Re: Garage 'ceiling height'

[Wood Grower [OP]]

I think that the roof could be jacked up and a couple three new courses of blocks added to get the needed height. That does hinge on whether the building is attached or free standing and being able to get matching siding.

This is a good idea but not possible.

[Wood Grower [OP]]

Any experienced carpenter should be able to open up the roof structure safely given enough wood to work with and maybe keeping one or two ties. The key here is experience, your questions don't inspire confidence in your knowledge to the point we should be encouraging you to DIY.
Rob

Well if it is possible then I am interested to figure this out. In theory I could build a new support beside old one and then take off each old one. I am not sure if my old books show this sort of thing or not. I guess I will have to study up on truss building. To me even if I could add new horizontal board but higher up than the wall top 2 or 3 extra feet would even be nice but having up to the top would be a dream I guess.

[Wood Grower [OP]]

This is a stick framed roof and you can't just remove all of the ceiling joists. They are what is keeping the ridge/roof in place. The joists could be removed if a beam was installed directly under the ridge, but this would involve a fair amount of work. Don't know the dimensions of the garage, but the beam may have to be substantial and supported properly at each end with posts, another beam over the door and possible upgrading of the foundation. The other option that has already been mentioned is to remove the roof and installed scissor trusses that would give you some vault. Yes, talk to the building official. There may be other issues not directly related to how it is constructed.

I could live with a beam but the support to the floor not so much. Unless can I make a timber frame inside beside walls to transfer the load to beside the walls instead of in the middle? That might be an option but also could be a pretty big pain......there are shelves built in to the sides there at least on the one side would probably be in the way but putting a timber frame in front of it and adding support to shelving might be an option I suppose. That would probably be way over the top option for a garage I don’t really want..... it is too small but I am trying to extent my stay in it a bit longer.....

[cstephens2]

The strength of the roof comes from its triangle shape, including the ceiling joists/rafter ties you are musing about removing. With those ceiling joists/rafter ties removed the weight of the roof will want to push the walls outwards. I highly doubt any inspector would approve what you are proposing, and I wouldnt want to chance a heavy snow load on that roof with the joists/rafter ties removed.

In the pic below, you see that the 'rafter tie/ceiling joist' is in *tension*, meaning that a stretching force is being applied to it. The strength of the rafter tie to resist the force of tension is what keeps the walls from being pushed out/bowed out. The more downward weight on the roof, like from a snow load, dramatically increases the tension force.

[cstephens2]

Well if it is possible then I am interested to figure this out. In theory I could build a new support beside old one and then take off each old one. I am not sure if my old books show this sort of thing or not. I guess I will have to study up on truss building. To me even if I could add new horizontal board but higher up than the wall top 2 or 3 extra feet would even be nice but having up to the top would be a dream I guess.

This isnt about truss building. Its about understanding the static and dynamic loads and how they transfer to your walls in your existing roof. .

[Wood Grower [OP]]

Isn't something like this able to do the same job as a horizontal board? This is what I am thinking of doing building in place the remove the old system out after something like this is built. It seems with the right geometry something like this is fully capable of doing the same job as the horizontal board.

[QC Inspector]

My shop is framed with scissor trusses like that but it was designed that way and brought in as part of the truss package. You would be the first person I have ever heard of that wanted to convert to them in situ. An engineer would need to work out the sizes and fastening schedule as even an experienced carpenter would not likely know how. It would be a lot of work but you could do it without being noticed unlike raising the roof I suggested earlier. ;)

Pete

[Wood Grower [OP]]

My shop is framed with scissor trusses like that but it was designed that way and brought in as part of the truss package. You would be the first person I have ever heard of that wanted to convert to them in situ. An engineer would need to work out the sizes and fastening schedule as even an experienced carpenter would not likely know how. It would be a lot of work but you could do it without being noticed unlike raising the roof I suggested earlier. ;)

Pete

Yes that's the idea, I have a legal non-conforming building, so anything external is a big no no. If it's work being done inside and nobody saw it, that seems to be exactly the way I bought it and always remember it....

[iamtooler]

Isn't something like this able to do the same job as a horizontal board? This is what I am thinking of doing building in place the remove the old system out after something like this is built. It seems with the right geometry something like this is fully capable of doing the same job as the horizontal board.

That is what I had in mind and not too difficult when you do not care about the cost of a few extra 2x6s, unlike when original supplier built them. You will be doing one at a time so not a big deal, especially as you don't cut the ceiling joist till it's replacement framing is bolted in.
Rob

[Kayak Jim]

An engineer would need to work out the sizes and fastening schedule as even an experienced carpenter would not likely know how.

This. So you just need to hire an engineer to design a truss system for you.

[Matt Matt]

What you are thinking about doing applies a lot of load spreading your outside walls from snow load and a collapse of the whole building. If you don't really care, just rip the whole trust system off and redo the roof. If you want to modify it you can do this with a few sheets of plywood, but if it is bigger than 100 ft.² you will have to have an engineer sign off on it.

[Egon]

I have a concrete block wall garage with a wooden roof and everything to hold it up. Inside the wood goes straight across from wall to wall. Is it possible to cut off that long piece and change the ceiling height into a vaulted ceiling to give more working height inside the garage? And if this is possible, how do you go about getting it done?

Thank you.

Go to a truss supplier with all your details. They should be able to spec the truss you require. Buy one for design details that you copy and use in prefabricating replacement parts for your truss.

You might be able to sister a new truss to the existing one and then remove parts of the old truss???

[Wood Grower [OP]]

Go to a truss supplier with all your details. They should be able to spec the truss you require. Buy one for design details that you copy and use in prefabricating replacement parts for your truss.

You might be able to sister a new truss to the existing one and then remove parts of the old truss???

Do you estimate it isn’t bad for a single truss? I have a friend out of area who is a journeyman carpenter I just might consult with.

The twin then remove method is more or less exactly what I am thinking.

I think 6 to 10 feet roughly would do. I could even double or triple the horizontal Work at the start/ finish area....Probably right at rear wall and right by bay door track ending.....

[cstephens2]

Isn't something like this able to do the same job as a horizontal board? This is what I am thinking of doing building in place the remove the old system out after something like this is built. It seems with the right geometry something like this is fully capable of doing the same job as the horizontal board.

Yes, an engineered truss like that changes the location of the 'in compression' and 'in tension' truss members.

When you purchase a vaulted truss like that from a truss manufacturer it comes with an engineering drawing thats been signed off by a structural engineer. I highly doubt you can site build something like that and have it a) be approved by a structural engineer and b) pass any sort of inspection.

There is a reason we have engineers and inspections. But you do you boo.

[Inspector Ron]

As I said in a previous post ("There may be other issues not directly related to how it is constructed.") it has come to light that the building is illegal non-conforming. Therefore the desire to not do any work on the exterior or discuss any changes with th building official.
Fair enough. However, it doesn't mean you should make interior changes that compromise the structure. You could change the roof framing to act as some form of truss, but you would need an engineer to design the changes. Manufactered trusses are engineered and use specifically designed metal connection plates. I don't think those plates will be available to you and making up a plywood gusset isn't the same thing.
That said, its possible to make some changes that might work, but if you want it done properly...