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Another Deck Collapse Injures Dozens


hausdok
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2008916225523_URIDeckCollapse.jpgThe collapse of a deck at a Narragansett residence sent at least 50 people plummeting 15 feet to the ground Saturday night during a party.

Around 11:40 p.m. Narragansett Police responded to 37 Sakonnet Blvd. in Narragansett's Eastward Look neighborhood to find a second-story L-shaped deck had caved-in, crushing a mini-van and injuring dozens. To read more click here.

Source: The Good 5 Cent Cigar - Student Newspaper at the University of Rhode Island. Thanks to Prof. Frank Woeste, Virginia Tech University, for tipping TIJ off to this article.

For those interested, Prof. Woeste's next two day course for inspectors is Repair Design for New and Existing Wood Trusses and it will be held at VTU in Blacksburg, VA on October 15-17, 2008. For details and registration, visit www.cpe.vt.edu/sdww/

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A bit too far for me, but close enough to make me wish.

Got a kick of of this part:

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The deck, constructed in 1988 with pressure-treated lumber, was built in accordance with 1980 building codes.

Narragansett Building Official Anthony Santilli, Jr., who arrived on scene within an hour of the collapse, said there was no question the deck was built correctly.

However, after 20 years, "water and mother nature" weakened the wood. In any condition, Santilli said, the deck was not meant to support that many people.

In his report, submitted to Narragansett's Department of Building Inspection, Santilli said, "It is the opinion of this office that deterioration and rot due to water damage behind the ledger board and overcrowding resulted in the collapse."

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If it was properly flashed how did water get behind the ledger board to cause rot and deterioration.

Reminds me of this rotted one: http://b4uclose.tripod.com/cockamamieph ... oists?i=28

I hope everyone heals well.

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I'll agree that the science behind ledgers is flawed, and even that the code needs to be revised, but adding columns and beams at the building is not always a viable or even desirable option. My prefered method is to protect the building with ice and water shield that starts well above and extends well below the ledger, and then install the ledger on standoffs at each through bolt. This provides plenty of room to manage run off and allows good air flow for drying.

Is it just me, or does any one else have a problem with the catastrophic failure of a correctly built structure?

Tom

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Narragansett Building Official Anthony Santilli, Jr., who arrived on scene within an hour of the collapse, said there was no question the deck was built correctly.

However, after 20 years, "water and mother nature" weakened the wood. In any condition, Santilli said, the deck was not meant to support that many people.

As Brandon said,

These statements are contradictory. If the deck is large enough for x number of people and collapsed, it was not built correctly.

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The deck, constructed in 1988 with pressure-treated lumber, was built in accordance with 1980 building codes.

Narragansett Building Official Anthony Santilli, Jr., who arrived on scene within an hour of the collapse, said there was no question the deck was built correctly.

Really...No question at all?

However, after 20 years, "water and mother nature" weakened the wood. In any condition, Santilli said, the deck was not meant to support that many people.

What are the rules here...and where should the limits be posted on an SFR? Tough to tell from the photos, but I'm guessing the deck is around 300sf (20x20 with one 10x10 section missing where it joins the house. The estimate of people on the deck varies from 50 to 70 so let's take 60 as the average. That's one per 5sf. Even if they were all members of the football team and weighed an average of 200lbs, that's still only 40 psf, which I think might have been the minimum live load requirements(???).

Now...I have to say a drunken student every 5sf (2'3" x 2'3") is well under my comfort level, even on terra firma. That was one crowded deck! How many more were in the house?

In his report, submitted to Narragansett's Department of Building Inspection, Santilli said, "It is the opinion of this office that deterioration and rot due to water damage behind the ledger board and overcrowding resulted in the collapse."

I certainly won't argue that lack of flashing and subsequent rot may have contributed but, looking at the photo, I notice the right ledger is still in place with the joists cleanly pulled away (no hangers?). Which went first? My guess is that there was a lack of diagonal bracing, both at the posts and under the joists, that allowed the sway in the first place, that then pulled the deck away from the house. It also wouldn't surprise me to find that some of the inebriated crowd deliberately got the deck "swinging". Even a sound and bolted ledger may have eventually succumbed to that.

Cause of the collapse...too many drunks (possibly), poor design with too little bracing (probably), and poor construction methods (certainly).

"You could tell the deck wasn't kept up with," Fisher said. "I don't think landlords care about their houses. They're just renting them to make as much money as possible."

Well...maybe. But did the students inform the evil landlord they were going to be over-stuffing the house and deck with party animals when they signed the lease for this SFR? I doubt it.

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I've built 100's of decks. 95% were self supporting. Most were on newer construction. In the midwest I always tied to be at least 1 rise below the door so the customer did not have to push snow every time they opened a storm door. This often times would mean their was little to bolt a ledger too. Self supporting was a little more labor and material but usually easier.

Rick

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