A dip or sag in the roof


  #1  
Old 06-13-02, 06:50 PM
JSG
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A dip or sag in the roof

Not sure on how to descripe it. I have a dip, it looks like a sagging rafter. From the out side you can see a dip or maybe it can be described as a valley in the roof. Its about 2-3inches deep in the center. My rafters are 16 OC and the roof is 4in12, plywood deck, about 1/2. An inspection in the attic and i do not see any cracked or sagging rafters. Someone said to me that the rafter might just have been installed upside down, that the builder misread the crown. Does this sound possible and if so my question is how can this be corrected? Do I have to ripe off the deck and replace the rafter?
 
  #2  
Old 06-15-02, 06:02 AM
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There are a variety of reasons for this. yes, maybe the crown is upside down, maybe the wood was wet, maybe too much weight on your roof like two layers of shingles, but also the most common is 1/2" plywood or OSB for a roof deck. It really will not hurt anything, mostly a eyesight problem. But when you do re-roof your house, you can just put shims on the rafter slopes that are down and flatten it out.
 
  #3  
Old 06-27-02, 04:17 PM
JSG
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Thanks... And an update. The roof has one layer of shingles. I am in the process of re-roofing now. (Tear-off) And I want to fix the sagging rafter. On closer inspection the rafter has sagged a good 2 - 3 inches. I do remember one winter we had an unusually amount of snow and then it rained. Anyway to repair. Can I put a second 2x8 next to the original one, after lifting the deck, then nail and bold the two rafter together as a repair? I would also do the rafters on either side of the sagging one as they show slight signs of sagging. I did notice that one of the rafters in question does have a very large knot in the wood. Is this an acceptable repair mehod? Thanks again.
 
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Old 06-28-02, 05:29 PM
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That would work just fine, however it would be alot better instead of using bolts to use a stick nailer using 16 d nails, and shooting them in about every 4 inches in a zigzag pattern. Using bolts means you must drill a hole in the truss and thus making it weaker.
 
  #5  
Old 06-28-02, 06:58 PM
T
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Sistering

Sistering in new rafters to the old ones to make roof repairs is frequently done.
 
 

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