Truss Modification for Car Lift

[Falcon67]

> there isnt going to be any more weight than there was originally.
Not an engineer but had pretty much come to that conclusion after looking at it. If anything, point loads from the end doubled rafters (rafters here not trusses) are just closer to the ends of the header.

I'm now really wishing I'd run the breaker box feed to the middle of the shop, because every power circuit in the place, except for two, run across the lift area. Lotsa splicing to be done.

 

[RyanEricW]

> there isnt going to be any more weight than there was originally.
Not an engineer but had pretty much come to that conclusion after looking at it. If anything, point loads from the end doubled rafters (rafters here not trusses) are just closer to the ends of the header.

I'm now really wishing I'd run the breaker box feed to the middle of the shop, because every power circuit in the place, except for two, run across the lift area. Lotsa splicing to be done.

Honestly I think the engineer is wrong with his statement, I have 3 2x4 trusses I'm removing. I added 4 girder trusses that are at least twice their size. Plus I'm adding purlins.

Maybe he's just saying that to alleviate any worries, but I would think it's a just a little more weight overall (just my opinion)

Unless anyone else sees it differently

 

[lakeroadster]

You are correct RyanEricW, there will be more weight on the header now than there was before the modification. Additionally instead of uniformly spaced loads at 24", the loading now varies.

Not saying it is excessive, or a problem, just more of a load, in different locations. No way to say definitively without measuring the parts and running the numbers.

Did you ever say where you are located?

 

[RyanEricW]

You are correct RyanEricW, there will be more weight on the header now than there was before the modification. Additionally instead of uniformly spaced loads at 24", the loading now varies.

Not saying it is excessive, or a problem, just more of a load, in different locations. No way to say definitively without measuring the parts and running the numbers.

Did you ever say where you are located?

Here, we have very high snow loads, and he took that into consideration + adding a full finished ceiling. When we were originally speaking, he was going to have me do 2x6 top chord, 2x6 bottom chord. The new girder trusses are overkill for the load, but even the original design from what I was told is way overbuilt than necessary.

The only thing I was actually really worried about was the top plate cut, but seems that's a common thing people do, especially with plumbing pipes. Most people seem to repair them with simpson steel ties. I'll be reinforcing with boards on top/bottom and verticals too, so I don't foresee there being any problem with it unless anyone else has any other ideas.

Thank you

 

[Falcon67]

I don't see the load on the door overhead as an issue because the weight per sq/ft of roof load will not change between having three 2x12x24' beams running between the walls vs them not being there. The point loads should not move because the rafter tails don't move anywhere. The only issue would be the potential for some increased outward deflection on the beam/rear wall because of the loss of the three connectors. I figure the total roof load over my lift area at about 1200 lbs. (About 280 total sq/ft). That looks like about 120 lbs landing at each rafter tail - the 3 in free air plus the tails on each side of the opening x both walls - 10 total load points.

I WOULD see loads move IF I ran a beam under the ridge board and took the roof loads down to trusses at each end of said beam.

 

[LX-Markham]

When I cut them, I literally saw no deflection.

I believe manwithtools is referring to the fact that the top plate is part of the shear wall system. The sheathing, along with the wall studs and the top and bottom plate all work together to provide lateral resistance.

The "patch" detail should definitely be checked out by your structural engineer.

 

[LX-Markham]

Hats off to LX-Markham. Slick design that is very strong..

Thanks!
There was a lot of design work and engineering that went into it.

 

[Falcon67]

Thanks!
There was a lot of design work and engineering that went into it.

Pictures of napkin scratching Jethro ciphers or it didn't happen

 

[RyanEricW]

1) Grabbed sixteen 2x6x10s, joist hangers, etc.

2) Raised the trusses on back wall, slid 1x4 oak under heel to compensate for material removed. This leveled out the trusses.

3) Started hammering 10D nails in by hand, said screw that and went back to menards to buy a framing nail gun. Store didnt have ribbed shank, 10D nails, only smooth for nail guns wtf? Had to buy stainless steel ribbed 10Ds.

4) Bought special truss binding screws with a large head to secure top and bottom chords together.

5) Started nailing. Top chord, 2 rows of 10Ds across entire 26' span, 9" apart staggered pattern. Approx 50nails.

6) Web members single row 9oc, approx 20 nails

7) Bottom chord, same as top approx 50 nails.

8) REPEAT FOR OTHER SIDE

9) Cut 5 out of 16 perlins to 111 3/4", installed using 2x8 joist hangers manually with only 2 10D ribbed shank nails per joist hanger for now...

I really hope I dont have to beat 10D nails in manually for each hanger. 8 nails a hanger for 12" oc perlins is exhausting through these trusses

 

[lakeroadster]

Buy a pneumatic palm nailer. That's what the guys used that built my barn.

Best $60 you'll ever spend..... http://www.homedepot.com/p/RIDGID-3-1-2-in-Full-Size-Palm-Nailer-R350PNF/207103093

In regard to the number of nails per hanger, ask the truss engineer if they drawings do not specify. FWIW, on my barn, every hole has a nail.

 

[RyanEricW]

Buy a pneumatic palm nailer. That's what the guys used that built my barn.

Best $60 you'll ever spend..... http://www.homedepot.com/p/RIDGID-3-1-2-in-Full-Size-Palm-Nailer-R350PNF/207103093

In regard to the number of nails per hanger, ask the truss engineer if they drawings do not specify. FWIW, on my barn, every hole has a nail.

Andddd this is why I love the internet. My shoulders will thank you for that tip. Didnt even know that existed! Looks like it'll work for joist hangers too.

I plan on using all the holes but I have to ask what length he's requiring, if they're working in shear, I dont see a point in going into the 2nd truss if the two trusses are ply'd together

Ill ask though before I go any further.

Still have to add some cripple studs and what not, but I'm hoping to finish this next week. Unfortunately I can only get help on Saturdays, and always try* (note try) to rest on Sundays lol

 

[lakeroadster]

I plan on using all the holes but I have to ask what length he's requiring, if they're working in shear, I dont see a point in going into the 2nd truss if the two trusses are ply'd together

Ill ask though before I go any further.

While you're asking... did the engineer specify the type of joist hangers? The reason I ask is the hangers they used on my barn were designed to be toe nailed. There are about as many hanger designs and types as there are stars in the sky....

You know that lateral support that you removed early on that ran along the bottom chord of the trusses? Your new construction won't allow for that brace, so the new trusses and purlin sub-***'y has to deal with that lateral loading.

There are various ways to do this... again, something prudent for you to ask the engineer about.

Here's the detail of how the purlin to truss connection is on my barn. Be sure to get your engineer to specify what is needed for your application, but this detail may spur some discussion and thus help you to get answers to your questions:

 

[jdieter]

RyanEricW, I've red this thread a couple of times and don't understand with the purlin solution how the tension in the removed original lower truss chords is accounted for. Sorry if I'm rehashing a prior explanation but can somebody help me out.

 

[LX-Markham]

the top chord is being supported by the new purlins, so there's no tension in the bottom chord anymore.

It's looking really good Ryan. Although I'm surprised you needed that many purlins? Really just needed the purlins to support the old truss at the panel points.
And +1 on the palm nailer.

 

[RyanEricW]

I purchased the palm nailer above. Makes installing 10D nails so easy I feel like I'm cheating somehow.

If I ever sell my home, some guy in the future is going to wonder why I have like 10 nails in a piece of wood by the garage door lol.

As I thought, the engineer said the purlins will account for the lateral load. I only removed the lateral brace up until where it meets the new trusses. Since I tied the bottom chord of the old and new trusses together, it should all be as 1 unit now.

As far as connecting the OLD 2x4 top chords to the purlins, we both debated about this in the beginning, since the 2x6 sit UNDER the 2x4s perpendicular. The only two that we found that could work are JUS28 joist hangers and RT7 hurricane ties. Surprisingly he's not entirely sure which I should use 100%, but since the main purpose of tying the OLD top chords to the perlins is to resist uplift, I'm going to lean towards the RT7.


Honestly, this thing feels so overbuilt, I'd be surprised if it can't handle 10x more load than originally lol.

 

[RyanEricW]

the top chord is being supported by the new purlins, so there's no tension in the bottom chord anymore.

It's looking really good Ryan. Although I'm surprised you needed that many purlins? Really just needed the purlins to support the old truss at the panel points.
And +1 on the palm nailer.

You are exactly right. Before the top chord transfers the weight through the web members and into the bottom chord, and out and down through the walls into the foundation. Now, the weight is transfered from the top chord, to the perlins, to the gable trusses, down the wall, into the foundation. This allows me to remove the existing web members and bottom chord of the old trusses only after the modifications are completed.

After installing these I'm feeling the same way about the necessity of 12" OC. I probably would be fine with 24" OC, but I think since the engineer for the company is too far away, he's having me overbuild instead of risking under building it.

That's pure speculation though. These 2x6s are very strong placed sideways.


After interviewing a couple people out my way for this job, and seeing all of the different methods proposed, this method I'm using from the truss manufacturer was the most solid. One guy wanted to install a ridge beam, and double up the 2x4 top chords, and tie it into a board running across the span of my garage (sounded sketchy).

Another guy said he could do the perlin design without buying trusses, and fabbing up his own frame work, but again I had no paperwork on that and didn't feel confident in that decision.

The other guy I wanted to come by to do this work has been busy helping out some elderly people that had a tree fall into their home, so he's been *******.

The only thing I didn't like and am still possibly worried about is when I cut into the wall plate, but everyone seems confident this isn't an issue once reinforced with steel and wood framing.

 

[jdieter]

RyanEricW, if you find the time when you complete the project would you provide a brief summary and a few detail pics. I've been researching raising my 9ft. ceiling under the 4/12 roof ever since I installed a lift. The previous owner installed skylights and sistered three trusses together at each skylight location. I've since removed the skylights for a variety of reason and fortunately there are tripled trusses on each side of my lift bay. That makes your solution the simplest once I work out a structurally safe method to increase the top cords height to accommodate the purlins.

 

[RyanEricW]

RyanEricW, if you find the time when you complete the project would you provide a brief summary and a few detail pics. I've been researching raising my 9ft. ceiling under the 4/12 roof ever since I installed a lift. The previous owner installed skylights and sistered three trusses together at each skylight location. I've since removed the skylights for a variety of reason and fortunately there are tripled trusses on each side of my lift bay. That makes your solution the simplest once I work out a structurally safe method to increase the top cords height to accommodate the purlins.

Will do sir, stay posted for next Saturday/Sunday for when I finish this project up

 

[RyanEricW]

Installed the rest of the perlins (22 total)
44 joist hangers with 12 nails per hanger
Then installed rafter ties at all connections to old top chords to new perlins.
88 rafter ties with 10 nails per tie
Almost done. Need to reinforce the wall under the new truss heels and then cut out the old truss web members and bottom chords to finish this project up.

I'll probably be adding 4 more perlins after the web members are cut down. Right now I could probably fit 2 at the peak of the roof, and 1 on each end by the heel.

 

[lakeroadster]

Lookin' Good.

Are you planning on leaving the short section of the lower chord where the mending plate is attached?

Seems like that would make sense, just follow the roof line along the bottom of the purlins?

 

[RyanEricW]

Lookin' Good.

Are you planning on leaving the short section of the lower chord where the mending plate is attached?

Seems like that would make sense, just follow the roof line along the bottom of the purlins?

I actually planned on trying to make this look as unmodified as possible. So I was going to remove the nail plates entirely, thus removing the whole bottom chord at each end.

What are you thinking??

 

[lakeroadster]

I actually planned on trying to make this look as unmodified as possible. So I was going to remove the nail plates entirely, thus removing the whole bottom chord at each end.

What are you thinking??

Something like shown below.

Black is Existing
Red is Purlins
Blue is Ceiling

Not removing the truss nail plates that are near the wall plate will be to your advantage.. they'll add considerable rigidity to your finished assembly.

Typically the lower chord is what is attached to the wall plate, not the top chord, so you couldn't remove it entirely in any event.

 

[RyanEricW]

Something like shown below.

Black is Existing
Red is Purlins
Blue is Ceiling

Not removing the truss nail plates that are near the wall plate will be to your advantage.. they'll add considerable rigidity to your finished assembly.

Typically the lower chord is what is attached to the wall plate, not the top chord, so you couldn't remove it entirely in any event.

Gotcha, makes sense, I ended up just cutting it off like you had shown, just didn't add any extra purlins.

 

[RyanEricW]

Finished. Installed 3 ply studs under the top wall plate where the heel of the new trusses sit, had to reroute some electrical and such, then cut the trusses.

Didn't even see any deflection when I cut the roof, nor did I hear any popping or anything. Very confident in the look and feel of this and can now raise my car up all the way without any question

 

[RyanEricW]

Picked up a 20 gallon drain tank, and a couple tripod jack stands too

All I need is an alignment system, a wheel balancer, and tire installer and I'll have a full service shop in my garage lol

 

[LX-Markham]

Well done!


....except I used my reclaimed truss pieces for other projects, instead of burning them LOL.

 

[sean Buick 76]

Congratulations it turned out great you should be proud!

 

[prostreetamx]

I have a 14' ceiling in my new garage just for that reason. I do plan to install a taller 2 post lift. Even though I used pretty common 4/12 pitch prefab trusses, my local codes required that they were engineered and the cost of that was about 10% of the purchase price of the trusses. I would find a local truss manufacturer and have the draw up a few replacement trusses to your new specs. I would install them next to the existing units before cutting out parts of the old trusses. I would leave as much of the original trusses intact and tie them to the new trusses. A common fix I have seen in the field for modified trusses is to glue and plywood both sides of any modified or damaged truss. It will be tricky to install a hole truss next to your existing one but you can remove the soffit overhang tails without losing any structural integrity and angle them in place. You will probably end up with a scissor design to provide the clearance needed but even tough the bottom plates will be on an angle. The engineering and structure in that design will prevent the outer walls from bowing out. I used to wire some pretty big track homes in one development that used the cut and stack method for the roofs due to the complex roof structure they needed to create the fancy roof. They had one design where the interior walls that met near the center of the house had different ceiling heights. They met at a center load bearing wall with about 4' difference in ceiling height. The top cords for each ceiling were tied to the wall at different locations with no extra bracing. Once the tile roofing was placed on the roof, the center wall started to bend allowing the outer walls to spread out since there was no continues lower ceiling tie to stop it. This design flaw was noticed after the houses were finished and required a bunch of extra angle braces in the attic to solve it. It's not brain surgery but a proper fix before you have a issue is the way to go. Being in construction for many years has helped me look at these issues differently. A simple fix now will save a lot of headaches later. I am currently building a 30x38' garage that I thought I could build for about $25k. I'm well over $40k now with all the extra code and engineering updates that didn't exist when I built my previous 25x30' garage about 20 years ago for about $10k.

 

[GLTHFJ60]

Nice work!!

 

[lakeroadster]

Congrat's. It's been interesting watching this go from your concept to a reality.

Tell us more about your Camaro...

 

[laser3kw]

here is how mine was built. I requested a "bay area" and a "shop area".
They put scissor trusses over half and attic trusses above the rest. The bay area has a vaulted ceiling with 16ft to peak. The shop has 10 ft ceiling with a 5-1/2 ft attic space above. All is insulated and finished.
pics are after sign off and one after inside was done

 

[LX-Markham]

^^^I like that plan. Well done. Jealous of the extra attic storage space.

 

[sean Buick 76]

here is how mine was built. I requested a "bay area" and a "shop area".
They put scissor trusses over half and attic trusses above the rest. The bay area has a vaulted ceiling with 16ft to peak. The shop has 10 ft ceiling with a 5-1/2 ft attic space above. All is insulated and finished.
pics are after sign off and one after inside was done

Very cool, I brightened up the pics do I could see them...

 

[RyanEricW]

Congrat's. It's been interesting watching this go from your concept to a reality.

Tell us more about your Camaro...

Thank you, so glad I can actually work on things now not on my back lol. Thank you for all of your help guys

 

[bczygan]

To the OP....VERY nice solution and execution!

Bill

 

[lakeroadster]

Sweet Camaro.. Thanks for the info... you're going to love having a lift in your shop.

 

[larry4406]

Very nice! What ceiling height did you start with, what was the roof pitch, and what height did you net?

 

[lakeroadster]

Very nice! What ceiling height did you start with, what was the roof pitch, and what height did you net?

From previous posts...

.... Current height from floor to bottom chord is 9'.....

.....4/12 pitch ....

 

[Rickenbackerman]

Pretty cool! You took a different approach to how I attacked the same problem a couple of years ago. I used a couple of LVL's, two uprights, a ridge beam and rafters:

http://www.garagejournal.com/forum/showthread.php?t=101090

 

[byalegend]

Jealous. Very nicely done. I have a similar situation in my garage that has 8'4" ceilings, but I also have a couple gas lines that run perpendicular to the trusses and are located about 6 ft. from the rear wall . Also, the top chords are 2x6. I only need to modify three trusses in one bay of my 2-door, 2-car garage.

How much would you say it cost in total to do this mod? I guessed at somewhere around $800 in trusses and other materials. In my case, if I decide to have the gas lines moved by a pro, that could get spendy. Of course, the city will want their cut, also.

Thanks