12x16 shed roof ridge beam

[HerHusband]

Wow, that seems like a really undersized beam if it's spanning the 16' dimension of the shed. I'm surprised it hasn't started sagging over the years.

I can only think of a couple of reasons why it's still sound:

1. The connections at the ridge are so strong that they can't pull apart, and thus the ridge can't drop. But I'd think that would take some steel brackets to pull off. I have a 8'x8' pump house which uses brackets like this to create a gambrel shaped roof without using any rafter ties. It's the same approach most "shed kits" use, except they usually use plywood gussets instead of metal brackets.
2. The building is almost square and the top plate of the wall is acting like a ring to tie everything together. Kind of like the way a gazebo stays up without rafter ties. Essentially, the side walls keep the front and back walls from moving outward. This would only work if the building was small, and the top plates are strong enough to resist the sideways pressure from the rafters pushing out.

Then again, it could be the combination of all three, the ridge beam, the connections, and the top plates that are holding it all together.

I'm glad it has held up for you, but I wouldn't design it that way. Then again, I'm no architect, just an amateur builder...

Anthony

[willshak]

Yes, 4' x 8' x 1/8" plywood wall paneling, grooved like wainscoting, to all rafters. Nailed with 1" panel nails about 4" spacing along each rafter.

Yes, with the paneling attached.

About 1/8"

They are nailed to each rafter as paneling.

3/8" plywood sheathing with asphalt shingles on the roof.

1/8" plywood paneling

Just in case there are other questions, the shed was built to the usual housing standards (other than the foundation, since there is none. The shed joists just sit on a bed of gravel). 2 x 4 studs 16" OC center. The floor joists, underlayment and wall floor plates is PT. the roof pitch is about 4/12. The ridge beam is 2 x 8", the rafters are 2" x 6", 16" OC. The insulation between the 2 x 6 rafters is the usual R-13, 4" x

16", fiberglass to allow a couple of inches for air circulation between insulation and roof sheathing. Soffit vents and ridge vent for air circulation. Also has a working cupola that was used when it was an unpaneled and uninsulated garden shed. The cupola still works but it is not open to the ceiling, only to the air space below the roof sheathing, as does the ridge vent.

[Steve Barker]

According to this article the collar ties and ceiling joists can be one in the same.

[Glenn]

OK lets get real here. We are talking about a run of 6' on the rafters, pitch unknown. The length of the wall is only 16'. That's not much more than a dog house, Plywood sheathing nailed right even with no ridge would hold it. I would put a tie down on the plate every 4' but it really isn't needed for something that small.

[Dave]

Dan replied to: "Ceiling joists and collar ties are the same except the joists have two functions ceiling framing and collar ties for lateral components.

CID..."

The link you provided says nothing otherwise.

2/3 the way up or 1/3 down from the ridge, those are collar ties. A collar tie cannot support a ceiling in that location as you indicate that weblink indicated. A collar tie is usually 1X lumber. Fun attaching sheetrock to that for ceiling even if possible to act as a ceiling joist.

A collar tie still allows flex where the rafter is nailed to the second top plate (top plate is attached directly to the wall studs). A ceiling joist prevents that flex from occurring.

Go Dan, go.

[Chuck]

Collar ties can be any thickness you need they don't have to be 1X as you are indicating and providing the correct connections. You are the designer and you can size any structural member to the size you think is necessary as long as you know the functionality. True, if 1/3rd of the vertical distance it is then basically a collar tie. When the members are considered ceiling joists that are bearing on the top of stud walls and also attached to the rafters then they are doing double service.

CID...

[Chuck]

I am sorry but a 2"X8" ridge beam spanning 16'-0" is not enough for what you are describing. You are going to have wind and snow loading on the roof. The snow can drift on one side of the roof if there is wind forcing this situation. Unbalance loading with wind loading more wind pressure is on one side of the roof which causes loading on one set of rafters and not on the other. Not to mention the critical conditions for wind that are along the gable ends and corners of the building. These are the first areas that you will find damage in a critical wind storm. By the way a 3/8" sheathing is a good diaphragm for what you are building.

CID...