Repair joist with Flitch Plate

[jdbec...@usa.net]

I want to strengthen a sagging joist supporting the first floor of my 10 year
old two story home. The joist is currently a double 2x10 that spans 14 feet.
There is a 2x6 kitchen wall above it with stove and cabinets, but it is not a
supporting wall (or isn't supposed to be). We currently have a china cabinet
against the other side of the wall, and the adjacent floor is very bouncy.
One of the 2x10s is partially cut through to pass a 4" sewage line into the
2x6 wall above. The sag is about 1/2" at the middle. I have clear access to
one side of the existing joist.

I am considering jacking up the existing joist and adding a 3/8 x 9"x14'
steel "Flitch" plate to the accessible side, to form a sort of "Flitch beam"
in place. I don't mind that this is probably overkill, as the steel will
only cost $100 and I think the installation will be straightforward. I still
have a few questions I am hoping this group can help me with.

First, given that the two 2x10s are already in place, is it OK to simply bolt
the steel plate to one side of the existing 2x10s? Most Flitch beams have
the steel plate sandwiched between two 2xXX boards to provide lateral
rigidity for the steel among other things. This will be a much easier job if
I do not have to put up another 2x10 to sandwich the Flitch plate.

Second, is it essential to have the Flitch plate extend all the way to the
ends of the existing joist? Again, installation will be easier if I don't
have to overhang the beam and the foundation that supports the joist.

Finally, are these things just bolted together, or bolted and glued? If
glued, what adhesive should be used to join the steel to the wood?

Thanks in advance for your help.
John in SC

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[Larz]

Whoever cut that beam for the sewer pipe should be shot. I hope it
wasn't you. Anyway, the Flitch beam should be adequate. The more
securely it is fastened to the 2x10, the better. If it can be supported
at each end, even better.
If you really want to get into beam sizing, you can calculate the size
of the beam needed. I won't get into the math, but it's not rocket
science. I took a course at the Shelter Institute in Bath, Maine and
they taught it to me in about two hours. Really interesting.

[danh...@millcomm.com]

In <6ji752$iuu$1...@nnrp2.dejanews.com>, jdbec...@usa.net writes:
>I want to strengthen a sagging joist supporting the first floor of my 10 year
>old two story home. The joist is currently a double 2x10 that spans 14 feet.
>There is a 2x6 kitchen wall above it with stove and cabinets, but it is not a
>supporting wall (or isn't supposed to be). We currently have a china cabinet
>against the other side of the wall, and the adjacent floor is very bouncy.
>One of the 2x10s is partially cut through to pass a 4" sewage line into the
>2x6 wall above. The sag is about 1/2" at the middle. I have clear access to
>one side of the existing joist.
>
>I am considering jacking up the existing joist and adding a 3/8 x 9"x14'
>steel "Flitch" plate to the accessible side, to form a sort of "Flitch beam"
>in place. I don't mind that this is probably overkill, as the steel will
>only cost $100 and I think the installation will be straightforward. I still
>have a few questions I am hoping this group can help me with.
>
>First, given that the two 2x10s are already in place, is it OK to simply bolt
>the steel plate to one side of the existing 2x10s? Most Flitch beams have
>the steel plate sandwiched between two 2xXX boards to provide lateral
>rigidity for the steel among other things. This will be a much easier job if
>I do not have to put up another 2x10 to sandwich the Flitch plate.
>
>Second, is it essential to have the Flitch plate extend all the way to the
>ends of the existing joist? Again, installation will be easier if I don't
>have to overhang the beam and the foundation that supports the joist.
>
>Finally, are these things just bolted together, or bolted and glued? If
>glued, what adhesive should be used to join the steel to the wood?

Not an engineering opinion, but what you suggest sounds good. Since you
can't sandwich the plate you need to be sure it's attached to the beam at
a number of points so it won't buckle. Either lag bolts or large wood
screws should work, preferably in a zig-zag pattern down the plate. I
don't think glue would do much good -- it might hold in the near term but
would eventually let go. Though if you want to use a little construction
adhesive to hold the plate up while you add the screws that would
certainly be OK.

The other option would be to pull the beam and replace it with microlams.

Dan Hicks
Hey!! My advice is free -- take it for what it's worth!
http://www.millcomm.com/~danhicks

[Robert Allison]

jdbec...@usa.net wrote:

> I want to strengthen a sagging joist supporting the first floor of my 10 year
> old two story home. The joist is currently a double 2x10 that spans 14 feet.
> There is a 2x6 kitchen wall above it with stove and cabinets, but it is not a
> supporting wall (or isn't supposed to be). We currently have a china cabinet
> against the other side of the wall, and the adjacent floor is very bouncy.
> One of the 2x10s is partially cut through to pass a 4" sewage line into the
> 2x6 wall above. The sag is about 1/2" at the middle. I have clear access to
> one side of the existing joist.
> I am considering jacking up the existing joist and adding a 3/8 x 9"x14'
> steel "Flitch" plate to the accessible side, to form a sort of "Flitch beam"
> in place. I don't mind that this is probably overkill, as the steel will
> only cost $100 and I think the installation will be straightforward. I still
> have a few questions I am hoping this group can help me with.
> First, given that the two 2x10s are already in place, is it OK to simply bolt
> the steel plate to one side of the existing 2x10s? Most Flitch beams have
> the steel plate sandwiched between two 2xXX boards to provide lateral
> rigidity for the steel among other things. This will be a much easier job if
> I do not have to put up another 2x10 to sandwich the Flitch plate.
> Second, is it essential to have the Flitch plate extend all the way to the
> ends of the existing joist? Again, installation will be easier if I don't
> have to overhang the beam and the foundation that supports the joist.
> Finally, are these things just bolted together, or bolted and glued? If
> glued, what adhesive should be used to join the steel to the wood?
>

> Thanks in advance for your help.
> John in SC

In this instance, you would not have to extend the plate end to end or sandwich
it with
another 2x10. Just through bolt it every 2' minimum, top and bottom. Another
thing I
would add is that you should paint it with at least a red oxide primer before
installation.
Glue is not necessary.
--
Robert Allison robert2...@ix.netcom.com
Rimshot, Inc.
Please remove NOSPAM from address to reply.

[Richard & Alice Diotte]

To add my $0.02...if you were my client, I'd suggest that you visit your
local weliding shop and pick-up a 14' piece of channel that would fit under
the pipe....say 6"....jack up the joists and bolt through the channel and
joist using carriage bolts at 2' centres. Probably won't cost you anymore
than plate...they'll punch holes in it and it will make for a neat job....

That's it

Richard

[jdbec...@usa.net]

In article <355e6...@209.91.128.12>,

I'll check into this. I am not aware of what kinds of steel forms are
commonly available. The channel would have to be a nominal 3" wide inside
dimension to fit over the joists and nominal 6" or whatever deep. Would you
use 3/8" thick, or less? I suppose an L-shape would also be an improvement
over a plate.

The only problem with this is that I am already jacking the joist up SLOWLY,
so things have some time to adjust above it. I would either have to take
down the existing supports and jack it up again, or find some other way to
prop it up which leaves the bottom of the joist free. Still it is an
interesting possibility.

Thanks to you and everyone else for their input.
John

[prin...@mcmaster.ca]

I think the idea is sound. It wouldn't need to be sandwiched and I don't
think any glue out there would hold the two except maybe a two-part epoxy
(like west system). I think the two tricks here would be to jack up the
joists a little above you're desired spot and to use alot of bolts near the
top and bottom of the plate (maybe an inch from the top and bottom). You need
to be able to generate enough friction so that the bolts don't simply slip in
the holes. I might go so far as to recommend every 6" o/c at least near the
middle of the span. Definately lag bolts with washers and nuts would be
ideal. I imagine you'll want a shop to drill the holes. Get them drill the
holes with very little clearance between them and the bolt shank.