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-   -   Garage ceiling joist support (http://www.diychatroom.com/f19/garage-ceiling-joist-support-39147/)

mountainmike 02-25-2009 11:57 AM

Garage ceiling joist support
 
This is my garage ceiling. The problem is the ceiling joists are 21' long 24" OC 2x4s. The big problem is the one of the previous owners put 1/2" sheetrock up there and then 10" of blow in fiberglass on top.

As you can imagine the whole ceiling is sagging about 6" in the center. I know I need to put a beam across the center to support the whole thing.

The span for the beam will also be 21' the garage is 21x21. I will have to build this beam myself out of dimensional lumber for a few reasons. I would love to just use a gluelam.

On one side I have a window and the other a door. I can't just slide a beam up into place because of these obstacles. I plan to use scaffolding and assemble a beam with dimensional lumber above the window and door.

I know I will need to build a bigger headers above the window and door.

The attic above this garage will never be used for storage because of the insulation and the low roof.

This is a rafter roof so the beam will only be supporting the ceiling joists, sheetrock and insulation.

cocobolo 02-26-2009 11:58 PM

Mike: What size are the rafters?
The guy that hung that drywall must not have been very good at math. That's a fair weight hanging off 2 x 4's.
Have you considered the possibility of turning your rafters and ceiling joists into trusses? You actually have the base material in place already. That way, you would not need a beam at all.
You could jack up the center of the ceiling until it was level - or possibly even a small amount higher - and use plywood gussets, screws and building glue to hold your new "W" 2 x 4's in place. That way, there would be no pounding of nails to dislodge the drywall.
Using this method you won't have to re-do the headers, either.
Give it some thought.

allencd@cox.net 02-27-2009 07:14 PM

Quote:

Originally Posted by mountainmike (Post 236539)
This is my garage ceiling. The problem is the ceiling joists are 21' long 24" OC 2x4s. The big problem is the one of the previous owners put 1/2" sheetrock up there and then 10" of blow in fiberglass on top.

As you can imagine the whole ceiling is sagging about 6" in the center. I know I need to put a beam across the center to support the whole thing.

The span for the beam will also be 21' the garage is 21x21. I will have to build this beam myself out of dimensional lumber for a few reasons. I would love to just use a gluelam.

On one side I have a window and the other a door. I can't just slide a beam up into place because of these obstacles. I plan to use scaffolding and assemble a beam with dimensional lumber above the window and door.

I know I will need to build a bigger headers above the window and door.

The attic above this garage will never be used for storage because of the insulation and the low roof.

This is a rafter roof so the beam will only be supporting the ceiling joists, sheetrock and insulation.



Try to find a paralam, or truss joist. they are much lighter than a glu-lam, are rigid, and will never sag. You can put a simpsom connector to attach each joist to the para-lam,and add some cripple studs under each end. It may also be possible to beef up your window/door header with ply and shear nailing, "possibly".

mountainmike 02-27-2009 07:26 PM

I thought about that but this is a hip roof. The rafters are already overloaded. The dummies that owned this house before us put a concerete tile roof on it. Under that tile is 2 layers of asphalt roofing.

mountainmike 02-27-2009 07:28 PM

There are 3 lumber yards in the nearest town. I will have to see on Monday what my options are as far as gluelam or LVL, I will also ask about paralam. Thanks for the help guys

allencd@cox.net 02-27-2009 07:49 PM

Quote:

Originally Posted by mountainmike (Post 237945)
I thought about that but this is a hip roof. The rafters are already overloaded. The dummies that owned this house before us put a concerete tile roof on it. Under that tile is 2 layers of asphalt roofing.



yeooowww, you have your work cut out for you. I would then try and make trusses out of what you have, adding bottom chords and diag's, but you may really need an engineer to look at it too. doesn't it suck when boneheads do stuff like this and you end up with it? I've yet to see that one, tile on asphalt comp. 2x4s shouldn't have anything but sheet metal on it. the hips can be supported by running a joist, hanging from the top plate at 45deg, half the distance from the building corner, to the ridge, but the rake section is tough. pretty soon, you have a ton more of weight. I think you'll need to build a new "diaphram" below your roof, then struts from that to the hips and ledger supporting the joists. good luck. if you have a fax, send me a rough sketch with dimensions. I can have my brother take a look at it. he's the engineer in the family. boring guy, but he's pretty creative when it comes to stuff like this.

allencd@cox.net 02-27-2009 07:50 PM

Quote:

Originally Posted by mountainmike (Post 236539)
This is my garage ceiling. The problem is the ceiling joists are 21' long 24" OC 2x4s. The big problem is the one of the previous owners put 1/2" sheetrock up there and then 10" of blow in fiberglass on top.

As you can imagine the whole ceiling is sagging about 6" in the center. I know I need to put a beam across the center to support the whole thing.

The span for the beam will also be 21' the garage is 21x21. I will have to build this beam myself out of dimensional lumber for a few reasons. I would love to just use a gluelam.

On one side I have a window and the other a door. I can't just slide a beam up into place because of these obstacles. I plan to use scaffolding and assemble a beam with dimensional lumber above the window and door.

I know I will need to build a bigger headers above the window and door.

The attic above this garage will never be used for storage because of the insulation and the low roof.

This is a rafter roof so the beam will only be supporting the ceiling joists, sheetrock and insulation.



i forgot to send my fax # 760.806.8222

mountainmike 02-27-2009 09:32 PM

I am not going to deal with the roof right now. The tile is in real bad shape, it was not installed properly surprise surprise. In a few years I plan to do a complete tear off.

If you think your brother would look at what I have that would be a big help. I would hire an engineer to figure this out but I don't have the money. I already had to pay an engineer $800 to figure out how to fix the foundation. That is another story for another day.:furious:

Here are my numbers. I don't know if I figured it all correctly.

1/2" gypsum board = 2.2 psf
10" Glass wool = 3 psf
Rafters 24" centers .7 psf

Total 5.9 psf

I am going to go with 10psf for the weight when the garage doors are open, the openers and if somebody decides to hang bikes or something from the ceiling.

Ceiling is 21x21
441 sqft
4410 lb for the ceiling.

I divided 4410 by 3, the front of the garage carries a third of the load the beam will carry a third and the back wall will carry a third. This means the beam will carry 1470lbs.

1470 into 21' gives me 70 plf.

cocobolo 02-27-2009 10:15 PM

Mountainmike: Look at it this way.
Right now, you have NOTHING holding up the ceiling joists in the center of the span, and they seem to be staying in place. Granted, a 6" sag is not the sort of thing to inspire confidence.
Now that we know it is a hip roof and that the building is square, there is a bit more information to work with.
Are you planning on keeping this building for many years to come? The reason I ask is that if it has two layers of asphalt roofing, that suggests an age of 30-40 years, plus however long the tile has been on. So the building could be close to drawing its' old age pension pretty soon.
I would further guess that whatever the original roof sheathing was is still in place. Do you know if it is plywood, or shiplap, or...??
You can still turn your rafters and ceiling joists into trusses at minimal cost. It will just take a little effort is all.
Typical asphalt roofing weighs 210# per square (100 sq. ft.), and with two layers, that will be 420# per square. I do not know what the concrete tile would weigh, but perhaps someone who is familiar with that can enlighten us.
The weight of the roof itself has nothing to do with your ceiling joists, as the roof weight is supported in its' entirety by the top plates on your walls.
So, you still have the option of creating trusses, which will be quite inexpensive. Or, you have the option of installing a central beam of some kind.
Quite frankly, if the building is as old as it appears, I don't think I would sink a whole lot of money into it.
Do you have the option of installing a post in the center of the building, under a new beam? If so, that would greatly simplify things and at the same time reduce your expenses even further.
Doing it yourself, which is what this is all about, this should not cost you more than $100. Seriously.

mountainmike 02-27-2009 11:55 PM

The concrete tiles are 10lb each and they cover about 1sqft each. This is an attached garage so it will be here for the long haul. The house is 51 years old. The walls are 2x4 24"oc in the garage, in the house they are 16"oc. In a couple years I plan to do a tear off on the roof. The tile install was done real bad, I am sick of dealing with leaks.

The roof deck is plain old 1x8s, on 2x6 rafters.

If I cannot get a LVL or some 2x lumber that will do a clear span, I will have to put in a center post. That certainly would make this project much easier. I really hate to do that though. It would be right where the back doors on the car are.

The rafters are about 6" offset from the ceiling joists so making them into trusses seems like a huge pita.

cocobolo 02-28-2009 12:10 AM

Yes indeed, if the rafters don't line up with the joists you're right about that.
You can always move the post ahead or back a little as well. If you used 3 2 x 8's and set your post within a couple of feet of center, you would have adequate strength. The center point is only a maximum of 10' 6" from either end, not a big span. And you really don't have that much load there. If the joists had been 2 x 6's even, it would have been better. Still not enough, but better. Or perhaps you could put a post somewhat inboard from each end, say 4 or 5 feet, leaving a space in the middle. I bet you could figure out something like that easily.
There is always a fairly easy solution to this sort of thing. Just have to talk and think your way through it.

Wildie 02-28-2009 07:16 PM

Just to be radical, you could remove a 4' section of drywall, saving the insulation.
Slide a ceiling joist in that aligns with the rafters and fabricate a truss.
Replace the board and move the insulation from a second 4' section, onto the new board.
Remove the board from the second section, slide in another ceiling joist and fabricate another truss!
Board this section, insulate it from a fourth section. Remove the fourth board and do another truss.
When htis is boarded, put the insulation back, from the first section.
Or you could rip all the board and insulation down and scrap it!
Make up truss's and install new board and insulation!


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