Home Repair forum - Drywall sag

Author

Drywall sag

Eigenvector

2006-12-25, 3:25 am

If I have ceiling joists that are 48" apart, will 5/8" drywall sag if
mounted on it?

I'm not seeing too much information about that around, even though I'm
pretty sure 48" is pretty standard framing for a basement.

I made the mistake of putting 1/2" up the first time - bad bad mistake that
cost me dearly. But 5/8" isn't that much more. The idea of installing
2x4's between the studs isn't my idea of a fun time, especially since it
will introduce more margins for error unless I'm a demon for measurements.

I am also considering the idea of using plywood backing over the joists as a
way to give the drywall a larger surface to attach to - even if it isn't
structural it will still remove any sagging. But that option has the
detraction of reducing my headroom by 1/4" or more. I know it doesn't sound
like a lot, but it all adds up - not to mention it will make adding lighting
fixtures a huge pain in the XXX since you can't cut plywood with a drywall
saw.

tbasc@bellsouth.net

2006-12-25, 3:25 am

Eigenvector wrote:
> If I have ceiling joists that are 48" apart, will 5/8" drywall sag if
> mounted on it?
>
> I'm not seeing too much information about that around, even though I'm
> pretty sure 48" is pretty standard framing for a basement.
>
> I made the mistake of putting 1/2" up the first time - bad bad mistake that
> cost me dearly. But 5/8" isn't that much more. The idea of installing
> 2x4's between the studs isn't my idea of a fun time, especially since it
> will introduce more margins for error unless I'm a demon for measurements.
>
> I am also considering the idea of using plywood backing over the joists as a
> way to give the drywall a larger surface to attach to - even if it isn't
> structural it will still remove any sagging. But that option has the
> detraction of reducing my headroom by 1/4" or more. I know it doesn't sound
> like a lot, but it all adds up - not to mention it will make adding lighting
> fixtures a huge pain in the XXX since you can't cut plywood with a drywall
> saw.

USG recommends 5/8" gyp bd be supported by joists 16" O.C. if the gyp
bd sheets are parallel to the joists and by joists 24" O.C. if the
sheets are perpendicular to the joists.

TB

BobK207

2006-12-25, 9:25 am

Eigenvector wrote:
> If I have ceiling joists that are 48" apart, will 5/8" drywall sag if
> mounted on it?
>
> I'm not seeing too much information about that around, even though I'm
> pretty sure 48" is pretty standard framing for a basement.
>
> I made the mistake of putting 1/2" up the first time - bad bad mistake that
> cost me dearly. But 5/8" isn't that much more. The idea of installing
> 2x4's between the studs isn't my idea of a fun time, especially since it
> will introduce more margins for error unless I'm a demon for measurements.
>
> I am also considering the idea of using plywood backing over the joists as a
> way to give the drywall a larger surface to attach to - even if it isn't
> structural it will still remove any sagging. But that option has the
> detraction of reducing my headroom by 1/4" or more. I know it doesn't sound
> like a lot, but it all adds up - not to mention it will make adding lighting
> fixtures a huge pain in the XXX since you can't cut plywood with a drywall
> saw

Ceiling joists at 48" are way too far apart, even for 5/8" ....if you
want the ceiling to look flat

IMO even 5/8 is a stretch at 24" .....I would use 1/2 with joists at 16

cheers
Bob

PS the drywall / plywood combo will cut very easily with a jig saw

trader4@optonline.net

2006-12-25, 9:25 am

BobK207 wrote:
> Eigenvector wrote:
>
> Ceiling joists at 48" are way too far apart, even for 5/8" ....if you
> want the ceiling to look flat
>
> IMO even 5/8 is a stretch at 24" .....I would use 1/2 with joists at 16
>
>
> cheers
> Bob
>
> PS the drywall / plywood combo will cut very easily with a jig saw

I'd be curious to know where any building code allows 48" as routine
ceiling joist spacing, whether in a basement or anywhere else. I'm
betting you don't have a building permit.

Edwin Pawlowski

2006-12-25, 9:25 am

"Eigenvector" <m44_master@yahoo.com> wrote in message
news:k46dncJemt9l-xLYnZ2dnUVZ_vyunZ2d@comcast.com...
> If I have ceiling joists that are 48" apart, will 5/8" drywall sag if
> mounted on it?

Yes, it will look like crap

>
> I'm not seeing too much information about that around, even though I'm
> pretty sure 48" is pretty standard framing for a basement.

No, it is not
>
> I made the mistake of putting 1/2" up the first time - bad bad mistake
> that cost me dearly. But 5/8" isn't that much more. The idea of
> installing 2x4's between the studs isn't my idea of a fun time, especially
> since it will introduce more margins for error unless I'm a demon for
> measurements.

One method looks like crap and you have verified that. The other method is
correct. Your choice, do it right or a second half assed job. You can get
away with 2 x 3.

>
> I am also considering the idea of using plywood backing over the joists as
> a way to give the drywall a larger surface to attach to - even if it isn't
> structural it will still remove any sagging. But that option has the
> detraction of reducing my headroom by 1/4" or more. I know it doesn't
> sound like a lot, but it all adds up - not to mention it will make adding
> lighting fixtures a huge pain in the XXX since you can't cut plywood with
> a drywall saw.

That certainly narrow down the options. 1/4 plywood is not going to help
much anyway. That too may sag at 48" spans. That gravity thing is not going
away.

Joseph Meehan

2006-12-25, 1:25 pm

Eigenvector wrote:
> ..
> I'm not seeing too much information about that around, even though I'm
> pretty sure 48" is pretty standard framing for a basement.
> ..

No were I have ever seen.

Without seeing exactly what you are working with I can only suggest you
need to get that down to 24" or better yet 16". I would go for 16"

--
Joseph Meehan

Dia 's Muire duit

bamboo@localnet.com

2006-12-25, 1:25 pm

Now you know why furring stock is used as strapping.
Lay it out to make full use of the tapered drywall edges on 16" centers.

Eigenvector

2006-12-25, 1:25 pm

<trader4@optonline.net> wrote in message
news:1167050886.719317.313390@79g2000cws.googlegroups.com...
>
> BobK207 wrote:
>
>
>
> I'd be curious to know where any building code allows 48" as routine
> ceiling joist spacing, whether in a basement or anywhere else. I'm
> betting you don't have a building permit.
>
Not required, I'm repairing existing work - I asked first. But thanks for
playing.

As for 48" separation, I've seen a lot of houses with this kind of joist
separation. Perhaps its peculiar to my house construction, pier and post
foundation, but certainly not unique.

Eigenvector

2006-12-25, 1:25 pm

"Edwin Pawlowski" <esp@snet.net> wrote in message
news:07Qjh.6664$yC5.1814@newssvr27.news.prodigy.net...
>
> "Eigenvector" <m44_master@yahoo.com> wrote in message
> news:k46dncJemt9l-xLYnZ2dnUVZ_vyunZ2d@comcast.com...
>
> Yes, it will look like crap
>
>
> No, it is not

I see this in a lot of houses where I live, especially in downstairs
garages.

The roof joists are all 24".

>
> One method looks like crap and you have verified that. The other method
> is correct. Your choice, do it right or a second half assed job. You
> can get away with 2 x 3.
>
>
>
>
> That certainly narrow down the options. 1/4 plywood is not going to help
> much anyway. That too may sag at 48" spans. That gravity thing is not
> going away.
That sucks. That adds a hell of a lot more work that has to be done.

Attaching the studs to the existing joists itself is going to be a trick

Nothing for it then but to do it right.

Steve Barker

2006-12-25, 1:25 pm

yes,

s

"Eigenvector" <m44_master@yahoo.com> wrote in message
news:k46dncJemt9l-xLYnZ2dnUVZ_vyunZ2d@comcast.com...
> If I have ceiling joists that are 48" apart, will 5/8" drywall sag if
> mounted on it?
>

nicksanspam@ece.villanova.edu

2006-12-25, 1:25 pm

How about screwing 3 46" 2x3s or lighter steel studs to the drywall before
screwing the drywall edges to the joists on 4' centers?

Nick

Father Haskell

2006-12-25, 1:25 pm

Eigenvector wrote:
> If I have ceiling joists that are 48" apart, will 5/8" drywall sag if
> mounted on it?
>
> I'm not seeing too much information about that around, even though I'm
> pretty sure 48" is pretty standard framing for a basement.
>
> I made the mistake of putting 1/2" up the first time - bad bad mistake that
> cost me dearly. But 5/8" isn't that much more. The idea of installing
> 2x4's between the studs isn't my idea of a fun time, especially since it
> will introduce more margins for error unless I'm a demon for measurements.

Time to buy a chopsaw.

Cut each joist 1/8 - 1/4" long and test fit. Pare the ends until it
fits.

> I am also considering the idea of using plywood backing over the joists as a
> way to give the drywall a larger surface to attach to - even if it isn't
> structural it will still remove any sagging. But that option has the
> detraction of reducing my headroom by 1/4" or more. I know it doesn't sound
> like a lot, but it all adds up - not to mention it will make adding lighting
> fixtures a huge pain in the XXX since you can't cut plywood with a drywall
> saw.

Cheap circular saw or jigsaw with 2 x 4 guide fence.

Two more options: Hang 2 x 4s across the joists, 24" apart. Possible
downside is this will lower your ceiling 2". That, or a cathedral
ceiling.

BobK207

2006-12-25, 1:25 pm

Eigenvector wrote:
> "Edwin Pawlowski" <esp@snet.net> wrote in message
> news:07Qjh.6664$yC5.1814@newssvr27.news.prodigy.net...
>
> I see this in a lot of houses where I live, especially in downstairs
> garages.
>
> The roof joists are all 24".
>
> That sucks. That adds a hell of a lot more work that has to be done.
>
> Attaching the studs to the existing joists itself is going to be a trick
>
> Nothing for it then but to do it right.

I'm thinking that some mis-communication is going on
here........support members for drywall or even plywood would be
difficult to get to perform at 48" oc

that's just too far for the sheet material to span unless, in the case
of plywood, it was really thick

maybe we need a better description of the exisitng condition & the
project objective

You mention what seems to be a post & pier foundation system?

what size are these "ceiling joists" that are at 48" oc? are these
really "support beams" for the floor joists above?

I may have given poor advice based my lack of understanding of the
situation

cheers
Bob

Eigenvector

2006-12-25, 5:25 pm

"Father Haskell" <fatherhaskell@yahoo.com> wrote in message
news:1167074549.184460.58170@n51g2000cwc.googlegroups.com...
>
> Eigenvector wrote:
>
> Time to buy a chopsaw.
>
> Cut each joist 1/8 - 1/4" long and test fit. Pare the ends until it
> fits.
>
>
> Cheap circular saw or jigsaw with 2 x 4 guide fence.
>
> Two more options: Hang 2 x 4s across the joists, 24" apart. Possible
> downside is this will lower your ceiling 2". That, or a cathedral
> ceiling.
>
A 1x4 may work as well. I was actually thinking of cutting 48" 2x4 spans
and mounting them between the joists at 16" spacings. It's a heck of a lot
of cutting and physically mounting the 2x4s to the joists will be an issue
(not insurmountable though). I'm not in a hurry so I can take my time.

Anyways, I got what I needed from you all, thanks again for the options and
the responses.

HeyBub

2006-12-25, 5:25 pm

Eigenvector wrote:
> If I have ceiling joists that are 48" apart, will 5/8" drywall sag if
> mounted on it?
>
> I'm not seeing too much information about that around, even though I'm
> pretty sure 48" is pretty standard framing for a basement.
>

Maybe you're trying to solve the wrong problem.

Forget the drywall - it's too heavy.

Perhaps ceiling tiles - they're 48" and should be quite easy to install
flush with your joists.

bowgus

2006-12-25, 5:25 pm

Eigenvector wrote:
> If I have ceiling joists that are 48" apart, will 5/8" drywall sag if
> mounted on it?

Let me suggest resilent channel (metal) at 16" centre perpendicular to
the joists. Then you can use 1/2 " drywall attached using drywall
screws. And the channel will reduce noise/vibration transmission
between the two areas ... if that's a consideration.

Edwin Pawlowski

2006-12-25, 8:25 pm

"Eigenvector" <m44_master@yahoo.com> wrote in message
> That sucks. That adds a hell of a lot more work that has to be done.
>
> Attaching the studs to the existing joists itself is going to be a trick
>
> Nothing for it then but to do it right.

I'd buy a cheap Harbor Freight nail gun and a $99 miter saw. It won't be
all that bad, especially if the dimension between existing studs are
consistent. It would be easier yet to put them on top of the joist, but you
lose a lot of headroom that way.

George E. Cawthon

2006-12-25, 8:25 pm

Eigenvector wrote:
> <trader4@optonline.net> wrote in message
> news:1167050886.719317.313390@79g2000cws.googlegroups.com...
> Not required, I'm repairing existing work - I asked first. But thanks for
> playing.
>
> As for 48" separation, I've seen a lot of houses with this kind of joist
> separation. Perhaps its peculiar to my house construction, pier and post
> foundation, but certainly not unique.
>
>
It is not pier and post, it is post and beam. Yes
it is common in some parts of the country and it
is for the bottom floor. The posts are usually on
8 foot center and the beams are 4 feet apart.
Beams are often double 2x8's or double 2x10's. It
is used for crawl spaces because who would want to
live in that kind of room? Sounds like a basement
that was put in after the house was constructed
with a crawl space.

Or, are you talking about old type of post and
beam construction with very large beams and longer
distances between posts?

In any case, the minimum you need are 2x4's
between beams with the 2x4's spaced on 16 inch
centers. Or use a drop ceiling, not drywall.

Don Young

2006-12-25, 9:25 pm

"Eigenvector" <m44_master@yahoo.com> wrote in message
news:M4ednZ1TLcDVtA3YnZ2dnUVZ_o-knZ2d@comcast.com...
>
> "Father Haskell" <fatherhaskell@yahoo.com> wrote in message
> news:1167074549.184460.58170@n51g2000cwc.googlegroups.com...
> A 1x4 may work as well. I was actually thinking of cutting 48" 2x4 spans
> and mounting them between the joists at 16" spacings. It's a heck of a
> lot of cutting and physically mounting the 2x4s to the joists will be an
> issue (not insurmountable though). I'm not in a hurry so I can take my
> time.
>
> Anyways, I got what I needed from you all, thanks again for the options
> and the responses.
>
Don't even consider 1x4's for this. 2x4's on 16" centers is the method that
will be most successful. You could install them with metal brackets if you
don't like accurate cutting and nailing but if you get set up properly it
should not be a difficult job to just cut and nail.

Don't forget to check the evenness of the existing joists. If they are not
reasonably straight and even (level is not very important) you would want to
use a guide string and shims as needed.

Don Young

Don Young

Bob (but not THAT Bob)

2006-12-26, 3:25 am

bowgus wrote:
>
> Eigenvector wrote:
>
> Let me suggest resilent channel (metal) at 16" centre perpendicular to
> the joists. Then you can use 1/2 " drywall attached using drywall
> screws. And the channel will reduce noise/vibration transmission
> between the two areas ... if that's a consideration.

The channels are designed to span 24" max, not 48" - so they'll sag too.

I thought of a suspended drywall ceiling, but the main runners couldn't
handle 48" spans either.

HerHusband

2006-12-26, 1:25 pm

> I have ceiling joists that are 48" apart
> installing 2x4's between the studs isn't my idea of a fun time,

Could you screw 1/2" drywall to the subfloor "between" the beams? Then
either wrap each beam with drywall, or wrap them with lumber and stain
(assuming the beams aren't attractive enough to leave exposed). Accent
the beams instead of hiding them. Just watch the length of the screws so
you don't have screws coming up through the floor.

Of course, this
approach would make it difficult to run wiring, piping, insulation, etc.

Alternatively, how far do the beams span? Maybe you could add a joist or
two "parallel" to the beams instead of short segments between beams. The
beams support the floor, so the new joists only need to be sized like
ceiling joists to hold up the drywall. So, depending on the span, you
could probably use a single 2x4 or 2x6 between the beams (I'd probably
opt for two joists for a 16" OC spacing).

> unless I'm a demon for measurements.

If you must run 2x4 blocking between the beams, mark out 16" spacing
along the two end beams, then snap chalk lines across the bottoms of the
beams so you'll know where the blocking needs to go.

Then take a few measurements at various places to find out what the
largest distance is. Then use a power miter saw and a stop block to cut
several blocks an inch or so longer than the longest you'll need.

Now grab a handful of the blocks, and go to one of the bays between the
beams. Hold one end of the block against the side of one beam, and mark
the exact length you'll need to cut the block. Write a number 1 on this
block, and a number one on the side of the beam so you know where this
block belongs.

Move to the next chalkline, and repeat the procedure, this time writing 2
on the block and beam. Repeat for the rest of the bay.

Take the blocks back to the miter saw and cut them all to the lengths you
marked.

Now you should have blocks ready to nail up in that bay. They should be a
snug fit, so tap them in with a hammer, centering over the chalkline. You
can toenail them in by hand if you don't have an air nailer, or use a
screwgun and 3" deck screws.

By marking the blocks in position, you'll avoid measuring errors and can
accomodate fluctuations in the spacing between the beams.

You can cut the blocks with a circular saw or even a handsaw if you don't
have a power miter saw. But this sounds like a good excuse to buy a new
toy.

Worst case, you could probably rent a miter saw from a tool
rental store.

Have fun!

Anthony

bowgus

2006-12-26, 1:25 pm

> The channels are designed to span 24" max, not 48" - so they'll sag too.
>
> I thought of a suspended drywall ceiling, but the main runners couldn't
> handle 48" spans either.

Sure, but you could use wire ... well, maybe something like steel
coathanger "hangers" ... at the midpoint (24") attached to the subfloor
above. I have suspended ceiling in part of my basement (that ugly 2' x
4' fiberglass stuff ... was a rush job ... I've got to strap (1x3s) and
put in drywall one of these days). It's suspended using steel wire ...
multiple loops.

Eigenvector

2006-12-26, 8:25 pm

"bowgus" <bowgus@rogers.com> wrote in message
news:1167152172.348709.81920@73g2000cwn.googlegroups.com...
>
>
>
> Sure, but you could use wire ... well, maybe something like steel
> coathanger "hangers" ... at the midpoint (24") attached to the subfloor
> above. I have suspended ceiling in part of my basement (that ugly 2' x
> 4' fiberglass stuff ... was a rush job ... I've got to strap (1x3s) and
> put in drywall one of these days). It's suspended using steel wire ...
> multiple loops.
>

Sounds like its getting too complicated for a simple solution job. Hanging
2x4's between the joists using nails is so much more simple and elegant than
messing around with wire hangers, false ceilings (I can't stand false
ceilings), or anything else.

I had the solution when I wrote the question, but sometimes you block out
that solution in your mind when you want to believe a simpler solution
exists - in some far off mythical plane.

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