Shimming plywood to ceiling joists


B

Borrall Wonnell

I plan to attach plywood sheets to my basement ceiling (2x10 joists,
16" OC). The application is an extension of a climbing wall (I will
be hanging climbing ropes and holds from the plywood).

Every inch (of height) counts, so I want to attach directly to the
joists rather than use furring strips. The structure is sound but the
lower surface of the joists aren't all at the same height...maybe up
to 3/8" difference across the area in question.

I can't use the traditional shim technique, so I was considering
building up 1.5" wide strips of material (felt paper?) along the
underside of "high" joists to bring them down to the level of the
others.

Aside from being a bit strange, is this a really bad idea? I'm
thinking that felt paper will also help to reduce sound transmission
to upper floors.
 
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D

dadiOH

Borrall said:
I plan to attach plywood sheets to my basement ceiling (2x10 joists,
16" OC). The application is an extension of a climbing wall (I will
be hanging climbing ropes and holds from the plywood).

Every inch (of height) counts, so I want to attach directly to the
joists rather than use furring strips. The structure is sound but the
lower surface of the joists aren't all at the same height...maybe up
to 3/8" difference across the area in question.

I can't use the traditional shim technique, so I was considering
building up 1.5" wide strips of material (felt paper?) along the
underside of "high" joists to bring them down to the level of the
others.

Aside from being a bit strange, is this a really bad idea? I'm
thinking that felt paper will also help to reduce sound transmission
to upper floors.
I can't see anything wrong with it. Might be easier to put up the ply
loosely then use wood shims in the low spots, then tighten all. Even easier
is to just put up the ply tight and let it bend as needed. If it doesn't
bend enough, no big deal.
 
O

Oren

I can't use the traditional shim technique, so I was considering
building up 1.5" wide strips of material (felt paper?) along the
underside of "high" joists to bring them down to the level of the
others.
A 4" electric hand planer, used with a long level, can bring down the
high spots. Less need for shims.
 
R

Red Green

I plan to attach plywood sheets to my basement ceiling (2x10 joists,
16" OC). The application is an extension of a climbing wall (I will
be hanging climbing ropes and holds from the plywood).

Every inch (of height) counts, so I want to attach directly to the
joists rather than use furring strips. The structure is sound but the
lower surface of the joists aren't all at the same height...maybe up
to 3/8" difference across the area in question.

I can't use the traditional shim technique, so I was considering
building up 1.5" wide strips of material (felt paper?) along the
underside of "high" joists to bring them down to the level of the
others.

Aside from being a bit strange, is this a really bad idea? I'm
thinking that felt paper will also help to reduce sound transmission
to upper floors.
Considered sistering on to the offending joists?
so I was considering building up 1.5" wide strips of
material (felt paper?)
Or why not just get a 2x6 (8, 10, etc) and rip it to the thickness desired.
Put the thin piece you want on the OUTSIDE of the blade. If you use a wide
enough 2x you can get many strips from one piece. Don't run the piece
between the blade and fence too thin!!!!
 
D

DerbyDad03

I plan to attach plywood sheets to my basement ceiling (2x10 joists,
16" OC).  The application is an extension of a climbing wall (I will
be hanging climbing ropes and holds from the plywood).

Every inch (of height) counts, so I want to attach directly to the
joists rather than use furring strips.  The structure is sound but the
lower surface of the joists aren't all at the same height...maybe up
to 3/8" difference across the area in question.

I can't use the traditional shim technique, so I was considering
building up 1.5" wide strips of material (felt paper?) along the
underside of "high" joists to bring them down to the level of the
others.

Aside from being a bit strange, is this a really bad idea?  I'm
thinking that felt paper will also help to reduce sound transmission
to upper floors.
Wouldn't the bends in the plywood give the ceiling a bit more "visual"
appeal? I assume you are going to paint it or cover it in some way.
Use the hills and valleys to enhance the look of the rock climbing
environment.
 
O

Oren

Or why not just get a 2x6 (8, 10, etc) and rip it to the thickness desired.
Put the thin piece you want on the OUTSIDE of the blade. If you use a wide
enough 2x you can get many strips from one piece. Don't run the piece
between the blade and fence too thin!!!!
These shims are used for drywall. They would work in lieu of felt
paper... dense cardboard...

36" x 1 1/2" Drywall Shims - Bundle of 50 at Lowes.

<http://www.lowes.com/pd_180652-157-..._Wallboard+Accessories_4294858281_4294937087_>
 
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B

Borrall Wonnell

Not to get philosophical but this newsgroup reaffirms my faith in
humanity. It is so rare for people to go out of their way to help
someone else.

Now, with that silliness out of the way, there seem to be many ways to
do the same job. I'm a bit surprised nobody suggested sistering a 2x
to the side of the joist to get a flush lower surface. That would be
impractical due to wires/blocking not to mention the plywood edges
would no longer line up with the nailing surface.

I would have ripped 2x stock *IF* I had the tools and skills to do
it. Unfortunately I don't have a table saw, and cutting a straight
line with a circular would be a (frustrating) challenge for me.
The drywall shims seem neat but aren't available locally. And yes, a
little variation in the plywood could make for a more interesting rock
climbing environment...but not really interesting enough!

Cheers,
Dave
 
D

dennisgauge

Now, with that silliness out of the way, there seem to be many ways to
do the same job.
No, just one way, the right way.
 I'm a bit surprised nobody suggested sistering a 2x
to the side of the joist to get a flush lower surface.
Nobody suggested it because that is the most overly-complicated,
wasteful, asinine way to do the job possible.
I would have ripped 2x stock *IF* I had the tools and skills to do
it.  Unfortunately I don't have a table saw, and cutting a straight
line with a circular would be a (frustrating) challenge for me.

The drywall shims seem neat but aren't available locally.
Here we go with the excuses as to why your overly-complicated, half-
baked idea is the only option open to you...

You can get a perfectly viable portable table saw that will do this
job and 100's of others for about $100. What self-respecting guy
doesn't need more tools?

The big problem with your original idea is that felt paper
deteriorates and compresses. This is going to be a load-bearing
structure. You want REAL WOOD supporting it.

Use plain old door shims if you are averse to doing it properly and
buying a table saw. All you need is a utility knife. Surely you have a
utility knife, or can spend the $4 to purchase one.

Two shims in opposite directions to make a level nailing surface. If
the gap is less than the thickest part of the shim, cut the thick end
of the shim off until it's thin enough.

Use a long straightedge to find the low spots. Slide the shims
together or apart until they fill the gap. Attach the shims to the
joists with some small finish nails. Drill and screw permanently with
the plywood.
 
D

DerbyDad03

Not to get philosophical but this newsgroup reaffirms my faith in
humanity.  It is so rare for people to go out of their way to help
someone else.

Now, with that silliness out of the way, there seem to be many ways to
do the same job.  I'm a bit surprised nobody suggested sistering a 2x
to the side of the joist to get a flush lower surface.  That would be
impractical due to wires/blocking not to mention the plywood edges
would no longer line up with the nailing surface.

I would have ripped 2x stock *IF* I had the tools and skills to do
it.  Unfortunately I don't have a table saw, and cutting a straight
line with a circular would be a (frustrating) challenge for me.
The drywall shims seem neat but aren't available locally.  And yes, a
little variation in the plywood could make for a more interesting rock
climbing environment...but not really interesting enough!

Cheers,
Dave
re: "cutting a straight line with a circular would be a (frustrating)
challenge for me."

It shouldn't be. All you need is a straight edge clamped to the wood
to run the saw shoe against.

That straight edge could be anything from a 6 foot level (which you
should have for the type of project you are describing) to a store-
bought guide such as this:

http://www.amazon.com/Johnson-Level-Tool-J4900-Aluminum/dp/B00002N5OF

Of course, for $100 you could buy an inexpensive table saw and have it
for other projects - as long as you're not building cabinets or fine
furniture.

I, for one, got very lucky about 10 years ago and found a full-size
belt driven 10" tablesaw with 2 table extensions for $100 in my local
paper's Saturday Super Ads. To this day I still feel that it was the
best $100 I've ever spent. I can't imagine how I would have gotten
through some of the DIY projects I've done without it.
 
B

Borrall Wonnell

On Nov 29, 7:44 am, Borrall Wonnell <[email protected]> wrote:
No, just one way, the right way.

Nobody suggested it because that is the most overly-complicated,
wasteful, asinine way to do the job possible.

Here we go with the excuses as to why your overly-complicated, half-
baked idea is the only option open to you...
Bad day?
 
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B

Borrall Wonnell

re: "cutting a straight line with a circular would be a (frustrating) challenge for me."

It shouldn't be. All you need is a straight edge clamped to the wood
to run the saw shoe against.
Worth a try, and yes I have a long level. I managed a 1/4" strip, so
there's hope yet.
Table saw is a luxury I can't justify at this point (SWMBO).
 
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