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Photograph of  .

Deck Construction Defects Lead to Deck Collapse Catastrophe
InspectAPedia®  -    

  • Poor Construction Details and Improper Connections Can Lead to Dangerous Collapse of Decks and Porches
  • What structural connections are critical to porch and deck safety
Our site offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. our contact info is at InspectAPedia.com/appointment.htm.

Here we discuss critical and poor construction details that led to a catastrophic residential deck collapse. Our page top photograph shows the results of a poorly-constructed deck that collapsed and fell eight feet to the ground, sending three people to the hospital. Luckily there were no serious injuries but children playing below the deck ran out as it collapse - otherwise they may have been killed. Also see DECK FLASHING LEAKS, ROT Case Study for an example of an older deck with rot and collapse due to improper construction and missing building flashing, and see Deck & Porch Construction for Safety for a comparison of good and bad deck or porch construction methods.

© Copyright 2009 Daniel Friedman, Steve Bliss, Wiley & Sons, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Deck Collapse Case Demonstrates Poor Residential Deck Construction

Photograph of  .Our photograph at left shows the results of a poorly-constructed deck that collapsed and fell eight feet to the ground.

During a home inspection we found these unsafe structural details:

  • The deck ledger was simply nailed to the building wall over vinyl siding, using common nails; no bolts were used.
  • Some deck joists were secured to the deck ledger board using steel connectors (not joist hangers) and with roofing nails. Hammering a roofing nail home against a steel joist hanger cracks the thin nail head and risks connection failure. Roofing nails are not structural fasteners.
  • Other deck joists were "set" into steel joist hangers with no nails whatsoever.
  • The deck joists were not all nailed to the deck outer girder.
  • The deck girder was simply tacked to the top of 4"x4" wood posts with no structural connections.
  • The deck posts went into the ground to an un-known depth. If the deck posts were not buried to an adequate depth that detail added to the risk of deck collapse.

Deck collapse details (C) Daniel Friedman

Deck collapse details (C) Daniel Friedman

Our photos above show non-structural angle brackets used to connect deck joists to a bolted ledger at a different property (above left), and a steel joist hanger used to connect a deck joist with no nails whatsoever (above right).

Despite our strong warning to the home buyer to stay off of the deck and repair it before use, a statement that it was very dangerous, and that it should be repaired immediately, on moving into the home the new occupants celebrated with a deck party. Sipping a beer, a heavy guest stood at the outer deck railing and idly bumped his weight against the guardrail. The deck detached from the building and fell to the ground, sending three people to the hospital. Luckily there were no serious injuries but children playing below the deck ran out as it collapse - otherwise they may have been killed.

Deck collapse details (C) Daniel Friedman Deck collapse details (C) Daniel Friedman

Our deck defect photos above are close ups of the collapsed deck. They show a questionable-application deck joist connector with roofing nails instead of structural fasteners (above left), and a deck post that extended only 11" inches into the soil (above right). Other deck posts were only 7" into the ground and none were anchored nor connected to piers.

Deck ledger nails exposed (C) Daniel Friedman

Our photo (at left) shows the common nails protruding from the inner face of the deck ledger board. These are the (inadequate) fasteners that pulled out of the house wall as the deck separated from the building and fell to the ground.

Despite multiple inadequate deck construction details and despite the deck having a "CO" issued by a local authority, our opinion was that had the deck ledger been bolted to the building this collapse may have been avoided.

Proper deck flashing at the building is also important to avoid both leaks into the structure and rot or weakening of this critical structural member that secures the deck against falling.

See Deck & Porch Construction for Safety for a comparison of good and bad deck or porch construction methods.

Also see Manual for the Inspection of Residential Wood Decks and Balconies for an excellent guide to deck construction inspection and deck safety.

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Technical Reviewers & References

  • Daniel Friedman - principal author/editor of the InspectAPedia® Website
  • 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 GuideĀ is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.



Mobile Phone/PDA website viewMobile View
STRUCTURAL INSPECTIONS & DEFECTS
ADVANCED INSPECTION METHODS
AGE of a BUILDING - how to determine
Basketball Mold Syndrome - BBMS
BEST CONSTRUCTION PRACTICES GUIDE
CHIMNEY INSPECTION DIAGNOSIS REPAIR
Cracks, Checking or Splitting Beams & Log Homes
CRAWL SPACES
DECK & PORCH CONSTRUCTION
  Deck Piers & Posts
  Deck & Porch Connections to Building
  Deck Flashing at Building
  Deck & Porch Structural Fasteners
  Deck & Porch Steps or Stairs
  Deck & Porch Railings
DECK COLLAPSE Case Study
DECK FLASHING LEAKS, ROT Case Study
DEFINITIONS of Mobile Home, Doublewide, Modular, Panelized
DEW POINT CALCULATION for WALLS
DEW POINT TABLE - CONDENSATION POINT GUIDE
DISASTER BUILDING INSPECTION & REPAIR SAFEY
EARTHQUAKE DAMAGED FOUNDATIONS
ENERGY SAVINGS in BUILDINGS
ENERGY SAVINGS PRIORITIES
ENERGY SAVINGS RETROFIT CASE STUDY
ENERGY SAVINGS RETROFIT LEAK SEALING GUIDE
ENERGY SAVINGS RETROFIT OPTIONS
FLOODS IN BUILDINGS-priorities
FLOODS IN BUILDINGS-mold
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FOUNDATION BULGE or LEAN MEASUREMENTS
FOUNDATION CRACKS & DAMAGE GUIDE
FOUNDATION WATERPROOFING
FRAMING DAMAGE, INSPECTION, REPAIR
FRAMING DETAILS for BETTER INSULATION
FRAMING DETAILS for DOUBLE WALL HOUSES
FRT PLYWOOD
HOUSEWRAP AIR & VAPOR BARRIERS
LOG HOME GUIDE
PANELIZED CONSTRUCTION & KIT HOMES
MODULAR HOME CONSTRUCTION
MOBILE HOMES, DOUBLEWIDES, TRAILERS
MOISTURE CONTROL in BUILDINGS
ROOFING INSPECTION & REPAIR
ROT, FUNGUS, TERMITES
  TERMITE SHIELDS vs TERMITICIDE
ROT, TIMBER FRAME
SINK HOLES

More Information

  • The Journal of Light Construction has generously given reprint permission to InspectAPedia.com for this article. All rights and contents are ©Journal of Light Construction and may not be reproduced in any form.
  • Best Practices Guide to Residential Construction, Steve Bliss, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from the publisher, J. Wiley & Sons, 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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