Sagging rafters

[Bert_]

Putting strapping on my garage roof today I noticed one area had a dip and a bit more spring to it. I crawled up into the attic and found one rafter had a crack and the ones next to it sagging noticably.

First thought was to sister them but the thought of getting a 14' 2x6, or probably should be 2x8, up in an attic didn't sound like fun. A few 2x4's was a lot easier and probably more effective.

The bracing looks effective to me but I'm sure you all will let me know if it isn't. The bracing is in compression and tension just like a truss. I only did the one side but I'm pretty sure that's ok.

 

[Bigblockyeti]

It looks like it should get the job done just fine. That being said, if I was that in a house i was consider buying, I run away fast.

 

[kd3pc]

the knob and tube adds to the intrigue....

 

[mitusa]

Maybe my eyes are playing tricks.....but are the rafters 2x4s or 2x6s?

If so, I think I would have tried to jack them back up straight and laid a sister on each side....

As a side note....now that I think of it, it's never a good idea to lay sisters.

 

[Bert_]

Maybe my eyes are playing tricks.....but are the rafters 2x4s or 2x6s?

If so, I think I would have tried to jack them back up straight and laid a sister on each side....

As a side note....now that I think of it, it's never a good idea to lay sisters.

2x6, each one is 14' long plus what extends to make the eave. Guessing 2x6 rafters spaced 24" is marginal for the span.

I cut the short part of the brace an 1- 1 1/2" long and hammered it into place after the long tension parts where nailed in place. It probably not perfectly flat but it's a lot better.


In my mind this is better than sistering since it cuts the span of the rafter in half. Not to mention the difficulty of getting 14' lumber into an attic.

 

[3onthetree]

found one rafter had a crack and the ones next to it sagging noticably.

The bracing looks effective to me but I'm sure you all will let me know if it isn't. The bracing is in compression and tension just like a truss. I only did the one side but I'm pretty sure that's ok.

If you have a cracked rafter first thing is to replace or sister it. Then I would check to make sure your walls haven't bowed out at the top and the ridge board hasn't sagged. Check your spans too, there is something causing failure.

The "fink truss chords" you installed won't quite work like "half a truss" because of what looks like existing vertical king posts at every ceiling joist. I believe what the new braces will do is turn that king post into a compression member, so your ceiling will sag. A better method would have been struts (purlins) to the king posts, like a "queen fan truss."