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drywall question

2K views 22 replies 7 participants last post by  evilboweivel 
#1 ·
putting aside doing things properly.. The room being made in the basement will not have its ceiling insulated. (The house 2x8 joists.) Since im trying to keep the basement room cold, im hoping it still works well.



But as such the top plate of the 2x4 frame still has to go under the 2x8 joists. Which leaves a big gap between the joists. Fo simplicity, speed, and moneys sake, im jsut extending the all up and will add insulation in there.



Cutting the drywall to fit around every joist and vet and object in the way is a rather imprecise task tho. So along the edges there will be a little bit of a gap. Im thinking i should seal it somehow. A can of spray foam insulation would expand to far, not to mention create quite a mess over the drywall. I was thinking maybe old fashion caulk? Im not sure. Any suggestions?


^top of the outside of the wall frame,





^a look form the inside of the rooms frame (havnt put in the insulation or dry wall on the inside yet.)

I added the little pieces of 2x4 in between the joists as a backing to screw the drywall to.
But cutting the drywall to size leaves those gaps as you can see. So what would be good to seal it with? (prevent cold air loss from escaping the room)
 
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#4 ·
It might save you some grief and look better to go ahead and rock the ceiling. Then tape and bed as normal.

No bigger than those gaps are you could probably just caulk it.

It would work alright to use drywall mud. Over time you might get some minor cracks in the mud do to wood movement but it shouldn't be enough to worry about.
 
#5 ·
I dont care at all right now how it looks. Long as i can control the temp (keep it cold) and humidity. My pets will be going in there, so look does not matter right now. Just safety and function.



That being said, im completely out of money and nearly time. Drywalling the ceiling is simply not an option.


Would caulk serve well to help seal off air flow in this manner? I could use drywall compound. But my first thought was caulk simply because it would be easier and cleaner to remove one day; when i can redo everything better. And would have a little more give in it then compound.
 
#6 ·
If the gap is more than 1/2 then you would probably be better off with mud. The five minute stuff that comes in a powder you have to mix would adhere better and be less likely to crack. Just common painters caulk would be a lot easier and would seal as good as anything. You might mud the big cracks and caulk the rest.
 
#7 ·
If the gap is more than 1/2 then you would probably be better off with mud. The five minute stuff that comes in a powder you have to mix would adhere better and be less likely to crack.

Less likely to crack than caulk, or than regular compound?
Is there any real difference from the powder stuff vs the mixed stuff in the green bucket i usually see?
 
#10 ·
many gaps on the edges are fairly thin. But i do have several that are maybe 1/4" or a few underneath the joist that might get closer to 1/2". Im guessing caulking the larger ones wouldnt be the best idea?

And assuming its not, for using the compound in areas like that one in the OP picture, would it be as 'simple' as just trying to throw a small bit in the crack/space? - Not worried about appearance. Just want to stop air flow and keep the cold in the room. And im thinking i wouldnt want to do it like a normal corner with tape as id rather not add compound to the joist itself as much as possible. (One day ill get a ceiling done normally.)
 
#12 ·
fwiw, I place insulation (batt w/paper face) in the cavity behind the drywall in the pic, in the recess above the sill plate - between the floor joists - against the band joist. i leave 1" extra paper on each side to staple to the floor joist. I insulate all around the basement that way. if you do that, nothing will pass to those cracks...


for your app, you could just caulk, or stuff loose insulation in the cracks.
 
#15 ·
fwiw, I place insulation (batt w/paper face) in the cavity behind the drywall in the pic, in the recess above the sill plate - between the floor joists - against the band joist. i leave 1" extra paper on each side to staple to the floor joist. I insulate all around the basement that way. if you do that, nothing will pass to those cracks...
I do intend to add insulation in the big(ish) square area between the backer 2x4s between the joists.





Wolf - the quick fix would be to use drywall compound for now.
Should i use the caulk on the smaller/thinner gaps and the compound on the larger ones? Or just compound all the way around?
Some are fairly thin gaps, but there are some that are around 1/2"
What type of compound would be best here? All purpose, setting, another? (of course all im seeing on lowes website [since thats closest to me] is all purpose and lightweight. So that kinda narrows it down)


Would a elastomeric caulk work for this? Iv never used it before. But the couple of caulks that came up when i searched it all mention needing to use a reinforcing fabric with it.
 
#13 ·
the quick setting drywall/joint compound is a lot like Plaster of Paris.
so if you are familiar with that, you will know that once it starts to set,
that's it. you have to stop right there and clean up your tools.
the thicker it is in the mixing pan, the shorter pot life you will have.
I have seen the pot sitting in ice water to lengthen the setting time, and it works.
I lost one of my best cooking pots to that stuff (that I used to mix it in).
so for your project, I would stick with the conventional methods as mentioned
above. the short cuts could cost you more in time and money in the long run.
best of luck.

.

.
 
#16 · (Edited)
in my world, I use drywall compound to seal just about everything
related to drywall and gaps. (with fiberglass glass tape).
but - that is for places that will be seen and should look good.
what you are wanting to do is just a quick fix to control air intrusion.
I would still mud everything over 1/8", that is just the way I am wired.
small spaces, less than 1/8" = caulk it with a caulking gun and call it good.
drywall mud is cheaper than caulk.
if this were my project, I would be very comfortable using the cheap painters
caulk which is only a couple of bucks a tube vs the more expensive ones.
you may be overthinking this a little.

a trick that may save you some time and material is to get the premade
drywall compound in the plastic tub. stir it well !!!!
with a big spoon, fill a quart size Zip-Top bag with the compound.
cut a 1/4" off of one corner and squeeze the compound into the cracks.
over fill just a little and pack it in with your finger and smooth it out as you go.
[sort of like a piping bag that cake makers use]
of course, the cloth piping bag would work better, as it won't tear if you
apply too much pressure. take your time and don't rush it. P A T I E N C E.
and in a year or two, if cracks do appear, and you don't like them,
you can use the same cheap painters caulk to seal them up.
it's not rocket science and your house won't fall down if you mess it up.

.

.
 
#17 ·
you may be overthinking this a little.

I can pretty much guarantee that. I started planning this out a year or two ago. Iv never done anything remotely close to this before. Then i had structural water issues that sprang up, designing the whole room around that, constructing the room around that. With very limited funding. Trying to do things as correctly as i could within the limitations i had. Then the stress of everything else in life (disability). - Then the fact that if its not done in time, i could lose my house (longer story). And if i screw up to badly and the room gets to warm, my pets will die.



So yea... im overthinking everything lol. One more reason i like asking about things hear. Not only good to learn, but good to help and try to get my head on straight again.
 
#21 · (Edited)
for the areas i can caulk, would any of these work? Or should it all be the same kind. (I have these three bottles from past projects that are unopened. Figured i mine as well use them if i can.)

https://www.lowes.com/pd/DAP-Alex-Plus-10-1-oz-White-Paintable-Latex-Caulk/3053791

https://www.lowes.com/pd/DAP-Dynaflex-Ultra-10-1-oz-White-Paintable-Latex-Caulk/1000364653

The third one was hard to even find online anymore. It is a gutter sealant.
http://www.ccitrade.top/index.php?main_page=product_info&products_id=4183
 
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