Hi,

Does anybody know of a stud finder that will look thru gypcrete? I
want to figure out which way the joists are running in my 3rd story
condo but I think my my sub floor is covered in gypcrete.

Thanks, Ryan

wrote in message
ups.com...
Hi,

Does anybody know of a stud finder that will look thru gypcrete? I
want to figure out which way the joists are running in my 3rd story
condo but I think my my sub floor is covered in gypcrete.

Almost always, the same direction as the ceiling joists in the same room.
Usually, the same direction as the roof slopes, and from the centerline of
the building to the outside edge, centerline being along the long direction.

Why does the direction of the floor joists matter?

aem sends....

Thanks for the advice.

I have a strange hobby. I collect and restore old arcade games.. that
weigh in at an average of about 275lbs each and have a foot print of
about 2'wide x 3'deep each. I have a spare 10' x 11' bed room (in a
third floor condo) and I am trying to figure out if the room can handle
the weight of 9 games. I will have the games positioned around the
edge of the room so.. I figure that if the joists are going 'with'
the games I will probably have at beast 2 joists supporting 4 games and
of the joists are going 'against' the games I will probably have
about 2 joists supporting 2 games which might be better.

If anybody more familiar with construction loads can give me some
advice that would be great. I think current building code in WA is a
minimum of 30lbs per square foot live load but I have received so much
input on the issue (negative and positive) that I am a little confused
at the moment. I know people do heavy fish tanks, water beads, grand
pianos, weight machines, etc, etc but I might be talking about a little
more weight than most of those.

Thanks, Ryan
www.ryansarcade.com

On 29 Mar 2006 08:54:01 -0800, wrote:

Thanks for the advice.

I have a strange hobby. I collect and restore old arcade games.. that
weigh in at an average of about 275lbs each and have a foot print of
about 2'wide x 3'deep each. I have a spare 10' x 11' bed room (in a
third floor condo) and I am trying to figure out if the room can handle
the weight of 9 games. I will have the games positioned around the
edge of the room so.. I figure that if the joists are going 'with'
the games I will probably have at beast 2 joists supporting 4 games and
of the joists are going 'against' the games I will probably have
about 2 joists supporting 2 games which might be better.

If anybody more familiar with construction loads can give me some
advice that would be great. I think current building code in WA is a
minimum of 30lbs per square foot live load but I have received so much
input on the issue (negative and positive) that I am a little confused
at the moment. I know people do heavy fish tanks, water beads, grand
pianos, weight machines, etc, etc but I might be talking about a little
more weight than most of those.


30 PSF live load is the minumum for a upper story (bedroom) in most
codes. A building that was purpose-built as a multi-family is
probably designed to 40 PSF, or possibly 50 PSF.

At 30 PSF, the room will theoretically hold 10' x 11' x 30 psf =3300
pounds, which works out to 12 machines, 11 machines and 1 person,
or 9 machines and a

Even at the 30 PSF that's supposed to be an average, so if you
don't put down a solid row of the ALONG the joists you should
be ok. And the failure more will be sagging, bouncy floors,
and cracking in the plaster/drywall of the ceiling below long
before an actual failure is likely.

If you know which way the floor joists go, and where a load-
bearing (generally exterior) wall is, then lay a pair of 2x6s
across the ends of the joists to spread the load a bit, and
then line the machines up on those, and you should be fine.
If the games have ballast in them, you might remove or
reduce that and store the ballast somewhere else.

Thanks Goedjn, your reply helps me a great deal.

The condo below me has an identical floor plan. Does this mean that
all of the walls in my room are load bearing? Also, I looked at the
roof over the room (it has a separate roof orientation from the rest of
the building) and it slopes along the 11' side of the game room so I am
guessing that the joists are lined up parallel to the 11' side. All
but one of the games are going to be positioned along the 11' sides of
the room as well.

So I will basically have three games lined up against one 11' wall
along two joists (approx 825lbs) and five games lined up against the
other 11' wall over two joists (approx 1375lbs). I will also have one
game centered up against one of the 10' walls (approx 300lbs). Make
sense? I am not sure how the 30PSF averaging works. Can the weight be
anywhere in the room or does is need to be evenly spread out? In other
words.. does the floor act as a single structure or do I need to be
concerned about weight on individual joists? Having games in the
center of the room would not really be feasible.

Thanks again, Ryan

On 29 Mar 2006 12:27:44 -0800, wrote:

Thanks Goedjn, your reply helps me a great deal.

The condo below me has an identical floor plan. Does this mean that
all of the walls in my room are load bearing? Also, I looked at the
roof over the room (it has a separate roof orientation from the rest of
the building) and it slopes along the 11' side of the game room so I am
guessing that the joists are lined up parallel to the 11' side. All
but one of the games are going to be positioned along the 11' sides of
the room as well.

So I will basically have three games lined up against one 11' wall
along two joists (approx 825lbs) and five games lined up against the
other 11' wall over two joists (approx 1375lbs). I will also have one
game centered up against one of the 10' walls (approx 300lbs). Make
sense? I am not sure how the 30PSF averaging works. Can the weight be
anywhere in the room or does is need to be evenly spread out? In other
words.. does the floor act as a single structure or do I need to be
concerned about weight on individual joists? Having games in the
center of the room would not really be feasible.

Thanks again, Ryan

If you assume that the joists are 16" on-center, and that the
floor is designed to support 30 PSF, then each joist
is sized to support (30/12)*16=40 Pounds/LINEAR foot.
If they're running the short way in a 10x11 room, then
that's 400 pounds/joist, or 800 pounds for a pair of them.
This assumes an even distribution, which you don't have.
For point-loads, you have to either do math (which I
don't know how to describe), or make sure that most of your
load is closer to the support walls than to the middle
of the span.

I'd say that the five games along one pair of joists
is more than you probably want.
Do you have to arrange the machines
so that they're all lined up on the same pair(s) of
joists, or can you go along the other wall(s)?
How do you know which way the joists are going, anyway?

(It's getting near time to draw a diagram of the room,
and post it somewhere.)

(It's getting near time to draw a diagram of the room, and post it somewhere.)

OK, I will try to wip out the AutoCAD tonight and make a simple
drawing. As far as the joist direction goes, I was following the logic
from the second post 'Usually, the same direction as the roof slopes'.
I think the plan now is to get a good stud finder and figure out which
direction the ceiling joists are going. Hopefully the floor joists are
going in the same direction as the ceiling joists.

I wasn't able to get a drawing done tonight but I did take a closer
look and, based on dryer vents on the front of the building, it looks
like my joists are running perpendicular to the games which is great.
So basically it's a 10' x 11' room with the joists running parallel
to the 10' wall and the games lined up along the 11' walls (3 on one
side and 5 on the other side). I think I am pretty safe because of the
perpendicular joists but any more input would be fantastic. I will
still try to post a diagram tomorrow.