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Guardrails Best Practices for Decks & Porches:
This article describes recommended construction practices for deck safety, deck railing requirements, guard railing construction and building codes, and critical safe-construction details for deck and porch rails, guardrails, and exterior stair guard railings and handrails.
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[Click to enlarge any image] - This scary guardrail is rotted, poorly fastened (note the nails have pulled away to left of the sagging gate), and the open balusters are a child hazard.
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Our photos (above and below) show an attractive railing with horizontal cables intended to permit a nice view of the Brooklyn NY skyline. We also demonstrate how easily the cables can be separated as well as how attractive this guard railing is to children.
See Cable Railings & Guardrails for details about cable type guard rails or "cable railings" such as shown above.
As detailed in Best Practices Guide to Residential Construction: The International Residential Code (IRC) requires a minimum 36-inch-high guardrail for all decks, balconies, or screened enclosures more than 30 inches off the ground. For child safety, the balusters or other decorative infill must be spaced less than 4 inches apart (a 4-inch-diameter ball should not pass between the balusters).
The railing must be strong enough to resist horizontal loads from people leaning on it. The IRC requires that the railing be able to resist a 200-pound concentrated load applied along the top in any direction, while some local codes still in effect specify a smaller load of 20 pounds per linear foot.
After an above-ground swimming pool was removed, the owners continued to use the deck in our photo (left). Deer netting was installed across the open edge of the deck - and it worked fine until someone fell thorough it. The torn remains of the deer netting can be seen on the left side of this photograph.
Continuing from from Best Practices Guide to Residential Construction:
Under the IRC, the infill or balusters must resist a concentrated horizontal load of 50 pounds applied to a square foot area. The baluster requirement is easily met with standard fastening techniques, but meeting the IRC guardrail requirement is difficult without adding steel hardware. The majority of residential decks, which rely on notched posts lag-screwed into the band joist, do not meet the 200-pound requirement.
Posts that run continuously from footings to railings (photo at left) are the strongest, but these are often not practical.
The stair and balcony shown at above had some other safety problems however, including non-graspable 2x6 on-edge handrailings along the stairway and balusters spaced too far apart.
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More commonly, the posts are attached to the rim joist or beam, preferably with through-bolts.
Posts should be no more than 6 to 8 feet apart, depending on local codes.
Details about how to install secure posts to support deck or porch guardrails or stair guard railings are now found at
The top rail for a guardrail can be a 2x6 either flat (photo above) or on edge. Use the longest pieces you can find—a continuous railing is best.
However for a hand railing on stairs, both flat and vertical 2x lumber are unsafe and violate good stair railing design because they cannot be grasped during a fall.
Our photo above (above right) shows a stair railing that could not be reliably grasped on a stairway where a fall, serious injury, and subsequent litigation occurred. The hand is of the website editor.
As detailed in Best Practices Guide to Residential Construction and in the figure at left:
Balusters can be nailed or screwed directly to the rim joist or attached to a bottom rail. Use either one screw or two spiral-shank nails top and bottom on each baluster. If you use a flat rail on top, it is best to slope or chamfer the top surface to shed water.
Many types of manufactured railing systems are also available, often from the same companies that provide composite decking products.
Examples include SmartDeck’s post and rail system made from an extruded wood-poly composite and a similar railing made of fiber-reinforced plastic (FRP) from Shakespeare Composites, best known for its FRP fishing rods (see photo at left of a pre-fab or manufactured porch railing system).
An advantage of the prefab systems, in addition to their easy assembly, is that most are engineered to meet the strength requirements of the model codes in the areas where they are marketed (see Deck & Porch Products, Manufacturers)
-- Adapted with permission from Best Practices Guide to Residential Construction.
Details for baluster choices and installation are at BALUSTERS, STAIR & RAILING
Subject: 30" railing: If there is a seat wall and a planter between an upper level terrace and a retaining wall with a height greater than 30”, can the railing be eliminated? Please see attached sketch. - M.B.
M.B. please see RETAINING WALL GUARDRAIL CODES for a discussion of retaining walls and guardrail requirements (or absence of them) in building codes & standards. Generally retaining wall guardrails are not addressed in building codes except in some cases where there is a requirement for a guardrail (not plantings) for public spaces where people might be expected to walk along the area close to the retaining wall.
That said, I have certainly seen a number of high decks (not quite your case) that had continuous seating at the perimeter and no other railings. I expect that ultimately the building code compliance inspector will decide the issue locally.
A concern might be that even though the seating can prevent someone from stumbling and falling off of the raised area, it would not stop a child from climbing right over - unless there were seat backs were high enough and made of vertical balusters rather than the typical horizontal materials.
Taking a look at your sketch (above left), as drawn, the same concept seems to apply: you may have protection against an adult trip and fall over the retaining wall provided by some space (say six feet) between the "seat wall" and the "planter wall" (a retaining wall). But this design does not provide child safety protection nor protection for someone walking in or working in that inner space (having stepped over the seat wall).
If this area is residential occupied outdoor space, I would be surprised if a building code inspection would accept the design you show: the "seat wall" is just 18" high, easily climbed over by a child; there is no safety railing at the planter wall above the dropoff - or are you planning to install a tall, impenetrable solid-growth hedge in the space where you show a shrub? That might be an acceptable alternative.
Our photo of a high retaining wall without a guard railing (above) illustrates an approach using dense shrubbery as a safety barrier at a property in New York State.
Typical building codes including local code interpretations that address the question of need for safety railings near high retaining walls give some latitude to the local building inspector.
"(B) Safety Railings. Safety railings may be required for any retaining wall two and one-half (2.5) feet or higher. The decision to require safety railing shall be based on specific site conditions, potential pedestrian and public access to the retaining wall, and applicable building codes." - City of Bella Vista, AR subdivision code.
Retaining walls more than 1220 mm high are required to have safety cable railing installed as required by Cal-OSHA regulations, Title 8, Section 1621, as well as the Department's Highway Design Manual Section 210.5. - California DOT DHR - SAFETY ALERT MEMO 03-08
For outdoor double-retaining walls outdoors, the lower retaining wall is 48" in height, the space between the retaining walls is four feet or more, and the top of the wall is 24" high. - Glen Cove, New York
Continue reading at GUARDRAIL CONSTRUCTION, DECKS & RAMPS for guardrailing specifications & codes, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Or see BUILDING CODE DOWNLOADS - free downloadable PDF files of building codes & standards
Or see BALUSTERS, STAIR & RAILING for additional examples of stair and railing designs and problems.
Or see STAIRS, RAILINGS, LANDINGS, RAMPS - home
Or see DECK CONSTRUCTION BEST PRACTICES - home
Or see DECK DESIGN & BUILD - home
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(May 9, 2015) Kate Hauserman said:
The question you have answered above about the seating vs. a guard rail doesn't appear to answer the question posted in the sketch. The question as I understand it, if there is a landscaped area adjacent to the retaining wall, can the guard rail be eliminated? You post a picture of dense planting alleviating the need for a guard rail-does the planting area have to be a specific width?
As as you are asking about guardrailings at retaining walls you'll want to see the specifics about codes, standards, accidents and some suggestions found at
RETAINING WALL GUARD RAILINGS - see inspectapedia.com/exterior/Retaining_Wall_Guardrails.php
and don't hesitate to ask if questions remain.
(June 8, 2015) Anonymous said:
what is the max. height of a deck before rails are required?
The maximum deck height before a railing is required varies by jurisdiction, typically 24-30" from ground level; some jurisdictions state the height as three step risers or more.
Keep in mind however that someone can be injured falling off a deck that's only a few inches high.
See the article series beginning at GUARDRAIL CONSTRUCTION, DECKS & RAMPS for railing height and other specifications.
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