Notching truss for 2 post lift

[Maine]

I built my 28x30 garage this past fall and planned on using an Atlas 9OHSC lift. My build allowed for 12' of ceiling height but I just went and measured and I am actually at 11' 8", due to an overly thick slab (must be 6-8" thick?!)

I have 60 PSF rated attic trusses with 2x10 bottom cords. I hate to ask this, but I need to notch out 2" on 4 of the cords to allow for the overhead bar- (the main support posts fall between trusses).

My rational for even considering this is that the trusses that are notched will be supported by the overhead lift bar.

Any feedback on this guys? I know this is a no-no but the trusses are heavy duty with 2x10 bottom cords (i've seen them as small s 2x6 cords).

Thanks for the feedback.

 

[CNGsaves]

If it were mine and had concrete that's plenty thick, maybe grind down the concrete those 2 inches at the lift mount locations. Notching 4 trusses is major no-no.

Curious what these lifts sell for across the country as I just found this dealer advertising $1,795 for 7 states (IN, DE, GA, AZ, NH, FL, & TX).
http://www.gregsmithequipment.com/Atlas-9OHSC-SS-Overhead-Two-Post-Car-Lift

 

[wedge40]

We could use a little more info. Are the trusses going be notched more then once per truss. You can't get the lift between the trusses?

Garage dimension, where the doors are located, and which direction the trusses run would help.

Wedge

 

[theoldwizard1]

The short answer is "yes" , but the integrity of the truss will be compromised.

******** !

The answers is noy just No, but HELL NO !

The bottom edge of truss, called the bottom chord, cares the HIGHEST tension load of the whole truss.

 

[rslaback]

Give me some more specs on the building. It may not be doable, but my first suggestion would be to add material between the wall's tie plate and the trusses. Essentially, raise the roof 4 inches or so.

 

[djjsr]

When it comes to the structural integrity of your building, do you really want to take the advice of some do-it-yourselfer that sounds like he knows what he's talking about?

Seek professional help. Maybe someone here is qualified, maybe not.

 

[WNYflyer]

As you know trusses are engineered to specific loads and dimensions. Any alteration to them that is not engineered is a no-no. Not to say folks haven't gotten away with altering them themselves but the correct way is to have an engineered alteration.

If the location of the proposed notching is out in the area of the attic/60 psf floor load then you are indeed in the location of maximum axial tension in the bottom chord when talking about gravity loads. The even bigger problem would be fact the bottom chord is also seeing significant beam action in the attic area. Notching 2 inches out of a 2x10 reduces its "beam" capacity by about 40% +-. Yes of course notching the bottom chord out 2 inches can be done but you really need someone who knows what they are doing from both an engineering and construction aspect to get it properly altered/reinforced.

 

[porschedude996TT]

Choose a different lift?

 

[zcar751]

A picture would help with some mark ups, where in the structure do you want to notch.

I would say yes you can notch the trusses but you will need to add support to those trusses. My suggestion is to take 3/4 inch ply wood of at least 7 layers and sandwich the bottom cords using 3/8s nuts & bolts with thick fender washers. You will want to carry the plywood at least a foot past the notch on each side.

 

[Rookie2]

just move the bar down ! redrill it or fab brackets , not a big deal !

 

[KPSquared]

Talk to the conmpany that designed your trusses. Don't take critical design advice from a bunch of armchair structural engineers.

This is the exact reason I went 12'6"... always leave room for error.

 

[Sureshot]

******** !

The answers is noy just No, but HELL NO !

The bottom edge of truss, called the bottom chord, cares the HIGHEST tension load of the whole truss.

Because it is in tension I would add to the top and remaining side to carry the tension across the compromised spot.

Since the issue is the walls spreading you could add a metal bar from one side to the other of the entire building. Maybe an I beam you could also use as a light trolley.

 

[J king]

Yep ,I'd mod the lift. Can't be hard to get 2".

 

[mds5951]

Personally this would be a question I'd ask whoever engineered the trusses, maybe even have them stop out...Im sure theres a way. Don't quote me on this but I always thought an engineer had to "sign off" on any notches to pass code.

 

[ez-duzit]

... HELL NO !

The bottom edge of truss, called the bottom chord, cares the HIGHEST tension load of the whole truss.

This is the right answer.

 

[BDAZSVT]

I would look at other liftas if that is an option

 

[KPSquared]

There are a couple of baseplate 9000lb Atlas hoists that would solve all your problems. It's going to be a lot more work to try and make an overhead lift work.

 

[Quijote]

You can't get the lift between the trusses?

This.

Because my town has height limits on accessory buildings I could not do a 12' ceiling. So I went with a 10' ceiling and I am going to stick the lift between the trusses (16 on-center which is enough to fit a Bendpak XPR-10A if my calculations are correct).

 

[hd54kh]

I have no knowledge of your truss design or lift but can your overhead crossover of the lift be extended to go between the trusses and cross over above your ceiling?

Terry

 

[JakeKohl]

This.

Because my town has height limits on accessory buildings I could not do a 12' ceiling. So I went with a 10' ceiling and I am going to stick the lift between the trusses (16 on-center which is enough to fit a Bendpak XPR-10A if my calculations are correct).

I'm pretty sure the top xbar on the lift is perpendicular to the trusses if I understand his question properly...so while you could probably get the main posts between them, the cross bar is a problem.

You may be able to get away with notching the bottom chord of the truss - but you should consult the truss manufacturer to get their input. The other idea that someone mentioned may have merit and be easier than all this notching stuff. If you have the lift shortened slightly, you don't loose much lift and it's probably cheaper than all this notching and refinishing (assuming that you have a finished space).

 

[DekeT]

A picture would help with some mark ups, where in the structure do you want to notch.

I would say yes you can notch the trusses but you will need to add support to those trusses. My suggestion is to take 3/4 inch ply wood of at least 7 layers and sandwich the bottom cords using 3/8s nuts & bolts with thick fender washers. You will want to carry the plywood at least a foot past the notch on each side.

Don't do this.

 

[ez-duzit]

...My rational for even considering this is that the trusses that are notched will be supported by the overhead lift bar...

The trouble with this rationale is that the bottom truss element you want to cut into is not a compression member but works in tension--the lift will not make up for that. And I assume you live in an area that regularly gets high snow loads.

 

[Bob C]

Rotary Lift SPOA10 Two Post - Overall height 11' 10-1/2"

Costs alot more but save money on things you work around NOT under!

 

[Cougar]

What if he made extensions for the lift and put the cross bar above the
2 x 10's.

 

[vhol5]

Fishplates. Simple.

 

[Maine]

Okay guys heard you all loud and clear, I won't cut any of the truss.

 

[Maine]

just move the bar down ! redrill it or fab brackets , not a big deal !

I would love to just do this- when I asked Greg Smith about it they wouldn't discuss any modifications with me, is it really as simple as re-drilling for bolts? There are cables, hoses in the overhead span.


Maybe I should just get the 9KOH lift.... really wanted the super symmetric arms and single point release. Anyone own the 9kOH?

 

[Diesel Dan]

If you were to get an engineer involved could the current trusses be safely modified into higher clearance scissor style trusses?

There are always options.
Just depends on the $$ to implement them.

 

[Maine]

Hi Dan,

I've got a room above the garage so that wouldn't be an option.

 

[Sureshot]

I would take another look at your original plan. You want to take 2" out of a 2x10. You could sister a 2x8 on each side of the 2x10. What would be stronger a single 2x10 or three 2x8 sistered together?

Glue and screw.

People need to look at it rationally and not react with the "engineered" storyline. Sometimes you need Swiss watch and sometimes a sundial will do.

 

[KPSquared]

http://cdn.gregsmithequipment.com/documents/manuals/2postlifts/9ohsc_manual_v4.pdf

Page through the manual for that lift. You shOuld be able get a good idea of how modifiable it is. Still betting modifying the lift is best option. That top bar is not structural at all as far as I know.

 

[Maine]

Cant move the bar down, it has plates welded to it that rest on top of the columns. Thank you for that link!

 

[zack99]

Anyone who has lived in an old house has probably noticed how much bounce there is to the floors. Floor joists used to be commonly done using 2x8 lumber. I once lived in a house with 2x6 floor joists and things on the table would rattle every time I walked across the room.

I sistered the joists with 2x10 boards and problem solved. It was an 80 year old house and no cracks or signs of impending collapse. Just an annoying amount of bounce.

Sent from my XT907 using Tapatalk 2

 

[Spudland_Dave]

I would take another look at your original plan. You want to take 2" out of a 2x10. You could sister a 2x8 on each side of the 2x10. What would be stronger a single 2x10 or three 2x8 sistered together?

Glue and screw.

People need to look at it rationally and not react with the "engineered" storyline. Sometimes you need Swiss watch and sometimes a sundial will do.

Best post of the bunch...Quick call to your truss co. will get you a free answer, and I bet that sistering a 2x8 or a small LVL/LSL will be sufficient...combined with a couple tubes of Liquid Nails and a box of screws, those 4 modified trusses would probably end up stronger then the rest of them.

 

[KPSquared]

Ok, no modifying lift.

Either hack it up and hope, call the truss company for a likely free answer, or buy a lower lift.

There are baseplate lifts with the super-symmetric arms. Unless you really want an overhead.

 

[theoldwizard1]

Best post of the bunch...Quick call to your truss co. will get you a free answer, and I bet that sistering a 2x8 or a small LVL/LSL will be sufficient...combined with a couple tubes of Liquid Nails and a box of screws, those 4 modified trusses would probably end up stronger then the rest of them.

While your comments on sistering a couple of 2x8 on the sides may be correct, I guarantee you no truss company would ever approve it, even verbally. To much liability at stake.

 

[JakeKohl]

While your comments on sistering a couple of 2x8 on the sides may be correct, I guarantee you no truss company would ever approve it, even verbally. To much liability at stake.

I don't know about that...the opportunity to sell some more LVLs? It's a pretty pure and safe science with a lot of history and safety factor. I bet they would look at it. There's only one way to find out. If the liability were that much of a problem, they probably wouldn't be in business to begin with.

 

[ez-duzit]

While your comments on sistering a couple of 2x8 on the sides may be correct, I guarantee you no truss company would ever approve it, even verbally. To much liability at stake.

And no building inspector would ever approve it.

Another thought is that you could probably jack up the lower truss element 2" near the center of its span.

 

[JakeKohl]

And no building inspector would ever approve it.

Another thought is that you could probably jack up the lower truss element 2" near the center of its span.

You have to sister floor joists occasionally because of plumbing and other penetrations - that passes code. You guys are being overly difficult.

 

[vhol5]

You have to sister floor joists occasionally because of plumbing and other penetrations - that passes code. You guys are being overly difficult.

^^^^^ this