Help with header strengh for a beam.

[mngundog]

I am on a very limited budget and I have built a 38x38 garage so right now I want to do things on the cheap but still build it to last. In the pic you can see a 2x6 spanning the back wall of the garage. From that I want a 4' shelf coming out from it and I don't want it supported from the ceiling. I'm thinking of building a wall out (4') to the left of the left window and left of the right window. That would allow me a unsupported span of no more than 14'. Then I was thinking of running 2 (doubled up) laminated headers 9 1/2" the length of the building with 2x4 or 2x6 strung to the back wall if that makes since. Then I would put 1/2 ply on top and maybe drywall underneath. I don't have plan on putting anything heavy up top, but I have a bunch of large light weight stuff that I would like to store there. So do you think 9 1/2" headers will support that weight over a 14' span? I don't have to worry about inspectors. Any thoughts?
http://www.garagejournal.com/forum/attachment.php?attachmentid=128175&stc=1&d=1312860839

 

[Torque1st]

Essentially you want to build a 'deck' up there. It sounds like you would not need a full strength deck but you might start with some deck design software online from one of the Box stores. It would give you a starting point to help figure out a design.

 

[D.J.]

Might help if we knew what "that weight" was?

 

[mngundog]

Might help if we knew what "that weight" was?

Well a couple items I know I want up there is my deck table and chairs, they are allum. and probably weigh less that 100# total. I also have a "suit case" fish house, it is 4'x6' and weighs about 100#. I have a lot of other storage shelves to store heavy stuff, so this I was going to use for misc, big items (light weight). Maybe golf clubs, and a smoker (20#). bikes and a plastic sand table and plastic swiming pool, thats what I can think of now. Yes it would be like a deck but its less than 4' to the ceiling, I would never walk up there, so I don't know if there would be software to spec something like this.

 

[Torque1st]

If you make it strong enough to walk on it would hold your stuff up. So start with that design and decrease it to save money as required.

 

[mngundog]

If you click on the link and look at the second photo down, you will get the general idea what I'm going after. No I don't plan on putting a compressor up there. http://www.ultimategarage.com/homegarage/UltGar2y-2.htm

 

[ddawg16]

Per standard tables....a 2x10, 24 OC would span the distance...and give you decent loading (40 lbs/ft).

Since cost is a factor...you don't want to be using Simpson hangers...so build the walls like you talked about....put the 2x8 on the wall (anchored real well) and run 2x10's 16OC from the front 2x10 to rear 2x8. The top of the rear 2x8 will be parallel with the bottom of the front 2x10....this way you nail your joists to the front 2x10 but the rear portion sits on top of the 2x8....

For some extra stiffness....rip some strips of OSB (1/2") 9 1/4" wide (that actual width of that 2x10) and attach them to the 2x10 using glue and screws. Do this before you put any weight on the structure....that OSB will really stiffen up the structure.

Top off with 1/2 plywood or OSB as you discussed.

The end result should be pretty strong.

 

[mngundog]

Per standard tables....a 2x10, 24 OC would span the distance...and give you decent loading (40 lbs/ft).

Since cost is a factor...you don't want to be using Simpson hangers...so build the walls like you talked about....put the 2x8 on the wall (anchored real well) and run 2x10's 16OC from the front 2x10 to rear 2x8. The top of the rear 2x8 will be parallel with the bottom of the front 2x10....this way you nail your joists to the front 2x10 but the rear portion sits on top of the 2x8....

For some extra stiffness....rip some strips of OSB (1/2") 9 1/4" wide (that actual width of that 2x10) and attach them to the 2x10 using glue and screws. Do this before you put any weight on the structure....that OSB will really stiffen up the structure.

Top off with 1/2 plywood or OSB as you discussed.

The end result should be pretty strong.

I not up on all the limbo, so I have a few questions. The front 2x10 will have to be two boards nailed together right (so 3" thick)? Since I allreading have that 2x6 allready secured to the wall, can I just use that (otherwise I would have to remove the drywall)? Since the 2x10s will be resting on the top edge of the back board, how do I secure them to it?
Thanks for all the replys

 

[darkk]

I've always found that when you build something like that, eventually heavier stuff always seems to end up there. Build it with some kind of support so you don't have to worry about weight later....be safe.

 

[mngundog]

I've always found that when you build something like that, eventually heavier stuff always seems to end up there. Build it with some kind of support so you don't have to worry about weight later....be safe.

Yes it will be supported in two locations with the greatest free span being 14'.

 

[Torque1st]

Just use the HD deck design software. Enter your dimensions and type of deck support. Pretend you are using deck planking then use 1/2" OSB instead. No guesswork required. Use KISS.

 

[bigdav160]

How is that 2x6 attached to the wall? I think, at a minimum you need support running to the floor under that 2x

Since the 2x10s will be resting on the top edge of the back board, how do I secure them to it?

I'd knock holes in the wall and secure them to the studs in the wall. You might be able to get away with a hurricane clip but if the front beam moves outwards there won't be much holding up that platform.

 

[Matt_G]

Yes it will be supported in two locations with the greatest free span being 14'.

So, I'm not sure if I understand this right but I'll take a stab at it. I think you are running along the wall with the longest span 14' and coming out into the garage 4'.

I ran a 2x10 joist on the software I use for work and it really doesn't work 24" o/c at 40psf live load and 10psf dead load (min. floor load for a house in Canada). You would have to go at a max spacing of 19.2" o/c.

At the ends you could either use a drop ledger nailed or lagged to the wall, an 1 1/2" of bearing is all you should need. I would just block between the joists. Your existing 2x6 nailer you could just use as a nailing edge for your sub-floor at the wall.

If I have this all wrong let me know and I wouldn't be that hard to run joists the short way either.

 

[nathank]

My span was a touch over 16'. I used two 2x10s with OSB sandwiched in the middle to make it match the 4x4 posts. I used 2x6s attached to the beam and the wall on 16" centers. Decked it with OSB. Didn't cost much at all to build.

 

[mngundog]

Yes the photo above this one is what I was thinking. My 2x6 on the back wall is secured dirictly to the studs using 3, 4" screws on each stud. I was hoping to have it build at that height, however I will move it if it has to be moved.

 

[Dag Blag Dave]

You have a couple things to decide and a couple things to look at.
1) How much load will you actually see up there. I would call it 20 lb/sq.ft. minimum - 50 is like a std. floor (i.e. 10 for the floor's own weight and 40 for load)
2) Do you want to base your design on strength or on deflection? For a floor that people use, the limiting factor is often deflection so it doesn't feel too bouncy. For storage, you can let it flex a bit more, as long as it doesn't look bad. I would say 1/2 inch is about the max I would accept, though, which puts it at about the standard L/360. (14 x 12/360 = .47)

You then need to use a standard load table to look up the various elements:
1) Wall ledger board
2) Attachment screws
3) Joists
4) Front Stringer
5) Support Posts

I will take a look in a few minutes to see what my tables say.

 

[Dag Blag Dave]

OK, here is some more info based on my own assumptions.
1 - You say maybe drywall, so L/360 to avoid cracking.
2 - Light loading, total of 20 psf
3 - Not worried about column strength if you are supporting with a section of wall.
4 - Conservative shear strength for the screws, I would say 180 lb each, still gives you plenty of load capacity. (Worst case, if studs are every 2 ft, load will be 2 x 4 x 50 = 400 lb, the ledger board will see half to hold up its end.)
5 - Wood is stud grade or better, SPF. Stringers on 24" centers.

You can use a single 2x10 (9.25 true dimension) as your front header with your stringers made of 2x4's with 1/2" plywood on top.

If you wanted to load it heavy, i.e. total of 50 psf, you could still do it with a 2x12 and 2x4 stringers. However, you would probably be better off with the doubled 2x10. Also, you say you want to get away cheap, but a really important part is how you attach your stringers. You should consider rafter hangers. Might make it look cleaner instead of having them sit up on top of your wall ledger board. Finally, if you use 1/2" plywood on top and put something really heavy up there, you are going to see bowing in between the stringers. Even a box of books could cause that over time. It might be a bit of overkill, but consider going 2x4 on 16" centers.

To check the numbers yourself, look at www.awc.org for their various calculators.

By the way, to calculate the long header I used 24" spacing numbers. My reasoning is as follows: the platform is 4 ft wide, the header is holding up one side, or half the weight, so the loading is equivalent to carrying 2' width.

 

[mobetta]

if you're already going to build the two walls,just use 2x8 on 12" centers, or 2x10 on 16" centers, spanning from garage wall-to- stub wall-to-stub wall- to garage wall. this way will be very quick build, using minimal materials=cheap.
price out 12 2x8x14's, or 9 2x10x14's. no hangers, no 2x4s. I'd sheathe it in 3/4 cdx, dont waste time on osb.

frame walls up so top plate is at the right height so as the 2x framing ends up at the same height as your already installed rim ledger. use hangers on the ends at garage walls.

 

[mngundog]

if you're already going to build the two walls,just use 2x8 on 12" centers, or 2x10 on 16" centers, spanning from garage wall-to- stub wall-to-stub wall- to garage wall. this way will be very quick build, using minimal materials=cheap.
price out 12 2x8x14's, or 9 2x10x14's. no hangers, no 2x4s. I'd sheathe it in 3/4 cdx, dont waste time on osb.

frame walls up so top plate is at the right height so as the 2x framing ends up at the same height as your already installed rim ledger. use hangers on the ends at garage walls.

How would you fasten the 2x10s to the back wall without hangers?