Load capacity of my loft

[cuznlucky]

I built a dedicated 12x24x9 (internal dimensions) wood shop inside my steel building to keep the different areas separate. The wood shop is anchored to the concrete floor, one long wall, and one short wall. I did 16" on center for the 2x4 studs, and 2x12 beams for the loft @ 16" on center nailed to the studs with 3/4" ply on top of that. The beams are sitting on a 2x4 ledger like the attached picture. I did 3/4" ply on the inside walls as it was cheaper than 1/2" at the time and I wanted to be able to drive nails, screws and hang things anywhere I wanted. The whole thing is in my opinion incredibly solid, but I'm curious possibly what the real world weight load is of the loft? Like can a put a couple engine and transmissions up there or is it more like I could put a motorcycle collection up there (I wish) Thanks for any useful input!!

 

[ericlar80]

Not much with that support method, maybe 15 psf. You would have been better off to put a Jack stud under each of the joists.

 

[cuznlucky]

Not much with that support method, maybe 15 psf. You would have been better off to put a Jack stud under each of the joists.

Really? I don't know that's why I'm asking. Anyway I get that your saying 15 psf but what does that translate into real world application. I weigh 185 and I don't fall through when I stand in the middle between joists, heck the sheeting doesn't even give any that I can tell.

 

[ericlar80]

The whole point is for it to not sag, so you don’t want to see deflection by you just standing on it. For a 12’ span you don’t want to see more than 3/8” deflection at the center (s/360 assumed) for a floor. Imagine the load being spread across the entire surface evenly - that’s what it means. So a 12x10 area would be 120x15 = 1800 lb. Point loads are a whole other thing.

You should also be using ledger screws, not nails for the ledger board, except you cut them into the 2x4 stud so that’s not a good idea either. 15 psf is probably a bit high because of the nailed in ledger, especially if you are in an earthquake zone.

 

[rayra]

That all sounds like a lot of nonsense. given the nature and position of the joints. And being 2x12 on a 12' span, AND 16" centers, that's plenty strong too. Wood is very strong in compression and much less so in span. notching that ledger / support board into the studs is an excellent way to economize on expensive brackets and is very strong. Having the joists resting on it right adjacent to the notches is also very strong, there's no span of moment arm to create weakness. And then you nailed the joists into the studs. The shear strength of the nails may be questions, but they are not unsupported either.
Put whatever you damned well please up there.

Residential second story floors are built lighter than that and are rated at 2-3x ericlar's 15/sq'

And span tables for 2x12s on 16" centers list spans of almost double yours, as acceptable for typical loads.

/but I'm not an engineer or playing one on the internet, I've just been building stuff for 40yrs+, wtf do I know

 

[Firebrick43]

Not much with that support method, maybe 15 psf. You would have been better off to put a Jack stud under each of the joists.

Balloon framing, such as shown above, was around before platform framing came about. There is nothing wrong with balloon framing in the least except the expense of the long clear 2x4 it takes. Its just a strong and transfers load well to the vertical members.

To the OP, go to the following link and choose the span/load table and see for yourself. Is the span 12' or 24'?

http://www.southernpine.com/span-tables/joists-rafters/

If its the 12' span, then it will conform to the 60lbs per sqaure foot rating, which will be fine for storing several blocks or motorcyles, i just wouldn't pile them up there.

If it 24', well you need to put a beam/post's mid span as there isnt enough joist there to span 24'.

 

[Uncle murph]

That all sounds like a lot of nonsense. given the nature and position of the joints. And being 2x12 on a 12' span, AND 16" centers, that's plenty strong too. Wood is very strong in compression and much less so in span. notching that ledger / support board into the studs is an excellent way to economize on expensive brackets and is very strong. Having the joists resting on it right adjacent to the notches is also very strong, there's no span of moment arm to create weakness. And then you nailed the joists into the studs. The shear strength of the nails may be questions, but they are not unsupported either.
Put whatever you damned well please up there.

Residential second story floors are built lighter than that and are rated at 2-3x ericlar's 15/sq'

And span tables for 2x12s on 16" centers list spans of almost double yours, as acceptable for typical loads.

/but I'm not an engineer or playing one on the internet, I've just been building stuff for 40yrs+, wtf do I know

This!I couldn’t have said it better myself,a notched in ledger under 2x12s over a 12’ span,I’ve seen cars parked on less.

 

[FordTruckWench]

Balloon framing, such as shown above, was around before platform framing came about.

Older North American towns are filled with 100+ year old two story homes built with balloon framing, except perhaps with just a 1x4 ledger. Nobody worries about the load capacity of the second floor. There is however a worry about fire - a fire can climb all the way up in the wall cavity.

 

[billconner]

I agree with rayra and Firebrick. Basic balloon frame. I am unclear when you say

one long wall, and one short wall

I assume your notched stud wall is one of these interiors walls, what supports the joists on exterior wall?

 

[ericlar80]

You guys are all forgetting that this wasn’t engineered for a specific load, and probably wasn’t inspected for conformance to a plan which would include a nailing schedule. We also don’t know whether the building has been sheeted with plywood to prevent racking, nor the height of the load. I’ve no doubt it can hold more than 15psf and still be standing, and OP can do what he pleases with the feedback, but it’s better to be on the conservative side.

I sure as hell wouldn’t place 7200 lbs (900 gallons equivalent of water) up there, which is what 60psf would suggest. Again, assuming 120 sqft of space on a 12ft span.

 

[billconner]

We also don’t know whether the building has been sheeted with plywood to prevent racking,

It is a steel building and therefore was probably engineered. This is just a light framed "room" within the steel building, walls covered in plywood. And no I don't know it's properly nailed but if a guy is building a wood shop, I give him the benefit of the doubt hell but enough correct sized nails in.

No, I'd probably be a little more careful if I was going to cover it with a 1' deep wading pool. Google suggests an average motorcycle is 400 pounds, and 8' long by 2 1/2' wide. That's 20 psf, with no room to walk between them. cuznlucky, I think you're fine assuming the other end of the 2x12 joists are equally well supported, and not on the steel frame building.

 

[ericlar80]

Ok, I missed the mention of sheeting in the original posting. That helps considerably.

 

[Firebrick43]

You guys are all forgetting that this wasn’t engineered for a specific load, and probably wasn’t inspected for conformance to a plan which would include a nailing schedule. We also don’t know whether the building has been sheeted with plywood to prevent racking, nor the height of the load. I’ve no doubt it can hold more than 15psf and still be standing, and OP can do what he pleases with the feedback, but it’s better to be on the conservative side.

I sure as hell wouldn’t place 7200 lbs (900 gallons equivalent of water) up there, which is what 60psf would suggest. Again, assuming 120 sqft of space on a 12ft span.

Interesting try about the water. I have not seen a 12' by 12' by 10 inch tall water tank before. 60 psf is spread out, not a point load like a conventional tank size that would contain 900 gallons.

But to put in in perspective, if the OP was placing an heavy engine, say 600 pounds on a standard pallet (42"x48" = 14 square feet) your get 42.85 pounds per square foot. Which is acceptable, again if its a few of them.

It would be different to have racking up there and stack them 3 tall or set them on the floor as close together as possible. Something it doesn't appear the OP is planning on doing.

A 500 pound motorcycle that was placed to lean on its kick stand is not going to exceed the loading either. Average motorcycle is going to occupy a 36" by 85" space (21.24 square feet) which is 24 pounds per square foot. Even a heavy bike will be ok.


Using span tables is "engineering". Even engineers when building conventional style buildings don't calculate out all the loads and deflections, they open up span tables or the machinery handbook(with I and W beams) and take information already calculated out in these tables. That is why they exist.

When I built my ICF house with a suspended composite slab, I simply printed out all the specific tables(with lines highlighted) and drew some cross sections and footer size/layout plans. The practicing engineer spent 30 minutes checking that I used the correct table/lines and that my ground pressure was suitable for my soil structure, told me I was the kind of guy that built brick s&(thouses and stamped my plans.

On the same hand, osb and ply all have nail schedules and nail size call outs in the application literature. There is no need to have/pay an engineer to repeat the same.

Very few conventional buildings built have engineered plans. The local building authorities in many incorporations allow the use of tabulated data in the American wood council or Southern pine association in place of plans stamped by a practicing engineer. Maybe yours is different but that is no reason to condemn the OP, first incorrectly for using balloon framing, and now being presumptuous about a lack of "engineering"

 

[ericlar80]

Interesting try about the water. I have not seen a 12' by 12' by 10 inch tall water tank before. 60 psf is spread out, not a point load like a conventional tank size that would contain 900 gallons.

But to put in in perspective, if the OP was placing an heavy engine, say 600 pounds on a standard pallet (42"x48" = 14 square feet) your get 42.85 pounds per square foot. Which is acceptable, again if its a few of them.

It would be different to have racking up there and stack them 3 tall or set them on the floor as close together as possible. Something it doesn't appear the OP is planning on doing.

A 500 pound motorcycle that was placed to lean on its kick stand is not going to exceed the loading either. Average motorcycle is going to occupy a 36" by 85" space (21.24 square feet) which is 24 pounds per square foot. Even a heavy bike will be ok.


Using span tables is "engineering". Even engineers when building conventional style buildings don't calculate out all the loads and deflections, they open up span tables or the machinery handbook(with I and W beams) and take information already calculated out in these tables. That is why they exist.

When I built my ICF house with a suspended composite slab, I simply printed out all the specific tables(with lines highlighted) and drew some cross sections and footer size/layout plans. The practicing engineer spent 30 minutes checking that I used the correct table/lines and that my ground pressure was suitable for my soil structure, told me I was the kind of guy that built brick s&(thouses and stamped my plans.

On the same hand, osb and ply all have nail schedules and nail size call outs in the application literature. There is no need to have/pay an engineer to repeat the same.

Very few conventional buildings built have engineered plans. The local building authorities in many incorporations allow the use of tabulated data in the American wood council or Southern pine association in place of plans stamped by a practicing engineer. Maybe yours is different but that is no reason to condemn the OP, first incorrectly for using balloon framing, and now being presumptuous about a lack of "engineering"

Despite you not having seen a water tank of that size, the idea of an evenly distributed load is just that - the whole floor supports the implied load. Span tables are just one consideration, which is why things are engineered.

I’ll just repeat that 60 psf would not be something I would do with this design. But 60 pounds in one location, of course, no problem.

 

[Firebrick43]

Despite you not having seen a water tank of that size, the idea of an evenly distributed load is just that - the whole floor supports the implied load. Span tables are just one consideration, which is why things are engineered.

I’ll just repeat that 60 psf would not be something I would do with this design. But 60 pounds in one location, of course, no problem.

I think at this point what you would do is irrelevant. You wouldn't do over 15psf because you didn't understand balloon framing.

 

[ericlar80]

I think at this point what you would do is irrelevant. You wouldn't do over 15psf because you didn't understand balloon framing.

I’m not dumb enough to recommend 60psf to someone on the internet without knowing more about how and where it was actually constructed, especially when most 2nd story floors are rated for 40psf.

 

[rayra]

You guys are all forgetting that this wasn’t engineered for a specific load, and probably wasn’t inspected for conformance to a plan which would include a nailing schedule. We also don’t know whether the building has been sheeted with plywood to prevent racking, nor the height of the load. I’ve no doubt it can hold more than 15psf and still be standing, and OP can do what he pleases with the feedback, but it’s better to be on the conservative side.

I sure as hell wouldn’t place 7200 lbs (900 gallons equivalent of water) up there, which is what 60psf would suggest. Again, assuming 120 sqft of space on a 12ft span.

Have you ever actually built anything? Or is this all out of your engineering textbook?
Maybe you should read some timber framing books, instead.

And this -
"You would have been better off to put a Jack stud under each of the joists."

There is not one damned bit of practical difference between a jack stud and those joists sitting on that notched in ledger. None.

These building methods have been used for centuries, including in barns with hay lofts. A single small bale is about 13/sq' when green. And they get stacked pretty high in those lofts.

I also noticed you moved the goalposts and inserted 60/sq' to argue against. Even the posited engine/trans on a pallet doesn't exceed 40/sq', or 10 such loads, which may approach your 7200. And even your inserted 7200# load is a 50/sq' static load on the OP's floor area.
Neither extreme condition is presented by the OP.
And even your extreme case could be handily dealt with by putting a centerline support beam and a few posts in.

 

[Firebrick43]

I’m not dumb enough to recommend 60psf to someone on the internet without knowing more about how and where it was actually constructed, especially when most 2nd story floors are rated for 40psf.

I didn't "recommend" 60psf, I clearly linked to the span tables, which are conservative, its up to the OP to look at the info and decide if his joists match up. Hense my quote "If its the 12' span, then it will conform to the 60lbs per sqaure foot rating." There was no "recommendation" in that statement. I even questioned the orientation of the joist.

As far as you "knowing more about how" its constructed is irrelevant, you quite obviously didn't understand balloon framing and made your arguments/assumption based on that.

What does "where it was actually constructed" have to do with anything? Physics and material sciences don't change due to location.

And yes, most residential houses are built to 40psf, except this isn't a house, its a mezzanine/equipment loft, not a house, built inside a building so it doesn't have to even deal with wind shear or roof loads being transferred through the walls

 

[ericlar80]

Have you ever actually built anything? Or is this all out of your engineering textbook?
Maybe you should read some timber framing books, instead.

And this -
"You would have been better off to put a Jack stud under each of the joists."

There is not one damned bit of practical difference between a jack stud and those joists sitting on that notched in ledger. None.

These building methods have been used for centuries, including in barns with hay lofts. A single small bale is about 13/sq' when green. And they get stacked pretty high in those lofts.

I also noticed you moved the goalposts and inserted 60/sq' to argue against. Even the posited engine/trans on a pallet doesn't exceed 40/sq', or 10 such loads, which may approach your 7200. And even your inserted 7200# load is a 50/sq' static load on the OP's floor area.
Neither extreme condition is presented by the OP.
And even your extreme case could be handily dealt with by putting a centerline support beam and a few posts in.

I didn’t change anything, Firebrick is the one who initially responded with 60psf. And nobody is talking about a centerline support. Go back to the rock you crawled out from under.

 

[Dozerhand]

I'm not going to challenge any of the engineering wisdom on here but if it was me and that's just a 12 foot span, I'd put anything up there that I wanted to. What's the worst that can happen?

 

[theoldwizard1]

The beams are sitting on a 2x4 ledger like the attached picture.

That 2x4 ledger is WAY TOO SMALL ! It should be at least a 2x12. I !ike the fact that the ledger is "set in" to the studs, but those studs should be at least 2x6 and probably doubled underneath the ledger.

 

[Moss]

Interesting to read the range of opinions on this! If you actually notched the ledger in the studs like the drawing and it's not just scabbed on using fasteners it's plenty strong in my uneducated opinion. I don't think the 2x4 ledger is too small it isn't a header i don't see any real span. The "beams" aren't out in the centre of span between studs but fastened to studs and load is going right to the ground.

 

[billconner]

In the two old houses I lived in and restored - 1886 and 1904 - the second floor joists and the attic floor joists sat on 1x6s let into 24' 2x4 studs. Sheathed with 1x12s and no headers over windows and doors. Both were straight and plumb.

 

[NUTTSGT]

I see no issues if the OP did in fact notch the stud for the ledger to sit it.

What worries me is the fact the he said he attached like in the picture. It's the Internet and we have to take his word, that's what he did as he did not post " his picture". No where does he say he notched the ledger in.

Personally, I would have used a jack stud under the joist rather than notching the 2x4 wall stud. If the wall was 2x6, I'd be fine with it. Just personally preference. Besides, for me cutting the jack studs and attaching probably would have been faster for me rather than notching.

 

[theoldwizard1]

Interesting to read the range of opinions on this! If you actually notched the ledger in the studs like the drawing and it's not just scabbed on using fasteners it's plenty strong in my uneducated opinion.

True !

I don't think the 2x4 ledger is too small it isn't a header i don't see any real span. The "beams" aren't out in the centre of span between studs but fastened to studs and load is going right to the ground.

The ENTIRE WEIGHT OF THE LOFT AND ANYTHING STORED UP THERE IS RESTING ON THAT 2x4 !

Sure it is only a 16" span, but hat is rediculos!!

Personally, I would have used a jack stud under the joist rather than notching the 2x4 wall stud. If the wall was 2x6, I'd be fine with it. Just personally preference. Besides, for me cutting the jack studs and attaching probably would have been faster for me rather than notching.

AGREE !

 

[jar944]

That 2x4 ledger is WAY TOO SMALL ! It should be at least a 2x12. I !ike the fact that the ledger is "set in" to the studs, but those studs should be at least 2x6 and probably doubled underneath the ledger.

Balloon framing is different. It's called a ribbon board.

R502.6
Bearing.
The ends of each joist beam or girder shall have not less than 1.5" of bearing on wood or metal and not less than 3" on masonry or concrete except where supported on a 1x4 ribbon strip and nailed to the adjacent stud or by the use of approved joist hangers.

 

[05snopro440]

Internet opinions aside, if you want a real rating for your loft then you need to get a structural engineer to do that work and rate your actual installation.

 

[Moss]

True !

The ENTIRE WEIGHT OF THE LOFT AND ANYTHING STORED UP THERE IS RESTING ON THAT 2x4 !

Sure it is only a 16" span, but hat is rediculos!!

AGREE !

This has me curious how we see it so differently. In conventional framing around here the floor joists would be on top plate of two 2x4's laying "flat" and not always directly above the studs. This is seems at least just as strong to me. The weight appears to be spread out through the studs evenly in my perception.

 

[Zeke]

There's nothing there that I see that can't be helped with some metal framing clips.

 

[billconner]

Balloon framing is different. It's called a ribbon board.

R502.6
Bearing.
The ends of each joist beam or girder shall have not less than 1.5" of bearing on wood or metal and not less than 3" on masonry or concrete except where supported on a 1x4 ribbon strip and nailed to the adjacent stud or by the use of approved joist hangers.

Yes! Has worked for well over a 100 years in millions of houses. It's fine. I agree the notching is important.

 

[rayra]

Internet opinions aside, if you want a real rating for your loft then you need to get a structural engineer to do that work and rate your actual installation.

That's the punchline, you see. Or don't see.

All this hem twisting and pedantry over what is obviously a very strong arrangement to anyone with building experience.

 

[NUTTSGT]

Balloon framing is different. It's called a ribbon board.

R502.6
Bearing.
The ends of each joist beam or girder shall have not less than 1.5" of bearing on wood or metal and not less than 3" on masonry or concrete except where supported on a 1x4 ribbon strip and nailed to the adjacent stud or by the use of approved joist hangers.

Your picture or random internet picture ?

Curious as to it appears the joists are actually notched to fit over the ledger board.

 

[Zeke]

Your picture or random internet picture ?

Curious as to it appears the joists are actually notched to fit over the ledger board.

Look at the perspective. The ribbon is on the inside and the joists run past to the outside face. That's where they look 'notched' but in fact are not.

 

[NUTTSGT]

Look at the perspective. The ribbon is on the inside and the joists run past to the outside face. That's where they look 'notched' but in fact are not.

Yeah, I can't see that Zeke. If that was the case, shouldn't the top of the notch in the stud meet the bottom of the joist ?

 

[Firebrick43]

That 2x4 ledger is WAY TOO SMALL ! It should be at least a 2x12. I !ike the fact that the ledger is "set in" to the studs, but those studs should be at least 2x6 and probably doubled underneath the ledger.

You obviously have no idea either, its not a ledger, doesn't act as a ledger, and the load transferred right to the stud so there is no beam movement like a ledger, it strictly a shear force.

And again, as mentioned earlier, 2x4 in platform framing(what some are calling "conventional" but balloon has been conventional far longer) on 16" centers support two or even three floors above them commonly with the roof loads as well. This has no roof load or snow load, no wind shear, and only a second floor.

 

[Zeke]

@ NUTTSGT: Perspectives are weird sometimes. That's exactly how I see it.

 

[billconner]

I thought it was notched too - as they were in my house. I assumed it was a means to achieve level with rough sawn lumber with varying widths.

 

[Firebrick43]

I see no issues if the OP did in fact notch the stud for the ledger to sit it.

What worries me is the fact the he said he attached like in the picture. It's the Internet and we have to take his word, that's what he did as he did not post " his picture". No where does he say he notched the ledger in.

Personally, I would have used a jack stud under the joist rather than notching the 2x4 wall stud. If the wall was 2x6, I'd be fine with it. Just personally preference. Besides, for me cutting the jack studs and attaching probably would have been faster for me rather than notching.

Many builders are trying to pull out the best energy efficiency of a house are actually going back to balloon framing. Doing what is in red is counterproductive to that end and wasteful of wood to boot if it doesn't considerably help in strength.

2x4 walls sheathed in 3/4 ply has an insane vertical load capacity. People forget that many time, only thinking of sheathing as a shear diaphragm.

 

[NUTTSGT]

Many builders are trying to pull out the best energy efficiency of a house are actually going back to balloon framing. Doing what is in red is counterproductive to that end and wasteful of wood to boot if it doesn't considerably help in strength.

2x4 walls sheathed in 3/4 ply has an insane vertical load capacity. People forget that many time, only thinking of sheathing as a shear diaphragm.

When I went back and reread the OP for a third or fourth time, I caught that about the 3/4 sheathing. I figured as much with it helping with shear. But it allows the 2x12s to sit on 2 3/4" rather than 1 1/2". . . . something to think about.

 

[jar944]

Your picture or random internet picture ?

Curious as to it appears the joists are actually notched to fit over the ledger board.

Random internet picture. It looks notched to me.