# What do I do with 2x4 ceiling joists?



## Scuba_Dave (Jan 16, 2009)

At a min you would need to install 2x6's on 16" centers
2x8's would be much better depending upon the weight of your storage
My house is from the 50's & has 2x6 as floor joists

If you have anything heavy up there - spread the weight around
If you have an area that has a wall directly below that is you best option for storage right now


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## MT Stringer (Oct 19, 2008)

With 18" centers, it sounds to me like you will have some wasted drywall.
Ditto what Dave said.


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## jogr (Jul 24, 2007)

Are you sure it's not trusses?


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## benjamincall (Apr 25, 2008)

jogr said:


> Are you sure it's not trusses?


I'm 100 percent certain that I have no trusses.  The roof frame forms one big isosceles triangle.

So sistering up half a dozen 2x4s to each existing ceiling joist wouldn't work? Replacing the 2x4 joists with 2x6s seems like it would be a lot of work. I have 2x6 rafters at a 5/12 pitch, so I guess 2x6 joists might fit without my having to notch the top plates. I'll have to put on a respirator and go figure out how much room I have.


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## Scuba_Dave (Jan 16, 2009)

You don't have to replace the 2x4's
Just add the 2x6's as close as you can to 16" OC
2x4's will still support the ceiling


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## benjamincall (Apr 25, 2008)

Well, I'm finally getting around to this project. I'm a lot wiser and more experienced than when I first posted this question, but some questions remain.

I'm thinking of adding 2x10 joists centered between the 2x4 joists at 24" on center. How should I fasten these joists to the top plates? Would some sort of simpson tie be the best solution? 

A 2x10 joist has a thickness to width ratio of 1:5, so it requires some sort of stabilization. Would the simpson tie be enough to stop lateral movement? If I need to use 2x10 blocking, what would I do about the rafter and 2x4 floor joist in between each 2x10 joist? Should I just avoid blocking at the outer top plates and notch the blocking to fit over the 2x4 joists?


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## <*(((>< (Mar 6, 2009)

I don't know if your 2x4 rafters will get in the way but you could use 'bridging straps' to stabilize the 2x10 rafters and keep them from rolling on you.


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## josall (May 7, 2011)

Seems like it would be easier to sister them to the ceiling joists it might cost you 3 more boards on a 20' room. Then you could cap off the open end of the 2x10s with a 2x6 sitting across the top of your ceiling joists. Assuming your rafters are 18" oc you could put a block on your rafter to attach the exterior end of your 2x10 to.


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## benjamincall (Apr 25, 2008)

I'll take a look at the bridging straps. Are you aware of some sort of an inverted joist hanger to attach the new joists to the top plates on the exterior wall? I can't imagine trying to toenail the joists in a such a tight space.


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## benjamincall (Apr 25, 2008)

josall said:


> Seems like it would be easier to sister them to the ceiling joists it might cost you 3 more boards on a 20' room. Then you could cap off the open end of the 2x10s with a 2x6 sitting across the top of your ceiling joists. Assuming your rafters are 18" oc you could put a block on your rafter to attach the exterior end of your 2x10 to.


I was thinking that I would have fewer drywall problems with the 2x10s centered between the 2x4s, but the benefit might not outweigh the additional labor. How would you sister with the big difference in width between the 2x4 and the 2x10? What would you do about the lapped portion of the existing rafters, sister to the "outside?" Wouldn't I want the 2x10s to be in contact with each other?

On a side note, I'll have to double check the rafter spacing, since I may have measured a portion of the house that is not representative of the overall framing.


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## pyper (Jul 1, 2009)

hurricane clips?


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## Ron6519 (Mar 28, 2007)

I would sister the 2x10's to the 2x4's and block the tops with 2x3's. You could also use any 2x material and lay them flat, even with the tops of the 2x10's.


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## benjamincall (Apr 25, 2008)

Ron6519 said:


> I would sister the 2x10's to the 2x4's and block the tops with 2x3's. You could also use any 2x material and lay them flat, even with the tops of the 2x10's.


OK, so I'll try just blocking the tops with 2x3s. To clarify, I'll be running the 2x3 perpendicular to the joist in the joist bays and flush with the top of the 2x10s. I imagine the 1.5" dimension of the 2x3 would be facing up, the 2.5" dimension would be facing to the side. At what interval would you block?

Should I bother trying to fasten the new joist to the top plates, or should I just nail the 2x10 to the existing joists and to a 2x block on the rafter to make up the 1.5" gap created by the existing joist?


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## Ron6519 (Mar 28, 2007)

benjamincall said:


> OK, so I'll try just blocking the tops with 2x3s. To clarify, I'll be running the 2x3 perpendicular to the joist in the joist bays and flush with the top of the 2x10s. I imagine the 1.5" dimension of the 2x3 would be facing up, the 2.5" dimension would be facing to the side. At what interval would you block?
> 
> Should I bother trying to fasten the new joist to the top plates, or should I just nail the 2x10 to the existing joists and to a 2x block on the rafter to make up the 1.5" gap created by the existing joist?


Correct, you're perpendicular to the 2x10's. At 13 feet, I'd install three or 4, dividing up the 13 feet. So every 4 or 3 feet. If you stagger them a bit, joist bay to joist bay, you can easily nail them in on the side.
If you can get a few 12 or 16 penny nails into the top plate, it can't hurt. But usually the roof angle at this point, is hard to work around. 
You might be able to install 2x4 blocking, it all depends on the actual joist dimensions.


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## pyper (Jul 1, 2009)

benjamincall said:


> Should I bother trying to fasten the new joist to the top plates,


H3 Hurricane Tie

http://www.strongtie.com/products/connectors/H.asp


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## benjamincall (Apr 25, 2008)

Cheap and easy. Thanks!


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## benjamincall (Apr 25, 2008)

I noticed that we have several ceiling joists that do not lap over a bearing wall. They must have been supported by a closet wall at one time. Since I was planning on sistering new 2x10 joists to the existing 2x4 joists, the 2x10 joists will not be connected to each other. Should I alter my plan in some way to tie the 2x10s directly together?


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## Gary in WA (Mar 11, 2009)

If only ceiling joists, “exceeding 2x10”: *R802.8 Lateral support. *Roof framing members and ceiling joists having a depth-to-thickness ratio *exceeding *5 to 1 based on nominal dimensions shall be provided with lateral support at points of bearing to prevent rotation. For roof rafters with ceiling joists attached per Table R602.3(1), the depth-thickness ratio for the total assembly shall be determined using the combined thickness of the rafter plus the attached ceiling joist.” ” 

You sound as if there will be storage, different requirements. If this will be a storage floor, you need lateral support at the ends; http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_5_sec002_par025.htm

Gary


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## benjamincall (Apr 25, 2008)

Thanks, Gary. I was planning on putting blocking between the joists, so I guess tying the sisters to each other isn't such a big deal. I managed to crack one of the 2x4s completely as I was nailing. I tried using a hammer at first, but this job definitely requires a palm nailer.


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## benjamincall (Apr 25, 2008)

I don't mean to have you guys hold my hand so much, but I'm still a novice. :thumbsup:

I jacked up one of the old joists a little too high when I sistered it, and now both joists float about 1/8" over the bearing point. Should I shim the joists and let a drywall guy deal with the out of plane joist, or should I pile some weight on the joist and try to pull it back down?


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## Gary in WA (Mar 11, 2009)

1/8" isn't too bad if on 24" centers....
He can also shim it if you point it out to him. You should shim under it before nailing if it won't go down with your weight.

Gary


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## AndyGump (Sep 26, 2010)

I have no suggestions for you as I do not know the full extent of what you are trying to do.
Andy.


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## benjamincall (Apr 25, 2008)

GBR in WA said:


> 1/8" isn't too bad if on 24" centers....
> He can also shim it if you point it out to him. You should shim under it before nailing if it won't go down with your weight.
> 
> Gary


Yeah, 230 lbs doesn't do anything to it. I'll shim it up. In this area, they're 16" on center, but a skilled mudman should be able to deal with it, right?


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## benjamincall (Apr 25, 2008)

Since I'm going though the trouble of adding 2x10s at 16" on center, why don't I build so I can add a level at a later date?

Will the clipped ends of the ceiling joists present a problem when I go up?

What other considerations should I bear in mind as I add new ceiling joists?

Edit: I just framed an opening for the attic stair using 2x10s. Half of the header on the "landing" side rests on the top plate of a wall. I end nailed each 2x10 with 10d nails, and facenailed the two 2x10s together. I'm not worried about the absence of a hanger here, since one of the 2x10s rests completely on the top plate. I am concerned about the other end, where the outer header board is end nailed (4x10d per end, and one toenail to the joist) and facenailed to the interior board, which is also end-nailed to the perpendicular joist. Should I use a hanger on this header since I plan on adding a level at some point? Are the 45° nails on the hanger likely to split the lumber since I have aldready end nailed?


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## Gary in WA (Mar 11, 2009)

Here on floor openings with hangers: http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_8_sec002_par030.htm

Clipped joists, pp.33: http://books.google.com/books?id=iw...=X&oi=book_result&ct=result&resnum=3#PPA32,M1

Adding hangers is fine…..

Foamboard and canned foam to air seal the rim joists on exterior walls to skip at later date: http://www.buildingscience.com/documents/information-sheets/critical-seal-spray-foam-at-rim-joist/
Keep a photo record for Inspector later.


Gary


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## benjamincall (Apr 25, 2008)

Thanks, Gary. I think I might be in trouble with the "1/2 original joist depth" criterion for the clipped floor joists. Would I measure the depth at the interior edge of the bearing surface? Can I do anything to repair the clipped ends if the depth is under 4-5/8"?


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## Gary in WA (Mar 11, 2009)

*R802.6 Bearing. *The ends of each rafter or ceiling joist shall have not less than 11/2 inches (38 mm) of bearing on wood or metal and not less than 3 inches (76 mm) on masonry or concrete. From: http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_8_sec002_par023.htm


Measure from the 1-1/2" in if on wood. Probably need an Engineers stamp to pass inspection if under code minimum.


Gary


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## benjamincall (Apr 25, 2008)

I think I'm good on the height if I get to measure from 1-1/2" in. I'll probably end up sistering a small piece of 2x10 to the end of each joist as a bearing surface to keep the bottom plate from rolling inward off the rim joist. The additional 2x10 pieces should also provide a little more shear strength.


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