Building a 50' x 25' garage with 2nd floor

[EddieWalker]

Interesting that you are cantelivering the second story floor over the garage doors. That should make for a very interesting look that I'm very curious to see the end result.

Why plywood for the sheathing?

Eddie

 

[Builder]

The 5' cantilever creates more of a useable room space for the 2nd floor.

I use plywood more than OSB for sheathing because architects spec it more than OSB. This architect speced plywood.

I actually like OSB, it's easier to handle and lays much flatter.

 

[yooperdave]

Did you get a set of sealed structural calculations from a professional engineer?

I only ask because I have never seen I-series joist cantilever for 5'. Most manufacturers only recommend a 2' cantilever. Are web stiffeners required? A professional engineer would evaluate this due to its uniqueness. A detail of this cantilever length is not typical or usual for I-series joist. It might be ok, but an engineer or technical help from the manufacturer would be a good idea.

A licensed architect saying this is acceptable without documented structural justification is not doing you any favors. I do not know your specifics, but it is not uncommon for an Architect to get a structural inspiration and get himself in a heap of trouble. On the other hand, do not rely on an engineer for Architectural Design Services...

Hoping you are ok

Regards,

Yooper Dave

 

[CurlyDave]

As an amateur, I have a framing question for all you professional builders.

When I look at the framing pictures, I see that there is a separate header for each garage door, with maybe a 1 foot gap between headers. Why is it almost always done this way, instead of one long header over all three doors?

In my first year of engineering school, I learned that a continuous beam is stronger than interrupted beams, so it looks like the beam is deliberately weakened. But everyone does it that way, so there must be a good reason.

In everything I build, I use one continuous header in that kind of a situation, what am I doing wrong? The extra material cost is offset by lower labor costs if the header is continuous.

 

[Red55]

As an amateur, I have a framing question for all you professional builders.

When I look at the framing pictures, I see that there is a separate header for each garage door, with maybe a 1 foot gap between headers. Why is it almost always done this way, instead of one long header over all three doors?

In my first year of engineering school, I learned that a continuous beam is stronger than interrupted beams, so it looks like the beam is deliberately weakened. But everyone does it that way, so there must be a good reason.

In everything I build, I use one continuous header in that kind of a situation, what am I doing wrong? The extra material cost is offset by lower labor costs if the header is continuous.

Dave

I have no professional training but I used your idea when I framed up my garage back in 2001. Did it cause if I ever decided to go to 16' wide door it could be an option. I tripled up the flooring joints for the garage header Didnot use engineered lumber cause solid 2x was less and cost was a factor. Also figured that if one of my sons took out the corner of the garage door the building would still be standing (building dept had no problem I have a habit of asking before changing something)

I was kinda laughing when they come out with this code-plus standards I always rather pay less for more wood structure then engineering fees. Just seems like common sense -Ed

 

[Builder]

Did you get a set of sealed structural calculations from a professional engineer?

I only ask because I have never seen I-series joist cantilever for 5'. Most manufacturers only recommend a 2' cantilever. Are web stiffeners required? A professional engineer would evaluate this due to its uniqueness. A detail of this cantilever length is not typical or usual for I-series joist. It might be ok, but an engineer or technical help from the manufacturer would be a good idea.

A licensed architect saying this is acceptable without documented structural justification is not doing you any favors. I do not know your specifics, but it is not uncommon for an Architect to get a structural inspiration and get himself in a heap of trouble. On the other hand, do not rely on an engineer for Architectural Design Services...

Hoping you are ok

Regards,

Yooper Dave

Thanks for the concern Dave. I know what you mean about the cantilever. The whole project was designed by a commercial architectural engineer. The garage 2nd floor floor joists are 16" tall I-joists and they're on 12" centers.

All the flooor joists have 8' long x 16" high x 3/4" plywood web stiffeners nailed to both sides. (and boy does my aching shoulders & back know it )

The engineer actually only speced 5' long web stiffeners. We decided to make them 8' long just for extra strength. So they go back behind the front wall 3' instead of ending at the wall. If we made them 5', we would have had about 100- 3' x 16" scrap pieces of plywood just being thrown away. So I made the web stiffeners 8' long.

Up on the second floor, we are installing a continuous 2x4 knee wall above the load path of the front wall to help support the roof rafters and put some of their load on the front wall. They also include angled braces.

Same in the back. There's a knee wall with braces to support the back rafters. All the rafters have 2" x 10" ceiling collars on them, too.

The thing I dislike the most about the high floor joists is it forces us to have a 16" tall fascia board on the front. That of course means a 16" tall fascia board aon the sides & back, too. Just looks to massive for my liking.

 

[Builder]

As an amateur, I have a framing question for all you professional builders.

When I look at the framing pictures, I see that there is a separate header for each garage door, with maybe a 1 foot gap between headers. Why is it almost always done this way, instead of one long header over all three doors?

In my first year of engineering school, I learned that a continuous beam is stronger than interrupted beams, so it looks like the beam is deliberately weakened. But everyone does it that way, so there must be a good reason.

In everything I build, I use one continuous header in that kind of a situation, what am I doing wrong? The extra material cost is offset by lower labor costs if the header is continuous.

That's a legit question. In this case, with a 3 car garage, the continuous header would have been 2+9+2+9+2+9+2 = 35' long. You can imagine how difficult it would be to build a wall partition with a 35' x 3&1/2" x 12" parallam at the top. Now add to that that the wall has studs with 3 huge 9' gaps between them. Very difficult to stand up without losing control of it. If it were a continous wall with studs at 16" or 12" o/c and bottom plates, it would be even heavier, but stiffer. It's much easier and still plenty strong if we just build the garage openings one at a time.

Think of the size, weight & "flopiness" of a 35' partition with a 35' continuous parallam.

 

[CurlyDave]

You can imagine how difficult it would be to build a wall partition with a 35' x 3&1/2" x 12" parallam at the top.

When I built my house, the front wall had a 43' long Glulam which served as headers for 22' of windows, the front door, and 4' of cantilever. It didn't seem particularly hard, but thanks for the answer.

 

[Builder]

You can imagine how difficult it would be to build a wall partition with a 35' x 3&1/2" x 12" parallam at the top.

When I built my house, the front wall had a 43' long Glulam which served as headers for 22' of windows, the front door, and 4' of cantilever. It didn't seem particularly hard, but thanks for the answer.

If you put a wall that big up by yourself, then you're a better man than me.

I think the difference here is that the larger (9 foot) garage openings with only an occassional set of legs (studs) in between make it more difficult to handle. In your case, you have a bunch of smaller openings so you also have more studs closer together. I would have done a continuous header like you did, too.
You see, each job presents a different set of challenges to overcome.

I do framing carpentry & construction almost everyday for a living for the last 20 years and find no difference in outcome, strength or customer/architect satisfaction when complete using seperate headers for each door over garage doors.

The architect wanted it built this way and I do my best to make him happy.

 

[CurlyDave]

If you put a wall that big up by yourself, then you're a better man than me.

I doubt that -- I had two other guys helping me. And, I built it in the vertical position. Braced the corners and two studs, & we lifted the beam into place. Then we added the rest of the studs.