[Nealtw]

Hi all,

I'm in the middle of turning my 1.5 car detached garage into the ultimate mancave/home office. Electrical is underway, and soon I'll be spray foam insulating the whole place, but one thing that has always bothered me is the ceiling height.

Right now, the building has 7.5 ft walls, which are not very high, and the rafters for the garage run from wall-to-wall on top of these walls. As you can see in the photos, they weren't done very well. Many of the rafters are made of several pieces of wood that are bolted together, and they're randomly tied into the roof, vertically, in various places, usually with a barely nailed-in 1x3... Not ideal.

I had initially planned to just make those look nicer, and then paint them, and the spray-foam insulation flat black in hopes that it wouldn't really be very noticeable, but as I've progressed on plans for the rest of the project, it's now obvious that the ceiling needs to be finished to match how the rest will look.

So my thoughts are, finishing the existing rafters at only 7.5 ft is going to make the place very closed in and small, so I had the idea that I could raise the height of the rafters from tying into the walls at 7.5 ft, to having them tie into the roof deck at 8.5 ft, and then it could all be dry-walled to make the room feel much airier.

My thought was to replace the single 2x4s at 7.5 ft with 2x6s or 2x8s at 8.5ft and to add them to both sides of each board of the roof deck to give it more strength, and then add additional vertical and diagonal bracing along the way.

Given that the current rafters are a total mess, it seems like adding these much beefier, stronger beams and in more places than we currently have them would be enough to keep things in good order. I had one builder out and he suggested that my township would never approve that, but that if I wanted to do it myself, it would be structurally sound and I'd likely never have any issues. That said, I am not a builder, or a structural engineer, so I wanted to get more information.

I wanted to get the thoughts of you all, here, as I've seen many people get great advice from these boards.

Below is a picture of my current structure, as well as some diagrams of kind of what I'd like to accomplish. View attachment 722709

View attachment 722712

You can go up 1/3 of the total height.

 

[Nealtw]

Just to make sure I understand, that's 1/3 the total height of the roof deck?

Yes and that is the top of the new ceiling joist.
How far apart are the rafters, they look like more than 24" apart?

 

[Nealtw]

Cool.

The existing rafters are all over the place. Some are placed 24" apart. Some 48". "Janky" doesn't describe it, today....

My plan for the new ones would be to do a new raised ceiling joist on BOTH sides of each roof deck section (which are all 24" apart, to make it even stronger, using probably 2x6s instead of 2x4s.

See the blocks below the ceiling joist.

 

[Nealtw]

That was going to be another question. That way, the load is being directed down onto the walls, too, right?

So for the 1/3, you mentioned it's 1/3 from the TOP of the new joist. Is that starting point measured from the top or bottom of the existing one? Effectively, am I taking 1/3 from 36" or 39"?

Also, would 2x4s still be fine? or should I look to use a beefier 2x6?

From the top of the wall so the bottom of the existing ones, depending on span, 2x4 may not be enough.
So I would calculate the height for a 2x4 with the top 13" above the wall and then change to 2x6 and put the top at 15".
So you would be gaining 9 1/2" of ceiling height. With just a little cheating.

 

[Nealtw]

That was going to be another question. That way, the load is being directed down onto the walls, too, right?

So for the 1/3, you mentioned it's 1/3 from the TOP of the new joist. Is that starting point measured from the top or bottom of the existing one? Effectively, am I taking 1/3 from 36" or 39"?

Also, would 2x4s still be fine? or should I look to use a beefier 2x6?

For the hip end you will have to change direction and then figure out the corners when you get there.

 

[Nealtw]

What exactly am I looking at, here? Having trouble comprehending the drawing.

Are you basically just saying get the new horizontal rafters in place, and then figure out how the pieces from the bottom of the new rafters, down to the top of the walls need to be?

At the far end in your first picture you have a hip roof where the rafters go the other way
The picture I posted brown is your rafters and the yellow is how you would do the end ceiling but the corners will be a bit finicky and will have to be worked out when you get there.
Does this picture help?

 

[Nealtw]

What a difference a little work will do, looks good.