Sagging Ceiling Joists - Adding Beam In Attic

DoItMyselfToo

I just removed some insulation from my attic to discover that the ceiling joists are 2"x4". They are sagging. I would like to install a beam in the attic from gable end wall to interior wall and then attach each joist to the beam using metal hangers.

As you can see from the diagram, there are two rooms - dining room and kitchen. The width of the rooms is 15'-3". You can also see a load bearing wall separating the kitchen from the dining room. This wall has a beam under it in the basement with a post in the beams center that sits on a concrete footing.

I plan to attach a 2"x12" ledger board to each end wall using lag bolts and washers. And then attach a double 2"x12" from ledger board to ledger board using beam hangers to attach each end. The double 2"x12" beam will rest on the intermediary bearing wall. The ceilings can then be jacked up 1"-2" so that each 2"x4" ceiling joist can be attached to the beam with metal hangers. Essentially the ceiling joists will be suspended from the beam.

I based my design on 20# per square foot ceiling load. This attic is not living space or storage. It will hold insulation and provide ventilation for the house.

The beam is based on the longer of the two rooms and kept as one continuous beam for ease of installation rather than having two different sized beams.

In the dining room, since the beam carries half the load of the ceiling and the area of the ceiling is 239 square feet, then half of the ceiling area is 119.5 square feet. Multiply 119.5 by 20# per square foot to get a total beam load of 2390# for the larger room.

I then went to the beam load calculator at the following link:

http://www.forestryforum.com/members...eamclcNDS2.htm

Using Hem/Fir as the species, which is what I can get from my local Menards, a double 2"x12" works.

Anyone have any tips, suggestions, or practical experience to lend to this project? It's getting cold here in Wisconsin, so I need to get this done very soon, so I can insulate.

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jlhaslip

I'd be looking at using an LVL instead of a 2 x 12.
Any idea how to get that piece into the enclosed space?

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ENGINEER10

An upturn beam like this one will have the top portion in compression. To achieve its full strength it needs to be braced to the ceiling joists in several places, let's say every 4 feet, otherwise it will be worthless. In addition another thing to do is to nail a continuous 2x4 lying flat on the top beam flange.

ENGINEER10

Irrelevant

DoItMyselfToo

ENGINEER10, when you write "needs to be braced to the ceiling joists in several places," do you mean some kind of angle bracing from the top of the double 2"x12" beam to the ceiling joist below it? If so, I'm inferring that you're saying that I need to prevent the beam from twisting. Is this correct?

As for the "2"x4" lying flat on the top beam flange," do you mean that I should nail a 2"x4" flat directly to the top of the beam? What will this achieve?

Thanks in advance for your input.

BigJim

I have done like your drawing several times before and also to remove a bearing wall, it will work and every one I have installed years ago are still holding. I did put a block the thickness of the ceiling joist on the walls at the ends of the 2-2X12 to take the pressure. If you put 3/4 inch plywood between the 2-2X12s it will stiffen it up and will hold easily. Be sure there are studs in the walls directly under the blocks which support the beam.

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Jim

SteelToes

Agree.
LVL , one full continuous piece.
I wouldn't go with ledger board , you are transferring a load to the wall studs and not supporting gable end framing and ridge board.
Place the LVL inside the wall ,support and transfer the load to the bottom plate.
If you are doing all of that work go an extra step..

mrgins

Don't NAIL the 2x4, screw it! I replied yesterday to a similar situation on the sistering joists thread on the carpentry or the contruction thread. Stiffness is more important than strength as these are ceiling joists.

DoItMyselfToo

I may be missing something here so I'll ask a few questions. By lag bolting the ledger to each 2"x4" on the end walls and attaching the beam to the ledger board, I would think the load would then be transferred to the sill plate of the wall via the ledger/studs without creating a point load which would occur if I placed the beam within the wall pocket with a couple of 2"x4" post directly under it.

As for support the ridge board, I planned to add a 2"x4" from the ridge board to the top of the beam at 4' intervals to provide extra support.

If I'm missing something with this line of thinking, I definitely would appreciate any insight that you have. Thanks in advance.

mrgins

[quote=DoItMyselfToo;543079]

As for support the ridge board, I planned to add a 2"x4" from the ridge board to the top of the beam at 4' intervals to provide extra support.

I/quote]
Extra support to what? You're putting unnecessary stress on the beam and the ridge. Glue and screw whatever you use as a stiffener. Plywood is cheaper and will work well

ENGINEER10

Yeah, you got it right about the bracing, although it is not because of twisting but more like sideway buckling in a wave shape.

The 2x4 will also help add to the rigidity of the top of the beam being in compression, an extra measure to reduce the number of bracings, otherwise you will need to have top of beam continuously braced which is obviously not practical here.

Gary in WA

The ledger will work as you surmised, the info from SteelToes was wrong. The gable is non-bearing, The ridge board is only to hold the tops of the rafters together on layout, and possibly support some overhang roof load unless there are gable rafters above the gable wall. You do not need ridge board supports, as brought out. The interior running 6" wall is probably non-bearing requiring post, footing, etc.

If access is limited, I would use a dozen 2x8's sistered to the ceiling joists after lifting them straight if bearing at both ends (18'6" span, 20#live load- 10# dead load).

Gary

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