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Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
STRUCTURAL INSPECTIONS & DEFECTS
ARCHITECTURE & BUILDING COMPONENT ID
COLUMNS & POSTS, DEFECTS
CONNECTORS, FASTENERS, TIES
DECK & PORCH CONSTRUCTION
DEFINITIONS of ENGINEERED WOOD OSB LVL etc
FOOTING & FOUNDATION DRAINS
FOUNDATION CRACKS & DAMAGE GUIDE
FRAMING DAMAGE, INSPECTION, REPAIR
GRADING, DRAINAGE & SITE WORK
INSECT INFESTATION / DAMAGE
PORCH CONSTRUCTION & SCREENING
PRE-CUT & KIT HOMES
RETAINING WALL DESIGNS, TYPES, DAMAGE
STAIRS, RAILINGS, LANDINGS, RAMPS
STRUCTURAL WOOD ASSESSMENT
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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During a home inspection we found these unsafe structural details:
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).
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
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.
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.
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..
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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