Wood beam to steel for ceiling support - hard to size

[Matt Neil]

I have an old barn and to make more useable space, I want to replace two wood beams with steel and remove some of the support columns.

It's a barn from 1930 and in a couple of weeks I'll be replacing the foundation. It's 30x50 and I plan to put a wood shop in the back half. There are two 6x8 wood beams under the ceiling joists that run the 50' direction, splitting the 30' length (so from each wall they're about 10' in). Then there are 6x6 wood columns every 8' supporting the beam. The barn used to hold tons of hay and grain in the haymow. Now it sits empty and it won't be used for hay and grain, but I'd like to keep the steel beam at a close capacity to the wood, just in case someone sometime decides to put a lot of stuff up there.

Instead of having so many columns supporting the beam, I want to remove all but the center ones, a column in the middle. The shop clearance to the bottom of the ceiling joists will be about 9' to 9 1/2'. So I want to keep the depth of the steel beam to a minimum to preserve headroom. I could go with two rows of beams set 10' apart, or I could run 4 rows of beams set 6' apart or just about any number of rows of beams. I also don't know if I-beams or tubing has greater support. I was wondering if 4x6 tubing that's a quarter inch thick could be used.

Any ideas out there? I attached a poor picture of the inside to help show what I mean.

[Mitchell Andrus]

Seek the advise of an engineer. He'll measure a few things, open a spreadsheet and have a solution in a few minutes. No kidding here, get someone who knows what they're doing to do this for you.
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[David Helm]

+1 on what Mitchell said. Not only do you need that engineer for safety, but if you sell it, the buyer will need to know also. As a home inspector, I would immediately advise my client to get an engineer to check it. If you already have the paperwork you'll not get the process slowed down.

[Dan Hintz]

In addition to what others have said, realize that the columns will also need beefing up due to the reduced number of them, not just a beefier I-beam.

[Matt Neil]

I've talked to a couple places that sell steel, but they're not willing to offer advice for fear of liability. Two days ago I talked to an engineer that I know who has a similar barn. He posed the question to someone else and will get back to me when he learns something. I'm just impatient since I'll be moving the barn for the foundation work and would like to get this nailed down by then. I was hoping someone reading this might be able to say that it's a simple solution. Increasing the distance between columns from 8' to 25' requires an increase in beam dimension by X. Then convert wood dimension to an equivalent in steel, or LVL or whatever would be shallowest. Apparently, these things aren't this simplistic! I am reassured by the fact that the haymow will never be loaded to the same capacity as when it's full of alfalfa bales. It won't get that kind of use again.

[Mitchell Andrus]

In addition to what others have said, realize that the columns will also need beefing up due to the reduced number of them, not just a beefier I-beam.

Also, the footings for each bearing post will not be up to snuff... this isn't a small project.
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[Henry Ambrose]

I've done this before and its not impossible but it can be a lot of work.

Finding an engineer who will touch this will be a problem. Old barns are full of questions that confound the apparent simplicity of your request. The best approach is to build a new support structure in place that completely replaces the old. This will involve some assumptions that contain a high margin of safety. In other words - you will overbuild this to be sure of the end result.

I think you want to have two beams running the 50' direction with a support in the middle and spanning 25' from each end to the mid support post. Is that right? If so, the question becomes "how can I support "X" amount of weight with this design"? The design being a 50' beam with supports at each end and one in the middle. So what is the weight you need to carry?

From the little information your photo supplies I'd think about bolting steel plates to the sides of the existing beam. The whole thing needs to be through bolted every six inches or so. I'd build temporary supports to the beam on each side of the center position and dig a massive footing for a new larger post, put in the new post with knees like whats there now. I'd do the same at each end post. Shore it up, remove the old support and build the new support right in place. That will probably work but its not a promise, I'm not an engineer and if it falls down its all yours. But this ought to give you an idea how to proceed.

[Matt Neil]

Interesting idea to use side plates on the current beam. I'm excavating the concrete floor and will pour a new one. Over the decades it's been used for so many purposes that there are multiple pours and multiple levels and slopes to the current floor. So new footings for the support posts will be a piece of cake. Now, figuring the size of those footings gets to be the tough part!

[Henry Ambrose]

Determine the weight the supports will bear and you can get an answer to the footings question from a local engineer. Getting 25' long steel delivered and installed may be one of the harder items to accomplish. You need an answer from a local engineer on the steel and the footings to be sure.

[Jim Becker]

I was hoping someone reading this might be able to say that it's a simple solution.

Therein lies the rub...it's not a simple thing. A structural engineer needs to do load calculations to determine what will be required to support the structure, both relative to the span including both the beam size and the support column(s).

[Lee Koepke]

removing the columns is one thing ... but eliminating column lines (beams) is another .. the joists need the support and their spacing will determine how many beams are necessary. Steel / LVL / Composite beams can be designed to eliminate the columns, but I too engage engineers for that adventure!

[Bill LaPointe]

I think that you can see from the various suggestions that the only way to grt a correct and SAFE answer is to get the engineer that some others have suggested! Just MHO.

[Mitchell Andrus]

Determine the weight the supports will bear and you can get an answer to the footings question from a local engineer. Getting 25' long steel delivered and installed may be one of the harder items to accomplish. You need an answer from a local engineer on the steel and the footings to be sure.

A hole in the side of the barn, a crane and a few strong men will be involved in the installation - that's after the delivery to your house.

Sounds like you'll be spending $3-4K by the time you're through. Is it worth it?
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[Dan Hintz]

Not to mention the wear/tear on your lawn as they move the tractor trailer carrying the beam in/out, as well as the crane that will most likely be used.

[David G Baker]

Unless the barn has a tremendous amount of sentimental value you may be well ahead to tear it down and build a pole building. You wrote that you are planning on adding a new foundation, you need to replace support beams, you need serious engineering help, you mentioned moving the building and your cash register is ringing off the wall. Spend some very serious time thinking and planning to figure out the total cost of what you are trying to do, then get some bids on a new building that will duplicate what your needs are.

[Don Alexander]

any attempt to do what you are talking about without consulting a structural engineer is pure folly

better safe than sorry

+1 on the investigating cost comparision of remodel vs. building new

you might very pleasantly surprised :)

[Mitchell Andrus]

Matt, we're gonna talk you into putting up a new building if it's the last thing we do. $27-33K plus a little more for a nice facade..... You were going to spend half that just to get a half refurbished, out of plumb barn.

C'mon.... Man-up. You know you want it.
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[Matt Neil]

You guys do make me laugh. Every contractor that came out to look at the project told me that a new building would be cheaper. And everytime I agreed. But if you've seen the aesthetics of these historic barns, you know they can be intoxicating. The costs to lift one of these beasts, move it 50', excavate the old foundation and floor, place a new foundation that reaches the frost line, move the barn back and pouring a floor will surpass a new building alone. Then there's siding that needs replacing, electrical, insulation...will I be able to move tools in then? It's a long process but I'm still young. I'll take it slow and pay as I go.

A lot of you have suggested I talk to an engineer. Good thing I did (as I posted earlier). But great ideas coming from this. Neither I nor the engineer talked about the side plate idea. I'm going to email him that tomorrow. I'm still open to ball park educated guesstimates on this. One thing I don't want to do is overbuild these beams. I know the haymow holds well over 100,000 pounds, and I don't need it to support that much when I'm done.

[Lee Koepke]

You guys do make me laugh. Every contractor that came out to look at the project told me that a new building would be cheaper. And everytime I agreed. But if you've seen the aesthetics of these historic barns, you know they can be intoxicating. The costs to lift one of these beasts, move it 50', excavate the old foundation and floor, place a new foundation that reaches the frost line, move the barn back and pouring a floor will surpass a new building alone. Then there's siding that needs replacing, electrical, insulation...will I be able to move tools in then? It's a long process but I'm still young. I'll take it slow and pay as I go.

A lot of you have suggested I talk to an engineer. Good thing I did (as I posted earlier). But great ideas coming from this. Neither I nor the engineer talked about the side plate idea. I'm going to email him that tomorrow. I'm still open to ball park educated guesstimates on this. One thing I don't want to do is overbuild these beams. I know the haymow holds well over 100,000 pounds, and I don't need it to support that much when I'm done.I am a contractor ... I probably would tell you the same thing ... followed by "it can be done" .. personally I could cringe at the thought of tearing something like that down and putting up a new 'modern' conventional structure. I, personally, would take the time to understand what you need and figure out a way to do that. Make sure you let us know how it turns out.

[Chris Parks]

Everyone gets carried away with the size of beam needed to span 50 feet. Supporting a beam in the middle has cut it down to 25 feet with appropriate footings, that's easy. Now put a lighter than usual beam in which is easier to handle and add strength to it in position. What I did with engineered approval was put a lighter beam in and then bolt a post onto the beam in the middle which dropped about 1 foot. I then fabricated a long rod bolted to the ends of the beam and which ran under the centre post. This rod was threaded on the ends and the rod was tensioned with nuts to support the middle of the beam, we in fact initially tensioned it too much and pulled the beam upwards and had too loosen it off. The big "if" here is to have footings each end to support the extra load. Engineers don't need to know the load going onto the beam, they have standards that allow for this. I was told that the greatest load is a crowd of people on a floor and not machines etc which we all regard as very heavy. Others may be able to correct me if this is wrong. I in fact suggested this method to the engineer and he was very agreeable and drew up the specs with no hesitation at all. It has not fallen down since I did it so I guess the idea works.

[Dan Hintz]

If you don't mind the money, nothing stopping you from creating a new building that has all of the charm of the old barn style...

[Don Alexander]

I was told that the greatest load is a crowd of people on a floor and not machines etc which we all regard as very heavy.


no doubt about it , live load is always greater than static load on the same or comparable weight ..........has to do with movement and vibration for starters

as for fixing the old , nothing wrong with that old barns have a certain appeal :)

[Nick Laeder]

Depends on the use of the structure. Live load on a library floor will never come close to the dead load, even when factored for uncertainty.

I have a degree in structural engineering, but don't practice. What you're talking about is certainly possible. I'd consult a practicing Professional engineer to come to the site and look at it. Your buddy the engineer can probably figure it out, but a firm that provides design services for new-built commercial structures may not be able to assess the existing conditions properly. Thankfully you're doing new foundations, that removes possibly the biggest unknown.

If you were on the Front Range, I know a company that would love to help you.

[Henry Ambrose]

Don't give - up you can do this and it'll be great when you're done.

[Matt Ellis]

I'm a structural engineer by profession, and we regularly see this sort of thing. I've read the thread, and I think what you're proposing is a possibility, but there are a couple of things that need to be addressed.

If I understand your problem correctly, you have a second story/mezzanine that is supported by your joists. You want to retain some of the live load capacity of that second floor, but you don't necessarily need the original design capacity.

If I were evaluating this structure, I would get an estimate of the dead load weight of the structure (probably about 15 psf) as well as the desired live load capacity. I'd probably assign a live load capacity for the 2nd floor of about 40 psf...maybe 50 if you're going to have lots of stuff up there. You said that existing floor supported 100,000 lbs at one point. If that is true, and the load was evenly distributed over the footprint of the barn (1500 square feet) that corresponds to a live load of about 67 psf.

One other thing to consider, which has not been mentioned yet, is the roof framing. Are there any interior supports? Do you have posts that support roof framing, and fall on the beam lines that you want to modify? If so, you need to take that into account when sizing the new steel. Code required roof live load is 20 psf, but snow loads may control wherever it is you're located.

I'd also suggest bolting channels to the sides of the beams in lieu of the steel plates. Rolled channel sections are more efficient than flat plates, which means you'll end up with lighter sections. Lighter sections equal less material, less labor to install and less money for you.

Beyond strength considerations, you need to consider deflections and serviceability requirements. I can't give you any specific recommendations without access to the entire situation, but generally a 6"x4" tube section will NOT be acceptable on a 25' span. Deflection is a function of the loads applied and the area that the beam supports, but a 6" beam spanning 25' with the load magnitudes you're talking about will be like a limp piece of spaghetti. Walking across the 2nd floor would be very similar to walking across your kids trampoline.

You're probably looking at a 12" channel minimum (bolted to each side of the existing wood beam) to be able to span the distances you're talking about.



-matt

[Don Jarvie]

Have you looked into engineered wood I beams? My BIL has been building a few houses with them to eliminate the row of posts in the basement.

I have to lean towards a new building. You can take the best outside features of the barn and replicate them but having a new interior like high ceilings, customized second story storage features, etc may be worth building new.

[Matt Neil]

I can put up a new building for the same money I'm putting into this one. But it won't be the same building. Sure I could have a brand new pole building for the shop I'm envisioning. Instead I'll end up with a 25'x30' shop that uses only 1/2 of the first floor. That will give me room to expand should I choose to. Plus I have a second floor that's 30'x50' with no walls or supports. Just open space. The ceiling is supported by the exterior walls. The second floor has an easy 20' ceiling height. And none of that includes the 14'x50' lean-to on the side.

W8x31 king beams will be used for support. The barn was moved Friday and most of the concrete was tore up yesterday along with a hole to bury it. The excavator should be done Monday and footings will be poured this week.

I'll be getting quotes on new siding in the next week or two but will probably delay that until next year. I'm leaning towards either tin (cheap) or fiber cement 4x8 sheets (more pretty).

[Matt Ellis]

Nice looking old building. If you have the funds for the renovation I can definitely understand the appeal.

Am I reading that you're planning to used a W8x31 for the 25' beams you were trying to size earlier? If so, and you have the headroom, I'd suggest using a W14x30. Should cost the same (steel sold by the ton) but have MUCH better strong bending/deflection performance.

-matt

[Matt Neil]

The headroom is the kicker. I'll have about 9 1/2' to the joists. Then the two beams below that.

[Jim Becker]

Wow...what a classic building! If you have the resources available, that's a very nice structure to save, update and enjoy. Bravo.

[Stephen Cherry]

I'm an engineer, and the first thing I would think about is calling in an engineer.

[David Gutierrez]

+1 on the engineer. you really should engage a engineer. a competent engineer would have had the beam sized correctly in lesstime than it has take for this thread to get this far.

for what its worth i am a architect with a good working knowledge of sizing structural members and would not hesitate to call in a structural guy to help me size this beam.

[Tom Scott]

As a structural engnineer, I'm glad you're saving the existing building. I would love to have an old timber-framed one like that.
As others have said, check out and hire a local structural engineer that you like. I'm sure he would anyway, but if not don't hesitate to pay him the little extra to come out for an hour and see it in person. He will see and think through things that you may not know to consider. From what I've seen, nothing you've proposed is that crazy. It's just a matter of sizing members and thinking through the detailing and connections.
We do a lot of historical preservation work, and you always try to first save what's there and work around it to bring up to code or meet the new plan.
Glad you are saving and reusing the old structure.

Tom

[Henry Ambrose]

And there is no way that fixing this will cost as much as a new building. Not if you do it yourself or pay someone. Anyway, let us know what you do.

[Mike Cruz]

Ahhhh, maybe not by you, but the next owner may want to load it down quite heavily and not know that what you did was not for that intention...

[Thom Porterfield]

Find a structural engineer!

Say that to yourself seven-hundred times or until you accomplish the task.

Besides the vertical load issues (a 25' span is nominal or tremendous, depending on what is or will be on the structure above), there are lateral loads to consider as well. Your photo shows knee braces at each post--these not only reduce the span of the beam but add a measure of lateral support to the entire building. Removing all of that will put additional lateral stresses on the exterior walls.

The idea of applying side plates to a wooden beam to strengthen it is intuitively sound--but it doesn't do much structurally. Consider a wide-flange beam (I-beam). It has most of its "beef" in the top and bottom flanges and a relatively thin web separating them. The bottom flange resists tension forces while the top flange resists compression forces when the beam is loaded. About all the addition of side plates does is add weight, and a little strength, and a lot of cost.

By the way: Did I mention that you really should find a structural engineer?