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Finishing Butt Joints

68K views 196 replies 32 participants last post by  moore 
#1 ·
Have had different ways shown to me but what is the best way to finish Butt Joints in the most effiecient way? Do you just go over twice w/ a 12" bowed trowel or make a mud path on both sides of the tape one your first coat and then a mud path over the tape itslef on your second coat then what?
 
#2 ·
You could get 6 people to answer this and get 6 different answers on ways to do it. Some people run a box on each side of the tape for the first coat and then down the middle on the second and there done. As far as a bowed Trowel goes, I would say there are no good, you need a straight one. You could coat each side of the tape with your trowel for the first coat and on the second go over it all coating it a little wider with less mud. Its basically a preference thing I'd say.
 
#3 ·
When coating by hand i use a 12" flat to load the butt(both sides), then wipe it down with my 20"...no lap marks. Second coat use my 14", and wipe with the 20"....done. Maybe a light sand to lose any float ridges and blend the edges. If the butt is severe, I'll use my homemade 36" bull float trowel with welded handles and still have only a two coat butt.

I've actually heard good things about the curved trowels (bowed), I've just never bought one.
 
#6 ·
just curious,why such big trowels,are you a very big man or something,with big arms.If so I will call you sir slimpickins.don't you get a lot of ripples,skip marks,waves,or what ever you call them,the bigger the trowel the harder it is to push,the smaller the trowel the more SPEED you can get (which is what you want) .there's some misconception that plaster guys used big honking trowels to get their work level which is not the case at all.then guys carry this theory over to taping.
think of the machines (boxes) their 7,8,10,12,inches,a trowel that is any bigger than that is going to wreck your shoulders,wrist,or elbow down the road,and your coating will be smoother ,speed stroke your coats,not big coat.
just trying to save your arms:yes:
 
#4 ·
git-r-dun is right,except for the curve trowel part.I call the curve trowel the poor mans box without the numbers.just think about how boxes run,there's a arch in the blade.(adjustable arch)if your good with the trowel,you can fool SOME people that you were using boxes.
but I would drop down to a 10" curve trowel,till you can afford 10" boxes,12" too big(I'm assuming your running flats with it too)there's lots of reading on this site about butts ,just grab a beer or 2 and start reading,
 
#17 ·
Whats up with the naming of coats after you guys tape you all talk about first coating the butt seam. Don't you tapers out there realize the first coat is the tape coat then after that it is the second coat???? What do you consider the tape coat 0 coat? Good Grief I know most just call it a tape coat but I always learned to also call it the first coat.
 
#19 · (Edited)
Taping the butt seam is the 1st coat? If so, I won't argue. It doesn't matter to me what it's called.

Another reason to not use fibafuse or should we call it fibatear:blink:
Tear, sometimes, when used in ways it doesn't seem well enough designed for - at least not well enough designed for to me. In the right places, right instances, I'm finding I'm liking it better than paper. Like today.
 
#23 ·
Geeshee guys, lighten up abit,,,,,,, or are all you getting as old and cranky as me????

The first coat is just that, the first coat (thats when the tape is applied)

I have gotten alot of advice on butts since I posted my reply,,, Have you never gotten to a job where the hangers put a butt on a real bad ceiling joist, on a cathedral ceiling, where the light was pouring in???? Hence my referring to "you have to run it till it's flat" even it takes 6 or 7 coats,,, BTW, we refer to them as the 6th or 7th coat !!!!:thumbup:

Then I got to thinking,,, was I talking about the number of coats "after" the tape coat???? maybe it was the 7th and 8th coat????

If you have to just hit one side of a butt joint,,, is it the 6 1/2th coat,,, or does that qualify as the 7th coat???

Now I'm really confused,,,,,,,,

Capt>>>>>>>>>> heading back to the fridge for another homebrew
 
#33 ·
Does those 3 coats include the tape coat? :D (a 'joke' from another thread).

I can't imagine right now using a 24". Not saying it might not make sense enough, but I've never seen it done. Do you put on a bunch of mud with another knife and then smooth it out with the 24"?
 
#38 ·
Omg!

Ok first off
tape coat
first coat
second or finished coat depending on how it looks
anything after this is just soomething that wracks your head and makes you look at it waaaaaaaaaaaay to long.
And if they are being picky or want it to perfection Skim coat :thumbsup:

In my younger years I used a 14" pan but only a 12" knife on finish. I can only imagin how my thumb & index fingers would feel with anything more then that. I remember how they would feel after a dryspell when I was using those. Now its just a 12" pan and nothing larger then a 10" knife. Boxes however are 10" 12"

As for the but joint. By hand I ussualy rock my 10" on it first to see where its sitting at. Then a coat down each side for the rocky ones or just a fast one down the center. If its on both sides I do not feather the bad side unless I know I am going to get away with just 1 more coat. The bigest part on the hand end is your eyes. You know when its flat and thats that :thumbup:
As for the tools I got to the point where its just 2 on each side and 1 down the center then on my walk about I ussualy will check them out and skim or wip out the dirtybond and make it rite rite then and there. Of course there is more to it then that but its all in your eyes and if you can tell flat when its flat.
 
#39 ·
Ok first off
tape coat

In my younger years I used a 14" pan but only a 12" knife on finish. I can only imagin how my thumb & index fingers would feel with anything more then that. I remember how they would feel after a dryspell when I was using those. Now its just a 12" pan and nothing larger then a 10" knife. Boxes however are 10" 12"

I'm with you on the 10" knife that is all I ever use... I think anyone useing something in the 24" better go back to school... I know most will say you can't get anything flat with a ten inch knife. I guess you just have to learn how to use it.. as far as boxing 10-12 and still hand finish butts after boxing. I like to run the middle first then the sides going down the middle first lets you know exactly how bad a but can be... if it covers the tape running down the middle you know you already started with a nearly flat butt, otherwise it will show which side is high. Sometimes I just run down the middle with a box then hand finish, piece of cake.. I had a guy that worked for me and the guy that taught him started him off with a 14" knife if it didn't look right he would get his knuckles hit and handed a smaller knife, if that didn't work he would get hit again and the next smaller knife . This continued but did teach the apprentice one thing how to finish a flat butt with a small knife.. And of course not to work for that s.o.b again.
 
#40 · (Edited)
Gotta go back to school.LMAO thats a funny 1.:lol::lol:
All your doing with a 10 inch knife is making a smooth bump.I get paid to make it flat & smooth,not just smooth bumps.Bring that 10inch knife into a million dollar home & they will call you back untill its flat & they check it with 4ft levels.

I've seen guys think a but is crowned with a 10inch knife, for it to only be hollow stud to stud.Next time run a level stud to stud & tell me what you think.
 
#41 ·
Gotta go back to school.LMAO thats a funny 1.:lol::lol:
All your doing with a 10 inch knife is making a smooth bump.I get paid to make it flat & smooth,not just smooth bumps.Bring that 10inch knife into a million dollar home & they will call you back untill its flat & they check it with 4ft levels.

I've seen guys think a but is crowned with a 10inch knife, for it to only be hollow stud to stud.Next time run a level stud to stud & tell me what you think.
I'd tell u the same thing go back to school.... Where is your skill and talent? If you were running a plaster coat would u still be using such a wide knife,(trowel) I think most plasters would laugh too death....My seams flats or butts are flat, and yes I have done many multi million dollar homes not to mention high end commercial work, but you will not understand because people like u can be somewhat closed minded I guess... I guess since I am doing it wrong that must be why do not have any call backs or any punch list crap to do huh? Heck if you are running a level across a couple of studs you may as well run one completely across the whole wall and see how flat it is...
 
#43 ·
riiiiiiite

:jester:Ive been in this trade for over 20 years now. A 10" knife is just fine for everything you've mentiond. Now thats not saying that at times a bigger knife isnt needed but untill then the 10 stays in hand :blink:. Ive worked in some high class places as well as commercial. A knife is like a guitar. Its not what kind you play but how you play it. :D
 
#44 ·
If you don't do what I do then you're a sh!t-for-brains.

At least, that's the attitude I'm sensing here right now. If the guy wants to use a 24" knife, who cares? I've used a piece of cardboard to wipe mud in between an angle and a steel door frame. I'm going to have to agree with the Captain here...do what it takes to get it done right.

I broke out my 4 ft. trowel (homemade) a couple days ago on a remodel to a previous remodel where the wall framing was way out of whack...and my long time taper friend who comes from a family of plasterers says "I was skeptical, but now I see how handy that thing could be." He, unlike some people, is an old dog willing to learn new tricks. In the time it would take to float out 4 feet with a 10", and wipe it right, you can wipe it in one big pass....and not have to sand the he!! out of it. After all, while a plasterer may not always be using slicks, feather-edges, darbies, etc....they have them sitting around somewhere, for when they're needed.

Personally, if I start with the 20" trowel, I can almost always skip a third coat on the butts. That doesn't mean I'm trying to tell any of you how to do YOUR job, it's just how I do mine. For me, a pan and knife are for holding mud that's too sloppy to sit on a trowel.
 
#45 ·
If you don't do what I do then you're a sh!t-for-brains.

At least, that's the attitude I'm sensing here right now. If the guy wants to use a 24" knife, who cares? I've used a piece of cardboard to wipe mud in between an angle and a steel door frame. I'm going to have to agree with the Captain here...do what it takes to get it done right.

I broke out my 4 ft. trowel (homemade) a couple days ago on a remodel to a previous remodel where the wall framing was way out of whack...and my long time taper friend who comes from a family of plasterers says "I was skeptical, but now I see how handy that thing could be." He, unlike some people, is an old dog willing to learn new tricks. In the time it would take to float out 4 feet with a 10", and wipe it right, you can wipe it in one big pass....and not have to sand the he!! out of it. After all, while a plasterer may not always be using slicks, feather-edges, darbies, etc....they have them sitting around somewhere, for when they're needed.

Personally, if I start with the 20" trowel, I can almost always skip a third coat on the butts. That doesn't mean I'm trying to tell any of you how to do YOUR job, it's just how I do mine. For me, a pan and knife are for holding mud that's too sloppy to sit on a trowel.
Well said Slim. I have a 24" trowel left over from my days as an EIF stucco dummy. I kept it just for re-models where they take a wall out and it leaves that 4" gap in the ceiling. After hanging a piece of scrap in it, that 24" trowel (which is loaded by hand) will float that nasty gap out better than anything. Only need it like once every 5 years, but ,when ya need it, ya need it.
 
#49 ·
$100 a sq foot:eek:
so if you did a 8x12 wall for me it would cost $9,600
guess our system is the Russian lada (drywall/tape)
It's like one of the guys who taught me said "tapings like the world,it looks flat when you look at it,but when you investigate into it,it's round" .....so.....dips,valleys etc when you put a straight edge to it.
so ,what can I say,for 5000 years people thought the world was flat,and some still do,I'll just do work for them:whistling2:
 
#50 ·
$100 a sq foot:eek:
so if you did a 8x12 wall for me it would cost $9,600
For you, I hab berry good deal....$9585, vinyl offer....you like?

It's like one of the guys who taught me said "tapings like the world,it looks flat when you look at it,but when you investigate into it,it's round" .....so.....dips,valleys etc when you put a straight edge to it.
so ,what can I say,for 5000 years people thought the world was flat,and some still do,I'll just do work for them:whistling2:
:thumbup:
 
#54 · (Edited)
I guess we all make valid points... Bottom line there is no such thing as a perfect wall as far a being truly flat vertical & horizontal... the whole point is how well can we deceive the naked eye.. I can see how a wide knife or trowel may make it somewhat easier (theoretically) but then again you still have to load it up or load up the joint before using it... sounds kinda messy... and as far as one coat and done,? I have my doubts unless you like to sand or do touch ups.... Perhaps where you have a heavy texture you may get by but not on anything pertaining to a smooth finish.. If you are using a wide knife or trowel what are you shoulders and wrists going to be like in a few years if not shot already? Next thing is I suppose we will be using a 14" knife to skim out screws because the six leaves to much of a hump eh? Or filling in an outside corner are you going to float that six feet out also? The finish of a butt seam is only one aspect of making a wall flat.. Personally I have heard more complaints from contractors how some tapers leave the lower inside angle not allowing their base to lay flat..
 
#58 ·
and as far as one coat and done,? I have my doubts unless you like to sand or do touch ups....
I hope I didn't give the impression that I do one coat, and perhaps it's the numbering issue come back to haunt us. When I talk about coats, tape doesn't count. I coat tape, as opposed to wall joints.


  1. For a butt joint, tape it. Let dry.
  2. Load it with mud pretty thin.
  3. Pinch edges.
  4. Grab big trowel, pull down the middle tight enough that tape is visible.
  5. Pull both sides.
  6. Skim coat is about the same but a couple of inches wider. On all but the most demanding butts, this is the finished product.
My shoulders are fine, and I didn't just start doing this. I work with mud as thin as I can handle free of messiness (ie. will sit on the hawk) to avoid having to work to hard and make a mess.







Without doing as you said about floating, it is all smooth bumps. Right now.

My interest in many things lies not in 'what is', but in 'what can be', or even 'what could be' (for 'what could be', think Star Trek). And my interest in taking things further is especially when 'what is' isn't all that I need, or would like.

So if flat walls are what I would like, how could I pull it off, without doing things like floating whole walls?

Rebel introduced us to Vario, with which one can V out a butt joint and use Vario in place of a tape. That would give a flatter wall.

I'm still a bit squeamish about the thought of doing it without any tapes, however. But if I was to do it, one thought I had about how to MAybe reduce the risk of any cracking coming through at the butt seam is to put some Vario into the V'd seam, and then press some FibaFuse into the seam, let that dry, and then cut off what's sticking above the board. Or maybe just cut FibaFuse into strips and try putting that in.

Could that possibly work well enough? Might it create/increase the possibility of things cracking along where the Vario and board would meet? Any other thoughts for getting a flat/'flat' wall?
I'm totally with you on "what could be". One way to avoid the bumps is to break the rock in between studs and use hollow-center butt shims. I believe the hollow introduced is about an 1/8", allowing the wall to be flat if the framing is done within smoothwall specs. I've never installed them, but I've sure thought about it. (http://www.finehomebuilding.com/how-to/tips/invisible-drywall-butt-joints.aspx) I've also been thinking a lot about alternatives to drywall. It seems like perhaps it's an outdated process, but I could be wrong. There's all sorts of cool things we could do with the product though...I'm looking into airtight drywall assemblies right now...just another way to keep on the cutting edge ;):yes:
 
#59 ·
Butt joints? Finish them out so they dont show--if it takes 4 coats so be it--we are hired to finish the walls,not just a number of certain coats-period!When using trowels,I coat fown the middle with a 16" curved,double the sides with a 1o" curved and double over that with a 14" [when using PC sander] or skimout when hand sanding,some bad ones require more coats. Lately on my larger ceilings Ive used Rocksplicers when hanging[about $3.85 each] and requires finishing out like a flat. And on the plaster tool side of things I only use my 11" plaster trowel when skimcoating-no other plaster tools for drywall---but I own alot of them[2buck].
 
#67 ·
Saul,

I did a bit more thinking on your V'd out butt joints hairline cracking. If I remember right, someone, maybe it was you, said on another thread that they were getting what seemed like excessive shrinkage with Vario, and Rebel suggested that maybe too much water was being added. The person agreed.

Do you think that could've contributed to the cracking problem? If a person was to maybe make it more paste-like, could that help?
 
#68 ·
I'd mixed this stuff thick so it wouldn't shrink. It cracked to one side of the V, right next to the paper. It was second coated with vario too. Any thicker and it would have involved as much feathering as taping. Sanding the dry vario off to tape it proper was less than fun. Vario does sand better wet than any other setting compund I have available to me though. I'm not sure what to do about taping with it yet. I like my mud thin to tape with. I'll have to experiment to see if thick vario can go on top of thin vario (thin enough to cause shrinking) after just 50min. That'll have to wait for another out of sight opportunity (like the drywall in a utility room that will be behind the furnace)
 
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