Can I Vault this Ceiling?

[Colin Len]

Let me preface this post by saying that I know the best thing to do would be to consult an engineer. Please, no need to restate this if that's your only input. I'm simply looking currently to get some general knowledge and direction from GJ members who may have some experience or insight to help me know if I'm barking up the wrong tree or if this is a worthwhile direction to keep figuring out. This is a very small garage so I'm looking to maximize everything I can. A few inches of ceiling height makes a big difference in this tiny space and something as simple as being able to do a high lift garage door that followed the rafters would give me a TON of extra clearance.



Background:
There's a little bit of backstory in my thread, here. It's an older house with a small, detached garage. It's a basic open gable design with 2x4 rafters @24" OC and a 2x6 ridge board. Originally, there were a couple small collar/rafter ties and a couple "ceiling joists"/rafter ties in place. You can see some of this in the photos in my thread linked above. However, it's hard to see due to the storage the previous owner installed.

Unfortunately, the aforementioned storage was not intelligently installed and resulted in significant downward forces on the ridge board (which was not intended to be load bearing. This and other factors caused the ridge to sag about 3" and there was also sagging similar to this picture:

When I had the roof replaced I had someone come in and fix the roof sag. Ideally, I should have just vaulted it at that time but I didn't have the money then and it would have triggered a bunch of permitting issues. Below are some photos of how the sag was fixed - basically a parallam beam was installed directly under the ridge board which allowed for extra supports to be added and hold the roof back up where it was supposed to be (roof was jacked up with hydraulic jacks then supports nailed in place).

• Vertical 2x4's were installed between the parallam beam and ridge board to take the sag out of the ridge.
• Some "ceiling joists" were installed between the parallam and the front/back walls. Some truss-like supports were added to jack up and support the faces of the roof.

I realize that the parallam beam isn't going anywhere, but keeping that in mind I'm wondering how much of this framing I can remove in order to open up the ceiling. I'm wondering if it'd be possible to keep the beam, possibly even add some additional support between the beam and ridge board and then remove the "truss-like" supports. And if those supports can't be removed outright maybe there's a way to replace them with better looking/less obtrusive supports that would allow me to open up the ceiling more.

Here are some thoughts/questions/ideas I was hoping for some thoughts on:

1. The roof repair was done 4yrs ago, is there any chance the sag has been fixed long enough that it wouldn't come back if the supports were removed? Talking about the roof faces here (rafters) not the ridge board. I'm assuming if the "truss-like" supports were removed it would likely sag again. Thoughts?
   
2. I've heard that adding spray foam can add a lot of rigidity to a structure. I plan to insulate the garage and was wondering if spray foam on the underside of the roof might help prevent it from sagging?
   
3. Similarly, how helpful would it be to sister a 2x4 or 2x6 to each rafter? If I sistered new 2x's wouldn't that prevent the sag in the original rafters from coming back?
   
4. If the ridge board is sufficiently supported by the beam, are the ceiling joists still needed? My understanding is that they are there to help prevent the weight of the roof from pushing the walls outward. But, if the ridge board is supported my understanding is that the rafters would then essentially be holding the walls in place rather than pushing them outward.

I'm obviously no engineer but I feel like there's got to be some kind of compromise here. Some way I can remove the obstructive framing supports entirely or replace them with a different design that's less obstructive. So, is there some possible option here or is this a tear the roof off and start from scratch kinda thing to achieve better overhead clearance?

 

[fourbyford]

I'm not an engineer either... but, here goes... lol

I agree with your thoughts on the paralam beam. The vertical 2x's transfer the load from the ridge to the beam so, as long as the beam was sized correctly, that part should be good.

I looked (maybe overlooked) for the size of the garage? More specifically, the length of the rafters. I know, years ago, it was very common to use 2 x 4's for rafters but, with a shallow roof pitch, they may not be up to the task. I would think that if you're willing to sister 2x6's onto all of the existing rafters, you might get by with removing the "truss like" structures. It doesnt look as if you need to be concerned with snow load... I'm guessing you don't have extremely high winds? If this were my project, I'd sister the rafters, remove the structure and get some measurements across the walls... and watch for movement. If you do sister the rafters, I would use a good quality urethane construction adhesive and good quality nails or screws to attach them. I would also use a 2x and a hydraulic jack to make sure the 2 x 6 is firmly pressed to the underside of the roof before fastening.

Spray foam can add rigidity to a building but, in this application, I'm not sure the foam alone would give the result you're looking for. If you sister the rafters, spray foam might be worth the price of admission. Adding OSB to the underside of the roof (after all wiring/insulation is in place) would also add rigidity.

I think you're on the right track... I think this is something that can be done!

HTH...

...D

 

[cvairwerks]

You’ve got band-aids on band-aids. The easiest solution without calling in a licensed structural engineer, is to convert over to carriage type doors. No additional weight on the roof structure, but some driveway space loss when swinging the doors. Doors could be built as two part folding doors for each side too.

You won’t gain any rigidity or overhead space without extensive rework, and might end up being less hassle and cost to rebuild from scratch. That of course comes with it’s own set of challenges, but it might be worth it in the long run. Something to consider....

 

[firebirdparts]

There is very little reason to resist what you want to do, as long as the beam stays. It’ll be fine. However, I’m surprised you want to. To take your “joists” Out over the door is harmless but also fruitless. Obviously you have some job you want to do with the door in the “attic” but I don’t know what that is.

Rafter ties are usually important, but The building was built without them and your solution didn’t rely on them. yours don’t have any strength and they aren’t doing anything in this case.

2 x 6 rafters should have been Very adequate. Are those 2 x 4’s? If so that’s insane.

 

[Loose Nut Buster]

My thought would be to buy maybe like two gable & eight+- scissor truss and give It a pitch to your liking for headroom, you could even add some height too the walls if needed. A whole new garage effect for the cost of a roof.
Just a thought

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[Loose Nut Buster]

Just an example with a 14/12 pitch, just put in LEDs. Amazing difference.

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[The Tool Tyrant]

Private message sent.

 

[Gotcha640]

I would not be able to vault that roof, but I bet this guy could

 

[nadogail]

IMHO, Give me enough Time and Money I can make almost any mistake or design error go away.

The question now, IMHO, is there any limit to the time and money available?

 

[Innovate1]

When the beam was added it could have been put higher since the main point was to hold up the ridge. Then the ceiling joists could have been added at an angle to make something similar to a scissor truss. That would have added very little cost at the time but now it is a major project. You say you avoided permits but I'll bet the AHJ would have thought differently since you cut the cross ties and attached them differently. My only point is that if you say making it a scissor truss with lifted beam would have triggered permits I think you were already there but somehow you and your contractor convinced yourselves you didn't need one.

OSB will add rigidity against racking but does nothing for sag - actually makes it worse by adding more weight. Only way it would help is to use in on the sides of the trusses.

Sistering the rafters will help with their sag but you should use a bigger board. A 2 x 6 will hold a lot more than a 2 x 4 and likely sag less than two 2 x 4s. To resist sag a taller board is MUCH better.

 

[Bigblockyeti]

Well, I am an engineer, but I'm not licenced in CA so take this for what you paid for it. You are correct, the beam isn't going anywhere, don't remove any of the rafter supports, it's likely the rafters wouldn't sag immediately, it is likely they would again over time.

If I were you, I'd place some shelving along each gable wall high enough to clear the garage door rails and keep everything up there light. If you need to put something heavy up there (and have the ability to do so safely) I would run a beam, probably 2x6 under the front edge of the shelf and run legs from there down to the floor so the only load the wall sees is compression.

 

[fourbyford]

[/Quote] Sistering the rafters will help with their sag but you should use a bigger board. A 2 x 6 will hold a lot more than a 2 x 4 and likely sag less than two 2 x 4s. To resist sag a taller board is MUCH better.[/QUOTE]

...this is the reason I was curious about the span... depending on the length of the rafters, 2 x 8's may be required to resist sag... hard to determine until we know the length.

...D

 

[fourbyford]

Innovate1 brought up a good point... it may be feasible to raise the height of the paralam beam... as long as it can be adequately supported. That and strengthening the rafters might get you where you want to be!

...D

 

[Innovate1]

Cross ties are really needed to keep this whole thing together. Raising the beam would eliminate the cross ties, minimal as they are. Particularly since the roof slope is the wrong way on the building, and rafters bear on the overhead door beam, instead of a non-load bearing end gable being over that door beam.

I would hope to see a simpson strap tie tying the cross ties together under the middle parrallam, where they are hidden by the lights. Given the quality of the rest of the remodel work on the roof, I have no doubt they're there.

I am not suggesting to remove the cross ties. Just angle them up to the raised beam similar to the way a scissor truss is. With the beam supporting the ridge there is very little (theoretically zero if all the ridge load is on the beam) side force on the walls. It would still be a lot of work but it is possible. Probably only feasible to raise the beam about halfway to the ridge without serious study and it would require well thought out bracing to keep the beam supports from folding up - no joints in the support post at the top of the existing wall and cross bracing in direction of the beam.

You could also raise the cross ties to the top of the beam or just above it without moving the beam but that would need bigger rafters running up to at least the next brace point above the cross tie. Much less work and worry than moving the beam.