I am installing drywall in the basement. I just put the boards
as close as each other, leave no gap in between.
But this site:
suggests that there should be 1/8" gap for vertically layed boards
and 1/8 to 1/4" gap for horizontally layed boards.
What is the reason for that? Do the drywall expands/shrink? Will the
boards buckle at joints for no-gap setting? I guess the celling boards
also needs the breathing gaps.
Do I need fill the gap with mud? if so, then does the mud also
What do most people do?
Yes, there is expansion/contraction of drywall, plus slight
movement of the underlying studs etc. No, you should not
have butted them against each other. You're going to end up
with some pretty ugly seams after a year or two.
Grab a circular saw, mask, fans, water, etc., and cut in the
seams to create the gap you need. And yes, then tape-seal,
properly, and mud the joints. Proper feathering will make
them stay hidden and won't crack as long as they're on
stable materials (studs et.). Whether it'll bow or not
depends on what/how they're fastened. It's hard to say
without seeing the setup. NOW is the time to fix it though;
not down the road where you can't get to it all and the
damage gets unsightly. The gaps are important to a correct
If you used standard drywall and thickness, your numbers
are OK. If you used anything else, the gaps might be
differend (e.g. fireboard, etc.). The gapping's usualloy
stamped right no the drywall; is yours?
Do you need to fill the gap with the mud? if you leave the
gap alone, and tape with, say perforated selfstick tapes, then
the gaps can be easily punctuated for the 1/4" gap, right?
Pop Rivet wrote:
Same here. The advice to cut 1/4" short or about that is to aid in
installation only. You will see no drywaller cutting to exact measure
but the resulting gaps (if any) are not to 'allow expansion', they are
only to speed things up. The tape/mud takes care of covering any
It's an easy experiment: Took two 4 x 8 sheets into air
conditioned kitchen for 24 hours, measured, took them out to
garage, opened door, left in hot, humid air for 24 hours,
remeasured, with SAME tape, SAME edge, SAME surface,SAME
time of day: Diff = 3/16" (give or take a 64th) on BOTH
sheets! The weather's so humid it might have been more with
more time in the house's much dryer environment.
Let's talk facts.
This is true. I left 100 of 4x8 sheetrock in the humid basement
for a year. While they are still 96" long, they are about 1/4"
wider then before.
Now the question: does sheetrock only expand, but will not shrink
(make sense to me). If they shrink, then they will be gaps on the
wall/ceiling when it is drier.
When the sheetrock will stop expand then? I would guess 1/4"
is the equlibrium state of expansion, in which case I am OK to
have the boards closely butt ended.
Short answer: That's correct. You do not leave a gap between sheets.
I took a look at the site. I don't see where they're saying to do that.
My guess is that whatever you were reading was talking about leaving a
bit of a gap around the _perimeter_ of the ceiling. This isn't a problem
since any small gaps at the room perimeter will be covered when you hang
the walls. The same applies to hanging the walls in a room. For example,
after you hang the north wall, the wallboard you install on the East
wall will cover any small gap you left in the NE corner.
Why leave any gap? Well, if you try to get the pieces to fit perfectly
you're going to spend a lot of time cursing and trimming and rasping
when your measurement is a tiny bit off or when the framing is not
perfectly straight, square, and plumb.
I would consider wallboard to be very dimensionally stable, especially
compared to the studs they're being attached to. There are some
instances where you need to account for the movement of the wallboard
itself. In those cases you'd be installing a control joint every 30
feet, not between individual sheets. (Take a close look at the drywall
or plaster in commercial buildings and you'll see the joints.)
Control joints are used in residential construction too, but I'd say
they're to account for movement in the framing rather than the
wallboard. It's common to put a control joint along the peak of a
cathedral ceiling, but you probably don't have to worry about that in
your basement :). Other problem areas where control joints may be
- In stairways or other areas where wallboard has to bridge the junction
- in ceilings where the joists or rafters change direction.
Don't intentionally leave a gap between sheets. If you do end up with a
gap, pre-fill it with mud before taping.
The gap requirements are labeled on the Figures
(Fig 4 of http://doityourself.com/wall/installdrywall.htm )
also has 1/8" gap requirement on Fig 4.
My guess is that the joists/stud will deform over time and cause seam
along the joints. My 2x10 ceiling joists should measure 9.25" in depth.
But I can only measure them at 9", and some boards with cupping
were measured less than that. And they are only 4 years old.
Plus, if you leave a gap, you're just filling it in with mud, which is
very similar to what the drywall is made of to begin with. It's not
like you're putting in rubber joints or something similar for
expansion. So, what sense would it make to leave a gap and then fill
email@example.com (Chet Hayes) wrote in message
If it was required for 'expansion' every rock job in the country would
be showing problems within a year as once it is taped it is in effect
one solid sheet, the joints cannot move without cracking/bulging,
If you are going to leave a gap between sheets when hung vertically then you
need to move your studs further apart then 16" on center. Since sheets are 48"
wide and after a few sheets are hung the edges will not land on a stud set at
16" center. Leave no gap at all with drywall between sheets.
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