Deck Issues Again

[ccurrins (Christopher Currins, CMI)]

http://www.nachi.org/forum/attachments/f16/64650d1367182465t-deck-issues-again-bay-window-deck-calcs.jpg

@rmayo

Chris,

I roughed out the calculations for the worse case where the deck projects 16’ from the house and clear spans a 16’ wide bay window (bumped out 2’). I did not take the time to draw in all the extra joists, but you can see the header beam next to the bump out requires (5) 2x12x16’, and (3) 2x12x16 on each side. The biggest problem I see in this design is the load transferred to the ledger beam. In this case we are looking at a 3000 lbs concentrated load at the end of the beam. The connection requirements would be expensive. The best solution is to add extra support posts next to the house. This is all designed using 40 lb/sf live load and 10 lb/sf dead load with a L/240 total deflection and #2 southern pine lumber. As a side note, with the size of the loads involved, if there is a stud wall below the ledger board it too may need strengthened.

Excellent Randy, very much appreciated.

I agree with what you said on another post, we can point cantilever/ledger defects out and will mostly likely still receive the typical “it’s been this way for ten years” comments.

[Dan_Koehler]

We’re having BIG problems with our balcony decks. KB Home build balconies thare are literally imploding and falling down. We have a 3 story building (2 decks and 1 patio) and both the top and middle decks are imploding. The county has come out and deemed our home as UNSAFE. What an epic failure! There are quite a few videos and pictures to see at this website of the problems KB Homes is having http://TheKBHome.com

[cbrown1 (Carl A. Brown)]

How much ROT is hidden by the sideing on the bump out?

[ryoung7 (ROBERT YOUNG, CMI)]

@mlarson

Decks are often a source of concern during inspections.

Things can look fine if you don’t understand the issues.

I see this type of defect all too often even on high end homes.

Michel,
Unable to see the full defect. Please elaborate.
Thanks in advance.

[ryoung7 (ROBERT YOUNG, CMI)]

No need to reply. Sorry.
I see the defect. Anchorage, lack of flashing.

I thought the bump-out did not take up that much space.

[mlarson (Michael Larson, WI Lic. # 1672-106)]

@ryoung7

No need to reply. Sorry.
I see the defect. Anchorage, lack of flashing.

I thought the bump-out did not take up that much space.

Robert, please read the thread. I should have been built as free standing as ledger board attachment to cantilevers is a really bad idea puts undo stress on the house wall that it is not designed to carry.

Robert Meirer also provided a nice graphic that illustrates this.