On Jan 24, 2:11*pm, Vic Smith wrote:
On Tue, 24 Jan 2012 09:48:00 -0800 (PST), DD_BobK
wrote:



Take a look at this joist calculator. *You can "play" with the joist
size, timber species & timber grade and see how the allowable span
changes.

http://www.awc.org/calculators/span/...e.asp?species=....

That's handy.
Reason I asked is I put 2 extra ceiling joists in my garage when I
bought this place.
How it was built didn't seem right. *6' centers in some places.
Probably built in 1959.
Those joists are 21' 2x6 and from what I can figure basically just tie
the top sills together and square.
Good place to hang lights and the door opener too.

Anyway, I've seen too many garages fall out of square.
Besides that I wanted to put plywood up there as a storage platform.
When I ordered the joists from HD I said pine, because I thought
that's what the old ones were.
They said they only had Douglas fir that long, so that's what I got.
Precut the angles, jigsawed a hole in the fascia, and slid them onto
the plates. *Nailed them in. *Patched the fascia hole.
A couple years later I put up alum gutters, soffit/fascia.

Put a few 4x8 x1/2 plywood up there and started storing stuff, nothing
real heavy.
Boxes of Christmas decorations and the like.
Garden tools in the winter, snow shovels in the summer, etc.
Then I told my kid to get rid of the 4 tires he was keeping in there
because the alloy rims were "special," or put them up on the platform.
I was tired of them getting in my way.
He did that. *2 stacks of 2, alongside each other.
A couple years later I was chatting with my 80-year-old neighbor in
the garage and he pointed out one of my new joists was sagging.
He's retired building trades and has the eye for it, but when he
pointed it out I saw it.
Tires came down and it sprung back up.
*6" won't take much load over 21'.
I learned that quick.
But I'm still tripping over or moving those tires.

Drywall screws should only be used for drywall and temporary, rather
than permanent loads.

I started using them to put together 8' workbenches at least 30 years
and they're good for that. * You can knock them down if you have to,
though I never did any of 6 or so I built.
No real load on the screws. *Solid as the day they were built,









" He told me once that 2 nails can be better than 6 screws for
resisting shear in some circumstances."

that's a pretty general statement, I know for a fact that a single
1/4" SDS will take the place of a handful of nails.
His statement tends to be more correct for small screws but IMO screws
(SS) are better in a lot of locations (exterior exposure & esp open
patio covers) since over time they will not rust and encourage rot or
lose strength. *Galvanized timber connector nails will last a long
time, SS ones even longer but #10 SS screws in the same application
will last a long time plus provide better withdrawl resistance.

I know nails are shear fasteners and better than screws in shear but
over the years I've seen those shorty connector nails rust out / rot
out in patio covers to the point that I changed my tune.....

what good is a screw that's rust away & help rot out the wood?
IMO better to drill out the hanger nail hole and use a larger dia SS
screw (larger root diameter) than stick with nails that I know will
cause the failure of the entire system.

Fasteners are a science in themselves. *I wouldn't do anything
structural without expert advice on fasteners.

I always clamp (or screw) when using traditional glues.
When I top sistered my ceiling joists there was no easy way to clamp
so I used epoxy paste that was forgiving of joint gaps.
I pretested a sample made with rough timber, dirty just brushed off.
The sample failed at 175 psi shear when a knot in the bottom member
failed.

Based on my crappy sample, I knew that my sistered joists would
perform better since I wire brushed both faces of the glue joint and
none of the bottom chord members had large flaws. *Plus, based on my
calcs, my shear demand was WAY lower than 175 psi more like less than
50 psi

You did your homework.

--Vic

Vic, those "joists" you describe from the 1959 garage are not
joists.
They were not designed or installed to resist bending loads.
They are "tension ties" to resist the spreading force generated by the
roof.
To span 21' as a joist you would need at least a 2x10.

I stand by my comments on drywall screws. They are easily the most
mis-used fastener in America.
They are not the appropriate fastener for anything other than
drywall. Hacks use them to hang kitchen cabinets.

cheers
Bob

On Jan 24, 3:33*pm, JIMMIE wrote:
On Jan 24, 12:22*am, DD_BobK wrote:









On Jan 23, 12:42*pm, JIMMIE wrote:

On Jan 22, 11:02*pm, Steve Barker wrote:

some time ago i inquired about fastening some steel plate to the sides
of some 100+ year old, full dimension, rough cut oak floor joists to
stiffen them up. I've decided to sister them with like sized (2x8) wood
instead. *These are the second story floor joists and they are 2x8 and
span 15.5 feet. *I've got the ceiling out on the lower level and want to
stiffen them up before i go back with new ceiling. My question is, what
is the best way (and frequency) to attach them? *Screws, nut and bolt,
nail, glue, etc?? *It's a balloon style house and i'll be able to *set
the new sisters up on the ledger board like the originals. *My main
concern is pulling them together in such a fashion as to best create a
"oneness" .

thanks!

--
Steve Barker
remove the "not" from my address to email

If you have oak up there I would be thinking about a way to display it
and not put up a ceiling . *I cant imagine the oak beams you described
not being strong enough for the job. They have worked for 100 years
they will be doing the job in 100 more. Don't even think about nails.

Jimmie

Steve's situation is an issue of stiffness not strength.
Too much bounce means he needs to add stiffness and that relates
mostly to joist depth.

Per the joist calculator mentioned recently in another thread, a 15'
span needs a 2x10 of decent timber or a 2x12 of lesser material.

If my calcs are correct, *Steve's original joists sistered with new
2x8's will be stiffer than a 2x10 by 13% but t only be 55% as stiff as
a 2x12.

cheers
Bob

Bob, just wondering your if your calcs take into account the existing
wood is 100+ year old oak.Usually these timbers were made from
heartwood. *It is surprising to me it is not rigid enough already. I
would look to see if it is in fact the joist that are giving when he
walks on them and how they are giving. The problem could be that the
flooring is not strong enough to properly distribute the weight from
joist to joist. Lack of a proper subfloor could cause this which is a
common condition in old homes. Just something else to think about.

Jimmie

Jimmie-

The wood is not the problem. The joist depth & span are the issues.
Steve made no mention of the subfloor construction and, yes,
the subfloor construction can influence overall floor behavior but
it's pretty much a secondary effect.

Steve could "box out" his wimpy joists with a lots of blocking, lots
of glue and a structural skin on the bottom surface of the joists to
create composite action floor. This would increase the floor stiff
and get adjacent joists to share load. It would be a LOT of work and
still probably not work as well as sistering especially if Steve used
deeper sisters.

A number of year ago I worked on a floor vibration problem. It
involved a kitchen and living space over a 25' garage. Unfortunately,
the joists were spec'd as 12" floor trusses. They skimped on the depth
to stay within a city overall building height limitation. The condos
were three story.

The 12" floor trusses were too flexible, should have been at least
14". A real PITA to fix.

cheers
Bob

On 1/24/2012 11:28 PM, DD_BobK wrote:
On Jan 24, 3:33 pm, wrote:
On Jan 24, 12:22 am, wrote:









On Jan 23, 12:42 pm, wrote:

On Jan 22, 11:02 pm, Steve wrote:

some time ago i inquired about fastening some steel plate to the sides
of some 100+ year old, full dimension, rough cut oak floor joists to
stiffen them up. I've decided to sister them with like sized (2x8) wood
instead. These are the second story floor joists and they are 2x8 and
span 15.5 feet. I've got the ceiling out on the lower level and want to
stiffen them up before i go back with new ceiling. My question is, what
is the best way (and frequency) to attach them? Screws, nut and bolt,
nail, glue, etc?? It's a balloon style house and i'll be able to set
the new sisters up on the ledger board like the originals. My main
concern is pulling them together in such a fashion as to best create a
"oneness" .

thanks!

--
Steve Barker
remove the "not" from my address to email

If you have oak up there I would be thinking about a way to display it
and not put up a ceiling . I cant imagine the oak beams you described
not being strong enough for the job. They have worked for 100 years
they will be doing the job in 100 more. Don't even think about nails.

Jimmie

Steve's situation is an issue of stiffness not strength.
Too much bounce means he needs to add stiffness and that relates
mostly to joist depth.

Per the joist calculator mentioned recently in another thread, a 15'
span needs a 2x10 of decent timber or a 2x12 of lesser material.

If my calcs are correct, Steve's original joists sistered with new
2x8's will be stiffer than a 2x10 by 13% but t only be 55% as stiff as
a 2x12.

cheers
Bob

Bob, just wondering your if your calcs take into account the existing
wood is 100+ year old oak.Usually these timbers were made from
heartwood. It is surprising to me it is not rigid enough already. I
would look to see if it is in fact the joist that are giving when he
walks on them and how they are giving. The problem could be that the
flooring is not strong enough to properly distribute the weight from
joist to joist. Lack of a proper subfloor could cause this which is a
common condition in old homes. Just something else to think about.

Jimmie

Jimmie-

The wood is not the problem. The joist depth& span are the issues.
Steve made no mention of the subfloor construction and, yes,
the subfloor construction can influence overall floor behavior but
it's pretty much a secondary effect.

Steve could "box out" his wimpy joists with a lots of blocking, lots
of glue and a structural skin on the bottom surface of the joists to
create composite action floor. This would increase the floor stiff
and get adjacent joists to share load. It would be a LOT of work and
still probably not work as well as sistering especially if Steve used
deeper sisters.

A number of year ago I worked on a floor vibration problem. It
involved a kitchen and living space over a 25' garage. Unfortunately,
the joists were spec'd as 12" floor trusses. They skimped on the depth
to stay within a city overall building height limitation. The condos
were three story.

The 12" floor trusses were too flexible, should have been at least
14". A real PITA to fix.

cheers
Bob


just for informational purposes, the flooring upstairs is 1x6 yellow
pine T&G 90 degrees to the joists. Same age as. The ceiling downstairs
will be 1x4 pine T&G (painted) so i won't get any benefit from that
either. I'm mainly just not wanting the china cabinet upstairs to sound
off (as bad, i know i won't eliminate it entirely) every time we walk
across the bedroom or sewing area.

--
Steve Barker
remove the "not" from my address to email

On Jan 25, 12:20*pm, Steve Barker wrote:
On 1/24/2012 11:28 PM, DD_BobK wrote:









On Jan 24, 3:33 pm, *wrote:
On Jan 24, 12:22 am, *wrote:

On Jan 23, 12:42 pm, *wrote:

On Jan 22, 11:02 pm, Steve *wrote:

some time ago i inquired about fastening some steel plate to the sides
of some 100+ year old, full dimension, rough cut oak floor joists to
stiffen them up. I've decided to sister them with like sized (2x8) wood
instead. *These are the second story floor joists and they are 2x8 and
span 15.5 feet. *I've got the ceiling out on the lower level and want to
stiffen them up before i go back with new ceiling. My question is, what
is the best way (and frequency) to attach them? *Screws, nut and bolt,
nail, glue, etc?? *It's a balloon style house and i'll be able to *set
the new sisters up on the ledger board like the originals. *My main
concern is pulling them together in such a fashion as to best create a
"oneness" .

thanks!

--
Steve Barker
remove the "not" from my address to email

If you have oak up there I would be thinking about a way to display it
and not put up a ceiling . *I cant imagine the oak beams you described
not being strong enough for the job. They have worked for 100 years
they will be doing the job in 100 more. Don't even think about nails..

Jimmie

Steve's situation is an issue of stiffness not strength.
Too much bounce means he needs to add stiffness and that relates
mostly to joist depth.

Per the joist calculator mentioned recently in another thread, a 15'
span needs a 2x10 of decent timber or a 2x12 of lesser material.

If my calcs are correct, *Steve's original joists sistered with new
2x8's will be stiffer than a 2x10 by 13% but t only be 55% as stiff as
a 2x12.

cheers
Bob

Bob, just wondering your if your calcs take into account the existing
wood is 100+ year old oak.Usually these timbers were made from
heartwood. *It is surprising to me it is not rigid enough already. I
would look to see if it is in fact the joist that are giving when he
walks on them and how they are giving. The problem could be that the
flooring is not strong enough to properly distribute the weight from
joist to joist. Lack of a proper subfloor could cause this which is a
common condition in old homes. Just something else to think about.

Jimmie

Jimmie-

The wood is not the problem. *The joist depth& *span are the issues..
Steve made no mention of the subfloor construction and, yes,
the subfloor construction can influence overall floor behavior but
it's pretty much a secondary effect.

Steve could "box out" his wimpy joists with a lots of blocking, lots
of glue and a structural skin on the bottom surface of the joists to
create composite action floor. *This would increase the floor stiff
and get adjacent joists to share load. It would be a LOT of work and
still probably not work as well as sistering especially if Steve used
deeper sisters.

A number of year ago I worked on a floor vibration problem. *It
involved a kitchen and living space over a 25' garage. *Unfortunately,
the joists were spec'd as 12" floor trusses. They skimped on the depth
to stay within a city overall building height limitation. The condos
were three story.

The 12" floor trusses were too flexible, should have been at least
14". * A real PITA to fix.

cheers
Bob

just for informational purposes, the flooring upstairs is 1x6 yellow
pine T&G 90 degrees to the joists. *Same age as. *The ceiling downstairs
will be 1x4 pine T&G (painted) so i won't get any benefit from that
either. *I'm mainly just not wanting the china cabinet upstairs to sound
off (as bad, i know i won't eliminate it entirely) every time we walk
across the bedroom or sewing area.

--
Steve Barker
remove the "not" from my address to email

Steve-

I found an email I wrote back in 2005 to another engineer about a
floor he was designing
but the most important thing I found was this link to a Canadian
report

http://www.nrc-cnrc.gc.ca/eng/ibp/ir...igest-173.html

The section about Vibrations from Walking is most applicable,
particularly the last two paragraphs.

If you really want to reduce that vibration "go big" on the sister
joists...... like ~ 2x12 engineered timber.
But you'll lose ~5" of room height.



Robert Kazanjy
4/5/05
to seaint
Dave-

Ralph's comments are right on target, I cannot emphasize too strongly
that this could generate problem that dwarfs your design fee.

Talk to the customer (end user ideally).

This really could be a problem downstream depending on the room usage
& their perception of the floor performance.

I highly suggest reading
Canadian Building Digest
CBD-173. Floor Vibration

http://www.nrc-cnrc.gc.ca/eng/ibp/ir...igest-173.html

I've done a fair amount of dynamic floor vibration testing & once
people get sensitized to it, it can be a real problem making them
happy.

I suggest forgetting about span/360 or span/whatever

deflection less than 1/16" under a 220 lb load is a good check. Also
joists at 12 o/c are much better than 16" o/c. Blocking is generally
not effective in achieving load sharing for vibration loading.

I'm not exactly clear on your floor system layout

You've also got to consider the dynamic response of the steel beams in
conjunction with the timber; the floor system as a whole. If the
customer is involved, has informed consent & is aware of possible
consequences of the "cheaper" solutions you're much better off.

To prevent vibration you need stiffness or mass; your choice.

cheers
Bob

On 1/26/2012 12:07 AM, DD_BobK wrote:


Steve-

I found an email I wrote back in 2005 to another engineer about a
floor he was designing
but the most important thing I found was this link to a Canadian
report

http://www.nrc-cnrc.gc.ca/eng/ibp/ir...igest-173.html

The section about Vibrations from Walking is most applicable,
particularly the last two paragraphs.

If you really want to reduce that vibration "go big" on the sister
joists...... like ~ 2x12 engineered timber.
But you'll lose ~5" of room height.



Robert Kazanjy
4/5/05
to seaint
Dave-

Ralph's comments are right on target, I cannot emphasize too strongly
that this could generate problem that dwarfs your design fee.

Talk to the customer (end user ideally).

This really could be a problem downstream depending on the room usage
& their perception of the floor performance.

I highly suggest reading
Canadian Building Digest
CBD-173. Floor Vibration

http://www.nrc-cnrc.gc.ca/eng/ibp/ir...igest-173.html

I've done a fair amount of dynamic floor vibration testing& once
people get sensitized to it, it can be a real problem making them
happy.

I suggest forgetting about span/360 or span/whatever

deflection less than 1/16" under a 220 lb load is a good check. Also
joists at 12 o/c are much better than 16" o/c. Blocking is generally
not effective in achieving load sharing for vibration loading.

I'm not exactly clear on your floor system layout

You've also got to consider the dynamic response of the steel beams in
conjunction with the timber; the floor system as a whole. If the
customer is involved, has informed consent& is aware of possible
consequences of the "cheaper" solutions you're much better off.

To prevent vibration you need stiffness or mass; your choice.

cheers
Bob

Bob, thanks for all the info you've put up. I could afford to lose a
little ceiling height, (it's 8'4" now). But it's not all that GREAT big
of a deal. Also, my hvac and electrical is all finished, and i have a
great big sun pipe coming down through there, so I can't sister EVERY
joist. If it were before all this, I probably could have gone to a 10
or even 12" sister. It's just the two of us living here and the one
room above is our bedroom and the other side of the upstairs (no
partition) is her sewing room. There'll be no dances going on up there
or kids running around.. LOL!

--
Steve Barker
remove the "not" from my address to email

On 1/26/2012 9:05 AM, Steve Barker wrote:
On 1/26/2012 12:07 AM, DD_BobK wrote:


Steve-

I found an email I wrote back in 2005 to another engineer about a
floor he was designing
but the most important thing I found was this link to a Canadian
report

http://www.nrc-cnrc.gc.ca/eng/ibp/ir...igest-173.html

The section about Vibrations from Walking is most applicable,
particularly the last two paragraphs.

If you really want to reduce that vibration "go big" on the sister
joists...... like ~ 2x12 engineered timber.
But you'll lose ~5" of room height.



Robert Kazanjy
4/5/05
to seaint
Dave-

Ralph's comments are right on target, I cannot emphasize too strongly
that this could generate problem that dwarfs your design fee.

Talk to the customer (end user ideally).

This really could be a problem downstream depending on the room usage
& their perception of the floor performance.

I highly suggest reading
Canadian Building Digest
CBD-173. Floor Vibration

http://www.nrc-cnrc.gc.ca/eng/ibp/ir...igest-173.html

I've done a fair amount of dynamic floor vibration testing& once
people get sensitized to it, it can be a real problem making them
happy.

I suggest forgetting about span/360 or span/whatever

deflection less than 1/16" under a 220 lb load is a good check. Also
joists at 12 o/c are much better than 16" o/c. Blocking is generally
not effective in achieving load sharing for vibration loading.

I'm not exactly clear on your floor system layout

You've also got to consider the dynamic response of the steel beams in
conjunction with the timber; the floor system as a whole. If the
customer is involved, has informed consent& is aware of possible
consequences of the "cheaper" solutions you're much better off.

To prevent vibration you need stiffness or mass; your choice.

cheers
Bob

Bob, thanks for all the info you've put up. I could afford to lose a
little ceiling height, (it's 8'4" now). But it's not all that GREAT big
of a deal. Also, my hvac and electrical is all finished, and i have a
great big sun pipe coming down through there, so I can't sister EVERY
joist. If it were before all this, I probably could have gone to a 10 or
even 12" sister. It's just the two of us living here and the one room
above is our bedroom and the other side of the upstairs (no partition)
is her sewing room. There'll be no dances going on up there or kids
running around.. LOL!


If you can loose a little ceiling height, how about a small beam
perpendicular to the joists right down the middle, maybe a post in the
middle could make it a very small beam? That would make things really
solid and oh so much less work.

On 1/26/2012 8:47 AM, Tony Miklos wrote:
On 1/26/2012 9:05 AM, Steve Barker wrote:
On 1/26/2012 12:07 AM, DD_BobK wrote:


Steve-

I found an email I wrote back in 2005 to another engineer about a
floor he was designing
but the most important thing I found was this link to a Canadian
report

http://www.nrc-cnrc.gc.ca/eng/ibp/ir...igest-173.html

The section about Vibrations from Walking is most applicable,
particularly the last two paragraphs.

If you really want to reduce that vibration "go big" on the sister
joists...... like ~ 2x12 engineered timber.
But you'll lose ~5" of room height.



Robert Kazanjy
4/5/05
to seaint
Dave-

Ralph's comments are right on target, I cannot emphasize too strongly
that this could generate problem that dwarfs your design fee.

Talk to the customer (end user ideally).

This really could be a problem downstream depending on the room usage
& their perception of the floor performance.

I highly suggest reading
Canadian Building Digest
CBD-173. Floor Vibration

http://www.nrc-cnrc.gc.ca/eng/ibp/ir...igest-173.html

I've done a fair amount of dynamic floor vibration testing& once
people get sensitized to it, it can be a real problem making them
happy.

I suggest forgetting about span/360 or span/whatever

deflection less than 1/16" under a 220 lb load is a good check. Also
joists at 12 o/c are much better than 16" o/c. Blocking is generally
not effective in achieving load sharing for vibration loading.

I'm not exactly clear on your floor system layout

You've also got to consider the dynamic response of the steel beams in
conjunction with the timber; the floor system as a whole. If the
customer is involved, has informed consent& is aware of possible
consequences of the "cheaper" solutions you're much better off.

To prevent vibration you need stiffness or mass; your choice.

cheers
Bob

Bob, thanks for all the info you've put up. I could afford to lose a
little ceiling height, (it's 8'4" now). But it's not all that GREAT big
of a deal. Also, my hvac and electrical is all finished, and i have a
great big sun pipe coming down through there, so I can't sister EVERY
joist. If it were before all this, I probably could have gone to a 10 or
even 12" sister. It's just the two of us living here and the one room
above is our bedroom and the other side of the upstairs (no partition)
is her sewing room. There'll be no dances going on up there or kids
running around.. LOL!


If you can loose a little ceiling height, how about a small beam
perpendicular to the joists right down the middle, maybe a post in the
middle could make it a very small beam? That would make things really
solid and oh so much less work.

I really did consider that option, but there's really not that much
UNDER the floor (and no access) to hold the posts. PLUS, one of them
would be dead center of a window.

--
Steve Barker
remove the "not" from my address to email

On Jan 26, 9:53*am, Steve Barker wrote:
On 1/26/2012 8:47 AM, Tony Miklos wrote:





On 1/26/2012 9:05 AM, Steve Barker wrote:
On 1/26/2012 12:07 AM, DD_BobK wrote:

Steve-

I found an email I wrote back in 2005 to another engineer about a
floor he was designing
but the most important thing I found was this link to a Canadian
report

http://www.nrc-cnrc.gc.ca/eng/ibp/ir...igest-173.html

The section about Vibrations from Walking is most applicable,
particularly the last two paragraphs.

If you really want to reduce that vibration "go big" on the sister
joists...... like ~ 2x12 engineered timber.
But you'll lose ~5" of room height.

Robert Kazanjy
4/5/05
to seaint
Dave-

Ralph's comments are right on target, I cannot emphasize too strongly
that this could generate problem that dwarfs your design fee.

Talk to the customer (end user ideally).

This really could be a problem downstream depending on the room usage
& their perception of the floor performance.

I highly suggest reading
Canadian Building Digest
CBD-173. Floor Vibration

http://www.nrc-cnrc.gc.ca/eng/ibp/ir...igest-173.html

I've done a fair amount of dynamic floor vibration testing& once
people get sensitized to it, it can be a real problem making them
happy.

I suggest forgetting about span/360 or span/whatever

deflection less than 1/16" under a 220 lb load is a good check. Also
joists at 12 o/c are much better than 16" o/c. Blocking is generally
not effective in achieving load sharing for vibration loading.

I'm not exactly clear on your floor system layout

You've also got to consider the dynamic response of the steel beams in
conjunction with the timber; the floor system as a whole. If the
customer is involved, has informed consent& is aware of possible
consequences of the "cheaper" solutions you're much better off.

To prevent vibration you need stiffness or mass; your choice.

cheers
Bob

Bob, thanks for all the info you've put up. I could afford to lose a
little ceiling height, (it's 8'4" now). But it's not all that GREAT big
of a deal. Also, my hvac and electrical is all finished, and i have a
great big sun pipe coming down through there, so I can't sister EVERY
joist. If it were before all this, I probably could have gone to a 10 or
even 12" sister. It's just the two of us living here and the one room
above is our bedroom and the other side of the upstairs (no partition)
is her sewing room. There'll be no dances going on up there or kids
running around.. LOL!

If you can loose a little ceiling height, how about a small beam
perpendicular to the joists right down the middle, maybe a post in the
middle could make it a very small beam? That would make things really
solid and oh so much less work.

I really did consider that option, but there's really not that much
UNDER the floor (and no access) to hold the posts. *PLUS, one of them
would be dead center of a window.

--
Steve Barker
remove the "not" from my address to email- Hide quoted text -

- Show quoted text -

i would sister to a steel plate...........