Photograph of  . Deck Construction Defects Lead to Deck Collapse Catastrophe
     

  • DECK COLLAPSE Case Study - CONTENTS: Deck Collapse Case Demonstrates Improper Residential Deck Construction. List of structural defects leading to deck collapse - what structural connections are critical to porch and deck safety. Photos of improper Deck Joist Hangers & Missing Nails in Joist Hangers - Deck Collapse
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Deck collapse case study documents causes of catastrophic failure: this article explains 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.

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Deck Collapse Case Demonstrates Improper Residential Deck Construction

List of structural defects leading to deck collapse

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

[Click to enlarge any image]

Article Contents

During a home inspection we found these unsafe structural details on the deck shown in these photographs

  1. The deck ledger was simply nailed to the building wall over vinyl siding, using common nails; no bolts were used.
  2. 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.
  3. Other deck joists were "set" into steel joist hangers with no nails whatsoever.
  4. The deck joists were not all nailed to the deck outer girder.
  5. The deck girder was simply tacked to the top of 4"x4" wood posts with no structural connections.
  6. 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.

Photos of improper Deck Joist Hangers & Missing Nails in Joist Hangers - 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 right), and a steel joist hanger used to connect a deck joist with no nails whatsoever (above left).

Owner Ignores Warning to Stay off Unsafe Deck - Leads to Collapse

Despite our strong warning to the home buyer to stay off of the deck (witnessed, orally and in writing) and to repair the unsafe deck before use, including a report on whose front page was highlighted a statement that the deck 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.

Photos of Improper Deck Framing Connectors, Insecure Deck Supporting Posts - contributors to deck collapse

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.

Photos of inadequate connection of deck ledger to building

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.

 

 

Continue reading at DECK DESIGN & BUILD or select a topic from the More Reading links shown below.

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

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

Suggested citation for this web page

DECK COLLAPSE Case Study at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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