Garage Loft Planning Help

I am planning on building a small loft in a part of my garage. The loft will be about 5'-6" feet by 6'-8". There are existing walls on three side, made of 16" oc studs and drywall over them. My plan is to attach 2x8 ledger boards to the three walls and a 2x8 across the open end (the span is 6'-8"). Then use joist hangers to run 2x6 floor joists across the 6'-8" span. Then use 3/4 plywood for a floor. This is for storage as I have a 14' ceiling to work with. Planning on putting Christmas stuff up there. Planning on no posts - just using the existing walls to carry the weight.

My question is about attaching the ledger boards to the walls. I am going to use ledgerlok bolts for the attachment on each stud, but would rather not have to remove the existing drywall. I realize that the structure would be stronger with the ledgers bolted directly to the studs without the drywall sandwiched inbetween, but how much stronger? Can I get away with not removing the drywall?

For that size, I think you're fine bolting through the drywall. I would double the one you're using to span the third side, however.

I wouldn't worry about the drywall. I might double up the header across the open span, and make sure its well attatched to the side pieces

Then don't decide to store used engine blocks up there next year.

You'll be fine. Double up the open span beam as noted above.

I doubt I'll gain enough strength to get an engine block up there.

Thanks for the inputs. What is the rationale behind doubling up the rim joist on the open side? I planned to use a 2x8 there and 2x6 for the inside joists. Looking at span tables I don't see why I need to double it. It would be easy to do - i'd just need to buy the correct joist hangers and another 2x8, but is there really a reason I need to do that?

You typically want to provide extra stiffness when spanning any openings. It's less important since you do not have studs sitting on top of it (needing the 3-1/2" wide bearing) but it's just common practice in case one of the joists in the header has a flaw or starts to check. It gives you some redundancy.

it's a little wider than than 4 ft so I made the depth 4 ft to make it easier on cutting.

you probably could support an engine block on your setup with the addition of a center support beam. I know my setup is capable of supporting 500lbs or so and it is just 3 sides anchored to cinder block walls with a 3/4" piece of plywood floor

Thanks Duke. I've seen decks built with doubled up rim joists and I thought that was to provide more support to the railings. I'll have no railings. Mine will look like Internetautomarts - just a little larger with 16" oc floor joists and a 2x8 rim joist. I see your point in the double joist if there is going to be a wall on top of it so the studs have a place to go. That makes sense. I think I'll try it with just the single 2x8 and see. Before I screw down the floor I can test it out. If there is any doubt I'll double it up.

Hang on.

I'm gonna have to disagree about the wall.

The point of the double joist is to support the weight of all the other joists in the event when they are nailed to it (which assumed they were running in the 5'-6" direction). In this case, 1/2 of the weight of all of the floor would be sitting on the outer rim joist. However, I mis-read your original post. If you are running the joists in the 6'-8" direction, you will not need the double rim joist.

And, with all due respect to Mr. Internetautomart, that thing doesn't come close to adequately supporting 500 lbs. I can SEE the sag in it, with only the weight of empty boxes and PVC pipe on it. 1 1/8" thick plywood panels are required to span 4' unsupported for normal floor load. More for storage areas.

just build another garage

SVrex, Yes I am planning on running the joists from wall to wall and the open side will just be another joist. I figured I'd use a 2x8 there and 2x6s for the interior joists.

aussiemg, I'd love to build a detached garage/shop - I have the room and I've made some measurements and done some dreaming, but I am not willing to spend the money on it at this time and on my current house. I am unwilling to take out a mortgage or other loan for something like that as well. I'd love to have a garage for parking cars and a shop for working on them and doing messy/smelly/sparky things that don't have to take place a few feet from my master bedroom. Someday - more than likely at another house.

SVreX wrote: Hang on. I'm gonna have to disagree about the wall. The point of the double joist is to support the weight of all the other joists in the event when they are nailed to it (which assumed they were running in the 5'-6" direction). In this case, 1/2 of the weight of all of the floor would be sitting on the outer rim joist. However, I mis-read your original post. If you are running the joists in the 6'-8" direction, you will not need the double rim joist.

What he said ^^^^^

SVreX wrote: Hang on. I'm gonna have to disagree about the wall. The point of the double joist is to support the weight of all the other joists in the event when they are nailed to it (which assumed they were running in the 5'-6" direction). In this case, 1/2 of the weight of all of the floor would be sitting on the outer rim joist. However, I mis-read your original post. If you are running the joists in the 6'-8" direction, you will not need the double rim joist. And, with all due respect to Mr. Internetautomart, that thing doesn't come close to adequately supporting 500 lbs. I can SEE the sag in it, with only the weight of empty boxes and PVC pipe on it. 1 1/8" thick plywood panels are required to span 4' unsupported for normal floor load. More for storage areas.

there is sag in it. actually the lower one has the serious weight on it. How long it would support a full 500lbs would at least in part depend on how the load is spread out. I have load spread out to the edges.

Built the loft this evening. Nice and strong, at least with a 220 pound fatass sitting on it. I'll take a picture tomorrow. Still have to get all the crap up there. It's a little taller than my step ladder, but doable. Since it is Christmas stuff going up there I think I'll be able to live with it just fine.