does the irc require pressure treated bottom plates on a slab on grade house?

[marson]

does anyone know if the irc requires treated bottom plates on partition
walls on a slab on grade house? is it acceptable to use white wood
with a capillary break such as tarpaper on the bottom?

[bodega]

I just completed an addition to my wife's commercial daycare and was
required to use treated wood for a bottom plate on a concrete slab. I
did this in Auburn,WA which is in King Co. but I would check with
you're local authority where you get your building permits.

Post by marson
does anyone know if the irc requires treated bottom plates on partition
walls on a slab on grade house? is it acceptable to use white wood
with a capillary break such as tarpaper on the bottom?

[Bob Morrison]

In a previous post marson wrote...

Post by marson
does anyone know if the irc requires treated bottom plates on partition
walls on a slab on grade house? is it acceptable to use white wood
with a capillary break such as tarpaper on the bottom?

The relevant section is IRC2003 R319.1. This section allows the use of
untreated sill plates and sleepers if the wood is separated from the
concrete by an impervious moisture barrier.

However, it seems to me that the cost of using treated plates in this
instance is pretty nominal so why not go ahead and use them? I would
think you would spend more horsing around with the "tar paper" than it's
worth.

[marson]

thanks once again Bob. I definitely agree that you should use treated
bottom plates. In this case, someone in our company framed partitions
without and I'm just wondering if I have to them go back and change
them. The building inspector didn't even know if it was in the code or
not!

Post by Bob Morrison
In a previous post marson wrote...

Post by marson
does anyone know if the irc requires treated bottom plates on partition
walls on a slab on grade house? is it acceptable to use white wood
with a capillary break such as tarpaper on the bottom?

The relevant section is IRC2003 R319.1. This section allows the use of
untreated sill plates and sleepers if the wood is separated from the
concrete by an impervious moisture barrier.
However, it seems to me that the cost of using treated plates in this
instance is pretty nominal so why not go ahead and use them? I would
think you would spend more horsing around with the "tar paper" than it's
worth.
--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com

[Jonny]

Use actual stainless steel 1/2" all-thread in the slab, and stainless bolts
and washers to hold the plate to the slab.
Use ceramic screws if already poured slab.
Both are used to holdup against chemicals used in current treated lumber.
You will need galvanized nails, or non-ferrous or treated screws to hold the
treated lumber to the studs. Same reason. There are galvanized nails out
there that don't have much zinc, be careful.

Maybe you should invest in your own hired home inspector. The municipal
code inspector is not there to protect you by any means.

15# felt is standard under the bottom plate. Don't matter if its standard
lumber or treated lumber. It should be 4" wide if the bottom plate is 2X4.
The inside should be flush with the inside of the bottom plate. This gives
1/2" overlap downwards outside with the felt paper. This causes any water
intrusion to fall below the bottom the plate. Wider bottom plate requires
same 1/2" protrusion to the outside and folded downwards. Any sissy framing
carpenter's helper can cut #15 felt to the proper width on the roll. And
follow the chalk line on the layout on the slab. Its not big deal.
I'd go with the treated lumber for the long term. Not because of anything
else.
--
Jonny

Post by marson
thanks once again Bob. I definitely agree that you should use treated
bottom plates. In this case, someone in our company framed partitions
without and I'm just wondering if I have to them go back and change
them. The building inspector didn't even know if it was in the code or
not!

Post by Bob Morrison
In a previous post marson wrote...

Post by marson
does anyone know if the irc requires treated bottom plates on partition
walls on a slab on grade house? is it acceptable to use white wood
with a capillary break such as tarpaper on the bottom?

The relevant section is IRC2003 R319.1. This section allows the use of
untreated sill plates and sleepers if the wood is separated from the
concrete by an impervious moisture barrier.
However, it seems to me that the cost of using treated plates in this
instance is pretty nominal so why not go ahead and use them? I would
think you would spend more horsing around with the "tar paper" than it's
worth.
--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com

[RicodJour]

Post by Bob Morrison
In a previous post marson wrote...

Post by marson
does anyone know if the irc requires treated bottom plates on partition
walls on a slab on grade house? is it acceptable to use white wood
with a capillary break such as tarpaper on the bottom?

The relevant section is IRC2003 R319.1. This section allows the use of
untreated sill plates and sleepers if the wood is separated from the
concrete by an impervious moisture barrier.
However, it seems to me that the cost of using treated plates in this
instance is pretty nominal so why not go ahead and use them? I would
think you would spend more horsing around with the "tar paper" than it's
worth.

Do you specify fasteners that won't corrode at an accelerated rate in
the ACQ? The metal connector tie downs and the hanger nails are
corrosion resistant with ACQ already, but the sheathing and stud/plate
fasteners should also be specified resistant. The shear walls are of
particular concern.

R

[marson]

If hot dipped galvanized fasteners are needed in nailing into the
bottom plate if it's ACQ treated lumber, then there are a lot of
builders out there in trouble. I don't know of anyone who is doing
that, and i've never seen that spec on a plan. You just try to get a
framer to dig out his galvy hand bangers to nail off the bottom plate.
It just isn't happening.

I use treated bottom plates as I said before, but I do think it's
overkill. if you have enough moisture in your slab to rot your bottom
plate on an interior partition, then what about your drywall, not to
mention your finish floor coverings? Plus, I have taken apart numerous
buildings that had good old white wood against concrete that were
fine--including my own seventy year old house which not only has
untreated mud sills but has concrete poured between the joists.

Post by RicodJour

Post by Bob Morrison
In a previous post marson wrote...

Post by marson
does anyone know if the irc requires treated bottom plates on partition
walls on a slab on grade house? is it acceptable to use white wood
with a capillary break such as tarpaper on the bottom?

The relevant section is IRC2003 R319.1. This section allows the use of
untreated sill plates and sleepers if the wood is separated from the
concrete by an impervious moisture barrier.
However, it seems to me that the cost of using treated plates in this
instance is pretty nominal so why not go ahead and use them? I would
think you would spend more horsing around with the "tar paper" than it's
worth.

Do you specify fasteners that won't corrode at an accelerated rate in
the ACQ? The metal connector tie downs and the hanger nails are
corrosion resistant with ACQ already, but the sheathing and stud/plate
fasteners should also be specified resistant. The shear walls are of
particular concern.
R

[Bob Morrison]

In a previous post marson wrote...

Post by marson
If hot dipped galvanized fasteners are needed in nailing into the
bottom plate if it's ACQ treated lumber, then there are a lot of
builders out there in trouble. I don't know of anyone who is doing
that, and i've never seen that spec on a plan. You just try to get a
framer to dig out his galvy hand bangers to nail off the bottom plate.
It just isn't happening.

Unfortunately, that is all too true. However, the bottom edge nails will
corrode after a fairly short period of time and that nice shear wall will
no longer be of any value. IRC and IBC require stainless steel or hot-
dipped fasteners when connecting PT lumber. The framers need to be made
aware that if they are not doing this, then they are not following the
code. And, building inspectors need to enforce this provision.

[dpb]

Post by Bob Morrison
In a previous post marson wrote...

Post by marson
If hot dipped galvanized fasteners are needed in nailing into the
bottom plate if it's ACQ treated lumber, then there are a lot of
builders out there in trouble. I don't know of anyone who is...

...

Post by Bob Morrison
Unfortunately, that is all too true. However, the bottom edge nails will
corrode after a fairly short period of time and that nice shear wall will
no longer be of any value. ...

Yep, this is a perfect example of the "law of unforeseen/unintended
consequences" and a case where the cure is likely to be far worse than
the disease ever was or would have ever been... :(

[Rudy]

What if they're using "cement coated" nails ? Will that protect the metal
from the ACQ ?

Post by Bob Morrison
Unfortunately, that is all too true. However, the bottom edge nails will
corrode after a fairly short period of time and that nice shear wall will
no longer be of any value. IRC and IBC require stainless steel or hot-
dipped fasteners when connecting PT lumber. The framers need to be made
aware that if they are not doing this, then they are not following the
code. And, building inspectors need to enforce this provision.
--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com

[RicodJour]

Post by Rudy
What if they're using "cement coated" nails ? Will that protect the metal
from the ACQ ?

The cement coating is an adhesive and not designed as a protective
coating. Will it help extend the life of the nails? Possibly - but
possibly is not a desirable result in structural engineering circles.

R

[Wayne Whitney]

Post by Bob Morrison
In a previous post marson wrote...

Post by marson
If hot dipped galvanized fasteners are needed in nailing into the
bottom plate if it's ACQ treated lumber, then there are a lot of
builders out there in trouble. I don't know of anyone who is
doing that.

Unfortunately, that is all too true. However, the bottom edge nails will
corrode after a fairly short period of time and that nice shear wall will
no longer be of any value.

Is this corrosion a problem only while the PT lumber is still wet from
the PT process, or does it continue to occur after the PT lumber has
dried?

I'm retrofitting shear walls on a foundation installed 2.75 years ago
with ACQ sill plates. Untreated nails that had been installed in the
sill plate over 1 year ago and recently removed show no signs of
corrosion. My work so far has been with standard nails; wondering if
I need to install SS nails between the standard nails on the sill
plate.

Cheers, Wayne

[RicodJour]

Post by Wayne Whitney
I'm retrofitting shear walls on a foundation installed 2.75 years ago
with ACQ sill plates. Untreated nails that had been installed in the
sill plate over 1 year ago and recently removed show no signs of
corrosion. My work so far has been with standard nails; wondering if
I need to install SS nails between the standard nails on the sill
plate.

ACQ is relatively new territory. Wet PT lumber is far more of a
problem, but it is unclear at what rate the corrosion will proceed as
the wood dries out. Guesses don't work in structural engineering. The
few extra bucks for corrosion resistant fasteners is money well spent.

R

[Wayne Whitney]

Post by Wayne Whitney
I'm retrofitting shear walls on a foundation installed 2.75 years
ago with ACQ sill plates. Untreated nails that had been installed
in the sill plate over 1 year ago and recently removed show no signs
of corrosion.

After making this statement, I realized that I hadn't really been
paying attention to the nails I had been removing. So I pulled some
nails I had installed 2 years ago, 4 nails from one piece of the sill
plate and 4 nails from a cripple stud, and I took a closer look.

The nails from the cripple stud basically looked the same as unused
nails, finish wise. The nails from the sill plate did show some signs
of corrosion: the yellow/silver zinc dichromate finish was missing in
spots, anywhere from 10%-40% of the surface area of the nail, and they
all showed a few spots of brown rust at the point.

Based on this level of corrosion, if I want the nails to be
structurally sound in 50 or 100 years, do I need to use corrosion
resistant nails?

Thanks, Wayne

[Bob Morrison]

In a previous post Wayne Whitney wrote...

Post by Wayne Whitney
Based on this level of corrosion, if I want the nails to be
structurally sound in 50 or 100 years, do I need to use corrosion
resistant nails?

Wayne:

AS I said in an earlier post: my specifications require the use of
corrosion resistant fasteners when connecting to PT lumber. So, I
recommend that you use HD galvanized nails when putting together any
pieces attached to PT lumber.

[Robert Allison]

Post by Bob Morrison
In a previous post Wayne Whitney wrote...

Post by Wayne Whitney
Based on this level of corrosion, if I want the nails to be
structurally sound in 50 or 100 years, do I need to use corrosion
resistant nails?

AS I said in an earlier post: my specifications require the use of
corrosion resistant fasteners when connecting to PT lumber. So, I
recommend that you use HD galvanized nails when putting together any
pieces attached to PT lumber.

Bob,

Just a side note. I no longer use the term "HD" galvanized
nails. I had a client that asked my advice about building a
deck and I told him to use HD galvanized nails. The next time
I saw him, he was using zinc coated nails on his deck. When I
pointed out to him that these were not the ones I specified,
his reply was: "Yes they are,... they are from Home Depot!" (HD)

As my father used to say: You can't make anything foolproof,
'cause fools are too ingenious.

[Bob Morrison]

In a previous post Robert Allison wrote...

Post by Robert Allison
Just a side note. I no longer use the term "HD" galvanized
nails. I had a client that asked my advice about building a
deck and I told him to use HD galvanized nails. The next time
I saw him, he was using zinc coated nails on his deck. When I
pointed out to him that these were not the ones I specified,
his reply was: "Yes they are,... they are from Home Depot!" (HD)
As my father used to say: You can't make anything foolproof,
'cause fools are too ingenious.

Robert:

Thanks for the chuckle! My structural notes do spell out hot-dipped
galvanized.

[Wayne Whitney]

AS I said in an earlier post: my specifications require the use of
corrosion resistant fasteners when connecting to PT lumber. So, I
recommend that you use HD galvanized nails when putting together any
pieces attached to PT lumber.

OK, good enough, if that's the standard, I guess I shouldn't mess
around trying to figure out if it really is necessary in my case.

Now I need to redo some nailing I already did with standard 8d common
nails 4" o.c., between the 1/2" struct one plywood and the PT 2x6 sill
plate. Would it be a problem to interleave corrosion resistant 8d
common nails, yielding a 2" o.c. straight nailing pattern?

Thanks, Wayne

[Bob Morrison]

In a previous post Wayne Whitney wrote...

Post by Wayne Whitney
Now I need to redo some nailing I already did with standard 8d common
nails 4" o.c., between the 1/2" struct one plywood and the PT 2x6 sill
plate. Would it be a problem to interleave corrosion resistant 8d
common nails, yielding a 2" o.c. straight nailing pattern?

That's pretty close nail spacing. My inclination would be to recommend
that you put one galvanized nail every other space, or that you put the
galvanized nail right next to (1/2") the plain nail.

Another option is to add blocking between the studs on top of the existing
sill. Fasten the blocking to the PT sill with galvanized nails, then put
in a row of plain nails through the sheathing into the untreated blocks.
Kinda of a pain in the backside, but it depends on how much work you want
to do.

[Wayne Whitney]

Post by Bob Morrison
In a previous post Wayne Whitney wrote...

Would it be a problem to interleave corrosion resistant 8d common
nails, yielding a 2" o.c. straight nailing pattern?

That's pretty close nail spacing. My inclination would be to recommend
that you put one galvanized nail every other space, or that you put the
galvanized nail right next to (1/2") the plain nail.

OK, thanks, I think I'll do both of these, put two new nails in
between two existing nails, at the ends of the space, and then skip a
space. So the spacing will be {1/2", 3", 1/2", 4", repeat}.

Cheers, Wayne

[Bob Morrison]

In a previous post RicodJour wrote...

Post by RicodJour
Do you specify fasteners that won't corrode at an accelerated rate in
the ACQ? The metal connector tie downs and the hanger nails are
corrosion resistant with ACQ already, but the sheathing and stud/plate
fasteners should also be specified resistant. The shear walls are of
particular concern.

Yes. Here are a few selected lines from my "Structural Notes":

Sill anchor bolts shall be hot dipped galvanized or stainless steel, 1/2"
minimum diameter, with a minimum embedment of 7 inches, unless noted
otherwise on Shear Wall Schedule or Foundation Details. Bolts shall be
tied in place prior to pouring concrete and shall not be "wet-set" or
"stabbed" into wet concrete.

Connectors and fasteners for pressure treated wood shall be hot-dipped
galvanized or stainless steel in accordance with IBC Section 2304.9.5.

Hardware for pressure treated wood shall be hot-dipped galvanized or
stainless steel in accordance with IBC Section 2304.9.5.

[Jonny]

I'd go with stainless or nonferrous as the manufacturers of hardware can't
mess this up as easily as galvanized hardware.
--
Jonny

Post by Bob Morrison
In a previous post RicodJour wrote...

Post by RicodJour
Do you specify fasteners that won't corrode at an accelerated rate in
the ACQ? The metal connector tie downs and the hanger nails are
corrosion resistant with ACQ already, but the sheathing and stud/plate
fasteners should also be specified resistant. The shear walls are of
particular concern.

Sill anchor bolts shall be hot dipped galvanized or stainless steel, 1/2"
minimum diameter, with a minimum embedment of 7 inches, unless noted
otherwise on Shear Wall Schedule or Foundation Details. Bolts shall be
tied in place prior to pouring concrete and shall not be "wet-set" or
"stabbed" into wet concrete.
Connectors and fasteners for pressure treated wood shall be hot-dipped
galvanized or stainless steel in accordance with IBC Section 2304.9.5.
Hardware for pressure treated wood shall be hot-dipped galvanized or
stainless steel in accordance with IBC Section 2304.9.5.
--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com

[Goedjn]

Post by Bob Morrison
In a previous post marson wrote...

Post by marson
does anyone know if the irc requires treated bottom plates on partition
walls on a slab on grade house? is it acceptable to use white wood
with a capillary break such as tarpaper on the bottom?

The relevant section is IRC2003 R319.1. This section allows the use of
untreated sill plates and sleepers if the wood is separated from the
concrete by an impervious moisture barrier.
However, it seems to me that the cost of using treated plates in this
instance is pretty nominal so why not go ahead and use them? I would
think you would spend more horsing around with the "tar paper" than it's
worth.

Yes, but sheet-metal termite barriers serve both purposes.

[Tom The Great]

Post by Bob Morrison
In a previous post marson wrote...

Post by marson
does anyone know if the irc requires treated bottom plates on partition
walls on a slab on grade house? is it acceptable to use white wood
with a capillary break such as tarpaper on the bottom?

The relevant section is IRC2003 R319.1. This section allows the use of
untreated sill plates and sleepers if the wood is separated from the
concrete by an impervious moisture barrier.
However, it seems to me that the cost of using treated plates in this
instance is pretty nominal so why not go ahead and use them? I would
think you would spend more horsing around with the "tar paper" than it's
worth.

I think, the foam padding, used to seal against slab,bottom plate air
leakage counts as a moisture barrer too. However, I have to say you
are reasonable to belive the use of 'treated' lumber, isn't cost
prohibitative.

Sounds like good advice,

tom @ www.FreelancingProjects.com

[Rudy]

is it acceptable to use white wood with a capillary break such as tarpaper
on the bottom?

Sure, use white plastic mudsill gasket material..the polyfoam stuff thats
about 1/4" thick X 4" or 6" and comes in rolls