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Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
STRUCTURAL INSPECTIONS & DEFECTS
ARCHITECTURE & BUILDING COMPONENT ID
CHIMNEY INSPECTION DIAGNOSIS REPAIR
COLUMNS & POSTS, DEFECTS
CONNECTORS, FASTENERS, TIES
DECK & PORCH CONSTRUCTION
DEFINITIONS of Mobile Home, Doublewide, Modular, Panelized
DEFINITIONS of ENGINEERED WOOD OSB LVL etc
DISASTER BUILDING INSPECTION & REPAIR
EARTHQUAKE DAMAGED FOUNDATIONS
FIRE DAMAGE vs MOLD DAMAGE
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FOOTING & FOUNDATION DRAINS
FOUNDATION CRACKS & DAMAGE GUIDE
FRAMING DAMAGE, INSPECTION, REPAIR
GRADING, DRAINAGE & SITE WORK
HOUSE PARTS, DEFINITIONS
INSECT INFESTATION / DAMAGE
KIT HOMES, Aladdin, Sears, Wards, Others
LOG HOME GUIDE
MOBILE HOMES, DOUBLEWIDES, TRAILERS
MODULAR HOME CONSTRUCTION
MOISTURE CONTROL in BUILDINGS
PORCH CONSTRUCTION & SCREENING
PRE-CUT & KIT HOMES
RETAINING WALL DESIGNS, TYPES, DAMAGE
ROT, FUNGUS, INSECT DAMAGE
SINKHOLES, WARNING SIGNS
STAIRS, RAILINGS, LANDINGS, RAMPS
STRAW BALE CONSTRUCTION
STRESS SKIN INSULATED PANELS
STRUCTURAL WOOD ASSESSMENT
TIMBER FRAMING, ROT
TRUSSES, Floor & Roof
WATER ENTRY in BUILDINGS
Deck flashing errors & deck collapse: Here we provide a case study of the effects of missing or improper deck connections and deck flashing details leading to structural movement, risk of imminent collapse, rot and building leaks at the deck ledger board and at the building to which a deck was attached.
Our page top photo shows a rotting, collapsing residential deck whose deck ledger was separating from the building, threatening imminent collapse. Readers will also see that the deck railings were unsafe (open) and that no building flashing was installed. This residential deck was very unsafe and should not be walked-on nor should people stay below it as it could collapse at any moment. This photograph and other photographs and text in this article were provided by ASHI home inspector David Grudzinski.
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Photos Show What Happens When a Deck was Not Properly Flashed & When the Deck was Not Properly Secured to the BuildingPhotographs and text about this rotting, collapsing deck case study were provided by David Grudzinski, a professional home inspector in Cranston, RI.
What Happens if the Builder Omits Proper Flashing & Waterproofing at a Deck or Balcony Ledger Board
The deck shown at page top and in Mr. Grudzinski's photographs below was built in Tiverton RI without a deck inspection or building permits. The deck was not properly flashed to shed water away from sheathing. The deck platform was also not bolted to the house for safety (and to meet building code requirements).
Mr. Grudzinski's photo (left) shows the collapsing deck from below. Notice that the inspector knew better than to spend time standing below this dangerous structure.
Because building flashing was omitted when the deck was built, water leaked behind the deck, rotting the building sheathing to the point of disintegration.
The nails, which were the only means of fastening the deck to the building, then pulled away from the house. See Deck & Porch Connections: Ledger Boards for a description of proper deck-to-building connections and fasteners.
Carpenter ants had also infested the rotten wood, and water was leaking into the building basement as we show in additional photographs below.
As you can see, the deck was falling away from the house and sinking. The sheathing was exposed to the elements, and was rotten beyond repair.
Water was actively leaking into the basement and growing mold and mushrooms. The entire wall section 25 'x 8' needed a tear down and reconstruction, as well as the deck itself. The structural portion of the wall studs and sill plate were also rotten at this home.
Building Leaks & Water Damage from Omission of Proper Flashing & Waterproofing at a Deck or Balcony
This was the interior view of the wall inside behind the leaky, rotten, insect-infected, collapsing exterior deck.
The structural members were rotten beyond repair, and sheathing was deteriorated and crumbling (oriented strand board sheathing).
Mold and fungus were growing on the studs and sheathing.
Water was leaking into the basement and adding to the moisture level in the building, risking other hidden moisture or mold problems as high as in the building's attic and roof structure as moisture tends to move upwards in a building on convection air currents.
This entire problem could have been prevented with 25 feet of flashing, and $5.00 worth of lag bolts. See Deck Flashing at Building for a description of proper flashing at the meeting of a deck or balcony to a building wall.
The repair cost for this home, just associated with damage caused by improper deck construction, stands at $10,000.00 to replace the damaged wall and deck. Mold clean up and carpenter ant treatment will also be required.
But the most important and immediate concern with this deck was that the deck was unsafe. Someone walking on the deck could precipitate its immediate and sudden collapse, leading to serious injury. Deck Collapse Case Study includes additional photos of improper connections between a residential deck and the building that led to a catastrophic deck collapse.
Missing Deck Flashing Leads to Rot and Leaks & Invites Insect Pests, Holes in the Building, Other Damage
Here is a closeup of the hole in building sheathing shown in the lower right of the photograph just above.
As you can see, the 2x4 wall stud was rotten half way through, and the 7/16" OSB sheathing was soft and crumbling.
At the time of the home inspection that found these conditions, this house was 9 years old. Even the pressure treated sill plate was rotten.
Also see DECK COLLAPSE Case Study (collapse of a new, "code approved" deck) and see our guide to details of Best Construction Practices for Decks including Deck & Porch Connections: Ledger Boards also Deck Flashing at Building and Deck & Porch Connections: Ledger Boards.
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