# Replacing Garage Ceiling Joists?



## reventropy2003 (Dec 2, 2014)

I have a garage with a ~22 foot span.  It was built cheaply in the late 70s with 2x4 joists 24'' on center.  Two of the joists have vertical cracks in them and should be taken care of.  It seems like the most common way to deal with this is to repair and reinforce.  My question is:

Instead of repairing them, can I replace the joists with something more structurally sound (2x8s or 2x10s)?  One at a time of course... What are the dangers/difficulties in doing this?  If this is a bad idea then why?  

Thanks,

Jeremy


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## oldognewtrick (Dec 2, 2014)

Is this dimensional lumber or truss's?


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## joecaption (Dec 2, 2014)

Most often they crack from someone trying to store over head items.
2 X 4's where never intended to be top loaded.
There just to keep the roof from spreading out.


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## reventropy2003 (Dec 2, 2014)

joecaption said:


> Most often they crack from someone trying to store over head items.
> 2 X 4's where never intended to be top loaded.
> There just to keep the roof from spreading out.



Yeah.  It wouldn't surprise me.  We just moved in and inherited the current condition.


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## reventropy2003 (Dec 2, 2014)

oldognewtrick said:


> Is this dimensional lumber or truss's?



It's a Howe truss design.  Dimensional lumber connected with tie plates.


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## oldognewtrick (Dec 2, 2014)

reventropy2003 said:


> It's a Howe truss design.  Dimensional lumber connected with tie plates.



Do NOT cut the 2X's. Sister on to them, but do not cut. Is there drywall in the ceiling? Insulation?


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## nealtw (Dec 2, 2014)

Sister on a a 2x4 as long as you can 2 nails or screws every 6 to 8 inches. Increasing the lumber size will only increase the temptation to store stuff up there. They are designed to carry 5/8" drywall and insulation and not much else. And if you could get full length 2x10s up there they would be overspanned.


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## reventropy2003 (Dec 3, 2014)

oldognewtrick said:


> Do NOT cut the 2X's. Sister on to them, but do not cut. Is there drywall in the ceiling? Insulation?



No drywall or insulation.  I'm not planning on drywalling either.  Is the idea that if I do cut and replace, the roof will splay out?  I can always sister the 2x4s but I was mostly wondering why this is preferable to replacing.


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## reventropy2003 (Dec 3, 2014)

nealtw said:


> Sister on a a 2x4 as long as you can 2 nails or screws every 6 to 8 inches. Increasing the lumber size will only increase the temptation to store stuff up there. They are designed to carry 5/8" drywall and insulation and not much else. And if you could get full length 2x10s up there they would be overspanned.



I probably will do this, but I was wondering if there is a reason not to replace instead (other than that it sounds like it would be a waste of time/effort).  Are there structural concerns if I were to replace?  I won't be storing anything or even drywalling for that matter, but these are supporting a garage door.


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## bud16415 (Dec 3, 2014)

The bottom member of a truss is in tension. A 2x4 is very strong when built into a truss framework and forces are distributed all different directions within the truss. You haven&#8217;t shown a picture of the damaged lower members you are worrying about. if you feel that member is bad you need to attach something with the idea of tension in that member. The lower member is acting like a cable running across your building. I can&#8217;t see any advantage in replacing it with something larger. Once you break those joints or any joint in a truss the whole strength of that one truss is next to nothing. And you would have to figure out how to reattach all those joints. It would be a lot of work and you would have to do them one at a time and let the others share the load of the one you were rebuilding. 

Have you shown it to anyone else in the trade to see if they felt you were undersize?


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## nealtw (Dec 3, 2014)

If you loose one of those pressed in joiners, which happens from time to time the repair is a 6 ft 2x4 sistered over the damaged joiner with even more nails. So do not replace it just sister it.


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## GBR (Dec 6, 2014)

"Vertical cracks"--- in the vertical web members? Or in the horizontal bottom chord member---(which would be a horizontal crack)... picture would be helpful. A plywood gusset on sides would repair a gusset plate--- are you needing that as well?  Did I miss a picture? not the first time, lol.

Gary


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