I am neither a builder or carpenter. I saw a shed today at Home Depot,
that measured 16 x 16. It had a loft second story to it for additional
storage.

There are no internal supporting posts. The joists were 2 x 10, and
spanned the full 16 ft width of the shed.

I was wondering if a person could use 2 x 12s, and span up to 24 feet
without supporting posts? I doubt it. Yet, I walked up into the loft 2nd
level and jumped on the floor (I weigh 200 lbs), and the floor felt
"pretty" solid. Not rock solid , of course. Of course, going to 24 feet
would be 8 more feet of span, and could make a big difference

Bottom line, how far can you span with 2 x 10's, and how far with 2 x
12's ? By the way, these joists were 12 inches apart.

Thanks for any comments !!

--James--

In a previous post James says...
I was wondering if a person could use 2 x 12s, and span up to 24 feet


The hard part will be finding 24-foot long 2x12's

--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA

"James" wrote in message
...


I am neither a builder or carpenter. I saw a shed today at Home Depot,
that measured 16 x 16. It had a loft second story to it for additional
storage.

There are no internal supporting posts. The joists were 2 x 10, and
spanned the full 16 ft width of the shed.

I was wondering if a person could use 2 x 12s, and span up to 24 feet
without supporting posts? I doubt it. Yet, I walked up into the loft 2nd
level and jumped on the floor (I weigh 200 lbs), and the floor felt
"pretty" solid. Not rock solid , of course. Of course, going to 24 feet
would be 8 more feet of span, and could make a big difference

Bottom line, how far can you span with 2 x 10's, and how far with 2 x
12's ? By the way, these joists were 12 inches apart.

Thanks for any comments !!

--James--



Rather than me quote what I think, go here and get accurate data:

http://www.southernpine.com/spantables.shtml


Colbyt

"James" wrote in message
...


I am neither a builder or carpenter. I saw a shed today at Home Depot,
that measured 16 x 16. It had a loft second story to it for additional
storage.

There are no internal supporting posts. The joists were 2 x 10, and
spanned the full 16 ft width of the shed.

I was wondering if a person could use 2 x 12s, and span up to 24 feet
without supporting posts? I doubt it. Yet, I walked up into the loft 2nd
level and jumped on the floor (I weigh 200 lbs), and the floor felt
"pretty" solid. Not rock solid , of course. Of course, going to 24 feet
would be 8 more feet of span, and could make a big difference

Bottom line, how far can you span with 2 x 10's, and how far with 2 x
12's ? By the way, these joists were 12 inches apart.

Thanks for any comments !!

--James--



Try Wood I-Beams -- Here's a link. Be sure to go to the two PDF files on
the linked page to see how they're designed, and a chart of load capacities.
http://www.abctruss.com/woodibeam.htm

Bob Morrison wrote:
In a previous post James says...

I was wondering if a person could use 2 x 12s, and span up to 24 feet


The hard part will be finding 24-foot long 2x12's


Use steel trusses. Going 60+ feet is no problem.

"Bob Morrison" wrote in message
k.net...
In a previous post James says...
I was wondering if a person could use 2 x 12s, and span up to 24 feet


The hard part will be finding 24-foot long 2x12's

Not hard........just expensive ;-)

--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA

James wrote:
I am neither a builder or carpenter. I saw a shed today at Home
Depot,
that measured 16 x 16. It had a loft second story to it for
additional
storage.

There are no internal supporting posts. The joists were 2 x 10, and
spanned the full 16 ft width of the shed.

I was wondering if a person could use 2 x 12s, and span up to 24
feet
without supporting posts? I doubt it. Yet, I walked up into the
loft 2nd
level and jumped on the floor (I weigh 200 lbs), and the floor felt
"pretty" solid. Not rock solid , of course. Of course, going to 24
feet
would be 8 more feet of span, and could make a big difference

Bottom line, how far can you span with 2 x 10's, and how far with 2
x
12's ? By the way, these joists were 12 inches apart.

Someone already posted the Southern Pine span table link. The Canadian
Wood Council's Spancalc tool covers other species as well.

R

In article t, Bob
Morrison wrote:

€ The hard part will be finding 24-foot long 2x12's

They can be had here, but any quantity of them would be a special order
item, and they would be priced accordingly.

Unless they were called out specifically, and, therefore, included in
the bid, I would look for an alternative, simply because of the money.

--
Lyle B. Harwood, President
Phoenix Homes, Inc.
(206) 523-9500 www.phoenixhomesinc.com

"Gerry Atrick" wrote in message
...
In my kitchen, my espresso machine is making the GFCI trip. When
plugging something else (such as toaster), it doesn't trip.
Also, plugging the espresso machine to another GFCI in my kitchen, it
doesnt' trip neither.
So is it due to the espresso machine or shall I just change the GFCI ?

BOTH.

The machine is close to the upper limit on "leakage" and the GFCI is on the
lower side of the sensitivity threshold.

Is it a good sized machine with a grounding (3 conductor) plug, does it have
a polarized plug (one blade wider than the other) or is it "double
insulated" using a non-polarized plug (both blades the same width)?

Anyway, if you can, reverse the plug and see if it still trips. If it
does, put in a new GFCI (they are relatively cheap). If it still trips,
consider junking the machine unless it has a three conductor (grounding)
plug.

It also depends on your building code. where I live, you can't go more
then 12 feet in any direction without applying for a building permit, so
the sheds are limited to be no larger than 12x12 if you don't want to
apply for a permit and deal with the footing issues.

James wrote:

I am neither a builder or carpenter. I saw a shed today at Home Depot,
that measured 16 x 16. It had a loft second story to it for additional
storage.

There are no internal supporting posts. The joists were 2 x 10, and
spanned the full 16 ft width of the shed.

I was wondering if a person could use 2 x 12s, and span up to 24 feet
without supporting posts? I doubt it. Yet, I walked up into the loft 2nd
level and jumped on the floor (I weigh 200 lbs), and the floor felt
"pretty" solid. Not rock solid , of course. Of course, going to 24 feet
would be 8 more feet of span, and could make a big difference

Bottom line, how far can you span with 2 x 10's, and how far with 2 x
12's ? By the way, these joists were 12 inches apart.

Thanks for any comments !!

--James--

Gerry Atrick wrote:
In my kitchen, my espresso machine is making the GFCI trip. When
plugging something else (such as toaster), it doesn't trip.
Also, plugging the espresso machine to another GFCI in my kitchen, it
doesnt' trip neither.
So is it due to the espresso machine or shall I just change the GFCI
?

thanks.

Fred.

You have an extremely dangerous condition. Plan on ripping out the
kitchen and starting over...assuming the kitchen doesn't burst into
flames before then.

R

James writes:

I was wondering if a person could use 2 x 12s, and span up to 24
feet
without supporting posts? I doubt it. Yet, I walked up into the
loft 2nd
level and jumped on the floor (I weigh 200 lbs), and the floor felt
"pretty" solid. Not rock solid , of course. Of course, going to 24
feet
would be 8 more feet of span, and could make a big difference

Forget dimensional lumber and use TJI framing. Engineered I-joists
will do any span you want, cheaper than lumber, and they are lighter
and easier to handle.

Larry

On Fri, 01 Apr 2005 00:32:12 GMT, someone wrote:


The hard part will be finding 24-foot long 2x12's
--
Bob Morrison, PE, SE

Well Bob you are a PE, but do you commonly work with lumber? I recall
having bought 24' lumber and didn't think it was a big deal, my
understanding was that 24 foot was the longest standard size.
Nowadays it is usually finger jointed out of several shorter pieces.


Reply to NG only - this e.mail address goes to a kill file.

On Thu, 31 Mar 2005 18:24:13 -0500, someone wrote:

There are no internal supporting posts. The joists were 2 x 10, and
spanned the full 16 ft width of the shed.

I was wondering if a person could use 2 x 12s, and span up to 24 feet
without supporting posts? I doubt it. Yet, I walked up into the loft 2nd
level and jumped on the floor (I weigh 200 lbs), and the floor felt
"pretty" solid.

Why do you say ":yet" you walked onto the floor and it was solid? At
16 feet with 2x10s it should be solid. Your Q has to do with
anticipated loading, joist spacing, and allowable deflection not just
"can I or can't I".

2x10s spanning 16 feet, if on anything like "normal" 16 inch centers
(are you sure they are 12" like you said, that would be unusual), is
in the ballpark for typical framing for residential loadings, so it
SHOULD feel similar to the floor in a typical house. The old
carpenter's rule of thumb (for feet and inches) is "half the span (in
feet) in inches, plus 2".

Loading goes up exponentially as span increases, so there is MUCH more
to it than just "adding 8 feet". In particular, Deflection goes way
up - you could have a floor that was strong enough not to collapse,
but would sag or bounce quite a bit. (Also, on a short span you can
easily have a floor that is very stiff, but that could collapse
suddenly from overload.)

Why do you "need" 24 feet like this? 24 feet can be spanned with
engineered wood products but very often there is a better way, unless
there is a very particular actual NEED for no posts.


Reply to NG only - this e.mail address goes to a kill file.

In a previous post v says...
Well Bob you are a PE, but do you commonly work with lumber?

Yes. Most of my practice deals with light frame construction.

I recall
having bought 24' lumber and didn't think it was a big deal, my
understanding was that 24 foot was the longest standard size.
Nowadays it is usually finger jointed out of several shorter pieces.


I didn't say it was impossible, just that it is a little hard to find.
24-foot sticks are not something you can usually just go to the local
lumber yard and buy off the shelf.

Not to mention that 24-foot 2x12's will probably not be straight.

Finger jointed lumber has a lower allowable bending stress and should
not be used for members subject to flexure. A better choice is
engineered lumber from both a cost and quality point of view.

A typical spec might be 1-1/2 x 11-1/4 1.5E LSL as a replacement for
2x12's


--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA

APA has a booklet on rigid frame construction. Benefits are clear span of
48' with 2x10, 24"oc.

On Sat, 2 Apr 2005 22:12:00 -0600, someone wrote:

APA has a booklet on rigid frame construction. Benefits are clear span of
48' with 2x10, 24"oc.

All of this still begs the question - does he "NEED" the 24 foot
clearspan for any kind of residential use or storage shed? He said he
was looking at sheds - apparently prefabricated ones. If he buys one,
if its 24 x 24, they are not going to be able to deliver it.

If its 24 by something less, can it be spanned the shorter way? If its
to be two halves to be assembled on site, he is talking about a
modular building not a shed.

If he "needs" 24 x 24 clear because he is going to be building an
airplane etc., then he has need for a commercial shop building, not a
residential shed.

This kind of Q comes up all the time, and among homeowners, I'd
estimate that maybe 90% of the time, their use does not actually
require the clearspan they think it does, that's just the easiest way
out for their limited knowledge.


Reply to NG only - this e.mail address goes to a kill file.

My use is for a shed that doesn't have internal posts. The REASONS for my
stated use are not under consideration. Only the engineering/construction
is under consideration here.

Thanks for all of the good replies !!

--James--

James wrote:

...how far can you span with 2 x 10's, and how far with 2 x 12's ?
By the way, these joists were 12 inches apart.

If modulus S = bd^2/6 = d^2/4 in^3 for b = 1.5" and bending moment M = Sf
= 250d^2 in-lb for fiber stress f = 1000 psi and total load W = 8M/(12L)
= 167d^2/L pounds for an L' span, floor loading w = W/(LC) = 167d^2/(L^2C)
pounds per square foot (psf) for L' beams on C foot centers.

So 9.25" 16' 2x10s on 1' centers might support w = 167x9.25^2/(16^2x1)
= 55.7 psf. On 16" (1.33') centers, w = 42 psf... 11.25" 2x12s with
L = 24' make w = 167x11.25^2/(24^2x1.33) = 27.5 psf, with cross-bracing
for torsional longitudinal stability.

With a post and beam in the middle to halve the span, 12' 2x10s on
2' centers might support w = 167x9.25^2/(12^2x2) = 50 psf... 2x8s
might do w = 167x7.25^2/(12^2x2) = 30 psf.

Nick

In article ,
says...
James wrote:

...how far can you span with 2 x 10's, and how far with 2 x 12's ?
By the way, these joists were 12 inches apart.

original post hasn't appeared on my newsserver yet, so I'll reply to the
reply ...

I whipped out my old building code (NZ, 1981) and they reckon for floor
joists that for


joist spacing
400mm (~16 inches) 450 mm(18 inches) 600mm (2')
size
9x2 4.3m (~14') 4.1m (~13'8") 3.7m (~12'4")
10x2 4.8m 4.6m 4.15m
12x2 5.75m (~19') 5.5m 5.0m

this is for a 1.5kPa floor loading. If the joists cover two or more
spans, you can add 10% to the span. Huh, I want anybody to come up with
a truckload of 42' long 12x2. (actually, the table starts with 4x2
joists spanning 5' at 2' centres, so that note is not entirely
irrelevant).

So you can see that going on these numbers, the shed you looked at was
quite sturdily built.

-P.

I suppose the answer to my question then is 32 feet.


--James--

On Sat, 28 May 2005 14:08:32 -0400, someone wrote:

I suppose the answer to my question then is 32 feet.

For 2x10s? Fat chance of that. Not if you wanted to put anything on
them. You'll also not likely find 32 foot 2x10s commercially
available. And if they were, they would be Hell to handle and get in
place.


Reply to NG only - this e.mail address goes to a kill file.

Well then, I suppose the answer to my question is 17.432 feet.


--James--


------------------------


I suppose the answer to my question then is 32 feet.

For 2x10s? Fat chance of that. Not if you wanted to put anything on
them. You'll also not likely find 32 foot 2x10s commercially
available. And if they were, they would be Hell to handle and get in
place.

Well then, I suppose the answer to my question is 17.432 feet.


--James--


------------------------


I suppose the answer to my question then is 32 feet.

For 2x10s? Fat chance of that. Not if you wanted to put anything on
them. You'll also not likely find 32 foot 2x10s commercially
available. And if they were, they would be Hell to handle and get in
place.

Well then, I suppose the answer to my question is 17.432 feet.


--James--


------------------------


I suppose the answer to my question then is 32 feet.

For 2x10s? Fat chance of that. Not if you wanted to put anything on
them. You'll also not likely find 32 foot 2x10s commercially
available. And if they were, they would be Hell to handle and get in
place.