Raised tie ceiling joists in attached garage

[Freedom6178]

Hey all, it's been along time since I posted here I'm hoping ya all could give me some advice. If ya can't could you direct to where I might be able to get some more info?

A little background. My GF and I bought a house in SE WI with an attached garage. This garage was built in the 50's. It's 22'x22' with a roof pitch of 6/12 and snow load of 30. It is located in South East WI. When built they used 2x4 rafter ties at close to 48" centers. Not only that but they are sistered 2x4's on the ends, the ties are 20' with 2' added for a total length of 22'. The outside of the stud walls are wood plank with siding. I'm not 100% sure might be Asbestos siding then aluminum siding on top. The stud spacing is  (not exactly) 16". The roof is wood plank with architectural shingles the rafters are 2x6 at the same approx 16" spacing.

My ceiling height now is just shy of 9'. I'd like to install a mid-rise lift or 4 post car lift in the future to do basic maintenance on my vehicles.

I'm looking to raise the bottom chord/rafter ties by 1'-8" that's just less than 1/3 the height from tops of walls to the roof peak. This would bring my working height to 10'-7 1/2"ish.

I'm thinking 2x6's or 2x8's at 18' long nailed or bolted or ? to every rafter. That's 15 compared to the 5 now installed. I don't mind spending the extra on the 2x8's. I do plan on insulating the ceiling in the future. I don't plan to store anything in that attic space. I'd install all the new rafter ties then cut out the old ones.

Would you go with the 2x6's or 2x8's? Anything I'm missing? I can take and attach photos.

Thanks for your info and time.
Freedom

[Freedom6178]

I'm really hoping some one can guide me in the right direction. I know with how its built now almost anything I do should be better/stronger.

Here's a pic of my messy garage that's now somewhat clean



Well thanks again.

[Magicman]

I am not a structural engineer by any means, but I would nail 2X6's to the rafters as you suggested and be happy.  My thoughts are that it will be stronger than it is now.

[jdtuttle]

You can install collar ties on each rafter and it will be stronger than what you have shown in the picture. Typically collar ties are in the bottom 1/3 part of the rafter so you will gain plenty of height.

[Freedom6178]

Thanks guys.. I do understand most aren't engineers. I thought there were a lot of awesome guys/gals here that build all different structures and things. That's why I thought this would be the right place to ask these questions.. 

[Don_Papenburg]

2x8s aren't that much more than 2x6s .  Use them on all rafters and ad the collar ties to each set of rafters in the bottom 1/3.   Then fill in with the extra depth of insulation .  Do that just after you get the last collar tie nailed in .  If you don't you will wish you did , so don't get mad at me latter.   It is easier then also 'cause you got the ladder or the genie there and there is nothing in the way ,like when you do it in a month or 6 years later.

[Freedom6178]

Thanks Don but I already ordered the 2x6's. I bought my wood from a local lumber yard I got a bunch of 2"x4"x10's too. I want to install king posts (not sure if that's the name of them) install collar ties and to cut up for nailers for the ceiling and wall panels. The 2x8's were a lot more per board @ $18.60 each the 2x6 were $9.90 a piece. I can still put more insulation over them  . I'm going to put up my ceiling panels and install the insulation as I go. I'll have an access hole to the attic and figured that's the last stretch I'll insulate.
I'm going to install structural screws 3 or 4 per connection between the rafters and new rafter ties. I know nails would be OK but I think the screws are stronger. As a safety thing I'm going to put Simpson strong ties in on every other top plate to rafter connection.

[jwilly3879]

My neighbor did the same thing you are proposing and after a heavy snow some of the rafters broke between the collar ties and the wall. The collar ties limit the ability of the rafter to flex and move the load to the point between the tie and the wall.

[Freedom6178]

My neighbor did the same thing you are proposing and after a heavy snow some of the rafters broke between the collar ties and the wall. The collar ties limit the ability of the rafter to flex and move the load to the point between the tie and the wall.

Hi jwilly3879. I'm curious? Do you recall what the roof pitch was? and the snow load out there. I've been here 2 seasons and don't recall too much accumulation built up on that part of the roof. I was thinking of using any extra 2x6 material to sister from the top plate to the new rafter ties for strength. I think where I'm located and how my garage is situated peak runs NE/SW and gets good sun that I'll be ok   

I do want to thank you for your observation and concern.

[21incher]

When you put in a insulated, finished ceiling most codes want a 10 lb sq. ft rated truss. You will be adding quite a load that the original structure was not designed for so you may actually want to have it looked at by a engineer or code enforcement official before going to far. I went through that with a pole barn that I had built. The trusses were specd out at 2 lb per sq ft for a storage structure, and I had to upgrade the trusses to a 10 lb per sq ft lower cord so it could be finished later. .

[Freedom6178]

When you put in a insulated, finished ceiling most codes want a 10 lb sq. ft rated truss. You will be adding quite a load that the original structure was not designed for so you may actually want to have it looked at by a engineer or code enforcement official before going to far. I went through that with a pole barn that I had built. The trusses were specd out at 2 lb per sq ft for a storage structure, and I had to upgrade the trusses to a 10 lb per sq ft lower cord so it could be finished later. .

I can see your point. I'm not dealing with trusses tho. If these were trusses I wouldn't mess around with them. A truss is made generally with 2x4's that have a 'web' in them for strength and support. If you cut them they no longer have their strength.

I do thank you 21incher for your thoughts. This is making me go thru more checking for my material weights and doing more calculations. I did do some rough numbers and I'm at a little over 2.8 lbs per sq ft with the insulation and ply I was planing on. I'm also debating putting tin up for the ceiling material. I think that would lower the weight per sq ft as well.

Trust me if you saw whats there now you'd probably think anything would be better too.

I'll take another pic later that better shows the weak structure I have now.

Again thank you ALL for asking questions and making comments. It helps me to see others perspectives on a project like this. 

[Remle]

First off I'm NO Engineer, but if you are concerned about the rafter deflecting and pushing out on the top of the wall below the collar tie, could you add another 2X ?? from the top of the wall out to the end of the new collar tie across to the other rafter in effect making a modified scissors truss ??

[rjwoelk]

Your garage describes ours which is now a horse barn. I do not think they had a measuring device that was on beyween them spaci g was all over the place.

[Freedom6178]

First off I'm NO Engineer, but if you are concerned about the rafter deflecting and pushing out on the top of the wall below the collar tie, could you add another 2X ?? from the top of the wall out to the end of the new collar tie across to the other rafter in effect making a modified scissors truss ??

Actually to be honest when I first thought about this project I was thinking much the same. Here's a picture of one of my first thoughts.



This idea was using plywood gussets glued and screwed. This seems way overkill. Being that the rafters themselves are 2x6 I'm really not worried. If I sister every other one with my left over scrap the structure will be more sound.

Please note: This image is looking toward the front of the garage. 13'-6" of 22' of the right wall is attached to the house.

I was/am just looking for others thoughts on this, good or bad. I still need to get a better picture of the  current framing. I need to price/analyze metal panel weight with the insulation weight.

Thank you for your thoughts Remle.

[Freedom6178]

Your garage describes ours which is now a horse barn. I do not think they had a measuring device that was on beyween them spaci g was all over the place.

Isn't it fun trying to do anything with ill measured construction

[21incher]

In reality you are dealing with existing 2 x 4 trusses that are being modified to support a differently distributed load. It seems to me like it would pay to get someone to do some calculations to specify the hardware and verify the loading on the existing 2x4's will comply to current codes for that type of structure before you start buying materials. 

[Holmes]

On your drawing envision the snow covering the roof from the gussets up.  That load is trying to push the walls apart, the collar ties are holding them in place but a huge strain has been added to the rafters from the collar ties now with no ability to flex.  Your original collar ties are only to keep the walls from spreading apart.  Your idea of making the rafters into trusses will work but you should try to get some engineering assistance

[Freedom6178]

In reality you are dealing with existing 2 x 4 trusses that are being modified to support a differently distributed load. It seems to me like it would pay to get someone to do some calculations to specify the hardware and verify the loading on the existing 2x4's will comply to current codes for that type of structure before you start buying materials.

But I'm not dealing with existing 2x4 trusses? The rafters are 2x6 material like many standard roofs built today. Only the existing lower ties are 2x4. 

[Freedom6178]

On your drawing envision the snow covering the roof from the gussets up.  That load is trying to push the walls apart, the collar ties are holding them in place but a huge strain has been added to the rafters from the collar ties now with no ability to flex.  Your original collar ties are only to keep the walls from spreading apart.  Your idea of making the rafters into trusses will work but you should try to get some engineering assistance

The previous drawing is only to illustrate my first thoughts. I have put a lot of thought and done a good amount of research for this . I'm not just going willy nilly either. That's another reason I'm here asking questions. I really don't have the $$$ to put into an engineer.

I plan to attach the rafter ties to the sides of the rafters similar this:



using 5/16" x 3" structural screws.

I'll be adding 2x6 ties to every rafter. I'll also be adding hurricane ties to every other rafter. Like these:



Sorry if I sound defensive. I don't want it to sound like I'm disregarding your thoughts. I appreciate them. It's making me dig deeper is all. I'm getting the lumber Monday afternoon so we will see I guess
 

[Holmes]

 Looks like you have the right ideas.  I usually do things twice, right the 2nd time.