# Drywall butt joints question



## kupalino (Oct 13, 2009)

I bought a 12-inch knife and put enough mud to build up both sides of my butt joints to hide the hump. After it dried, I put my 12-inch knife in the middle of the hump and it still seesawed, but not as much as before. Is the goal to not have the knife seesaw, totally eliminate the hump? Or is it to reduce the seesawing? Using the 12-inch knife leveled on the peak of the hump, what is the acceptable distance from the edge of the knife to the drywall, 1/8"?


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## Big N8 (Oct 28, 2009)

You will never be able to make the joint go way totally. But you do need to feather the joint out a lot more then other joints. Just put another coat on and feather it out more.


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## kupalino (Oct 13, 2009)

Thanks for the response. I guess what I'm looking for is a good indication that says, "OK, I've feathered it out enough, I should stop adding more coat". The pros have eyes for it, I need to train mine. 

Thanks.


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## Willie T (Jan 29, 2009)

It's too late now, but here is something to keep in mind for your next drywall job: 
http://www.finehomebuilding.com/how-to/tips/invisible-drywall-butt-joints.aspx


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## acerunner (Dec 16, 2009)

i heard of two ways to do it. First is to score a V into the joint and mud & tape as usual. Second is apply a strip of mud on each side of the joint putting more pressure on the outside edge such that the inside edge forms a ridge. When that sets, mud down the middle to join the ridges.

The method Willie T posted looks promising, I'll have to try that.

At this point for you, i think the only choice is to feather it out more. Or maybe do some sanding.


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## beerdog (Dec 10, 2008)

I think the point is to feather it out enough so that it is not visibly noticeable after it is finished with paint or wallpaper.

I think even a tpered edge joint will have a slight hump. Maybe I am wrong.


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## kgphoto (Dec 2, 2007)

While a tapered edge could have a hump, it shouldn't. That is the whole point of the taper.

For most installations, flat is an illusion created by spreading out the hump and hiding it with flat paint. The more glossy the paint, the better the feather has to be.

Most butt joints get feathered out about 24 inches, so spread that one eighth (1/8) inch hump over 24 inches and you shouldn't be able to see or feel it.

OR you can use many different tools and products like the one Willie showed above. A commercial version is a Butt-Splicer or Butt-Backer, or Rock Splicer. I like the Butt-Taper tools as you can use drywall or plywood scraps on the jobsite instead of buying $3-$5 backers for each seam. Also the BT can work for patches as well. Google it if you are interested.


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