Need some framing help please.

[rluckie]

Need some help. I need to frame up my ceiling to support the weight of sheetrock. This will be constructed under my current roof structure which is 8” purlins spanning 25’. I have 2 options. The first option (top) I know will support the weight and the second option (bottom) makes sense that it would to me but I am NO framer so it may fail. I hope my question is clear.

 

[readhead]

Is this in a steel building? If so do you still have the original plans? The plans will tell you what, if any, collateral load is available. If it is enough you can attach framing and then drywall to the purlins.

If you do have to frame something like your sketches what will support the ridge? You can’t use the building structure if the load isn’t available.

 

[matt_i]

Option B would be acceptable but I'd reinforce every rafter with a LU- (?) adjustable rafter hanger from Simpson. I want to say its a 27 or 28 but the bottom bends slightly and then its a box of screws.

Its worth considering an LVL(s) as it will be straighter and less warp and also a more rigid piece of material. You don't show how the ends of this will be supported but that's going to be important as the system is going to be concentrating a lot of load on the end supports.

What I don't like about either design even with the LU joist hangers is that there's no real way to deal with the horizontal/outward forces. Since I think you have access to the top of it, I'd propose also putting ~12-18" of flat 16ga metal strapping on top and bending it over the peak.

 

[The Tool Tyrant]

Need some help. I need to frame up my ceiling to support the weight of sheetrock. This will be constructed under my current roof structure which is 8” purlins spanning 25’.

First, either method is fine. I've framed MANY roofs using either design.
Am I correct in assuming that this is strictly aesthetic as you state that it's to be built UNDER your current roof?
If it's structural rather than aesthetic, and will be sheeted, either design needs to allow the sheathing to be nailed at the ridge to create a diaphragm. The design on top would need a row of blocking at the centerline and the bottom design would require the center 2X12 to be raised to plane with the rafters.

 

[blkhonda1991]

so you are framing this totally independent of your current roof structure? how are you dealing with the eave condition? not possible to just run furring between the current purlins and sheet rocking?

 

[rluckie]

Here is an additional drawing that shows a little bit more of a broader idea. I will note that the exterior wall is built inside the the purlin wall of my barndominium. The beams will be set on headers at the end walls. I was told by my builder of the shell that the existing purlin roof would not support the weight of sheetrock. Because of this I am needing to build a structure to support the weight of sheetrock. I hope this makes sense. I appreciate the help thus far also I had planned on the rafter ties however I never drew it in nor did I mention it but thank you for mentioning it.


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[The Tool Tyrant]

I'm confused as to your finished product. You drew one thing then say something else. What EXACTLY is your goal?

I understand that you are doing this in order to hang drywall on the ceiling, but is your ceiling going to be a sloped as per your drawings or are you planing on adding level ceiling joist (you stated you are adding collar ties)?

What is the span of the ridge beam?

Why are you lapping the rafters #1) only on 1 side? #2) why at all?

2X6 DF#2 @ 16"o/c can span 17'-8"
2X8 DF#2 @ 16" o/c can span 23'-4"

Questions, Questions, Questions...

 

[firebirdparts]

Are these beams 25 feet long?

 

[readhead]

It might be cheaper and faster to sister a C to the purlins and attach directly to them. No loss of head height. I have done that in the past where I confirmed that the rigid frames could take the extra load and then sistered a 6" C to the side of the 8" purlin to increase the span load. We then applied hat channels and drywall.

 

[K'ledgeBldr]

I'd do a single LVL for the ridge beam and 9-1/2" TJI's for the rafters/ceiling joists. Doubling/tripling dimensional lumber will not give you the strength that the LVL will. And you won't need intermediate support beams for the rafters with TJI's.

But, all of this really begs the question- if you knew you were going to do this; why didn't you have the roof designed to handle the additional weight of a finished drywall ceiling?

 

[rburke65]

I’m confused. Some photos would be real helpful.

 

[rluckie]

It might be cheaper and faster to sister a C to the purlins and attach directly to them. No loss of head height. I have done that in the past where I confirmed that the rigid frames could take the extra load and then sistered a 6" C to the side of the 8" purlin to increase the span load. We then applied hat channels and drywall.

I really like this idea!


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[rluckie]

I'd do a single LVL for the ridge beam and 9-1/2" TJI's for the rafters/ceiling joists. Doubling/tripling dimensional lumber will not give you the strength that the LVL will. And you won't need intermediate support beams for the rafters with TJI's.

But, all of this really begs the question- if you knew you were going to do this; why didn't you have the roof designed to handle the additional weight of a finished drywall ceiling?

When I had the “shell” built I never even thought about the weight of sheetrock hanging down. Looking back I wish I would have had my purlins spaced every 2’ vs the every 4’ they currently are.


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[rluckie]

I am not home but will take current pictures of what I have and then try to provide additional details and answer some questions. I appreciate everyone’s advice.


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[K'ledgeBldr]

What part of Texas is this build?

 

[rluckie]

What part of Texas is this build?

North Texas


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