I am nearing completion of my attic project. I recently put in an
attic stairs and putting in 3/4" OSB plywood for the floor, replacing
the old T&G planks I had up there. I live in a split level 50 year old
house. The attic is 2X6's spaced 16"OC. It spans approx 20' X20'.
Below are some walls forming a bedroom closet .Although I am not sure
if this is a load bearing wall for the attic, I would think it does
add some support. But realistically how much weight can be put up
there? Is there some sort of guidline?

Mikepier wrote:
I am nearing completion of my attic project. I recently put in an
attic stairs and putting in 3/4" OSB plywood for the floor, replacing
the old T&G planks I had up there. I live in a split level 50 year old
house. The attic is 2X6's spaced 16"OC. It spans approx 20' X20'.
Below are some walls forming a bedroom closet .Although I am not sure
if this is a load bearing wall for the attic, I would think it does
add some support. But realistically how much weight can be put up
there? Is there some sort of guidline?

Probably a lot more than you care to haul up those stairs.

"Mikepier" wrote in message
...
I am nearing completion of my attic project. I recently put in an
attic stairs and putting in 3/4" OSB plywood for the floor, replacing
the old T&G planks I had up there. I live in a split level 50 year old
house. The attic is 2X6's spaced 16"OC. It spans approx 20' X20'.
Below are some walls forming a bedroom closet .Although I am not sure
if this is a load bearing wall for the attic, I would think it does
add some support. But realistically how much weight can be put up
there? Is there some sort of guidline?


Not very much according to my reference manual. A 2x6 16OC is only rated
for 30 live floor load to about 11'2". A 20 foot span 16" OC need at least
a 2x10 for a 30 pound live load.

For a 20 lb live load, limited storage with SYP joists 16" OC is good to
about 14.5 feet of span. This calculation includes the weight of a drywall
ceiling under the joists.

The good news is your old wood most likely is SYP and better than anything
you can buy today so I provided the ratings for Select Structural grade
instead of the lesser grades. I suspect you can exceed the numbers a little
with no real fears.

I would not fill it up and I would keep the heavy stuff to the sides. Sorry
to be the bearer of bad news.


--
Colbyt
Please come visit http://www.househomerepair.com

On Sun, 7 Feb 2010 06:06:21 -0800 (PST), Mikepier
wrote:

I am nearing completion of my attic project. I recently put in an
attic stairs and putting in 3/4" OSB plywood for the floor, replacing
the old T&G planks I had up there. I live in a split level 50 year old
house. The attic is 2X6's spaced 16"OC. It spans approx 20' X20'.
Below are some walls forming a bedroom closet .Although I am not sure
if this is a load bearing wall for the attic,

I would think that what makes a load-bearing wall is not what is in
the attic. Because anything near the wall and in the attic will rest
on the wall to some extent.

And I didn't think what determined a load-bearing wall was the
construction of the wall, assuming it is made like a standard wall is
made and not of some flimsy construction.

I thought a load-bearing wall was determined by what is beneath it.
Is there another wall directly beneath the closet walls that hold them
up. All the way down either to the foundation or to steel girder that
spans the basement.

Am I right?

I would think it does
add some support. But realistically how much weight can be put up
there? Is there some sort of guidline?

Colbyt wrote:

"Mikepier" wrote in message
...
I am nearing completion of my attic project. I recently put in an
attic stairs and putting in 3/4" OSB plywood for the floor, replacing
the old T&G planks I had up there. I live in a split level 50 year old
house. The attic is 2X6's spaced 16"OC. It spans approx 20' X20'.
Below are some walls forming a bedroom closet .Although I am not sure
if this is a load bearing wall for the attic, I would think it does
add some support. But realistically how much weight can be put up
there? Is there some sort of guidline?

Not very much according to my reference manual. A 2x6 16OC is only rated
for 30 live floor load to about 11'2". A 20 foot span 16" OC need at least
a 2x10 for a 30 pound live load.

For a 20 lb live load, limited storage with SYP joists 16" OC is good to
about 14.5 feet of span. This calculation includes the weight of a drywall
ceiling under the joists.

The good news is your old wood most likely is SYP and better than anything
you can buy today so I provided the ratings for Select Structural grade
instead of the lesser grades. I suspect you can exceed the numbers a little
with no real fears.

I would not fill it up and I would keep the heavy stuff to the sides. Sorry
to be the bearer of bad news.

--
Colbyt
Please come visit http://www.househomerepair.com

Those load specs are likely based on acceptable deflection under load
(L/360?) for comfort in a living space i.e. not too much bounce, not the
limit that will cause structural failure. Cracks in the ceiling
sheetrock are probably a greater risk than actual failure.

I want to clarify, the entire attic is about 20X20, but the largest
span is 15 1/2' in my master bedroom then it rests on a wall that
creates the bathroom. all the other spans are 12' until hit rests on a
wall below, like the closet, bedroom wall, etc
I also heard it was good to screw down all the OSB to actually
strengthen the floor. So far it seems solid. I am not looking on
putting anything massive up there, just basic stuff.

I am nearing completion of my attic project. I recently put in an
attic stairs and putting in 3/4" OSB plywood for the floor, replacing
the old T&G planks I had up there. I live in a split level 50 year old
house. The attic is 2X6's spaced 16"OC. It spans approx 20' X20'.
Below are some walls forming a bedroom closet .Although I am not sure
if this is a load bearing wall for the attic, I would think it does
add some support. But realistically how much weight can be put up
there? Is there some sort of guidline?

Very simple: put stuff up there until it crashes down. That's the limit.
3/4" plywood sounds a little heavy to me by itself.

Steve

On Feb 7, 8:06*am, Mikepier wrote:
I am

snip

putting in 3/4" OSB plywood for the floor,

snip

OSB and plywood aren't the same thing. Maximum strength will be
achieved if you use 3/4" real plywood glued and screwed to the joists.
Your call as to whether that might be necessary.

Joe

I would be a bit surprised if the original 2x6 are 20' long. If
they met at some mid point and were side lapped, this would have
occurred over a wall, that wall was then a load bearing wall.
That load bearing wall would have another wall or girder below it,
also load bearing. I assume you do not have trusses if you were
able to deck out large expanses. I don't know that you gained
much trading out 3/4 T&G for 3/4 plywood, they would both be rated
about the same.

The length of the joists is measured from bearing to bearing. If
they truly span 20' they have no load bearing ability. #2 SYP
joists carrying a ceiling are maxed out at just over 15'.

here is an easy calculator that will let you play with the
numbers:
http://www.awc.org/calculators/span/...izontal+ Span

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




"Mikepier" wrote in message
...
I am nearing completion of my attic project. I recently put in an
attic stairs and putting in 3/4" OSB plywood for the floor,
replacing
the old T&G planks I had up there. I live in a split level 50
year old
house. The attic is 2X6's spaced 16"OC. It spans approx 20'
X20'.
Below are some walls forming a bedroom closet .Although I am not
sure
if this is a load bearing wall for the attic, I would think it
does
add some support. But realistically how much weight can be put
up
there? Is there some sort of guidline?

here is an easy calculator that will let you play with the
numbers:http://www.awc.org/calculators/span/...e.asp?species=...


Thanks for the link. How do I know what kind of wood I have? I assume
Douglas Fir, but what is SYP you mentioned?

"LouB" wrote in message
...
Mikepier wrote:
I am nearing completion of my attic project. I recently put in an
attic stairs and putting in 3/4" OSB plywood for the floor, replacing
the old T&G planks I had up there. I live in a split level 50 year old
house. The attic is 2X6's spaced 16"OC. It spans approx 20' X20'.
Below are some walls forming a bedroom closet .Although I am not sure
if this is a load bearing wall for the attic, I would think it does
add some support. But realistically how much weight can be put up
there? Is there some sort of guidline?

Probably a lot more than you care to haul up those stairs.



Ditto...As long as your just puting Christmas decorations , boxes of
seasonal clothes ect. you should be fine...Just don't put a pallet of bricks
up there...LOL...As usual use common sense...

I saw pics of some attics that there were some 2X4's nailed from the
roof rafters down to the ceiling joists I guess for extra support. Can
I put one or two in for the long span above my bedroom?

"Mikepier" wrote in message
...
here is an easy calculator that will let you play with the
numbers:http://www.awc.org/calculators/span/...e.asp?species=...


Thanks for the link. How do I know what kind of wood I have? I assume
Douglas Fir, but what is SYP you mentioned?


Add to what Dan said:

SYP Southern yellow pine sometimes labeled SP.
Still sold even at the BORG when the length of a 2x6 is over 12 feet.
Almost surely used in a 50 year old house.
Only moderately better rated.
50 years ago the grading standards were much higher than today.

Colbyt

Mikepier wrote:
I saw pics of some attics that there were some 2X4's nailed from the
roof rafters down to the ceiling joists I guess for extra support. Can
I put one or two in for the long span above my bedroom?

Sure, and that may help stop the roof from blowing off in a major hurricane.

Southern Yellow Pine, the other structural lumber. They both have
a similar modulus of elasticity. Lumber normally has a grading
stamp on it. If you've already decked the thing, you won't be
able to find one. You may see one on one of the rafters, the
lumber all came out at once from the lumber yard and is probably
the same grade and type.

I doubt that they would have used much better than #2 SYP. That
calculator calls it southern pine.

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




"Mikepier" wrote in message
...
here is an easy calculator that will let you play with the
numbers:http://www.awc.org/calculators/span/...e.asp?species=...


Thanks for the link. How do I know what kind of wood I have? I
assume
Douglas Fir, but what is SYP you mentioned?

On Sun, 7 Feb 2010 13:38:48 -0800, "Steve B"
wrote:



I am nearing completion of my attic project. I recently put in an
attic stairs and putting in 3/4" OSB plywood for the floor, replacing
the old T&G planks I had up there. I live in a split level 50 year old
house. The attic is 2X6's spaced 16"OC. It spans approx 20' X20'.
Below are some walls forming a bedroom closet .Although I am not sure
if this is a load bearing wall for the attic, I would think it does
add some support. But realistically how much weight can be put up
there? Is there some sort of guidline?

Very simple: put stuff up there until it crashes down.

Then you put up less than that.

That's the limit.
3/4" plywood sounds a little heavy to me by itself.

Steve

replying to Colbyt, Steve Johnson wrote:
Common sense says your calculations are wrong otherwise a 220lb person
carrying a 100lbs should fall through but they don't

--
for full context, visit https://www.homeownershub.com/mainte...or-423851-.htm

"Steve Johnson" m wrote
in message ...
replying to Colbyt, Steve Johnson wrote:
Common sense says your calculations are wrong otherwise a 220lb person
carrying a 100lbs should fall through but they don't

--
for full context, visit
https://www.homeownershub.com/mainte...or-423851-.htm

Ha Ha "Common sense" in replying to an 8 year old post.

On Tuesday, November 27, 2018 at 4:14:06 PM UTC-5, Steve Johnson wrote:
replying to Colbyt, Steve Johnson wrote:
Common sense says your calculations are wrong otherwise a 220lb person
carrying a 100lbs should fall through but they don't

--
for full context, visit https://www.homeownershub.com/mainte...or-423851-.htm

Those loads weights he's quoting are *per sq ft* across the area.