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:
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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 expand/contract?
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 installation. 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?
Then 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, right?
Y.
P> Yes, there is expansion/contraction of drywall, plus slight
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?
Y.
P> Yes, there is expansion/contraction of drywall, plus slight
I have NEVER seen drywall intentionally gapped except to avoid putting in 2 cut peices instead of 1 to finish out a room (1/4" short to run to the wall). The gap makes absolutely no sense as the standard procedure for taping involves laying down mud (which would fill any gap) and then covering with tape and then covering again with more mud. A gap would also make soft spots to buckle. Drywall is exactly 48" and to gap the pieces would mean you would have to scab studs in to have something to nail or screw to or run non-standard spacing and plan carefully where you will put your drywall. I do not see where this recommendation is on the page mentioned.
Basically, you are correct: Yes, no mud in the gap will indeed make it easy to puncture. Not only that, but you couldn't really keep it out of the gap if you are applying the tape correctly. Mud, tape, mud, feather. An 1/8" isn't much space, so perish the thought about the studs getting off center. I've yet to see old OR new construction where the studs were EXACTLY 16" or 24" on centers; it just doesn't happen. So, don't sweat the so called advice that leaving a 1/8" gap will make yuou miss a stud. In total, that is 1/16" PER sheet, of every sheet, if you think about it. You may or may not miss a stud and have to account for it whether you have one or a hundred pcs next to each other. It's usually best to avoid the overly technical responses of this nature. Pay particular attention to butt joints if they are the opposite side from the one with the manufactured indent: you must have the gap there, plus you might want to remove a layer of paper at the butt to give mud some spaceto be fathered in order to avoid seeing the mud buildup. Remember, only two sides of a sheet have the indent. If you might have to put them end to end, it might be better to get longer pieces of drywall. Have a talk with the guys at your local bldg supply; they'll likely give you good info. Actually, NOT leaving a gap would be a lot harder than using the recommended gaps. You'll see as you get going.
I think I'd recommend a little reading on the subject. I got thousands of hits using dryall +diy +gap at Google. Some excerpts follow:
From : When sizing a panel, cut it small enough to fit without binding but large enough that it doesn't leave a gap too wide (more than about 1/4 inch) to be taped and filled easily.
From:
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cut the drywall 1/4 inch less than the actual measurement for length. The drywall joint compound and tape will fill all of these gaps with ease. Hanging drywall is not finish carpentry!
From :
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you apply the drywall try not to leave a gap between boards more than 1/8 to 1/4 of an inch - less if possible
From:
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find: 1.. 2.. After the drywall is in place, apply dry-wall mesh tape along the joints between the two pieces of drywall (figure F). The mesh tape helps hold drywall compound in the gap. 3.. Use a wide drywall knife to spread joint compound over the mesh tape (figure G). Don't try to fill the entire gap all at once; apply a little at a time, and allow it to dry before applying a second coat. 4.. Cover the screw heads with drywall Those are just from the first page of hits: There are many more. Check out a few of them, do your own search if you wish, and read up on the parts you are weakest on first. You'll be pleased with the job when you get it all done and you're hte only one can see the "oopses"! . A word of unsolicited advice: I quit sanding mud years ago: Now I staple a washcloth to a piece of 2 x 4 and use it, along with a bucket of water, to smooth out the feathers to perfection. No dust, i'ts quicker, and lots cleaner. ymmv of course.
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 helpful are:
- In stairways or other areas where wallboard has to bridge the junction between floors.
- 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
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This site
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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.
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 cracks.
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.
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.
This makes me think you just measured wrong. Sheetrock doesn't have any grain, as far as I can tell. If it's going to expand/shrink, it's going to do it proportionally.
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 it in?
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.
Exactly. People are reading where about leaving gaps as good installation practice (saves time, saves trimming/rasping, saves broken board) as a 'requirement. It's bs.
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, something.
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