How much floor space does an average person occupy when standing.

[RARWOOD]

I'm a structural engineer with a friend, who is asking what is the maximum number of people, that her deck can safely support.

What I am trying to do is find an article that answers this question. I did several internet searches and could not find one.

The articles I found all took the deck area and multiplied by 175 then divided by 40. Which for a 12' x 12' deck would give an answer of 32 people. The articles all went on to say that you couldn't put 32 people in a 12' x 12' space.

Her deck provides a very good place to watch fourth of July fireworks, so I can see a lot of people crammed onto her deck.

 

[msquared48]

I would say about 3 square feet per person, but that does not take into account perceived personal space which depends a lot on ethnic background. I would double that for the US for singles, so for 144 square feet, 24 sounds reasonable. For all couples, I would use 1.5X, making the number 32.

Also, 144 X 40psf /200#/person = 29 people, based on loading alone.

Take your pick.


Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[SlideRuleEra]

Serious research was performed on this subject... over 100 years age. The results were printed in my 1937 "Trautwine - The Civil Engineer's Reference Book" on page 726 (copy attached below). The result is essentially 80 to 180 PSF, depending on assumptions.

I consider 100 PSF (200 pound person occupying an area 1 ft x 2 ft) to be a reasonable number for a packed crowd for two reasons:

1. IBC lists 100 PSF for several applications where crowds gather such as dance halls, restaurants, stairs (perhaps during fire drills), public rooms in hotels, etc.

2. Live load reduction for 100 PSF (and greater) is not allowed by IBC. IMHO, since people could gather just about anywhere for numerous reasons, live load reduction would not be wise anyway.

http://www.SlideRuleEra.net

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[FSS]

I would look at the deck before answering any question about capability. Some decks are built like a tank, but most would scare the heck out of the average engineer.

 

[MiketheEngineer]

Worse case scenario - I usually use 2 sq ft per person - but that is tightly packed. But can happen - like the day after Thanksgiving at a Walmart or when someone yells "Fire"

 

[RARWOOD]

I want to thank every one for their answers. SlideRuleEra, it was interesting to learn that people have actually packed subjects as close togther as they can to try to come up with a reasonable answer.

I have looked at the deck, it is very solidly built. Like most decks, one of the main weak points is the attachment of the ledger to the house. My friends is concern because her deck is 16'W x 50'L, and about 12' off the ground.

Have talking to her previously, I know to give her an answer of the deck capacity in terms of p.s.f. would not be meaniful to her. Maybe I can give her a rough occupancy estimate based on assuming the weight of a person at 250 lbs. and deviding by the deck capacity to determine the area the 250 lbs were need to be spread over to prevent overloading the deck. I could then adjust that by some swag factor.