Hanging Drywall for Dummies? Help with corners

[jasoncring]

Re: Hanging Drywall for Dummies? Help with corners

Uh oh. What am I missing?

A poorly hung backblock almost guarantees a crack or irregular plane. Is the IBC just playing it safe, or am I missing something about their disallowance of the BB? All responses appreciated!

[Dick Seibert]

Re: Hanging Drywall for Dummies? Help with corners

Jason:

I can see that as an individual inspector's call. Is a backblock a framing member? Off hand I'd say no, but the argument could be made that any piece of wood in the wall is a framing member. If the backblock is sheetrock, I don't see how that argument can be made (the only backblocks I've ever seen are sheetrock done by the rockers who couldn't cut a piece of wood if they had to, I saw one try once, he brought out a little sidewinder saw and the blade was so dull he couldn't cut through Swiss cheese!).

[dgbldr]

Re: Hanging Drywall for Dummies? Help with corners

Dick,
Yes, our inspectors do allow this when done properly. No, a piece of wood not connected to any other piece of wood is not framing, i.e. does not form part of a frame. It is generally understood (at least around here) that the purpose of off-stud butt joints is precisely to float the butt away from framing and to get better attachment by having wider support.
DG/Builder

[Dick Seibert]

Re: Hanging Drywall for Dummies? Help with corners

DG:

An inspector just cannot make the call that he knows something more than the code under the CBC, UBC, or I think IBC. I don't know what the IRC says, but the IRC is called a "performance based code" and the inspector may have that right. I hope Roger sees this thread and comments. Inspectors can only enforce the code as written, Roger has that changed under the IRC? I would think that if one inspector decided that backblocking was better and allowed it, that would be selective enforcement.

[Kgphoto]

Re: Hanging Drywall for Dummies? Help with corners

Dick,

I am sure you have heard about floating corners and ceilings especially to deal with truss lift? It is code approved and reduces cracks. This is

There is no 100% all the time system that will absolutely not crack under all circumstances. I have seen cracks develop in the middle of a board if subjected to enough force.

Manny,

It is important to realize that you must use the WHOLE system, not just part of it. You can use mesh tape, only if you use hot mud. That is what is required to make it work. The same is true with the Butt-Taper and the ply/OSB backer. You use the hot mud because is sets harder and shrinks less, same as with mesh tape. Since the OSB/Ply is providing the plane holding, the mud only fills the gap which is too small to use regular tape.

Perhaps it would work with General Purpose, but that is not the way it is specified, so I will do it the correct or recommended way.

Try it yourself and let us on the forum know what you come up with.

Kirk

[SteveH]

Re: Hanging Drywall for Dummies? Help with corners

The USG "Gypsum Construction Handbook" on page 115 recommends leaving a butt joint in betwen the studs. In the previous version it stated "to minimize butt joint cracking and ridging". You can go to the USG website at ww.usg.com and go to the Handbook. If the Bible of drywall recommends it, then what is the concern. The problem is that the drywall manufacturers also make the joint compound and the more wider the butt joint the more joint compound they sell.

It's the drywall manufacturers who write the codes..it's like allowing the fox to write the guidelines for guarding the henhouse. It's all about money not about quality!

I did a strip mall last summer and my supervisor asked the inspector for permission to use the ButtTaper system..I did a demo for the inspector and he allowerd it saying "it's better than on a stud". Too bad we can't post photos here. It was a strip mall with 10 stores in it.

The UL codes now insist on backblocking in between the studs for vertical firecode application using the same gauge steel stud for all rated firewalls except for 3 types.

[SteveH]

Re: Hanging Drywall for Dummies? Help with corners

Not taping joints is screwing the customer. I have no problem with backer boards. They've been around a long time, although they aren't always worth the trouble. And I have no problem with your gizmo. It's an ingenious idea and I hope you sell a million of them. I have a big problem with no tape.

My Reply:That's why the tape can be used..for those who cannot comprehend that tape is not needed. You did not answer my question on Rock Lath, perhaps you have never come across it.



Consider ceilings. No one is going to be pushing on the ceilings. Don't tape them and they crack. Tape them with mesh tape and reg mud and they crack.

My reply: It's not only the pushing; it's wood shrinkage and humidity which are the two principal causes of drywall failure. Hang your butts on roof trusses like I did once and they will all crack..I had to do 250 of them over.



Experience shows just the opposite. Even small joints crack without tape -- the corners in window wraps are a good example. Sheetrock expands and contracts just like many other building materials.

My reply: I'll get you a link on why there are cracks at window and door corners over the weekend. A study done by the University of Massachusetts. Sheetorck does not expand nor contract..the framing members do. Gypsum in an inert mineral and does not contain circular growth rings and is the only mineral that will retain it's original shape when altered with moisture.

You did not respond to my queery..will compound crack if finished off any edge. Cracking by door and windows is on the edge.





Then why do you need hotmud? If it's just like one piece then reg mud should be fine.

My reply: Because it speeds up the finishing process by allowing you to do the butts in minutes so you can pull your long seams and is not affected by humidity, and renders a stronger bond. Mainly for quality's sake!



Even if it cracks only 5% of the time it's no good. The current system doesn't crack if it's done properly.

My reply: Go to the ButtTaper website and read the National Asssociation of Home Builders Test Report. My way can take 3,000 pounds more in compression and about 500 pounds more in tennsion than on a stud. When will you ever see even 100 pounds more force? I'm the only one who ever had butt joints tested. Heck, this poor drywaller has to pay thousands of dollars to do a comparative butt joint test..why don't the drywall manufacturers do it? Can you find me any test data by anyone besides me on butt joint failure? You say butt joints never crack or ridge..oh please..I see them everywhere. If your premise is correct then why does USG on page 115 of their Gypsum Construction Handbook addresses butt joint failure if it never happens as you state?

I don't understand the point of trying to eliminate tape from butts. If you take the 20 seconds to tape it, then you don't have to worry about it cracking. If you forgo the tape, you are gambling with the customer's job. I'll tell you right now I would never do it, especially since the time saved is so small.

My reply: Because why do something that does not need to be done? If you are certain of what you are doing, have tested it, know the principles behind your action, why make another step that is unnecessary?

You still don't know why you use tape on long seams. In England they have a system that uses glue instead of compound and tape on long seams. All you want to do is bind the two boards together so that they won't move against eachother..whatever manner that is achieved is moot.

Of course the drywall manufacturers want you to use their products to do it with, but there are alternative ways.

Do an experiment:

Get a 8" wide by 4 foot long OSB or plywood and make two 4" strips of drywall each with the tapered edge. Join the two tapered edge boards on the backer board and screw the tapered edge boards every 4 inches. Apply joint compound without tape and finish it with 3 coats. Let it dry, and then bend the backer with the drywall on it lengthwise..no cracking. Try to bend it on it's width..you can't. Then go up to roof and throw it off the roof, preferrably two stories high..no cracking. You don't need the tape when the two boards are properly secured on a backerboard.

The USG Gyspum Constructiuon Handbook also states that screws or nails should be at least 3/8" off any drywall edge.
Because wood studs are 1-1/2" wide and hardly ever straight..this is impossible to achive. Have you ever seen screws or nails on butts that are right where the two boards meet..I have.

You know well that when you nail or screw near the edge of any type of wood, that the fastener will cause the wood to crack and rendering the holding power of the fastener useless.

Wood studs and many joists are 1-1/2" wide. The middle of the stud is 3/4" away from both edges. In order to follow the dictates of the Gypsum Construction Handbook, you should affix the nail or screw 3/8" away from the edge which just happens to be right at the edge of the stud..and presto..the wood cracks and does not hold the nail or screw which holds the butt joint boards.

Talkin' about screwing a customer..this method is the royal way!

You don't believe this..then screw some boards on a stud leaving 3/8" from the edge and look behind the stud.

This happens when a stud is straight and when it's crooked, which is the norm, you have big trouble..well then leaving a butt joint on stud is shafting the customer!

In summation, wood studs that are 1-1/2" wide is not enough width to properly secure two drywall boards. If the studs were 2" or wider..all the better, but you would still have to compensate for the circular growth rings which shrink on studs or joists width and how will you do that..by utilizing a backer board in between the studs that has minimal moisture content (4% versus 20% for a stud/joist).

And another feature of the backer board is that the walls and ceilings are straight which they should be..speed bumps on drywall are a no-no for quality oriented drywallers.

Manny, I'm dicusssing this with you as a drywall contractor and not as a peddler of a gizmo. I have several years ago come to the realization that only a relative few in the drywall trade are quality oriented, that most truly don't care about quality drywall work and are not interested in improving their workamship.

[Manny Davis]

Re: Hanging Drywall for Dummies? Help with corners

Sorry to everyone about the length of this.

Experience shows just the opposite. Even small joints crack without tape -- the corners in window wraps are a good example. Sheetrock expands and contracts just like many other building materials.

My reply: I'll get you a link on why there are cracks at window and door corners over the weekend. A study done by the University of Massachusetts.

We've gone through this before. I've read the study, as you have posted the link on this forum in the past and on the W&C forum. It didn't say what you claim it said. This time, instead of posting a link, copy and paste the actual text that supports your point.

Sheetorck does not expand nor contract..the framing members do. Gypsum in an inert mineral and does not contain circular growth rings and is the only mineral that will retain it's original shape when altered with moisture.

Sheetrock does indeed expand and contract, and it's fairly common knowledge. A quick google search spit out several relevant pages:

From www.drywallconstruction.com:

Thermal Expansion - All materials expand and contract to some extent with changes in temperature. The Thermal Coefficient of linear expansion is expressed in "Inches Per Inch Per Degree Fahrenheit". Example: gypsum board has a coefficient of 9.0 x 10-6 in. per in. per °F. This means that with an increase in temperature of 50°, a gypsum board wall 100 ft. in length will have a linear expansion of .54" or an excess of 1/2". The expansion characteristics of some other building materials are more pronounced; a 50° temperature increase would produce in a 100' length of approx. 3/4" in aluminum, 3/8" in steel and 1/2" in concrete.


That coefficient is also stated in the usg handbook here: http://urlx.org/usg.com/ca45

From www.askthebuilder.com:


Temperature

Drywall and gypsum finishing products should be installed when the temperature is 55 degrees F or higher. Many materials contract or expand with temperature changes. Drywall is one of them. Drywall installed at 28 degrees F will expand 1/2 inch over 100 feet when the temperature raises to 72 degrees F. So, if you install drywall panels in cold weather, be sure to leave a 1/8" gap between sheets to account for this expansion. Drywall finishing materials perform poorly in temperatures below 55 degrees. If allowed to freeze before they completely dry, the finish compounds can lose their strength and possibly lose their bonding qualities as well.

Humidity

Humidity can also cause expansion and contraction problems in drywall. Drywall can expand 1/2 inch per 100 feet when the relative humidity goes from 13 percent to 90 percent. This expansion can cause the boards to become wavy due to the expansion. Excessive humidity can also cause ceiling drywall to sag between framing members. In the event this happens, it cannot be corrected. The force of gravity pulls the drywall down and it will retain this bowed shape.


http://urlx.org/askthebuilder.com/9ac8

You did not respond to my queery..will compound crack if finished off any edge. Cracking by door and windows is on the edge.

Because I don't understand what you're asking.

Then why do you need hotmud? If it's just like one piece then reg mud should be fine.

My reply: Because it speeds up the finishing process by allowing you to do the butts in minutes so you can pull your long seams and is not affected by humidity, and renders a stronger bond. Mainly for quality's sake!

Without tape, is hotmud necessary or not? Yes or no please.

Even if it cracks only 5% of the time it's no good. The current system doesn't crack if it's done properly.

My reply: Go to the ButtTaper website and read the National Asssociation of Home Builders Test Report. My way can take 3,000 pounds more in compression and about 500 pounds more in tennsion than on a stud. When will you ever see even 100 pounds more force? I'm the only one who ever had butt joints tested. Heck, this poor drywaller has to pay thousands of dollars to do a comparative butt joint test..why don't the drywall manufacturers do it? Can you find me any test data by anyone besides me on butt joint failure? You say butt joints never crack or ridge..oh please..I see them everywhere. If your premise is correct then why does USG on page 115 of their Gypsum Construction Handbook addresses butt joint failure if it never happens as you state?

1. I never said anything about ridging. And for me, non-structural cracks are extremely rare -- probably because I tape everything.

2. Concerning the test report, what matters is tension, not compression. And you are misrepresenting the data.

Here is what the report actually says, emphasis mine:


Conclusions The data shows that the ButtTaper joints (as tested) tolerated greater displacement and higher loads in compression prior to cracking than the conventionally taped joints. The ButtTaper joints tolerated equivalent loads and displacements when compared to the conventional joint in tension. The ButtTaper joint with the backer board tested in tension showed slightly higher loads and displacements than the standard joint but the data scatter and uncertainty means the difference is not statistically significant. It must be noted that all the ButtTaper joints included the use of adhesive and the comparative standard joints did not. It is not possible to differentiate the extent of the higher loads and displacements attributable to the joint style versus the use of adhesive. In actual use butt joints may also be stressed in a shear and flexural condition. No conclusion can be drawn from this testing about performance of the joints in shear or flexure.


And how very convenient that you used glue on the butttaper joints and no glue on the conventional joints.

Because why do something that does not need to be done? If you are certain of what you are doing, have tested it, know the principles behind your action, why make another step that is unnecessary?

Then why on your website do you tell people to use tape and hotmud? You even sell a special notched knife and narrow tape.

Here's the text from your website:

In the first coat process, imbed the setting compound firmly again into the tapered edge and the space between the boards with a small spackling knife such as a 4 or 5 inch. Apply the tape into the tapered edge and wipe the tape with the notched knife (supplied with the order). This will embed the tape into the tapered edge. This is the most important step! Do not allow the tape to overhang over the drywall.

So why do you include tape and a notched knife if they are unnecessary? And why do you sell 1/2" tape separately if it serves no purpose?

Do an experiment:

Get a 8" wide by 4 foot long OSB or plywood and make two 4" strips of drywall each with the tapered edge. Join the two tapered edge boards...

That experiment doesn't mean anything. Sheetrock expands and contracts, just like other building materials. When it expands, sometimes you get ridging, when it contracts, sometimes you get cracks.

Wood studs and many joists are 1-1/2" wide. The middle of the stud is 3/4" away from both edges. In order to follow the dictates of the Gypsum Construction Handbook, you should affix the nail or screw 3/8" away from the edge which just happens to be right at the edge of the stud..and presto..the wood cracks and does not hold the nail or screw which holds the butt joint boards.

Talkin' about screwing a customer..this method is the royal way!

You're talking nonsense and what's worse is that you know it's nonsense. 3/8" from the center of the stud is not "right at the edge" it is 3/8" in from the edge.

Of course, breaking joints on studs and joists is the way I and thousands of other sheetrockers have been doing it for decades, but now all of a sudden it's no good. Interesting how that works.

This happens when a stud is straight and when it's crooked, which is the norm, you have big trouble..

No, you don't have "big trouble". If the stud is bowed, or if the stud is sticking out of the wall, or if there is any other problem whatsoever with the stud, the solution is..... <drumroll>.......don't break it on that particular stud.

In summation, wood studs that are 1-1/2" wide is not enough width to properly secure two drywall boards.

Which ignores the 500,000,000,000,000,000,000 times it has been done successfully. So I guess 1-1/2" really is wide enough after all.

I notice that you often refer to the usg handbook when it supports a point you agree with. I believe the backer method between the joists was invented by usg, as I remember seeing it in the handbook over twenty years ago.

Can you show me in the handbook where not taping joints is recommended if you use a backer and hotmud?

Manny, I'm dicusssing this with you as a drywall contractor and not as a peddler of a gizmo.

I don't doubt that one bit. This argument really doesn't concern your gizmo at all, it has to do with not taping joints. No disrespect intended, but when someone advocates not taping joints, whether it is you or Kirk, I am going to argue very hard against it, because I believe it is a shortcut that saves a tiny amount of time while greatly increasing the chances of cracks.

For f*ck's sake, it takes 20 seconds to tape the damn thing and be sure.

[Roger P]

Re: Hanging Drywall for Dummies? Help with corners

Dick : I’m not sure that I want to wade into this swamp; However, IRC Section
R702.3.5 Application states in part:
“…
All edges and ends of gypsum board shall occur on the framing members, except those edges and ends that are perpendicular to the framing members. Interior gypsum board shall not be installed where it is directly exposed to the weather or to water.”

As to “selective enforcement”, Section R104.11 (IBC 104.11) provides for alternative methods. While I don’t find the “Back-Blocked” method listed in either of the Gypsum Association referenced standards for the application of gypsum, GA- 216 (IBC) or GA-253 (IRC), I do recall seeing the technique presented in U. S. Gypsums’ Construction Handbook over 30 years ago. It is still listed in the latest edition. I’ve never seen the technique used in practice. It looks time consuming and clumsy to me. My sheetrock sub, now deceased, said that he preferred to have all the butt joints fall on the same stud (joist). He said it was easier to deal with that type joint all in one place rather than have to jump around. BTW, I challenge anyone to find any of his joints.
Since I’m here I’ll add the preferred sequence in this area. Hang the ‘lid’ (ceiling) first. Hang the top sheet horizontally next. Then finish by hanging the lower sheet. The technique for hanging the top sheet (my guy hung 16 footers by himself) is to stand the board against the wall where it’s going to go. Start a series of nails along the top edge in line with the studs. Standing approximately midway of the sheet, raise the board into position and while supporting the board with one arm (hand) drive in three or four of the central nails with your other hand. These nails will support the board while you then finish off screwing the field and lower edge. The lower sheet is easily raised into place using bar. I’ve made several from a piece (12"-14”) of leaf spring by welding a piece of rebar for a fulcrum at the midpoint. Simply insert the bar under the board and raise it into place by stepping on the other end of the bar. I should have applied for a patent because a few years later Goldblatt came out with this http://www.stanleytools.com/default....ll+Roll+Lifter.
Also the IRC is a “Prescriptive” (cook book) code not a “Performance” code.
FWIW, the referenced standards requires the framing to be within 1/8” plane. If the framing (corners) is (are) so out of plumb that the scribing is necessary, maybe you ought to correct the framing.

[jasoncring]

Re: Hanging Drywall for Dummies? Help with corners

Butt backblocks don't take too much time to install if you're a professional hanger. Novices will struggle. Hangers here are required to backblock (mud on sheet, not ply) all ceiling flat joints as well as butts in any room wide enough to require 3 or more flats. This is widely held as a standard so I suspect it is somebody's code, either general building or the manufacturer's. I have a couple of theories about this, but it is not the current topic....

I'm a believer in butt backblocking, and I think my reasoning is sound - placing the butt on an area of potential movement is a common practice and will probably be fine, but why roll the dice? And I like the recess, provided it is done well. I am concerned, however, about these codes Dick has brought up. I can remember when I was wrong about something back in '84, so it could happen again. JK.

While no material is perfectly dimensionally stable during heat and humidity change (as far as I know), surely sheetrock outperforms wood or steel. Manny, I know you gave the shift over a 100 ft wall, but a coefficient of 9 x 10(exp-6) over a 100ft wall gives my calculator only 0.0108 inches. I never knew sheetrock's coefficient of expansion before. I'm going to use that to fool people into believing that I know what I'm talking about.

Why do they advise leaving a gap between sheets to prevent ridging? They even make sheets with a "beveled edge" or "rounded edge" to address the problem. But you can't tape over a gap without having first prefilled it with hot mud or all purpose which has dried. So the prefill negates the "expansion zone." What's the point? Just curious.

Tape - A backblock will strengthen a butt. Whether it is wood or durabond, however, it is a movement-prone material too under changing conditions. I use standard 52mm paper tape.

[Kgphoto]

Re: Hanging Drywall for Dummies? Help with corners

I just want to clearify a point. I am not advocating not taping joints. I am advocating that when you do an off stud, butt joint and use OSB/Ply as the jointing material with hot mud, you don't need to do the face tape, it is redundant. I don't use glue, just screws. I use 5/8 thick or thicker plywood, depending what is on site.

If you joint on a stud or use general purpost or taping mud, use the 1/2 inch tape and the special knife. The point of the smaller tape is to avoid having to hide the tape by a wider feather thereby creating a minimal hump.

I haven't done any registered tests, I have just tested it on some short term projects I could break apart when done and some long term projects that I can watch over time. So far, no cracks. I agree that the two thin boards joined together isn't a real world test, that is why I tested it the way I did. I am happy with the results and stand behind my work with my customers. I can say I have never had a call back on drywall.

I don't have a financial interest in these products. I just like to use what works and shared it with the members on this forum as they have shared with me.

I am different than most in that I like mesh tape, but only use it with hot mud. I do this because I fix a lot of bubbles in paper tape and have had mixed results with my own projects. I also intend to use hot mud to speed the job along anyway. Again, I am very successful with this approach, your miliage may vary.

I agree that the two thin boards joined together isn't a real world test, that is why I tested it the way I did. I am happy with the results and stand behind my work with my customers. I can say I have never had a call back on drywall.

The Butt-Taper is a good tool and process for patches and butt joints in drywall.

Kirk Grodske

[Dick Seibert]

Re: Hanging Drywall for Dummies? Help with corners

Roger:

Since backblocking appears to be an industry approved, superior method of installation, I wonder why it hasn't worked it's way into the codes, especially since it's apparently code-mandated in Australia? As it is now an inspector should reject it during nailing inspection. I don't know what's going on with sheetrock nailing inspections, some AHJs are still doing them, but others are only looking at the firewalls walking right by the rest of the house saying they only do firewalls now.

I wish you would have patented your devices made from leaf springs. I bought the Stanleys to raise cabinets (I subcontract sheetrock) and promptly bent all of them.

[SteveH]

Re: Hanging Drywall for Dummies? Help with corners

Jason,

So backblocking is code in Down Under if there are more than 2 butt joints on a wall or ceiling..am I reading you correctly? What is the width of wooden studs and joists in Australia..is it 1-1/2" or 2" as in England?

[jasoncring]

Re: Hanging Drywall for Dummies? Help with corners

CSR is the leading manufacturer of plasterboard in Aus. One of their installation guides:

http://www.gyprock.com.au/technical/...g%20System.pdf

talks about butt joints for standard residential construction (non-fire rated, level 4 and 5 finish) on pages 19 and 26.

Boral and Lafarge are major suppliers as well. Their installation manuals say pretty much the same thing. These butts are on ceilings only.

These are the manufacturer's instructions only. They may or may not be mandated by the government's code - I don't know.

I have never read a manufacturer's code which recommends the use of a plywood backer board for wall butts. All the installation instructions I can recall have the wall butts being joined on a stud. That's why I'm sweating it a bit. Of course, we used to join on the studs all the time and I was always sweating it then since I just don't trust the wood. Building is booming here, and every carpenter I talk to agrees that the quality of their material has fallen in the last few years. I suspect the mills are laughing their way to the bank.

While I didn't see it in the above installation manual, the Aus standard (definitely manufacturer's, possibly gov's) for backblocking ceilings is: All joints in the ceiling (flats and butts) provided the room is wide enough (measured along the joists) to require three or more flats. The room may be short enough (measured perp to the joists) to have no butts, but BB is still required on the flats if they number 3 or more. The theory is that longer joists are more likely to twist. A nonsensical requirement in truss roofs where battening/joists do not contact top plates on partition walls, but universally enforced nonetheless. We just backblock everything on my contracts.

Joist/stud width is commonly 35mm or 1.378 inches. Sometimes you find 45mm or 1.772 inches. And yes, that 10mm sheet in the above installation guide is only .394 inches - barely more than a .375 (3/8) inch sheet. It is the standard thickness in housing. My own house, if it ever gets built, will have 16mm (.63/ 5/8 inch) sheet.

[SteveH]

Re: Hanging Drywall for Dummies? Help with corners

Manny,

I replied to your last post yesterday about 2 hours after I questioned Jason and my post has not appeared..strange!

I'll do it later..I know you are impatiently waiting.