Garage Ceilling joist removal.

[Vladmakh]

Hello all.

It's a gambrel (barn style) roof with attic space , semi finished with 5/8" OSB flooring. Bottom level cement floor to bottom of attic joist is 8'7. I'm looking to remove attic floor joists to put a car lift.
I've removed the drywall from the ceilling to find out that my ceilling joist going parallel and a header in the middle where the joist meet, Which to me seems like it's there strictly for the attic since there're not tying the roof trusses.
My idea is to remove all the joist to clear up the space since I have no use for the attic storage. The question is if I remove these joist would that comprise the structure? and if so what could I do in this case to prevent that.

I attaches a few pictures of interior/exterior.
Thanks In advance.

 

[JohnnyK8]

This should be a fun one [emoji6]

Subscribed.

I would like to do this too. But some of the engineering type dudes scared me away. If I do it their way I might as well bulldoze my garage and start over.

Physics is tricky.

Hopefully it's straight forward process for ya. Your roof is different.


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[GMCGarage]

Hello all.

It's a gambrel (barn style) roof with attic space , semi finished with 5/8" OSB flooring. Bottom level cement floor to bottom of attic joist is 8'7. I'm looking to remove attic floor joists to put a car lift.
I've removed the drywall from the ceilling to find out that my ceilling joist going parallel and a header in the middle where the joist meet, Which to me seems like it's there strictly for the attic since there're not tying the roof trusses.
My idea is to remove all the joist to clear up the space since I have no use for the attic storage. The question is if I remove these joist would that comprise the structure? and if so what could I do in this case to prevent that.

I attaches a few pictures of interior/exterior.
Thanks In advance.

If there is a ridge beam (doubtful) you could be ok. If not, what will keep those roof rafters from kicking outwards if you take the joists away?

 

[twalsh16]

Do the joists run front to back, or did i look at the pictures wrong? If yes, then the joists aren't tied to the rafters to begin with, so its only the gussets on the rafter joints and their connection to the top plate that is keeping them from going outwards.

no idea what impact would be of removing joists if they are oriented front to back though.

 

[GMCGarage]

Do the joists run front to back, or did i look at the pictures wrong? If yes, then the joists aren't tied to the rafters to begin with, so its only the gussets on the rafter joints and their connection to the top plate that is keeping them from going outwards.

no idea what impact would be of removing joists if they are oriented front to back though.

It could be the plywood is acting as a diaphragm to transfer the load.

In general, unless your roof has a ridge beam, you need joist ties or something to keep the rafters from spreading out.

 

[Vladmakh]

Do the joists run front to back, or did i look at the pictures wrong? If yes, then the joists aren't tied to the rafters to begin with, so its only the gussets on the rafter joints and their connection to the top plate that is keeping them from going outwards.

no idea what impact would be of removing joists if they are oriented front to back though.

If there is a ridge beam (doubtful) you could be ok. If not, what will keep those roof rafters from kicking outwards if you take the joists away?

It dosent have a ridge beam but I do have a 2x6 Ridge board. I was thinking of installing roof rafters and tying them with 2x4 on top to prevent it kicking out.

 

[Vladmakh]

Do the joists run front to back, or did i look at the pictures wrong? If yes, then the joists aren't tied to the rafters to begin with, so its only the gussets on the rafter joints and their connection to the top plate that is keeping them from going outwards.

no idea what impact would be of removing joists if they are oriented front to back though.

The joist are going from front to back with the header in the middle of the garage.

 

[May Pop]

Those are roof trusses. The plywood connectors on the roof rafters will just pull apart when the joists are removed. So yes it will compromise the structure.
Possibly removing one to make room for the lift "might" be OK but it leaves you with a low ceiling.
Think about what will stop the roof from pushing out the sides when the floor joists are removed.

 

[Shiftless]

If it is OK to do it, and you go ahead and remove those joists are you totally sure you will have enough headroom for the lift you want to install in the spot you want to install it in?

 

[-Brent-]

If there is a ridge beam (doubtful) you could be ok. If not, what will keep those roof rafters from kicking outwards if you take the joists away?

Collar ties.

We've built them without lofts (or in your case, an attic) but we did them a tad bit different since everything was built/fabricated on site. But, looking at the few details you have I think there's a decent chance you can get away with it without too much change pending there's not something funky that cannot be seen in the pics.

In the northeast there are quite a few barns that have been re-purposed and have the loft removed.

 

[-Brent-]

Those are roof trusses. The plywood connectors on the roof rafters will just pull apart when the joists are removed. So yes it will compromise the structure.
Possibly removing one to make room for the lift "might" be OK but it leaves you with a low ceiling.
Think about what will stop the roof from pushing out the sides when the floor joists are removed.

No. The way this building is set you'd need to run collar ties (some will web this area, too).

The beam is the only thing running the direction of the trusses. Likely this was done due to the width and the provision above the door - to keep the build simple.

 

[My Old Tools]

Looks like spreading is controlled by the front and back walls and the beam across the middle. The rafters (floor joists really) are there to support the plywood floor only. I believe the only thing you can't remove is the beam across the middle. As built I bet it didn't originally have a second floor, maybe just a loft across the back supported by that beam.

 

[-Brent-]

Looks like spreading is controlled by the front and back walls and the beam across the middle. The rafters (floor joists really) are there to support the plywood floor only. I believe the only thing you can't remove is the beam across the middle. As built I bet it didn't originally have a second floor, maybe just a loft across the back supported by that beam.

Based on the size of that beam and where it's located, it's hard to tell. The only way to know is exposing the framing to see.

 

[Vladmakh]

Collar ties are all ready there on every other rafter. To me since the ceilling joist are going from front to back it dosent seem like they are there to support the roof.
I will cut the drywall around the header to see what exactly is there and upload a picture.

 

[Vladmakh]

Im going to remove remaining drywall and plywood this weekend. Hopefully get a structual engineer out here.

 

[GMCGarage]

Im going to remove remaining drywall and plywood this weekend. Hopefully get a structual engineer out here.

Good call on getting a professional to check it out. Beats having it collapse on people.

 

[My Old Tools]

Seeing that, I would take them out without a second thought.

 

[GMCGarage]

Seeing that, I would take them out without a second thought.

Did you base that on the nail pattern of the collar ties or the type of glue used on those gussets?

2016 Baltimore had 30 inches of snow in a 3 day period.

 

[Falcon67]

Agree with OldTools - those are floor joists, not rafter ties. They have nothing to do with restraining the walls. And I'd argue, neither do the collar ties. Possibly only that big cross beam is being used to resist wall spread from roof loads. Depending on how it's installed. Maybe not that either.

 

[Falcon67]

http://www.jlconline.com/projects/design-gambrel-roof-structures-and-wind-uplift_o

 

[Zeke]

Im going to remove remaining drywall and plywood this weekend. Hopefully get a structual engineer out here.

Wait, hold the phone — what's that lally column doing?

 

[GMCGarage]

Agree with OldTools - those are floor joists, not rafter ties. They have nothing to do with restraining the walls. And I'd argue, neither do the collar ties. Possibly only that big cross beam is being used to resist wall spread from roof loads. Depending on how it's installed. Maybe not that either.

More than likely the plywood is transferring the load. Think of a cardboard box, not very stable until a lid is on it. Plywood is acting as a lid.

The beam is to break up the joist span front to back.

Any rafter/truss without a ridge beam, collar tie or flat bottom will have some horizontal load. Something has to control that load.

The OP is doing right by engaging a professional. If he or she says it will be alright, they have at it.

 

[dave*99]

This article gives some interesting perspective on Gambrel roofs
http://www.jlconline.com/projects/design-making-gambrels-work_o

 

[GMCGarage]

This article gives some interesting perspective on Gambrel roofs
http://www.jlconline.com/projects/design-making-gambrels-work_o

http://www.jlconline.com/projects/design-gambrel-roof-structures-and-wind-uplift_o

Take a look at the profile of his roof. Very shallow rise. More outward thrust than there is downward thrust. Not a true Gambrel roof, but just gambrel shape.

 

[Vladmakh]

I was thinking of actually of leaving 2 joists on each side of the garage and adding additional 2x6s horizontally to tie it all together in front and the back. That would free up the middle portion of the garage that I need, it will eliminate the header and will also keep the structure together.

 

[GMCGarage]

I was thinking of actually of leaving 2 joists on each side of the garage and adding additional 2x6s horizontally to tie it all together in front and the back. That would free up the middle portion of the garage that I need, it will eliminate the header and will also keep the structure together.

How far from the side wall can you come in with your joist? You could create a deep beam with the plywood that would help stiffen the side walls and transfer the load to the endwalls. Might discuss that with your engineer

 

[LX-Markham]

Take a look at the profile of his roof. Very shallow rise. More outward thrust than there is downward thrust. Not a true Gambrel roof, but just gambrel shape.

Was thinking the same thing, very shallow for a gambrel roof design.
Agreed that the floor is acting as a diaphragm to brace the walls.

 

[ard]

Also keep in mind when discussing 'the impact of modifications' that you may be starting with a questionable structure.

I cannot see where the lateral wall forces can be adequately resisted- plywood flooring seems inadequate....

 

[Vladmakh]

Also keep in mind when discussing 'the impact of modifications' that you may be starting with a questionable structure.

I cannot see where the lateral wall forces can be adequately resisted- plywood flooring seems inadequate....

The structure is definitely not in question in my opinion. It stood thru crazy amounts of snow. In my opinion the way the ceilling joists are installed ( front to back) underneat roof trusses it's very doubtfull it's supporting roof in anyway. I've been contacting a dozen structual engineers without hearing back from them in last couple of weeks.

 

[mr48chev]

I was thinking of actually of leaving 2 joists on each side of the garage and adding additional 2x6s horizontally to tie it all together in front and the back. That would free up the middle portion of the garage that I need, it will eliminate the header and will also keep the structure together.

A friend of mine did that when he modified a couple of trusses in his shop to put a two post in. It's actually boxed in and the vehicle is raised up into the box between the other rafters.

 

[ard]

The structure is definitely not in question in my opinion.

With all due respect- and not being snarky- you arent a structural engineer.

The point I am making is that the structure may be borderline, and has not failed- you whack stuff out, maybe not a long term plan.

While I recognize that getting an engineer out for a free consult will be a challenge, just because a dozen didnt respond doesnt mean you should just go ahead..

I wonder what our resident structural engineer bill (bczygan) would say....

 

[dave*99]

Take a look at the profile of his roof. Very shallow rise. More outward thrust than there is downward thrust. Not a true Gambrel roof, but just gambrel shape.

I do see that. And it is possible the plywood floor is providing some collar tie. It appears that a true gambrel design can be achieved without collar tie. But if the pictured design in the OPs garage is not a true gambrel.... YMMV.

I also had trouble getting a structural engineer to help me, but I had a framing contractor dig one up for me and finally got the answers I needed.

 

[GMCGarage]

Also keep in mind when discussing 'the impact of modifications' that you may be starting with a questionable structure.

I cannot see where the lateral wall forces can be adequately resisted- plywood flooring seems inadequate....

you are distributing it on a per foot basis....say 200 lbs/ft as an example, plywood can clearly handle that, and a couple nails will transfer the load and then transfering it down the floor to the side walls.

Seems 200 lbs/ft would not be alot, but take that floor out, and now you have that 200lbs/ft pushing outward on a wall that is 8 ft tall. At the base, thats 1600lb-ft overturning on that wall. Not going to work....for long.

 

[Orionrising]

You may want to find out what your town would require if you just pulled the whole roof off. Should only be a couple k in material to replace with scissor trusses. Especially if the shingles are near the end of life. How do they look?

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[LX-Markham]

You may want to find out what your town would require if you just pulled the whole roof off. Should only be a couple k in material to replace with scissor trusses. Especially if the shingles are near the end of life.

I like this idea.

 

[Orionrising]

I like this idea. [emoji106]

And if you take it down careful you'd pretty much only need trusses and shingles plenty of plywood for sheathing and lumber to ripdown for bracing. Price the trusses might cost less than an engineer.

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[GMCGarage]

You may want to find out what your town would require if you just pulled the whole roof off. Should only be a couple k in material to replace with scissor trusses. Especially if the shingles are near the end of life. How do they look?

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What would resist the load from the scissor truss?

 

[Trey T]

OP: How much height do you need to gain? If you can't find a professional, you need a backup plan. Let's see if anyone here can be helpful to you.

Everyone: If the OP wants to gain 3-4ft up, what are his choices (besides consulting a SE)?

 

[Orionrising]

Trusses are designed to be a vertical load so there is no spreading force. However if his jurisdiction has hurricane wind codes etc there could be other considerations.

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[GMCGarage]

Trusses are designed to be a vertical load so there is no spreading force. However if his jurisdiction has hurricane wind codes etc there could be other considerations.

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That is not true for a scissor truss. If its a sloped bottom chord, it will have a horizontal component unless you design the truss so there is zero deflection. As it moves down, it moves out.