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How should I modify my trusses?

Nidhogg

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Joined
May 7, 2014
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4
Hello!
I have a garage thats 180 m² (I think around 2000 ft²?), and I want to install a two post lift in it. The problem is, the ceiling height is a little too low to work under a car comfortably.
The height is 3.2m (126") and I would need around 3.7 m (145").
Those are the minimum measurements for the two post lift Im considering (Bendpak), but I want to aim between 12'-14'.


The carpenter I talked to wanted ~$5000 to modify the trusses... A bit pricey for me.
I will talk to another carpenter, but I thought I would ask here as well, to see if anyone had any ideas on what I should do.
I dont know how the first carpenter wants to modify the trusses.

I will probably have to modify two trusses, and create a "box" over the lift to get the car up into.
Right, some pictures will help me explain.

This is how my garage looks. Its divided in two sections, one big room to the right, and one small room to the left. Theres a wall where the roof is bent, so I want the lift on the left side of the big room, so I can drive a car straight in through the big door and on to the lift:


This is how my trusses look:
double-fink-truss.jpg


This is a picture from the attic entrance, its on the back of the garage, so the wall furthest back is the same wall from the first picture with the garage doors:


This is the side that I want to modify. The trusses are resting on the inner wall in the garage (formely the outer wall, the garage have been built upon to get the smaller room):


I want the lift on the LEFT side here, since I have the garage door on that side, and I want the right side free for other cars:


The planks represent the trusses, the one near the door I can ignore, then the next truss (plank) I need to modify, and also probably the next one after it as well:


Here you can see roughly where I want the lift. The wall with the door on the other pictures have been removed:


This is something I had in mind, but do I need a pillar for this design? I want to keep the open space in the garage so a pillar is not an option.
Its not exactly the right design of my trusses (I dont have the middle pillar) but you get the idea:
house-truss5.gif


Other options are a raised tie:
a-takstol.jpg


or scissors:
saxtakstolar.jpg


But, can I modify the existing trusses to these designs, or do I need to replace the whole truss? The roof is tin, so thats pretty easy to remove, but I dont know how easy it is to lift the old trusses.


Yet another option is to make a hole in the wall, install a glulam beam (is that the right word?) along the whole length of the garage, and hope that the other trusses can support the roof when distributing the load with two less trusses. I think there are 6 trusses, and removing 2 would mean 33% less support. Not really thrilled about those numbers....

Any suggestions or ideas? Or perhaps someone have done something like this already and can show me some pictures of what they did?
Thanks!
 
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69gp

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Jan 1, 2013
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Location
MA
I would not modify the trusses unless you have something in writing from an architect or engineer. Having a carpenter do the job without the proper documents is asking for trouble. You might want to see if you could remove the ceiling from in between 2 of the trusses and install the lift there. You would just need to keep an eye on things if you had a truck on the lift going up. With the post lift next to one truss you would have plenty of room to lift a car with the hood open. If that does not work or give you the proper clearance than you could look into modifying the truss or replace a few of them.

If memory serves me correctly there was a thread on here a few months ago about a member replacing trusses in place similar to the type of garage you have.
 
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Nidhogg

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May 7, 2014
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Do you know if your trusses were manufactured locally? If so, the manufacturer should be able to provide you with the necessary design and guidance on how to implement.

Good Luck

Don

The garage was used to build timber houses previously, thats why there is such a big driveway, they prepared the wood in the garage and built the houses outside, and then had trucks come pick them up in sections.
So, there is the possibility that the first owner built it himself.

Anyway, the garage (and the house we live in next doors) were built 1958, so I doubt much documentation is still available :)
 

dfiler2

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Dec 15, 2014
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NW Minnesota
I think i would use the scissor truss, it appears as though the roof would be easy to remove. I would remove the roof on the side and in the area you need the clearance. Slide the new trusses in along side the existing ones and attach them. You could then cut away the extra truss only on the side you need the clearance. This would allow the best of both worlds, an approved truss without disturbing the other half.
 
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Nidhogg

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May 7, 2014
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I would not modify the trusses unless you have something in writing from an architect or engineer. Having a carpenter do the job without the proper documents is asking for trouble. You might want to see if you could remove the ceiling from in between 2 of the trusses and install the lift there. You would just need to keep an eye on things if you had a truck on the lift going up. With the post lift next to one truss you would have plenty of room to lift a car with the hood open.

Oh no, I will get a proper carpenter to get the documents and make sure everything is in order, and make sure the roof is up to standard.

The distance between the trusses is 7 feet, if I would remove the ceiling just between two, I could work with normal sedans, but no station wagons, which we have two of.
 

David C

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Mar 10, 2014
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Location
Northern California
Regarding your truss redesign independent of the remaining structure:

If this were my garage I would draw up the existing truss framing, to scale, make note of the size of each member and look for grade stamps, and detail each of the panel point connections.

With this information I would input it into a frame computer program and tinker with different design concepts that would provide the ceiling height I desired. I would use current codes to determine roof and attic loadings. I would expect to increase the strength of some of the framing members by sistering additional wood framing to the sides of (E) framing. It is almost assured that the panel point connections will need to be upgraded as well.

Considering the project as it actually is constructed:

If I were practicing in your area I would refuse to redesign your trusses unless you upgraded other portions of your structure. Your framing does not include a roof diaphragm (for one example) and if you had a strong wind you might sustain some structural damage to your building. There might be an exceptional homeowner that wouldn't blame new wind damage on the recent roof redesign, but it far more likely that the designer would get sued.

Given that you don't have a roof diaphragm you might consider demolishing the existing roof and installing a roof with the ceiling height you desired, adding the roof diaphragm into the project.
 

Denwood

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Sep 22, 2014
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Thunder Bay, Ontario, Canada
We did a very similar project at my business. The trusses were a 50ft span, 8ft celing. We modified them to get an 11ft ceiling profile on one side of the building. They were clad on both sides with plywood (glue and screw) and cut/framed to the new profile. All work was done in place. The plywood cladding is done mostly over the new profile, not the whole truss. All was done by our architect and engineer. This is a screen grab of the reno drawings related to the truss mods. The top section is a different part of the building where we added a south facing clerestory. The bottom section is similar to what you want to do.

The first image was for a separate truss modification to create a raised clerestory, 2nd is the one you want.

truss.jpg
 
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JRC3

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Jun 30, 2014
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Location
Southwestern OH
The distance between the trusses is 7 feet, if I would remove the ceiling just between two, I could work with normal sedans, but no station wagons, which we have two of.

Damn, it's a shame the trusses don't run in the other direction.

Any chance of installing another garage door so you can pull cars in parallel to the trusses to lift between them? Or are things just setup for that not to be an option?

I love old Mopars, always been my fave.
 
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