EvanB
MegaDork
3/4/19 6:24 p.m.
My garage is 20x30 cinderblock with a stick framed roof. At some point the roof started sagging and it was reinforced with collar ties in the sagged position. The joists are unevenly spaced and not in great shape. There are maybe 9-10 across the span of the garage. Some are not even anchored at the ends (I assume that isn't good?).
My plan was to support the roof along the ridge board, remove the collar ties and slowly jack it back up. Then redo the collar ties while it isn't sagging and add new joists.
The question is about spacing. Would I be able to space the joists out in order to permit a lift to be installed so a car can be raised between the joists? Is this too much spacing? What is the minimum spacing on a stick framed roof on top of cinder blocks? There is nothing stored up there anymore and I don't plan to use it for storage.
Some bad pictures of the middle bay.
EvanB
MegaDork
3/4/19 6:33 p.m.
Also, another part of the plan is to do french style doors on the front to remove all the overhead door stuff.
SVreX
MegaDork
3/4/19 7:30 p.m.
Short answer, yes you can modify and improve it.
Slightly longer answer, I really don’t think you are gonna get a good answer on the Internet. We can’t give you good answers based on pictures and conjecture.
It almost needs an engineer.
Hows your budget? If you can afford it, it would almost be worth tearing the entire roof off and putting trusses back. It would be faster, and much more permanent.
SVreX
MegaDork
3/4/19 7:32 p.m.
That’s probably more than is necessary...
SVreX has it in a nutshell.
One question - if the ridge is sagging, are the walls also bowing out? That could potentially be a bigger issue, especially with block walls.
EvanB
MegaDork
3/4/19 8:50 p.m.
The long-term plan would be to tear it all off and redo with trusses. The shingles are approximately 10 years old and when they need replaced that would probably be my plan.
The walls do not seem to be bowing. It appears to be stable and from talking to the neighbors the roof has been sagged at the same amount for quite a while.
I'm mainly just thinking through some ideas and wondering what the standards for a stick framed roof on block walls typically call for. If I can make it a bit better for the next 10 years with a long weekend of work and <$1k in lumber it might be worth it until I can redo it completely. I do agree I need someone experienced to take a look at it in person.
SVreX
MegaDork
3/5/19 2:51 p.m.
In reply to EvanB :
The standard for a stick framed roof on block walls is a lot more than you've got. There really are no standards.
If you are thinking about trusses one day, then just wait.
Stuart is right about the walls... Get some string and a friend, and hold the string against the block wall at both ends near the top. Should be touching the wall the full length. If there is a 1/2" or more bow in it, the wall is compromised too much.
SVreX
MegaDork
3/5/19 3:39 p.m.
In reply to EvanB :
I failed to answer your original question- my apologies.
You asked about removing joists. I am assuming you are referring to the rafter ties (ceiling joists) at the bottom of the roof rake. (as opposed to the collar ties near the ridge).
No. I wouldn't remove any. You are already overspaced. If I am seeing things correctly, your rafters appear to be about 20" on center. That would mean your rafter ties are already spaced about 100". Pulling one out could be really bad.
But you could relocate them. Since you have already proven that 100" spacing works, how about relocating them to where the 100" space would be advantageous for a lift?
STM317
SuperDork
3/5/19 3:46 p.m.
Is wind loading a potential consideration? What about snow? Either could affect your spacing requirements
When you put in the trusses down the road, use scissor trusses over one bay for easy lift clearance, and a sturdy, storage truss spaced at 16" over the rest for, well storage.