Adding Height to Garage Walls

Avadon · Apr 1, 2012

Hello all,

I've been told that if I want to raise my garage wall height that I cannot just add a smaller height wall ontop of the top plate because this will act like a hing point. Is this accurate and if done not to code? I do intend to tear existing roof off and put a gambrel roof on at some point. But how do I go about changing my existing 8 walls to 10 walls?

So far the only thing ive done so far is start furring out the bottom plate to a 2x6. (I want to do a 2x4 staggered stud wall on these walls)

onthefence777 · Apr 1, 2012

Avadon said:
Hello all,

I've been told that if I want to raise my garage wall height that I cannot just add a smaller height wall ontop of the top plate because this will act like a hing point. Is this accurate and if done not to code? I do intend to tear existing roof off and put a gambrel roof on at some point. But how do I go about changing my existing 8 walls to 10 walls?

So far the only thing ive done so far is start furring out the bottom plate to a 2x6. (I want to do a 2x4 staggered stud wall on these walls)

I am no code expert, but just in my opinion it would be a big no no to just build another short wall on. And since you are changing the bottom plate to 2x6, you would need to change the top plates as well to 2x6. Since your studs will be too short even though you want to retain 2x4 just staggered studs, you basicially have to frame up all new walls to do what you want to do. Are you planning on a lift, is that why you want to raise the ceiling?

BD1 · Apr 1, 2012

are you required to get a permit ? Inspection ? Is it building and zoning department for your area saying this ??
I understand the hinge point but if it is sheeted with continuous plywood i would think that would remove the hinge point affect.
What if you jack up garage and add a 2' block wall on top of foundation and when mortar sets up lower bottom plate on top of new wall ? This could be left exposed on the outside without any additional expense for siding.
Or, jack up and cut bottom sill plate loose and replace 8' studs with 10'.
It all depends on location and your local codes.

yzair · Apr 1, 2012

If you add a wall on top in engineering terms its called a hinge affect, any side load could make it fold hence the term hinge. The best way to remedy this is at every other stud on btm wall pass a 4x4 or 2x6 from bottom plate to top plate of short wall, be sure to stitch nail the full length studs or post to existing wall. stud

Zeke · Apr 1, 2012

onthefence777 said:
I am no code expert, but just in my opinion it would be a big no no to just build another short wall on. And since you are changing the bottom plate to 2x6, you would need to change the top plates as well to 2x6. Since your studs will be too short even though you want to retain 2x4 just staggered studs, you basicially have to frame up all new walls to do what you want to do. Are you planning on a lift, is that why you want to raise the ceiling?

He's not changing the plate, only adding to it.

I think the answer is in the staggered studs. Run that new wall to the height you want. You will remove the top plates of the old wall so that the new wall isn't notched. You will then block the old wall at the top and continue it for whatever the outside wall is. Tie that into 2 x 6 top plates.

Avadon · Apr 1, 2012

Zeke said:
He's not changing the plate, only adding to it.

I think the answer is in the staggered studs. Run that new wall to the height you want. You will remove the top plates of the old wall so that the new wall isn't notched. You will then block the old wall at the top and continue it for whatever the outside wall is. Tie that into 2 x 6 top plates.

I guess I can't visualize it exactly. So does the existing wall have 2x10's screwed to the 2x8's (sistered)? and the new wall (the wall closest to the inside of the garage) will have all new 2x10's?

@ the other posts above: I really don't want to jack up the whole garage as as I just finished really securing the heck out of the bottom plate to the concrete and also because I am replacing the roof. The shingles are just about gone and I thought coming up this year would be a good time to do it.

danski0224 · Apr 1, 2012

I would have thought that plywood sheathing inside and out would eliminate the hinge effect.

I do not know if the IRC dictates how much the plywood must cover the old part and new part... or if it is allowed.

Hurricane straps?

I suspect that your local building department has the answer.

Don't forget that you will need to address the siding or whatever your exterior finish is.

I have been contemplating a similar project, and the numbers just don't work out. Lot of $$ for a little desired gain.

Avadon · Apr 1, 2012

danski0224 said:
I would have thought that plywood sheathing inside and out would eliminate the hinge effect.

I do not know if the IRC dictates how much the plywood must cover the old part and new part... or if it is allowed.

Hurricane straps?

I suspect that your local building department has the answer.

Don't forget that you will need to address the siding or whatever your exterior finish is.

I have been contemplating a similar project, and the numbers just don't work out. Lot of $$ for a little desired gain.

Good advice, I think i'm going to head down to my county building department. They really don't seem to be doing much ever down there when I call so I'll go down there and ask them what I can do to code. Even if something cheaper/faster is to code I still might do it the best/more expensive way just because it's my own home and i intend to live here forever.

I think if you intend to tear off your roof and re-build it then it's not such a major change, but failing that, I agree it's a lot of work for a little gain. My garage is my blacksmithing shop. That extra height actually will allow fumes and vapors to get further away from breathing area. Of course air scrubber or air exchanger is also planned.

K'ledgeBldr · Apr 1, 2012

I have run across this on several occasions. My engineers would usually recommend a "modified balloon framing" principle. I used your pic to demonstrate the principle that was used. Basically, you cut the double top plate 1-1/2" to allow a 2X4 to be slipped in and sistered to a existing stud. This would be carried out on every other stud. This was usually used on gable end walls. In your particular case (present framing) a truss gable end is sitting on top of a standard double top plate wall. There is a standardized framing sequence for that scenario (not worth explaining for your case), but nobody ever says anything about it or enforces the bracing criteria that I've ever had to deal with.

The other way deals with bracing off of a diaphragm (floor or ceiling). Again, using your proposed plans-
If you added a 2' kneewall on top of the existing walls, then added a floor system (the diaphragm) on top of that, then used a diagonal brace from the the mating region of the kneewall and existing wall that doesn't exceed 45* will effectively eliminate the "Hinge Effect".
Every PE has a different take on the principles involved. They also have to take into account regional wind loads; but as I say before, I've dealt with this many times. And the "fix" is usually something as I've outlined.

danski0224 · Apr 2, 2012

K'ledgeBldr said:
I have run across this on several occasions. My engineers would usually recommend a "modified balloon framing" principle. I used your pic to demonstrate the principle that was used. Basically, you cut the double top plate 1-1/2" to allow a 2X4 to be slipped in and sistered to a existing stud. This would be carried out on every other stud. This was usually used on gable end walls. In your particular case (present framing) a truss gable end is sitting on top of a standard double top plate wall. There is a standardized framing sequence for that scenario (not worth explaining for your case), but nobody ever says anything about it or enforces the bracing criteria that I've ever had to deal with.

The other way deals with bracing off of a diaphragm (floor or ceiling). Again, using your proposed plans-
If you added a 2' kneewall on top of the existing walls, then added a floor system (the diaphragm) on top of that, then used a diagonal brace from the the mating region of the kneewall and existing wall that doesn't exceed 45* will effectively eliminate the "Hinge Effect".
Every PE has a different take on the principles involved. They also have to take into account regional wind loads; but as I say before, I've dealt with this many times. And the "fix" is usually something as I've outlined.

How would you address interior walls that are closed in (finished)?

danski0224 · Apr 2, 2012

Avadon said:
I think if you intend to tear off your roof and re-build it then it's not such a major change, but failing that, I agree it's a lot of work for a little gain. My garage is my blacksmithing shop. That extra height actually will allow fumes and vapors to get further away from breathing area. Of course air scrubber or air exchanger is also planned.

I would also appreciate the extra height and it would provide a whole lot of space (about 100 lineal feet) for a shelf on the wall.

Most of the interior is finished off, though.

djkeev · Apr 2, 2012

What are you trying to gain?
A shelf on the wall?
A higher ceiling?
Useable attic space?

A higher ceiling, fast easy cheap would be a scissor truss. The ceiling would vault up to a peak.

You could also use a raised tie truss which will give you an angle from the existing wall but at a two foot high point would be a flat ceiling.

An attic truss will give you a "free" useable room above your garage.

You might talk to a truss company and see if they can combine a raised tie truss design with an attic truss design. That would give you be best if both worlds.
They could also give you the roof line you desire as well.

As a builder, I must wonder if the process of adding two feet, which presents some significant obstacles on an already finished structure is cost effective. The expense of retrofitting may not be worth gaining a shelf.
A higher ceiling? Easy peasy cost effective by using trusses.

Dave

danski0224 · Apr 2, 2012

Maybe I'll look into the raised trusses.

The room in attic trusses won't work in my application because the village has changed their maximum height rules. Because of this, I would rather have the added space below the ceiling vs more attic space. It boils down to either a 6:12 pitch roof and existing walls or 4:12 pitch roof and 2 extra feet below the ceiling.

Yes, the cost is difficult to justify, but it could be some nice extra space.

Moving and building something close to what I want is not an option. Becoming "self employed" has changed a lot.

Charles (in GA) · Apr 2, 2012

This has been discussed several times in the past 6 months on here. Also, Youtube has several videos (time lapse in a case or two) of raising a building and adding to the wall.

Charles

K'ledgeBldr · Apr 2, 2012

danski0224 said:
How would you address interior walls that are closed in (finished)?

Drywall is cheap.
Especially when you compare it to catastrophic structural failure.

darkk · Apr 2, 2012

After the existing roof has been removed, I would raise the walls,and build a 2' block wall beneath it. Then when it is cured, drop the walls back down and install the new roof.

Avadon · Apr 2, 2012

djkeev said:
What are you trying to gain?
A shelf on the wall?
A higher ceiling?
Useable attic space?

A higher ceiling, fast easy cheap would be a scissor truss. The ceiling would vault up to a peak.

You could also use a raised tie truss which will give you an angle from the existing wall but at a two foot high point would be a flat ceiling.

An attic truss will give you a "free" useable room above your garage.

You might talk to a truss company and see if they can combine a raised tie truss design with an attic truss design. That would give you be best if both worlds.
They could also give you the roof line you desire as well.

As a builder, I must wonder if the process of adding two feet, which presents some significant obstacles on an already finished structure is cost effective. The expense of retrofitting may not be worth gaining a shelf.
A higher ceiling? Easy peasy cost effective by using trusses.

Dave

Hey Dave,

Is it possible to get something like the bottom of a scissor truss on grambrel trusses? I intend to take the roof off my garage and raise the wall height. but I want that sloped ceiling. I guess I could always use some of my added height to just install 2x4's or 2x6's that slow from the walls up the bottom of the trusses to hang my drywall ceiling (right?). Or can they actually build a scissor truss bottom component/shape into a gambrel roof truss?

K'ledgeBldr · Apr 2, 2012

See if you can find some truss manufacturers in your area.
Ask them if they can build a Vaulted Parallel Chord truss with a Gambrel profile(?)
It would look something like the image below:

Avadon · Apr 2, 2012

K'ledgeBldr said:
See if you can find some truss manufacturers in your area.
Ask them if they can build a Vaulted Parallel Chord truss with a Gambrel profile(?)
It would look something like the image below:

Wow I had no idea such a truss was even available. That's very much what i'm thinking of. I'll ask my local lumber company what they have that comes close to this.

Thank you so much!
Max

Zeke · Apr 2, 2012

Avadon said:
I guess I can't visualize it exactly. So does the existing wall have 2x10's screwed to the 2x8's (sistered)? and the new wall (the wall closest to the inside of the garage) will have all new 2x10's?

@ the other posts above: I really don't want to jack up the whole garage as as I just finished really securing the heck out of the bottom plate to the concrete and also because I am replacing the roof. The shingles are just about gone and I thought coming up this year would be a good time to do it.

K'ledgeBldr cleared it up. His idea is basically the same as mine.

Adding Height to Garage Walls

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