Sanity check: Attic joist framing Q

[MikeDeuce]

Hey folks,

I'm pretty sure this is all OK, but for my car's sake, I'll make sure before proceeding.

Anyway, the previous owner built the following storage attic above the garage:

In other words:

And I'm replacing all the lights with the 1x4 2 light troffer setups seen being test fitted here.

My desire is to add 10 total lights, some of which you can see above, outlined in green.

Can I move that joist on the far right over, until it's 16" OC with the joist to the left of it? (And add a short section of joist to the other side of the attic ladder, I'm not sure why the previous owner never did).

Common sense dictates this is ok, but I also want to drywall it, and I already store a ton of stuff up there, so I'll let the paranoia force my hand.

Thanks much!

 

[e-tek]

Looks like the same strength will be acheived and also allow you to know where to put your DW screws (16 centres).

 

[bczygan]

Just a note to let you know that while putting that joist in where the attic ladder is will give you support for the flooring above and more nailing, it won't substantially reduce the loads on the full length joists on each side of the stair. Those joists carry 20% more load than the other full length joists after moving the one over to accommodate the light spacing. And they have point loads where the double headers for the attic stair are supported by them. Don't have the sizes or loads so can't say what the safety factors are. Just that the floor can support more away from the hatch area.

 

[PDACPA]

I am not an expert at all in the area. However, my pull down stairs have 2 - 2x4's running down the sides of the stair box. I only see the double 2x4 on the ends of your stair box. No idea if it is required or provides additional support as per bczygan mentions in the increased load, but makes logical sense that it would "help" at a minimum.

 

[soj]

Questions:

1. How long are the joists?

2. What size are they (ie. 2X6, 2X8, etc.)

3. Do the lights take up the full 16" between the joists?

 

[Nick M]

I would also double up the joists aside the attic box.

 

[MikeDeuce]

Thanks for the feedback everyone, it's very much appreciated.

bczygan: Everything you said makes a lot of sense – thanks!

soj: 2x8, ~14.5' in length... the lights themselves don't take up all the space, not exactly at least, but the brackets that hold them in place swing over the troffer frames (not sure if there's a proper name for the wood rectangles) which you can just barely see in the first pic.

Also, the storage attic is not very tall, it's basically knee height at best, and scooting around on your **** height everywhere but the middle... But I do have it stuffed with small boxes of ****.

 

[soj]

soj: 2x8, ~14.5' in length... the lights themselves don't take up all the space, not exactly at least, but the brackets that hold them in place swing over the troffer frames (not sure if there's a proper name for the wood rectangles) which you can just barely see in the first pic.

Also, the storage attic is not very tall, it's basically knee height at best, and scooting around on your **** height everywhere but the middle... But I do have it stuffed with small boxes of ****.

Disclaimer: I am not a structural engineer, I don't play one on TV, and I did NOT stay in a Holiday Inn Express last night.

I would double up on at least the one joist to the left of the attic stairs, unless you will have weight against the wall on the other side of the attic. It looks like you have duct work and vent pipes in that area, so I was thinking you weren't using that side for storage, maybe you are. What the heck, put in one on each side, just to be sure. The downside, and the reason I asked about the size of the lights, the extra 1.5" may reduce the open space enough that you can't put a light in it and would have to re-do your lighting plan. For sure fill in the cripple joist that the previous owner mysteriously left out, if nothing else to keep your 16" spacing for sheetrock nailing.

Another thing, what are those joist hanging from? On the far end (as looking at your pic) they appear to be on a header sitting on top of a wall. But on the end closer to the garage door, I can't tell from the pic, did he add a header across an open space? Whatever it is, do you feel it is sufficient to carry the load?

 

[Kevin54]

Hey folks,

I'm pretty sure this is all OK, but for my car's sake, I'll make sure before proceeding.

Anyway, the previous owner built the following storage attic above the garage:

In other words:

And I'm replacing all the lights with the 1x4 2 light troffer setups seen being test fitted here.

My desire is to add 10 total lights, some of which you can see above, outlined in green.

Can I move that joist on the far right over, until it's 16" OC with the joist to the left of it? (And add a short section of joist to the other side of the attic ladder, I'm not sure why the previous owner never did).

Common sense dictates this is ok, but I also want to drywall it, and I already store a ton of stuff up there, so I'll let the paranoia force my hand.

Thanks much!

You can move it BUT where does the flooring fasten to the joist at upstairs? If it is over that joist, then it probably can't be moved for obvious reasons. If it is not seamed above that joist then you should be fine. The attic ladder is fine the way it is. Most homes around here have 2x4 trusses at 24" on center and the attic ladder shoved between the two with nothing doubled up. But that is my opinion on how things go in this neck of the woods.

 

[mobetta]

how thick is the osb decking? what supports the "top(as viewed in pic 1)" side of the framing- as soj asked.

you really dont need to double up/ header off the framing on the stair opening until it gets to be more than 4'.

you can totally remove that second to last joist, but if the floor decking laps on it you will need to deal with that- but you could lay 2x mat'l flat across underneath where the seam is, perpendicular to joist.
moving is only worthwhile if you are hanging rock and a seam will be right where you are moving it to, but blocking can help you there.

 

[MikeDeuce]

The flooring is run perpendicular to the joists (woo!), so there's no seam there.

The OSB is 1/2" (but you can't walk on it, not enough clearance)

The headers are 4x10s... on the far side of the wall they're bolted into the wall studs:

But on the garage-door side, it's a great big wide span (18'):

In each of the walls on both ends it rests atop a 4x4:

+

 

[ducati]

I would be more worried about the front beam all the joists are hanging off of. Looks like it is doubled up, what is the total tenght of that beam? How much load are you going to put up on the attic floor?

 

[JeremyManning]

I agree with above I would double up the beam with all the joists hanging off it

 

[MikeDeuce]

I would be more worried about the front beam all the joists are hanging off of. Looks like it is doubled up, what is the total tenght of that beam? How much load are you going to put up on the attic floor?

D'oh -- was hoping not to hear that... It's a single, solid 4x10... 18' span, only supported at the ends. If I had to guess, there's less than 1000lbs of stuff up there, with more of the heavy stuff located towards the back (away from the open span).

 

[claymont]

Do you really need all that light in the back? Before you go to the trouble of moving that joist, get the other lights working to see if that's enough. If not, you could always put a single bulb eight footer in one the spaces there now. If you do move it, remember to put the hangers on the joist first, don't think you're going to be able to nail that one side up. With 1/2" OSB flooring, I'd put that cripple joist in. It's got to be a little bouncy at that spot now.

 

[ishiboo]

D'oh -- was hoping not to hear that... It's a single, solid 4x10... 18' span, only supported at the ends. If I had to guess, there's less than 1000lbs of stuff up there, with more of the heavy stuff located towards the back (away from the open span).

You'll be fine, 4x10 will do 1000 lb right in the center all day long at 18', plus your weight, the weight of the wood, etc.

Moving the joists as you plan will be fine as well. Use joist hangers and nail every hole.

 

[ducati]

You'll be fine, 4x10 will do 1000 lb right in the center all day long at 18', plus your weight, the weight of the wood, etc.

Moving the joists as you plan will be fine as well. Use joist hangers and nail every hole.

You do realize that that 4"x10" beam also has also carry 1/2 the joists weight, 1/2 the sheeting weight, plus what ever else he puts up there right? That 4"x10" beam 16' long wouldn't pass a lot of building codes on a garage door header on a gable end of a garage that isn't carrying any roof weight, little lone a 20' span, right? I do tend to over build verses under build though. It would **** to come out one morning and have it laying on top of your car. Not saying that it will, but I would rather know I spent the couple hundred bucks and don't have to worry about it.

 

[MikeDeuce]

I was hoping for a little more consensus amongst the participants here, but such is life

I'll likely be looking into picking up an additional 4x10 + 4x4s to sister up against the one there now. And perhaps I'll do that and not change my plan up with regards to the 2x8 joists*, so I can continue on with my current lighting plan.

*I don't store a lot of items near the ladder anyway, so I have a little room to navigate around up there via ****-scooting.

Thanks again for all your input, I'd rather over-do it than under.

 

[MikeDeuce]

Before I go and source this lumber, a couple more questions:

1) How best to sister such large timbers? Just a bunch of lag bolts? Any advice in particular?

2) Should it be another 4x10 or is there a smaller size (3x10? 2x10?) that would be sufficient? This is more for the material handling rather than cost considerations. I'm fine with overkill, but I'd rather avoid over-overkill.