A question about drywall cracks...

[john1056]

I was wondering what the best method is for filling in the cracks between drywall sheets. I know the ceiling, floor and corners get a bead of acoustic caulk (I'm using the Green Glue kind), but I am wondering about the other cracks. These are the permutations I can think of:

1. tape and compound (traditional)
2. acoustic caulk covered with compound
3. acoustic caulk covered with tape and compound.

3 seems safest, but also most work. Any pointers are appreciated!

I should also say that due to my lack of skill and the un-level-ness of the framing (which was already there) some of my cracks are almost 1/2 inch wide. This is an interior wall, so I have access to the other side. My plan was to use painters tape on the back side and fill the cracks completely with caulk, then do the tape and compound. Part of me wonders if this is overkill though...



http://2.bp.blogspot.com/_FIecI8KHjtU/S ... G_4378.JPG

[norton]

Ouch... 1/2" seams are pretty serious.

For something that big I'd say use some GG caulking... and your drywall mudding blade to make sure the seam is fully sealed.

I'd also recommend spending some time at drywallschool.com check out the videos and you'll make the whole process of finishing those walls out MUCH more pleasant.

If you're double rocking the wall... orient the outer layer of rock opposite to the under layer, that way your seams will be minimized. Usually, raw seams aren't much of a problem... and only leak extreme high frequencies which are easy to block out with standard mud and tape... but your situation sounds a little more extreme.

So any HUGE gaps, you should fill with insulation.... the fluffy kind.. Then if you've still got gaps, you can consider using "cauik saver" or "backer rod" which is essentially a foam gasket that you stuff in the gap then caulk over.


If you've got gaps that don't want to behave futher.. I'd suggest cutting small pieces of sheetrock to fill the void... then use a combination of insulation/mud and or caulk to shore it up.

Of course... you can't mix wet caulk and wet mud together.. at least very effectively.. so judge the situation by what goopy material is likely to hold.

Good luck! Drywall school will help.

[john1056]

Thanks Norton for your detailed response! I will check out drywallschool.com for sure. If I understand you response correctly, it sounds like:

1. I should be shooting for small gaps ( 1/8 ) between sheets,and plan to use mud and tape (no caulk). For double walls don't overlap seams.

2. For moderately larger gaps (> 1/8 - 1/2) fill the gap with caulk first, using a mudding blade to ensure the gap is completely filled, then cover with mud and tape.

3. For large holes (like around the top duct in my picture). Use a combination of fluffy insulation and some creativity with the goal being air tightness.

Does something like great stuff have any dampening benefit or am I better off using cuts of drywall to get more mass?

I have some backer rod, but I would imagine that a solid fill of caulk would be more effective, is this not the case?

Thanks again for taking the time to help me out

[letemin]

Does Green Glue make an actual acoustical caulk? I only know their laminating liquid glue, which goes between layers of drywall and is certainly not caulk. No experience using it as caulk to fill in seams and corners, so I won't make a judgement there, however, it would seem to me that a regular acoustical caulk makes more sense for cracks and what not.

For the gap around your duct, you might consider just using compound. That's what my contractor did for my ducts (he's done hundreds of studios for the best of them) and then some acoustical caulk over the compound where the duct meets the wall once it's dry.

[norton]

GG does indeed make an acoustical caulking. It used to go by "silenseal" i don't know what their parent company Saint Gobain calls it now.... but over time, it's the best I've used...

As far as the Backer Rod goes.. Any gaps that are too big for straight caulk.. I'd stuff them full of insulation... if that doesn't work, use backer rod...

As far as a mountain of caulking vs... caulk and backer rod goes... Not really. The gaps you should be filling in should be really only leaking high end information and the caulking should seal that off just fine.

BUT that's assuming that your gaps and seams are "average". If they're huge.. you'll need the insulation. If you can fit your hand through the gap.. that's bad... and you should fill that kind of thing with rock... and mud .

Gaps around ducts... You can mud up to it and caulk over that.. but if there's a huge temperature/humidity difference between summer/winter etc.. that mud's likely to crack... I'd strive to keep the distance as small as possible... then just caulk it. IF that's not possible.. insulation is your friend... and you can always use the fiber tape with a couple coats of mud to create something that will allow caulking to bridge the gap.

[beefy]

I do construction work and was wondering if you were caulking these gaps for sound proofing reasons?

As far as your seams go you should really try hard not to have any gaps larger than 1/4 inch. If it's bigger than that you should of probably of redone it but sense it's already up just use mesh tape on the larger gaps. In fact it might be easier for you to use mesh tape every where but try and buy it at a drywall supply place or maybe Sherwin Williams if they have it because if it doesn't stick well to the wall on its own it makes it tuff.

Around the duct you should really build a soffit around it. Not only will you not have any large gaps but it will also stop it from reflecting high frequencies so bad. It still will reflect but treating a room properly will fix those problems. If that is not an option I would do as previously suggested and use insulation. that ducting is flexible so I wouldn't tape and mud around it.

[john1056]

Here is a picture of the wall with acoustic caulk in the too-big gaps, and around the duct. There are also some wood slats I made where the drywall met the center beam in the basement, though its hard to make out in the picture. In places where the gap was smaller (it wasn't uniform along the length of the wall) I used backer rod.

http://1.bp.blogspot.com/_FIecI8KHjtU/S ... G_4410.JPG

Here's a shot of the finished wall. It didn't turn out too bad, but it could have been better.

http://4.bp.blogspot.com/_FIecI8KHjtU/S ... G_4521.JPG

Thanks again to everyone who provided the excellent information that helped me complete this part of the project!

[Ted White]

Big gaps tend to form cracks when drying. 1/2" is pretty big. Check for cracks when that dries.

[john1056]

I didn't take picture of the intermediate steps. After the acoustic caulk, I muded and taped just like you would any wall. I guess my description made it sound like I painted over the caulk There actually weren't many places where the gap was bigger than 1/4 inch.

[Brett Siler]

I used the first method you mentioned the traditional one and it worked fine.