Guide to Safe and Legal Porch & Deck Railing & Guardrail Construction InspectAPedia® -
Deck & Porch Construction Materials Choices
Deck & Porch Construction & Structural Fasteners
Deck & Porch Construction Details for Safety
Deck & Porch Railings, Code Requirements, Safety
Finishes for Exterior Decks
Poor Construction Details and Improper Connections Can Lead to Dangerous Collapse of Decks and Porches
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Here we discuss critical safe-construction details for decks and porches, including avoiding deck or porch collapse and unsafe deck stairs and railings. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.
Also see our review of that book.
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.
Readers should see Railings on Stairways for railing specifications and building code requirements, see STAIRS & RAILINGS for details about the inspection and documentation of unsafe or defective steps, stairs, and railings and see Balusters & Railing Enclosures for additional examples of stair and railing designs and problems..
Deck Railing & Guard railing Code Requirements
Our photos (above) 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.
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).
Deck Railing Strength Requirements
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.
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.
Post Connections for Deck or Porch Railings
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 had some other safety problems however.)
While 4x4 railing posts are often notched where they connect to the beam, this creates a weak point in the post that will not meet the load requirements. Another problem is that the rim joist needs to be reinforced to keep it from rotating when a strong force is applied to the railing.
This can be achieved with lag bolts, steel strapping, or steel connectors tying the rim joist to the abutting joists. On sides where the rim joist runs parallel to the joists, solid
blocking should be lagged in place to keep the rim joist from rotating. Additional steel connectors may also be required. Posts should be no more than 6 to 8 feet apart, depending on local codes.
Wood Deck or Porch Railings
The top rail for a guardrail can be a 2x6 either flat (photo at left) 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.
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.
Manufactured Deck or Porch Railings
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 Resources, page 157 of Best Practices Guide to Residential Construction)
Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education.
Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
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Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Wiley.com and also at Amazon.com. See our book review of this publication.
Manual for the Inspection of Residential Wood Decks and Balconies, by Cheryl Anderson, Frank Woeste (Forest Products Society), & Joseph Loferski, October 2003, ISBN-13: 978-1892529343, $39.00 at Amazon.com or at the InspectAPediaBookstore
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