, perhaps using wet pressure-treated wood balusters, to be constructed on 3 1/2" centers so that even after wood shrinkage (as it dries) the 4" maximum opening width will be preserved.

You'll see also that instead of a 4" sphere or ball, a 6" sphere may be used to test certain areas along the bottom of a guardrail along a stairway.

In the U.S. building codes typically require that balusters be spaced *no more* than 4" apart. Code inspectors use a 4" diameter ball to demonstrate that the spacing is safe: the ball should not be able to pass through any opening in the guard along a stair, balcony, or deck.

By some building inspectors, the balusters can be spaced more-closely than 4" but in the article above I warn of a serious child hazard - foot traps. Some spacings, around 3 " can form a foot trap. So I'd stay with 4" or else make the balusters so close that a little foot won't pass through and get stuck.

My godson Josh managed to stick his little foot between two balusters on his home's back porch, then turned so that he couldn't get it out.

The result was, happily, only an epoch of panic, as there were no injuries. But had he fallen he could have broken his ankle or leg.

Here is an example building code citation using CT's stair code (City of Bristol) deck code that is based on the 2012 IRC:

Guard rail baluster spaces – The maximum space between balusters must not allow the passage of a 4” sphere or more in diameter.

The use of #2 pressure treated wood will allow for substantial shrinkage, increasing the space between the balusters.

Use a 3 ½” space when laying out baluster location to compensate for shrinkage.

Stair Baluster Opening Exceptions –

1) The triangular openings formed by the riser, tread and bottom rail of a guard at the open side of a stairway are permitted to be of such size that a sphere 6 inches cannot pass through.

2) Openings for required guards on the sides of stair threads shall not allow a sphere 4 3/8 inches to pass through.

Two additional frequently-asked questions are about the required strength of the guard:

IBC 1607.7.1 Handrails and guards.

Handrail assemblies and guards shall be designed to resist a load of 50 pounds per linear foot (pound per foot) (0.73 kN/m) applied in any direction at the top and to transfer this load through the supports to the structure

IBC 1607.7.1.1 Concentrated load.

Handrail assemblies and guards shall be able to resist a single concentrated load of 200 pounds (0.89kN), applied in any direction at any point along the top, and have attachment devices and supporting structure to transfer this loading to appropriate structural elements of the building.


On 2018-09-27 23:24:23.482985 by Mark

Can stair ballisters be 4in apart

On 2018-07-21 13:13:16.745005 by (mod) -


A stair must be secure and stable and meet other requirements such as handrails, guardrails, step dimensions, consistency. But there is no innate reason that it must be physically attached to a building.

For example, one could construct a free-standing stairway and entry platform to the door of a building, touching or 1/8" away from the building front wall. As long as the stair and platform were sound and secure against movement there would be no functional difference than if the same construction had been built bolted to the home.

However, a stair that has been built and simply "leaned" against a building without complete support, such that the stair depended on support from the building, and if the stair were not also attached to the building, in that case the stair could in my opinion be unsafe.

Your local building code compliance inspector is the final legal authority on your question.

On 2018-07-21 01:55:20.496576 by KK

Do exterior steps (wood) have to be attached to the house?

On 2018-03-28 17:46:08.250410 by Candice

We had a large 2 story outdoor deck built. I just noticed 83 of the 186 balusters are split. Most are at the bottom of the baluster where it attaches to the lower rail, others are split where it's attached to the top rail How safe is this deck???

On 2018-02-12 22:40:32.977906 by (mod) -


Railings must be continuous along a stairway.

On 2018-02-10 15:45:34.105793 by TEACHNTEX

Does US Building Code allow railing from upstairs go a little less 3/4 down, and then no railing down the other a little more than a 1/4? While having this 2 more steps then uneven steps without railing?

On 2018-01-14 21:01:32.457639 by (mod) -


With the ducking and weaving qualifier that always, your local building code compliance official is the final legal authority on local code and code enforcement questions,

You can put the balusters on inside or outside of a guardrail. The technical question will not be to which side they're attached but rather whether or or not the guardrail is sufficiently strong and secure.

A baluster installed on the interior of a horizontal support is in my OPINION, more secure against being pushed off or loose by someone falling or leaning against the balusters than one nailed (ugh) or screwed (ok) to the outside of the same horizontal member.

Why has this question come up?

Use the picture frame icon next to the Comment button to post some photos so that we can be sure we're on the same page.

On 2018-01-14 02:25:59.487542 by Mike Grubbs

Does any US Building Code - Nationally or locally prohibit the installation of 2" X 2" vertical pickets from being installed on the inside of the deck, steps, or landing instead of customary such picket typical installation that is usually on the outside of the top and bottom rail ?

My question has nothing to do with spacing between the pickets or height of finished rail system. Location of the pickets on the top and bottom rail specifics is THE question.

On 2017-07-13 21:58:12.829033 by (mod) -

Gary, not that I've been able to find. Perhaps we could help more with some specifics, sketches, photos (page bottom CONTACT link)

On 2017-07-13 21:57:36.793698 by (mod) -


A ballpark answer is 8 ft. (varying by material and design) but there is no single right answer since the baluster structure may, in some guardrail designs, be structural and able to support the guard to sufficient strength.

On 2017-07-13 16:48:53.455262 by carol

length of span before you need a post in interiro railings

On 2017-06-26 19:49:52.129148 by Gary

Is there any code regarding how close or far the bottom newel post needs to be in relation to the nose of the bottom step?

On 2017-06-13 by (mod) - California code for balusters spacing distance in between each other


Rather standard is a 4-inch spacing for vertical members (balusters) in guardrailings and stair guards.

In California, since at least 2001, Section 509.3 1133B.5.7.4 Openings.

Open guardrails shall have intermediate rails or an ornamental pattern such that a sphere 4 inches (102 mm) in diameter cannot pass through.

This appears in the 2010 California code below and in the 2016 code as the same text but with the section number changed to Chapter 10 Section 1015.4. Here is the 2010 text:

1013.3 [Guardrail] Opening limitations.

Required guards shall not have openings which allow passage of a sphere 4 inches (102 mm) in diameter from the walking surface to the required guard height.

1. From a height of 36 inches (914 mm) to 42 inches (1067 mm), guards shall not have openings which allow passage of a sphere 43 / 8 inches (111 mm) in diameter.

2. The triangular openings at the open sides of a stair, formed by the riser, tread and bottom rail shall not allow passage of a sphere 6 inches (152 mm) in diameter.


1. The open space between the intermediate rails or ornamental pattern of guardrails in areas of commercial and industrial-type occupancies which are not accessible to the public may be such that a sphere 12 inches (305 mm) in diameter cannot pass through.

In California stair regulations that pertain are

Subchapter 7. General Industry Safety Orders, Group 1. General Physical Conditions and Structures Orders, Article 2. Standard Specifications, §3214. Stair Rails and Handrails.

(b) A stair railing shall be of construction similar to a guardrail (see Section 3209) but the vertical height shall be in compliance with Section 3214(c).

Stair railings on open sides that are 30 inches or more above the surface below shall be equipped with midrails approximately one half way between the steps and the top rail.

Note: Local building standards may require 4-inch spacing of intermediate vertical members.

§3209. Standard Guardrails.

This section specifies a horizontal midrail and permits 9-inch spaced horizontal members in guardrails. A stair guard might be similar.

Summary: [from California balcony guardrails] - in my opinion a good guide for all guardrails, balconies, decks, landings, stairs where one or both sides is open.

4 inches is the maximum distance between balusters or between a post and baluster, in the California building code.

In addition the space between the finished floor and the bottom rail must not exceed 4 inches.

The minimum balustrade height is 42 inches, and re strength: the balustrade must be able to withstand 200 pounds of force or pressure at any point. Stronger guards may be needed where loads are greater such as in an arena where there can be crowds.


California Code of Regulations

§3209. Standard Guardrails. - does not mention vertical balusters

§3214. Stair Rails and Handrails. - notes that local building standards may require 4-inch spacing of intermediate vertical members.

§3231. Stairways.

On 2017-06-13 by Dominic

What is the code to balusters distance in between each other California

On 2017-06-09 by (mod) - code to balusters distance in between each other California


Port Aransas TX uses these two model building codes

* International Building Code 2015
* International Residential Code 2015

- source: retrieved 2017/06/09

so you can follow the model code standards given in the article above and in this article series.

On 2017-06-09 by Kimi Pollard

What are the city codes for installing balusters in Port Aransas Texas

On 2017-05-14 by (mod) -

The location doesn't change the opinion I voiced yesterday, Marion.

On 2017-05-14 by Marion

Thank you for your opinion I was wondering because I live in Pennsylvania

On 2017-05-14 02:25:03.409127 by (mod) -


On 2017-05-14 by Anonymous

It s in Jim Thorpe pa

On 2017-05-14 by (mod) - requirements for a seller to bring guardrails up to current codes / standards


I don't think there's a law anywhere in North America that requires a home seller to bring their home up to current building codes.

However where a requirement to correct a safety violation such as open stair guardrails, might come up would be if your buyers Bank requires in order to Grant a mortgage for the new buyer that a code compliance inspection or certificate be performed or issued.

In some communities the building department will simply say no no violations on file. In other communities a building department may actually send an inspector who might call out a violation such as the one that you described.

In that case because your buyer can't get a mortgage without the item being corrected, the buyer might ask you to perform that work.

In any event, compared to the value of a home being sold in North America the, the cost to add balusters to enclosed spaces that are too far open is bound to be trivial and should not be a stumbling block for anyone - in my opinion.

On 2017-05-14 by Tmarion

If my house was built in 1990 and God rails on more than 4 inches Apart do I have to replace them before I sell my house

On 2017-03-14 by (mod) - Which is the correct place to install a stair rail post?

Good question, Norm.

In my OPINION the location of the bottom post is not critical, it's the position of the handrail and guardrail affixed to the posts that's most important. Posts have to be absolutely solid. So for a wood-framed stair I might bolt the post to the stringer near the front edge of the bottom tread, notching the tread side if necessary.

But I will make darn sure that the railing extends fully over the front nose (or further if required by local code) of the first step.

See DECK STAIR BUILDING START - at for some images (click to enlarge any photo) to show where deck stair posts are often affixed.

see DECK STAIR BUILDING DETAILS at for structural details and a close-up photo showing a post connection at first step.

Some connection details are at


On 2017-03-14 18:40:03.987859 by Norm

I'm installing new stair railing at the front of my house. There are three steps leading up to the patio and front door. I am not quite sure where the post at the bottom should start.

I've seen some installed that start on the first tread at the bottom and I've seen posts installed at the ground against the first riser. Which is the correct place to install a stair rail post? Thank you.

On 2016-10-11 15:24:05.662647 by mark

i have open steps 20
ft long railings on both sides ineed to put center rail up how high should it be above the steps and width between each post..

On 2016-05-16 by Beth

I live in a house that was remolded by the owner. I say he knew enough to be dangerous.

The major issue we electric and was taken care of however the interior stair balusters was and is still an issue. From the there is maybe 20 to 30 feet of railing with balusters anywhere from 6 to 9 inches apart. We took care of the issue for my grand children by putting up plastic gates so they couldn't fall through.

The inspector is saying that they are grandfathered in so not an issue I can't see any insurance agency insuring the house with these being so far apart.

( the house was bought with cash and because its a log design with siding put one we have had issue just getting a company to insure it)

The logs being hand milled Anyway just need some insight on the baluster issue if we put it up for sale. Is it required to be brought up to code ?

On 2016-04-05 by (mod) -

I'd apply the same stair rules. Trip hazards are even more severe outdoors.

On 2016-04-05 by JLB WELD ~JERRY

My client has cottage property with a lakeside embankment. There is currently a metal stairway laying against the top of the embankment, and ending at a concrete pier.

The current angle of the drop from horizontal is approximately 25 degrees (80" drop over 16' throw). She contacted me about adding a railing, but since the stairs are open on both sides, I'm believe that it's going to require a railing on both sides with <= 4" baluster spacings.

i know codes for ny interior railings, and i'm searching desperately for a code for this specific situation so that i don't sell her something that isn't required. thanks for any guidance. ~jerry>


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