Garage ceiling height increase project

[dimbmw]

Hi
I am considering increasing my garage's ceiling height by about 1 ft (to install the lift).

This is the roof frame structure I have now. I am looking to modify it a little so that the ceiling will be higher by 1 foot.

I will post the changes I am thinking of in the next post.

There is no snow here (Northern California), but the roof tiles look pretty heavy to me, so I still have concerns about the structural strength.

I haven't contacted any structural engineer as of now and I have no idea whether I do need a permit to do this kind of job or not. The outside of the garage building remains as it is so I definitely don't need to deal with the homeowners association (which is good).

If anyone has any idea of how much this project could cost to implement that would be great. Any recommendations are also very welcome. I don't have anybody to implement it as of now.

Thanks

 

[dimbmw]

Here is how I think this can be done.

Thanks for your time reading my thread. Suggestions are welcome!

Thanks.

 

[dimbmw]

Anyone?

 

[Redwolf947]

I just raised my lower rafter ties to gain some ceiling height in my garage. Tho I had a regular gable roof. It was pretty straight forward for me I raised it 1/3 of the overall height.

View media item 60241
But you have a different animal. I'm sure most are going to say you need to get an engineer to look into it.

Are those technically trusses in anyway? Doesn't look like it but have to ask. If so ask the truss manufacturer.

Do you have any actual pictures?

What I see looks good to me. Hope this helps some. I'm sure others will chime in..

 

[James-W]

We have had other threads where someone wants to modify their truss system to accommodate a lift or whatever else they may want to do. These threads turn into heated debates and when that happens the thread is in danger of being closed.

Basically, trusses are designed by engineers who take into account loads and other factors in order to construct a truss that is strong enough to do the job it was intended for. If a person who does not have sufficient knowledge of structural engineering in order to do this type of work tampers with an engineered truss trying to modify it, they are taking the risk of having a major catastrophe.

 

[Falcon67]

I'd like to know why somebody thought it required to build/place trusses under that hip. That all looks "done in place" rather than engineered. 2x12 hip ridge is damn stout too - big snow loads? We've got long hips on our house (and many others here - gables are old school) and nothing like that complicated support structure under the hips.

 

[chops101]

You mentioned tiles- as in concrete S tiles or flat concrete tiles?

If you have concrete tiles I wouldn't dare monkey with the truss system without a stamped engineer's drawing.
Tiles take a roofing system to a whole new dimension, unlike lightweight shingles.

 

[jrj3rd]

Not a structural engineer, but

It looks like the lower rafters are truly ceiling rafters to allow you to hang a ceiling and do not contribute much if any to the load bearing of the roof. vertical
ties look to be just to allow the rafter to remain level and "hang"

 

[Falcon67]

D'oh, I should read it again and I'd know something. Good luck, tiles weight 9~12 lbs sq/ft, no wonder it's braced like that. 1000ish lb per square vs 220 for 3 tab - you'd better get someone to really look at that before you cut anything.

 

[dimbmw]

Thanks for reading my thread and for a valuable discussion ! It really helps !

I've decided to post a couple of pictures of the structure - as you see these are not engineered trusses but they seem to be assembled in place.

As for the tiles, I have no idea how to check their weight, but attaching the picture here maybe someone can help to determine the type and weight per sq ft? In my opinion they are concrete tiles.


Thanks!!!

 

[dimbmw]

I'd like to know why somebody thought it required to build/place trusses under that hip. That all looks "done in place" rather than engineered. 2x12 hip ridge is damn stout too - big snow loads? We've got long hips on our house (and many others here - gables are old school) and nothing like that complicated support structure under the hips.

The two 2x12s are actually resting on these 3 structures, as the corner where they join together is actually in the air - it is not fixed anywhere and not supported by anything... See the picture please...

 

[Rod N]

Not sure which way the joists go, but can you not just stick your lift in between them if it's the right way?

 

[dimbmw]

Not sure which way the joists go, but can you not just stick your lift in between them if it's the right way?

Unfortunately no, as 2 cars one above another do not fit with the present ceiling height.

 

[Rod N]

Ah. You are putting in a 4 post!

Maybe rising the walls will be easier.

Either way, I think you will have a hell of a project here.

 

[ishiboo]

That looks like it has already been (incorrectly) modified. Good luck!

 

[chops101]

Yes those are concrete tiles and yes those are made to order engineered trusses (not the rafters) trucked to site....

 

[dimbmw]

Yes those are concrete tiles and yes those are made to order engineered trusses (not the rafters) trucked to site....

So if they are engineered - why does it make it more difficult ?

 

[James-W]

So if they are engineered - why does it make it more difficult ?

Trusses are designed in such a way so that they support the weight of the roof in all sorts of weather conditions, rain, wind, snow, etc. If you start cutting out parts of the trusses to accommodate a lift (or anything else for that matter) then you are compromising the structural integrity of the roof/building. It is certainly possible that you could modify the trusses yourself and it doesn’t cause any problems. But I have no idea how your homeowners’ insurance would work if the roof were to collapse because the engineered trusses were cut/modified by you. Worse, what if someone were to be injured or killed when/if the roof collapsed?

In your case, and especially with the concrete tiles, I would want someone who is skilled in this type of work to check everything over and make sure that what I did was correct and was perfectly safe from a structural standpoint. Keep in mind that if the roof does collapse, there is an awful lot of weight coming down on top of anything that is in the way.

My advice is, for your own peace of mind, get someone involved who knows exactly what they are doing and how to do it. It will cost you more initially, but if it saves you problems later on down the road it will be money well spent.

 

[chops101]

More complex, the level of difficulty is subjective.
You really need to have a structural engineer evaluate present loads and design an option that retains the load integrity for the county you reside.

If you ever want to sell your house, have insurance pay a claim or protect your assets should the roof collapse, you'll need a sign off. Tiles are heavy, it isn't a simple shingle job you have there.

Not what you wanted to hear but it's the right thing to do

 

[ssdave]

It's an interesting roof, not sure it was built as the trusses were originally designed. It looks like the diagonal 2x12's were goobered in over the trusses as a modification or afterthought. However, i doubt that it is unsafe as it is now, just a bit unconventional in how the trusses were loaded.

However, the trusses are defintely engineered trusses, and are the major load bearing components. You cannot safely just cut and modify the bottom chord to lift the headroom.

There are alternative that will be able to work. One is to install new trusses alongside the existing ones, that are designed for higher headroom, fasten them to the existing trusses at pre-determined points, and then cut out the components of the orginal truss that are in the way.

It may also be possible to sister some additional components onto the existing trusses that allow the bottom to be cut out.

You definitely need to get a qualified structural engineer to analyze the existing system and design the modifictions.

 

[DekeT]

That looks like it has already been (incorrectly) modified. Good luck!

I agree. It appears someone used a pre-made truss and modified it to fit the structure, and attach more lumber from there.

 

[carotene]

Tile roof and stucco walls. That is one tough project. I suspect the easiest path forward is to raise the walls and leave the roof as it is. Plus you get the option of a taller garage door.

 

[lakeroadster]

Raise the walls... really?

OP you have a beautiful home. Find a qualified P.E., Even then, you will likely find that they say to leave it as is.

Thanks for posting this, be sure to let us know how things progress.

 

[dimbmw]

No guys, raising the walls is not an option here, our HOA is crazy about such things and they will hardly approve. It may also make the house look ugly.And lastly, in my opinion it is much more work and will cost alot more.

 

[dimbmw]

There are alternative that will be able to work. One is to install new trusses alongside the existing ones, that are designed for higher headroom, fasten them to the existing trusses at pre-determined points, and then cut out the components of the orginal truss that are in the way.

It may also be possible to sister some additional components onto the existing trusses that allow the bottom to be cut out.

That's a good idea, of course the 2x12s need some support at the modification time. I was actually thinking to support them by the tall jack stand posts - I've seen them for around $50 at home depot - just thought to remove the load from the old trusses by lifting up the 2x12s by half an inch and then release the 2x12s back down when the mods are done. I thought 4 or 6 posts could do the job. Maybe one can even rent these, I don't know.

 

[dimbmw]

That looks like it has already been (incorrectly) modified. Good luck!

no it is not modified, we have dosens of similar houses in this neighborhood, all built at the same time.

 

[DekeT]

no it is not modified, we have dosens of similar houses in this neighborhood, all built at the same time.

Honestly that does not mean anything one way or another.

 

[jpinca]

You 100% need a PE to look it over and you are required to get a permit (whether you do or not...). You have a high load roof AND you are in earthquake country. Don't screw around!