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[zc15]

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[jack stand]

Trusses or rafters? You mentioning a 10' ceiling on 8' walls.
Is the interior still open framing for a picture?
You should be able to do this and it may be simpler than you're thinking (steel headers, etc). If it's a site built rafter roof the question is the ridge and any center support.

 

[zc15]

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[firebirdparts]

It's pretty peculiar, but yes it's somewhat possible. There's no weight on top of that door. As you can see, you didn't ever have a proper header to begin with.

When you move those ties up, then the strength of the roof is a somewhat affected, and the ability to hold snow up is somewhat affected. The modifications to the end wall are not the problem. The end wall can be super strong compared to what you actually require.

 

[sky jumper]

yep all the load is on the sidewalls. only load on the door header is the weight of the gable end wall itself, and even that is somewhat carried by the end rafters. + whatever load the door opener rail puts on the header = not much. but yeah moving up the rafter ties will be tricky, and reframing the door opening.

i don't recall what code says about header sizes in non-bearing gable end walls. I know my inspector wanted 2-2x12 for a 6ft window header in a similar situation, and I didn't have the desire to argue with him about it. for you a 2-2x8 would probably be just fine, but double check it. in any case it will be cheap and doesn't hurt to go bigger for cheap insurance. if you have to miter the ends to fit it in no big deal. forget the steel/lvl not needed.

 

[zc15]

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[sky jumper]

unless you're planning to store anything of significant weight in the attic, I don't think there's anything to be gained by going with 2x8 ties. or maybe if you're planning to drywall the ceiling, but even then it'll be a short span. save your $$ for the bigger door.

 

[zc15]

unless you're planning to store anything of significant weight in the attic, I don't think there's anything to be gained by going with 2x8 ties. or maybe if you're planning to drywall the ceiling, but even then it'll be a short span. save your $$ for the bigger door.

Drywalling the ceiling plus R38 insulation. Right now the only things up there are extra siding for the house, some golf clubs, and leftover flooring materials from the house. Rather be overkill than not enough

 

[ford33]

As others have stated you can increase the height of the header on the gable.

One item not mentioned is the finished width dimension and construction of the two garage side walls facing you in the picture. Too narrow a side wall or poorly constructed wall and you risk the structure racking and collapsing due to side wind loads, earthquakes, attic loads or snow loads. You are improving the situation by centering the door and making the side walls at the gable end wider. However, check how the side walls are constructed and improve them if necessary. Past construction practices left "portal walls" weak and prone to racking. Current building codes improve upon that situation. Now is the time to do this work.

Search "portal frame at garage door opening" for information on minimum wall widths and proper construction methods. Also see the journal of light construction (JLC) and the Engineered Wood Association. There is also a series of videos showing homes and garages destroyed due to high side wind loads and narrow or poorly constructed garage portal walls.

Simpson strong tie makes some simple brackets to support the header attachment into the vertical wall making for a very strong gable end.

Other ideas, consider a jack shaft garage door opener to save some header space. Use high lift door rails.

Good luck with this project.

 

[sky jumper]

like ford33 said... this is the general idea. a continuous piece of rated sheathing (use plywood) at the upper corner with 3" nail spacing. you can pretty much see what the framing inside looks like from the nail pattern. code also requires strapping on the inside from above the header to below - basically a rated metal strap like the Simpson ones. depending on the clearance from your opening to the roofline you may want to add extra strapping inside and get creative on how you attach it (run it up into the end rafter, etc). you basically want to make that corner as strong as possible.

 

[3onthetree]

I estimate replacing the 2x6 ties with 2x8 ties would only run $400-450 in materials, so I may as well just overdo those. The 2x8's are rated to a 18'2" span in my locale based on the rafter span tables, so raising them up 1/3 and reducing the span by 1/3 will be plenty conservative and still be more than I need for the span.

Not sure if the sentences are the same thought saying new 2x8 rafter ties would span 18'-2", or if you switched gears and are saying the existing rafters are 2x8 and span 18'-2" for your snow load (guessing 20psf?). So if it's 2x8 rafters, if you raise rafter ties 1/3 then .67 of 18'-2" is around 12' span, and assuming the garage width is about 24' - getting close so check your numbers on how high you can raise the ties. For the rafter ties, spanning 24' across with no storage you are at 2x10s at every rafter.

Also, the existing walls on both gable ends have top plates @ 8' which will now be below a higher ceiling. If you move your gable end bracing to the new higher top plate height, you've created a hinge @ 8'. So on the door end a portal frame could counter the hinge. But on the back wall you'd have to either run some gable end braces down to the old 8' top plate, or run some tall studs up to the new ceiling height to brace there and keep a clean ceiling.

Also, does the driveway location play in how far you move the door over, as you don't want to have a little jog to negotiate pulling in and out.

 

[sky jumper]

interesting. my attached garage has 2x8 ceilings spanning 22ft and hold drywall, overhead doors, a bunch of suspended stuff and a **** ton of attic storage. it seems the code has changed since 1984.

i think the OP's span would be closer to 16ft after being raised, if I understand it correctly. 2x8 should work for that, no?

 

[zc15]

I thought rafter span was only 1/2 the width of the garage?

https://www.awc.org/codes-standards/spantables/tutorial

 

[sky jumper]

yes rafter span is 1/2 the width. ceiling joist (aka rafter tie) is the full unsupported width, which is currently about 24' by the looks of it. after you raise them they will be shorter, something like 16' I think? so the question then is 2x8 big enough for 16' ceiling joist? I think yes, although I don't have the span tables in front of me. I'd think 2x6 would work if you don't plan to store stuff up there, but check the span tables.

 

[zc15]

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[3onthetree]

I thought rafter span was only 1/2 the width of the garage?

If your garage is 24' wide with a gable, then the span is 12'. The quick example I used based on assumptions reduced a 2x8 to around 12', which is close, not "plenty conservative." You do the exact figuring of what is existing, the new height, the reduction factor, etc. for a general idea of options.

interesting. my attached garage has 2x8 ceilings spanning 22ft and hold drywall, overhead doors, a bunch of suspended stuff and a **** ton of attic storage. it seems the code has changed since 1984.

i think the OP's span would be closer to 16ft after being raised, if I understand it correctly. 2x8 should work for that, no?

There are many old garages with 2x4 rafters and very few rafter ties holding stored lumber. There are houses where plumbers have made swiss cheese out of floor joists holding heavy dressers. There are decks attached to brick veneer walls holding family BBQs. Wood framing and nails are very forgiving. You'd be hard pressed to find many complete disasters for those scenarios, but would find many, many examples of racking, sagging, cracking mortar, etc. and continuing to deteriorate and cause problems in other ways. So anyone is free to do things by old design standards, rule of thumbs, or by eye tests. Or do things by the (current) book. If you get a permit, a span table saying 23'-10" max fails you if have 24'.

For the "no storage" defined in prescriptive code it is actually 10psf, which in reality easily holds some things. If you know exactly how high the OP's ceiling joists will be, then you can advise him on the ceiling joist size if you'd like.

 

[sky jumper]

well it looks like a 2x6 will get you 16'11" ceiling joist span for #2 SPF and 16" oc (IRC 802.5.1). i admit my trigonometry is rusty, but I believe if you go up by 1/3 in rafter tie height you decrease by 1/3 in the span - i'm talking about lengths not load ratings. something about the law of similar triangles. so if the rafter span is 12' at the wall plates then at 1/3 the way up it would be 8', or 16' all the way across, regardless of the exact ceiling joist height. of course that assumes the garage is 24' wide and he goes up 1/3. if it is more than about 25' wide then a 2x6 will not be code and he'll have to go 2x8, which by the same method is good for up to about 32' wide at the plates and it doesn't appear to be that big. point being its not 2x10.

incidentally it appears my house is still code after all, if I wasn't storing stuff in the garage attic that is.

so question for the OP -- how wide is your garage?

 

[zc15]

well it looks like a 2x6 will get you 16'11" ceiling joist span for #2 SPF and 16" oc (IRC 802.5.1). i admit my trigonometry is rusty, but I believe if you go up by 1/3 in rafter tie height you decrease by 1/3 in the span - i'm talking about lengths not load ratings. something about the law of similar triangles. so if the rafter span is 12' at the wall plates then at 1/3 the way up it would be 8', or 16' all the way across, regardless of the exact ceiling joist height. of course that assumes the garage is 24' wide and he goes up 1/3. if it is more than about 25' wide then a 2x6 will not be code and he'll have to go 2x8, which by the same method is good for up to about 32' wide at the plates and it doesn't appear to be that big. point being its not 2x10.

incidentally it appears my house is still code after all, if I wasn't storing stuff in the garage attic that is.

so question for the OP -- how wide is your garage?

24' wide