Old time lurker question.
I’m about to repaint our upstairs ceiling after about 6 years (20 year old house) and have noticed some of the tape joints now have ridges down their centers at the drywall sheet butt seams in the larger room. Also have a few stress cracks out from 270° interior wall corners that had not shown up before. Truss build house had been re-roofed with a tear off from 20 year to 30 year shingles last winter, and the attic vent motor died in the middle of summer (At 51, I’m getting lazy enough not to take that on in the heat of NJ summer). I’m guessing some truss movement from humidity or the added weight of the new shingles may have contributed to this ????.
Do I need to pull the old tape, re-tape and mud in all these areas? Is the above guess in the ballpark or are there other issues I should be looking at.
Thanks in advance,
Jack
Replies
Jack its always fun trying to guess what the problem is then fix it .
Since you and I didnt witness it its just guess but I would think the boys got a little rough throwing bundles of shingles down but the ventilation could be a contributing factor also. Roughness on the roof would be my guess since youve got butts busted. Those things are nailed solid to the truss and you are right about it sounds like movement . Maybe some busted trusses if they got really rough. Are they factory made trusses or homeade ? Ive seen homeade ones come apart if not correctly attached. Specualtive . Anyway if you would have said the running joints were comming loose also along with the wall corner joint then it would sound like truss uplift but I dont think it is as old as your house is now. You would have had it in the first 5 years.
An inspection of the trusses is going to be needed for safe bets.
That ventilation needs to be addressed anyway.
Then cut out the bad tape and resume fixing the drywall. I wouldnt do it till I found out what caused it .
Tim
Tim,
Thanks for the response. Guess I'm going into the attic this next weekend!
Yes, they were rough with the bundles! My wife thought they were going to come through the roof. I've found a few nail pops as well, and that should never had happened as I had gone over the ceiling years ago, taking care of loose ones with screws. I (used to) have comments from guests that the ceilings showed no divots or tape lines as I tend to go over and over everything, with a light shining down the surface.
The trusses are factory build units and never gave me a problem before. The area that shows the ridges goes sidewall to sidewall, about 28' across. The other areas where there are walls (and no the trusses are not attached) with shorter ceiling lengths are OK. Maybe the wall top plates kept the bottom chords from moving too much. Or provided a good anvil to stress crack the bottom chords. ;-)
Right now I have about 6" of insulation in the attic crossing the bottom chords and original insulation, so visibility of the bottom chord is an issue. Where would you expect the trusses to crack from that type of error? These trusses were built with web members between the top and bottom chords in a V formation, sectioning the bottom chord into thirds. There is no center web stringer, but there is a lateral brace running across the bottom chord at the centerline to prevent side buckling I presume. The seam ridges are at the center and over to one sidewall, 3 seams of the 4' drywall widths. My wife now remembers seeing this area of the ceiling deflect she believes 1 to 2 " during one of the bundle drops.
Jack
Ive seen braces break more than anything since all the deflection is compounded on them in an uneven blow .
Check and see if the butt joints busted is in line with the diagonal bracing in the web design of the trusses.
The trusses arent broken hopefully as they are supposed to deflect but a blow to the top is a hammer against the drywall. You should also be complaining about sagging if some were broke so probably not but you need to make sure before you fix it .
Tim
If the problem is new, you are probably correct. Builders often have this problem on ceilings if a house is drywalled before it has a chance to dry properly which is often the case in this day of the "build 'em as fast as you can" mentality. When the joists shrink accross the length, it actually pushes the drywall sheets togather (much tighter than it was hung) and causes the joints to ridge. We're only talking small fractions of an inch hear, but it's enough.
Create a login at this link https://www.usg.com/secure/Login.do and ckick on drywall construction. Then chapter 12. There is a wealth of imformantion (cause, prevention, and remedy) there.
kcoyner
So how long should you wait for the wood to dry before putting up the drywall?
Jack, I'm confused. What is a 270 degree corner? Isn't that just a 90 degree corner measured from the other angle?
Don K.
EJG Homes Renovations - New Construction - Rentals
Don,
Yeah, sorry. I was answering technical questions over in an automotive forum between this discussion and got into engineering mode. Should have said outside corner, but no, lets see how complicated I can make this .......
Guys, thanks for the help. I do have one area in the ceiling where there is a ridge in the drywall. It's in line with a truss location and in the region of all of these seam ridges. I have a feeling after I get up into the attic, I'll be back here asking how to repair a broken bottom chord.
Thanks,
Jack
The problem with drywall butt joints on trusses is that the span is too long, they are crooked. Further, the heat inside the house and the cold in the attic causes them to twist. You cannot adequetly secure two drywall butt boards on a 1 1/2" wide plane that is crooked, that will twist and that has severe forces on the truss.
I once had 250 butts ridge on me after 2 months and had to remove the tape and do them all again. Solution is to use a backer board and leave the butts in between the trusses. Since your house is 20 years, this should have occured in the first year or did you just notice it now?
All of these seam ridges are perpendicular to the truss layout. None of the seams (if) aligned with any truss show an issue.
Jack
If the twisting and the shrinkage is severe, the long seams will also ridge. One should use RC-1 Channel on roof trusses and leave the butts in between the channel with a backer board that is about 6 inches wide, glued and screwed well. Soeomeone on this thread mentioned that trusses shrink on the length, no they shrink on the width as the "O-Rings" of the tree contain the moisture.. All studs, joists, etc. shrink on the width and not on the length.
That's why a small space should be left between each piece of drywall to allow for wood shrinkage. On butt joints since you have only 1 1/2" wide stud/joist to secure them together, 99.999999% of rockers have the two boards tight and when the stuyd/joist shrinks on it's width you get tape ridging (someone earlier mentioned that).
Thanks for the contribution, I understand what your saying and agree with it. But this is something I would expect to happen in the first few years of a new house's life. This occurred only after getting the new roof on a 20 year old house. It was fine before the new roof so I'm not sure wood drying at this point would be occuring.
Jack
Yes, it should have happened within 6 months and now after all these years..humm. Those roofers must hve banged the hell out of the roof cause I can't think of any other culprit.
I think they did. My wife said see saw that area of the ceiling move pretty good.
I thought I was going to get up into the attic this past weekend, but other duties pulled me away. Now that I'm looking forward to get an overweight 52 year old body with arthritis up into an attic and dancing around on trusses.
But maybe I'll do it on Christmas day so the grandkids will think it's Santa coming through the ceiling!
Jack