Expert: Dan Griffin - 7/9/2008

Question
QUESTION: I have a second story wood deck (14 x 13). it is attached on two sides to a brick wall. the other two sides have two support columns each.  there is no center support below.  how much weight can it hold?

ANSWER: Helen, I can't answer your question with the information given.

What is the walking surface made of? Ply, 5/4 decking, 2x decking?
What size are the joists?  2x6. 2x8,2x10, 2x12
What species of wood and what grade?
How old?  How weathered?
Are the joists held on with joist hangers or just nails?
What size are the beams carrying the joists?
HOw many beams? one, two nailed together, three?
How are the beams fastened to the columns? Resting on top or bolted to the sides?
How is the rim joist attached to the brick?  What size bolts?  How close together?  Are they all just down the center of the board?

It sounds like it was well designed, but maybe it would be better to tell me what you are planning or why you are asking the question.  There have been several catastrophic failures of second floor decks that were not designed for heavy people loads being used for a party, heavily overloaded, sudden failure resulting in deaths and injuries.  I don't say this to scare you, but to make you aware that there are some major issues involved.  YOur deck is probably capable of carrying 20 to 30 pounds per square foot which would allow you up to about 5,000 pounds uniformly distributed (not all in one place).  


---------- FOLLOW-UP ----------

QUESTION: The surface is made of 2xdecking (treated wood)
joists are 2x10 (treated wood)
about 18 months old - no weathering
joist hangers are used and there's about 8- 10 single beams
the columns are bolted to the sides
the rim joists are bolted completely through the brick on one side and then bolted all around about 3 feet apart. bolts look big enough (not sure what size they are)
We don't really have large groups up there, however, I moved a patio table up there and began to worry about the load capacity.  There's seating for approx. 10 people.  
this is at a lake house we use on the weekends and I was wanting to post a sign limiting the amount of people at one time on this deck.  

Answer
Helen,if the joists are on 16" centers, they should be good for 40 lbs per SF live load and 10 dead load.  YOur 182 square foot deck x 40= 7280 pounds.  I usually figure 200 lbs per person (America is overweight, you know) which says about 36 1/2 people.  If you are trying to be conservative and cautious, you might cut that number in half.  It might be fun to post it as 18 1/4 people.

The reason I asked about the location of the bolts in the ledger at the brick - one of the big failures was a bar in Montana, the deck was overloaded with almost 100 people (a football team as I recall), the ledger board was installed with a single row of lag bolts down the center of the board and the board split full length down the center.  I assume your ledger is fastened to the rim joist behind the brick veneer.