Help with cracked interior window jamb

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  #1  
Old 07-07-14, 12:12 PM
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Help with cracked interior window jamb

Hello, I'm in the process of building a two story addition. I've installed 14 pella double hung windows and the siding is already on. The inside is not finished yet. The right jamb of one of the windows has a pretty good crack in it. The crack was there when it was installed (I've had the windows for a while before they were installed). It is a new construction window. My question is, what do I do with the cracked jamb? Do I simply shim on either side of the crack and nail the jamb into the trimmer stud? On the other hand, I've been told by a few people not to nail the window jambs to the rough opening to allow for expansion/contraction. Any help would be appreciated. Thank you
 
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  #2  
Old 07-07-14, 03:41 PM
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It depends how bad the crack is, and if the wood will be stained or painted. If the crack is bad enough, I'd probably just remove the cracked jamb and replace it with some nice #1 pine or fir.

Jambs need to be straightened and shimmed to the rough opening. If the window needs to be pushed in or out to flush the jamb up with the face of the wall, that needs to be done before the window is insulated (foamed) since it ain't going to move once you foam it. Generally you put a long level on the jambs to tell if they are bowed. If they are bowed out, you need to shim them in. If they are bowed in, you need to leave the shims loose, then nail them back until they tighten up on the shims.
 
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Old 07-07-14, 03:51 PM
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Thank you for the reply. I'm a little confused by your response. I'm not worried about the jamb being even with the wall face right now, as I'll be extending them later to make sure they are flush with the finished wall. The window in question is on the basement level of the addition, so I'm not overly concerned with the way it looks as I am about the structural integrity of the jamb. So you're saying it's common practice to nail the jamb through the shims and into the rough opening studs? I was told not to do that because if the structure shifted at all, the window glass could break if they are nailed as there isn't any room for movement. That then brings me to antoher question. Because I framed this myself with the help of a carpenter, everything was framed pretty square and plumb. There wasn't any need for shims on the sides of the windows. Is that ok? I was told that shims should only be used if you need help squaring/plumbing the window. Could you please clarify and thank you for your response, I appreciate it.
 
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Old 07-07-14, 04:04 PM
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I'm picturing a 3 11/16" thick window with a 7/8" jamb extension on it. (total of 4 9/16) The jamb extension may be thicker... or may not be on there at all. Pella usually adds an extension jamb onto the window at the factory to match your exact wall thickness so that you don't have to. Since you said the jamb was cracked, I assumed that meant the jamb extension was cracked. Maybe you need to upload a picture.
 
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Old 07-07-14, 04:08 PM
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yes, you are right, it is the jamb extension that is cracked. Sorry for the confusion. Am I right on not needing to shim the windows if they are square/plumb? Am I ok just shiming on either side of the crack and nailing through extension jamb, shim and into the stud? I'll try to take a picture it that will help. Again, thank you for the help.
 
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Old 07-07-14, 04:18 PM
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Here is a picture of the cracked jamb. Thank you
 
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Old 07-07-14, 04:32 PM
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Is there any space between the back side of the extension jamb and the stud that is your rough opening? If there is, that is where you shim. You shim it so that when you nail it, the nail doesn't pull the jamb in, making it bow or twist. Like I said, you put a level on the jamb to verify that it's straight, then you shim and nail it.

Since it's painted, I would squirt glue in the joint, shim behind it, and nail above and below the crack. A light sanding and some wood filler and more sanding would make it disappear.

If your vinyl window isn't shimmed to the rough opening, (or foamed so it can't move) they will tend to spread in the middle with time, and they will be very drafty.
 
  #8  
Old 07-07-14, 04:35 PM
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There is 1/2"-5/8" between the jamb extension and the rough opening
 
  #9  
Old 07-07-14, 05:02 PM
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thank you for the info. I'll be foaming the rough opening in a few weeks. I guess my only other question would be, if the other jamb extensions are level, do i need to shim and nail or can I simply wait till I put on the casing and have that hold the extension in place? I appreciate all your help, thank you
 
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Old 07-07-14, 05:48 PM
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At the risk of repeating myself 3x... I would shim them and nail them. All of them. 16" on center, prior to installing any casing. If you want to let the casing nails hold it that's your business.
 
  #11  
Old 07-07-14, 06:15 PM
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Thank you for your help, I appreciate it.
 
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Old 07-07-14, 06:37 PM
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Glad to help, good luck!

 
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Old 07-15-14, 03:34 AM
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XSleeper,
Just for clarification, are you saying that the foam can take the place of shims? Thank you
 
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Old 07-15-14, 05:48 AM
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No. I am suggesting you shim and nail the JAMB which is the wood part that should be shimmed and nailed straight before you foam. If it's bowed out or crooked, its about impossible to change once you foam it. If the jamb is bowed out after you foam, when you go to put your casing on you will understand why I keep saying to shim the jambs and nail them to the rough opening. The shims you use to straighten the jamb may slide behind the window itself or they may not- I have no way of knowing that because I can't see it.

I assume your window is already straight... it just may not stay that way if there is nothing to prevent it from spreading in the middle. A little foam between the window and the rough opening will usually prevent that from happening. The sashes will usually prevent the foam from bowing or twisting the frame, pushing the window in on itself. (this is why you use low expansion door and window foam... not plain old expanding foam, and you go easy on the amount you use, filling maybe 1/3 of the space with it.)
 
  #15  
Old 07-15-14, 04:25 PM
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thank you, I appreciate all your help I should have been more clear on my previous question. I plan on shimming and nailing the extension jamb to the rough opening. My question was concerning the area before the extension jamb. Basically, if I shim and nail the extension jamb, but the shims don't go past the extension jamb and I foam the area behind the extension jambs is that sufficient. I know you're getting tired of answering all the questions, but I just want to be sure before I actually start doing it, so it doesn't have to be redone. Thank you
 

Last edited by skoons6694; 07-15-14 at 05:07 PM.
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