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?

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.
marson wrote:
> 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?

In a previous post marson wrote...
> 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

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!

Bob Morrison wrote:
> In a previous post marson wrote...
> > 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

Bob Morrison wrote:
> In a previous post marson wrote...
> > 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

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.


RicodJour wrote:
> Bob Morrison wrote:
> > In a previous post marson wrote...
> > > 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

>>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

In a previous post RicodJour wrote...
> 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.

--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com

In a previous post marson wrote...
> 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.

--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com

Bob Morrison wrote:
> In a previous post marson wrote...
> > 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...
....
> 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...