Need some advising on sagging ceiling joists

[Rubberdown]

Hey all,
I recently moved in with my mother in law to help take care of her. Alzheimer's ***** and that's all I have to say about that. The garage ceiling joists had been decked with 1/4 inch plywood, and about 500000000000000 lbs of **** had been thrown up there in addition to filling up the garage. At somepoint someone realized their folly, and had shoved some notched 4x4 posts in the middle to shore things up.

I have cleaned everything out and its empty up there. My question is, how to best deal with these saggy ceiling joists. They are 2x6x22 (give or take on length) on 2 foot centers. The ends have been tapered to match the slope of the roof. Looking at any sort of span table these just wouldn't do with no load. I should mention that these are not trusses or anything, and the roof structure is in no way attached to these.

The options I see without doing an unreasonable amount of work on a house that isn't mine are:

1. Replace with 2x6 like was originally framed

2. replace with 2x8 or 2x10 or 2x10. That would require me replacing ALL joists and temporarily removing stiff backs, etc. The problem I run into is I have always worked with the rough understanding don't cut more than a quarter of the board off, within the width of the board.
(example, you can cut 4 inches off the edge of a 2x12 within 12 inches of the end) So to fit a 2x12 under the existing decking I would have to cut about 5 inches to 8 inches off depending on the slope of the roof. That doesn't follow the rule. I MAY be able to get away with a 2x8 but that doesn't seem like it meets the span table that I looked at.

What do you guys suggest? Half of me says its not my house, screw it and put back what was there and don't complicate your life. Lets be honest more than half of me is saying that.

 

[Cypress]

How much are they sagging?

 

[Shiftless]

How bad is the sag? Over the whole 22 foot or so length, how many inches is it down in the middle? One or two inches is completely different than 12 inches.
Measure with a laser or a really tight string line.

Edit: Cypress posted while I was still typing. Same question.

 

[Rubberdown]

Im not sure exactly. I hesitate to pull the 4x4 out without having something to put up there immediately. Enough that my father in law who didn't give a **** about anything stuck 4x4s in there. I see cracking in one of the beams, as well as an idiotic splice in one. Both of those have 4x4 posts right in the middle of the span.

That being said it would probably be ok... they arent holding anything up, just the keeping the walls from moving.

 

[bczygan]

Why bother with it?

Bill

 

[nadogail]

IMHO, get some jack posts with screw threads and then place them under the low point of the sagging joists, after you have turned them up until the are snug against the joists crank them about a quarter turn every week until the sag is gone.

Then sister the sagging joists.

I remember those adjustable posts being listed in the Montgomery Ward Catalog.

You could also set posts on opposing wedges and drive the wedges against each other to raise the ends of the posts and the joists they are pushing against.

 

[KenC]

Two big stiff backs. wall to wall and tied to each joists with metal straps. If the joists are open on the bottom joist hangers work well. Otherwise, get a roll of the punched banding concrete formers use.

But first use some of 4x4s and boards against the bottom of the joists to raise them 1/2" or so above level. That may take a few days of driving the 4xs a little each day to do that without cracking them.
I've done this several times in older homes, some with 24' 2x4s! works well.

 

[Chris705]

If you never plan to put the stuff back up there..... jack the ceiling joists/rafter ties (to take sag out) and then support with 2x4s up to the roof rafters right near the ridge board..... then the posts won’t be needed. This was a common framing method where the rafter ties were not sized to support any load, only meant to keep walls from splaying out.

 

[johnnyradiant]

I think I would lean towards jacking beyond level then sistering. Getting both ends of the new sistered joists on top of permanent support may or may not rank high in this case, depending if the 500000000000000 lbs of **** was permanently removed from the site. It's odd because the span table I checked rated existing good for 500000000000300 on a 22'6" span. You must have under estimated the **** load by more than 300 lbs.

 

[Rubberdown]

Ok all. Thanks for all the advising.

To answer a few questions.

I bother because I have some fairly nice special things that can’t be easily replaced to put under the ceiling joists and the thought of something falling down makes me nervous. I’d hate to do 10k of damage because I didn’t spend the 300 bucks (delivered) on new boards.

I might throw a few 1/2 ply Christmas yard cutouts back up there but that’s about it.

I’m glad to hear most of you think sistering a 2x6 to the existing board after going past level is the way to go. Would you glue these beams together or just sink screws every X inches to marry them together. Or both?

The existing stiff back (2x6 on 2x6) didn’t keep this from sagging so I’m not sure how effective that would be. I think the boards all just sagged together like a bunch of lazy wankers.

I may have over or underestimated the 5 gazillion pounds. It was a 40 yard dumpster worth plus a bit more. My load table was google. I realize that doesn’t take into account much of anything but you know... have to start somewhere.

Thank you again for all your advising. I’ll put in the lumber order this weekend.

Ryan

 

[theoldwizard1]

I think I would lean towards jacking beyond level then sistering. Getting both ends of the new sistered joists on top of permanent support may or may not rank high in this case, ...

My Dad had the same issue in an old garage. There was no way to get the sistered joist to rest on the top of the wall.

After jacking level, he used 2x6s that were about 2/3 of the span. One end was trim to fit on top of the wall. The other end had a long diagonal cut so that 3'+ was overlapping between the two pieces. Glue and through bolts held it together.

If you are having a problem jacking, you need to remember that you are probably pulling the tops of the wall together. It might be easier to use a come-a-long to pull the top plates in (so that the walls are closer to plumb and the span between the top plate and bottom plate are equal) and then jack in the middle.

 

[nadogail]

Ok all. Thanks for all the advising.
......I’m glad to hear most of you think sistering a 2x6 to the existing board after going past level is the way to go. Would you glue these beams together or just sink screws every X inches to marry them together. Or both?.....

Ryan

IMHO, Lots of both Glue and Screws, maybe Steel also.

 

[jake28]

My Dad had the same issue in an old garage. There was no way to get the sistered joist to rest on the top of the wall.

After jacking level, he used 2x6s that were about 2/3 of the span. One end was trim to fit on top of the wall. The other end had a long diagonal cut so that 3'+ was overlapping between the two pieces. Glue and through bolts held it together.

If you are having a problem jacking, you need to remember that you are probably pulling the tops of the wall together. It might be easier to use a come-a-long to pull the top plates in (so that the walls are closer to plumb and the span between the top plate and bottom plate are equal) and then jack in the middle.

The come along is genius. I wouldn’t have thought of the walls moving.

 

[Rubberdown]

I think the good news is that i have enough room in the eve to lay the 2x6 flat and slide it past it’s final spot in order to get the other side in. Then rotate it to a vertical orientation once both side are up. At least that’s how it’s looking. Good news is I put in the new master cylinder in my old Chevy and bled all the brakes. Now it will easily go in and out. (That’s what she said).

Thanks again for your help fellas.

Ryan

 

[Michigan Mike]

It seems obvious but I will say it anyhow. The boards will have a crown. They won't be straight. Mark the high side and keep it up when you place and fasten the new boards to the old.

 

[CraigStu]

I would also use a level to see if the walls are vertical. If these ceiling joists are attached to the walls, as they sag, they might actually be pulling the walls together. Which ever way the walls have moved, it would be good info to have before doing any work.

 

[theoldwizard1]

I would also use a level to see if the walls are vertical. If these ceiling joists are attached to the walls, as they sag, they might actually be pulling the walls together.

Actually they will push the wall OUT !

Instead of using a level to check for plumb, check the distance, at each joist, between the two top plates and the two bottom plates. If they are equal, Then check for plumb to see if the building is "racked" to one side or the other.

 

[Innovate1]

My Dad had the same issue in an old garage. There was no way to get the sistered joist to rest on the top of the wall.

After jacking level, he used 2x6s that were about 2/3 of the span. One end was trim to fit on top of the wall. The other end had a long diagonal cut so that 3'+ was overlapping between the two pieces. Glue and through bolts held it together.

If you are having a problem jacking, you need to remember that you are probably pulling the tops of the wall together. It might be easier to use a come-a-long to pull the top plates in (so that the walls are closer to plumb and the span between the top plate and bottom plate are equal) and then jack in the middle.

No way i'd trust a 3' scarf splice on a 2 x 6 even if glued and bolted. If I remember correctly a good carpenter friend told me a rule of thumb was the overlap should be double the amount of extension. For example if you need to extend a 10' piece to 12' then the extension is 2' and it should overlap the other board at least 4'. I haven't seen that in code or calculations but it seems like a reasonable guideline. If it's for a critical location then I would try for a solid piece or find better guidance.

Jacking a sagging joist is not going to pull the walls in. If anything it will push them out as the joist becomes straight. If the roof is sagging then the walls likely need pulling in but not with a joist.

 

[KenC]

I recommended stiffbacks. But didn't specify lumber size. No, your 2x6 ones didn't work. but, I'd bet a #2 2x12SYP on either side of the existing flat 2x6 would. Take the existing vertical 2x6 off, replace it with a 2x12, add a 2x12 to the other side and put the other 2x6 between the 2x12s at the top. Now you have a 10x12 box beam. tie that to each joist with steel straps.

I'd much prefer that to sistering 2x6s. You are already at a disadvantage when doing that. The existing joist is bowed down. When pushed up it will want to return to its existing shape. That load will be added to the load that bowed it in the first place and both will be born by the added 2x.

The box beam stiffback is very effective in reducing the 2x6 span.

the original stiffback was more for leveling the joists one to another than bearing weight.
Box beam does both.

Just use lots of the right type of nails. Short hanger nails for the steel strap or hangers and 3 1/4 gun nails about every six inches in the beam attachments.

 

[firebirdparts]

I had an attached garage exactly like that, and the 22 foot 2 x 6's were plenty adequate when not bent. So it would be okay to replace them in kind, if you could get comparable lumber (I can't) and if you don't want sheetrock. If you want sheetrock, you'll need something more complex than that.

Mine were western, Fir or Hemlock or something but they had no load on them at all. I took them down after about 20 years and put in floor trusses.

 

[Innovate1]

Two big stiff backs. wall to wall and tied to each joists with metal straps. If the joists are open on the bottom joist hangers work well. Otherwise, get a roll of the punched banding concrete formers use.

But first use some of 4x4s and boards against the bottom of the joists to raise them 1/2" or so above level. That may take a few days of driving the 4xs a little each day to do that without cracking them.
I've done this several times in older homes, some with 24' 2x4s! works well.

Not sure what you mean by "stiff back". I tried to google it but only got results from lots of medical places with treatments for a stiff back. LOL. Care to explain?

 

[Charlie51]

I recommended stiffbacks. But didn't specify lumber size. No, your 2x6 ones didn't work. but, I'd bet a #2 2x12SYP on either side of the existing flat 2x6 would. Take the existing vertical 2x6 off, replace it with a 2x12, add a 2x12 to the other side and put the other 2x6 between the 2x12s at the top. Now you have a 10x12 box beam. tie that to each joist with steel straps.
The box beam stiffback is very effective in reducing the 2x6 span.


Could you draw an illustration so I can visualize what a "stiff back" is? Thanks much.

 

[sreeb]

Actually they will push the wall OUT !

Instead of using a level to check for plumb, check the distance, at each joist, between the two top plates and the two bottom plates. If they are equal, Then check for plumb to see if the building is "racked" to one side or the other.

Really? Why would they push out? The distance between the ends will get shorter as they bend. Note that he said they aren't tied to the rafters except at the ends.

 

[theoldwizard1]

Basic static load analysis. First, think in 2D. Assume the load of the roof is at one point at the peak of the roof. As gravity pulls that load down the only way the forces can be distributed is down the rafters.

In engineering they would say "draw free body diagram".

 

[NUTTSGT]

If you set a level on the floor is it relatively flat ? At the walls. at the center where the 4x4 post resides ?

If it is, you can get a ballpark measurement and see how bad the sagging 2x6s are.

 

[sreeb]

Basic static load analysis. First, think in 2D. Assume the load of the roof is at one point at the peak of the roof. As gravity pulls that load down the only way the forces can be distributed is down the rafters.

In engineering they would say "draw free body diagram".

If you pull the center of the joist down (effectively shortening it), it will pull the walls in and force the roof ridge up.

 

[Innovate1]

Basic static load analysis. First, think in 2D. Assume the load of the roof is at one point at the peak of the roof. As gravity pulls that load down the only way the forces can be distributed is down the rafters.

In engineering they would say "draw free body diagram".

I think they would say you are not looking at what the OP is talking about. There has been no mention that I could see of the ROOF sagging (although if that is happening that may change the whole discussion). The issue is JOIST sagging. When they sag they pull the walls in but only slightly unless there is a lot of sag.

 

[CraigStu]

Thank you sreeb and Innovate1.

 

[Mainiac Mat]

My take is that the structural purpose of the ceiling "joists" is really to tie the opposing walls together and to resist the outward thrust component associated with live and dead roof loads. So the walls bowing out and the ridge sagging is what you need to be concerned about... more so than the joists sagging.

So make careful measurements across the garage from top plate to top plate to see if the walls have bowed out. Sight down the ridge line and the eaves to see if the roof is drooping. Then put a level on the walls to see if they are vertical, or leaning out.

Logic may lead you to believe that if the joists are bowed, they must have pulled the walls inward, but more than likely, the fasteners at their end have bent and shifted.

If the walls are plumb hand haven't kicked out. I would add add'l 2x6 (or better yet 2x8) ties and see if you can get a few long screws (Simpson truss screws would be ideal) up through the plates and into the joists. Don't worry about taper cutting the 2x8 to <25%...it will be better than what you have.

Sister a 2x6 up to the cracked joist with glue and screws.

If the walls are bowed out, use multiple come-a-longs to pull them back into plumb and then do the reinforcement work detailed above.

And finally.... don't store stuff up there.

There seem to be many, many under-built garages out there. And it amazes me that people were so careless.

 

[Copymutt]

Im probably misunderstanding here. If the roof is still true and the joists are sagging, I’d jack them back into position and tie the rafters and joists together creating truss support.

 

[Innovate1]

My take is that the structural purpose of the ceiling "joists" is really to tie the opposing walls together and to resist the outward thrust component associated with live and dead roof loads. So the walls bowing out and the ridge sagging is what you need to be concerned about... more so than the joists sagging.

So make careful measurements across the garage from top plate to top plate to see if the walls have bowed out. Sight down the ridge line and the eaves to see if the roof is drooping. Then put a level on the walls to see if they are vertical, or leaning out.

Logic may lead you to believe that if the joists are bowed, they must have pulled the walls inward, but more than likely, the fasteners at their end have bent and shifted.

If the walls are plumb hand haven't kicked out. I would add add'l 2x6 (or better yet 2x8) ties and see if you can get a few long screws (Simpson truss screws would be ideal) up through the plates and into the joists. Don't worry about taper cutting the 2x8 to <25%...it will be better than what you have.

Sister a 2x6 up to the cracked joist with glue and screws.

If the walls are bowed out, use multiple come-a-longs to pull them back into plumb and then do the reinforcement work detailed above.

And finally.... don't store stuff up there.

There seem to be many, many under-built garages out there. And it amazes me that people were so careless.

^ This! +1