16 x 24 Pole barn planned for the spring

[EddieWalker]

There ya go! Using 2 by 4 stock for roof beams will never hold up. When we bought this place I was sure disappointed with the construction methods on the barn we inherited. The roof is all 2x4s and simple iron nails!
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I sure would like to have a long talk with the builder! The way things are going it won't make it another 70 years.

Bob

You are free to build with whatever size lumber you want. It's your barn and you have to live with the results. But if you ever build for somebody else, and take money from them for your services, I would suggest building it with the best materials available today and not relying on what may have worked in the past for a few buildings that have survived and ignoring the tens of thousands that didn't.

Eddie

 

[YardBikeBob]

I would suggest building it with the best materials available today and not relying on what may have worked in the past for a few buildings that have survived and ignoring the tens of thousands that didn't.

Eddie

The southern Missouri Ozarks has never been populated by a lot of money but it has been populated for a long time. There are a lot of old barns and I get a kick out of poking through them and trying to imagine the difficulty of building them back in the day. Fallen-in barns are not as common as you think so I haven't explored them much. Folklore says they usually burned up full of wet hay, though, instead of collapsing.

When the OP was asking about thoughts and ideas, I thought he might be open to other ideas including what has worked in the past.

My decrepit old barn is not unusual for the area. There is a retired fellow up the road with stories of splitting 18 cents a square bale 3-ways when he was hired to fill the loft up to the rafters when he was a teenager. He says the barn was old then, too.

Site mixed and hand poured concrete footings. 8 by 8 beams, 1x12 slab sides. Loft of 2x8 joists and 1x planks. Then that gambrel roof of long 2x4s probably sawn locally and cured since last Tuesday when they built that roof 15 feet off the loft deck. And that lumber dimension is exactly 2x4, too, and not SPF but oak. Purlins and a tin roof must provide an awful lot of rigidity for it still to be here for me to marvel at. Yes, I would have liked to talk to the builder.

No Lowes, few tractors, wooden ladders not cherry pickers. No calls to the ready-mix yard. Pickup trucks were puny. No power so no power tools. 4" uncoated nails. No codes or inspectors, either. No running water. Right adjacent is a 10' diameter, 12' deep, concrete and rock lined cistern, though. Hand dug is the legend.

No offense meant. I'm sure with 12" roof joists the OP can host a Square Dance up there in his little out building with no bounce. Using engineered trusses, the whole roof might roll by like a tumbleweed in the next twister. I just thought some might find it interesting how they kept many tons of hay out of the rain for half a century.

Bob

 

[Hiltz]

Eddie, Did you have a bad experience with 2x4 trusses ? I see a lot of 2x4 trusses in all types of buildings commercial and residential. I would think engineers and architects who design these have done all the necessary calculations for span and strength. I see now builders are using what they call floor trusses on homes and these are also made with 2x4's. These are really neat as all mechanicals (wire, plumbing, heat and air) are run through the space between the truss. No drilling of floor joists. Not trying to start an argument just wondering why you seem really against 2x4's in trusses.

 

[EddieWalker]

I'm not an engineer and I haven't build a lot of houses. I have built enough to understand how they work and how to size materials. I repair and remodel houses and barns. Failure in the structure is pretty common and always caused by a couple of things. Undersized materials, or somebody modifying it poorly or damage caused by water and bugs.

I've never seen a truss where they didn't use 2x6's for the top chord, or rafter. I've seen where 2x6's failed and they needed more support, or larger lumber should have been used quite a few times. Finding an example where something was done doesn't mean it is the best way to do it in other cases.

As for the flooring trusses built with 2x4's, that's a whole different animal. With the floor truss, they are creating a tight, rigid truss that has a lot of lumber used to create the bracing that keeps it together. A truss design is all about making triangles that take the load over a span. The bigger the triangle, the larger the lumber you need. Lots of small triangles are very strong!!! A triangle cannot move, so failure is caused by the strength of the material used or how well it's connected. Usually the connections are such that the ends of the triangle is forced together by the weight of the truss or the span, so we are back to the material used. For a roof structure, and especially a gambrel roof, you are very limited in design, so stronger lumber is going to give you a stronger roof.

Look at the design of the gambrel roof and you will notice that it's really just two angled walls with a wide triangle at the top. The lumber itself is doing a lot of the work, more so then the ability of a truss because of so few triangles to lock it all together. The bigger the span, the more triangles will have to be incorporated into the design of the truss.

https://www.google.com/search?q=gam...4FoyekQeAooCQAg&ved=0CCkQsAQ&biw=1344&bih=746

The link shows a variety of designs for a gambrel roof. Some are very strong, others terrify me. If it was your building, what one would you build?

Eddie

 

[paulharvey]

I've never seen a 2x4 truss. I've seen where they are used in some of the cribbing, but never for the rafters or joists. In my experience, a 2x4 on edge will sag over time with just a six foot span. Not every one of them, and not even half of them, but some of them will. Just going off memory, I believe that 2x4's are not allowed structurally for anything other then in a vertical position in building a house. I have seen and repaired quite a few 2x6's in roof structures that haven't been strong enough because of the design of the roof, or a flaw in the lumber.

Two things to remember. Just because you can find an example where it was done before, doesn't mean it's the best way to do it today. It might be a quality of material issue, like comparing old growth oak to fast grown southern pine, or it might be comparing an extremely talented builder to everyone else who did the same thing, but theirs failed. Second thing is that Code is a minimum that is based on past failures and what is known to work with modern materials.

I'm not an engineer and I haven't build a lot of houses. I have built enough to understand how they work and how to size materials. I repair and remodel houses and barns. Failure in the structure is pretty common and always caused by a couple of things. Undersized materials, or somebody modifying it poorly or damage caused by water and bugs.

The only place I've ever seen 2x4's used for roof structure are those premade sheds you can buy at the box stores. They are usually so flimsy that it's kind of fun to guess how long they will last. If you have an engineered truss with his stamp on it for a truss built with 2x4's on the rafters, I'd be surprised. I'm not saying it's impossible, but it sure seems unlikely that they would use them instead of 2x6's.

Eddie

I have used thousands of 2x4 roof trusses. Not on little sheds but on 40 ft spans and longer on 2 and 3 story apartment buildings, in 150 mph wind zones. It's all in the engineering design, the web member, ect. Top cord, bottom cord are often 2x4, and most Web members, although some times you'll see 2x4 bottom cord.

 

[EddieWalker]

I can't argue what you are saying, but I will maintain that it's not something I'm going to do for a client and not something that I would recommend that anybody else do. There are some very smart people out there that make a lot of money figuring out ways to do more with less. Spending less money on materials for a truss means using less material and going with smaller material. In some cases, making it lighter also factors into the formula. In most cases, these designs work, but we also know that after every Hurricane, code changes because so many of these ideas fail. Bridge failure is also common enough to realize that the wrong materials, poor craftsmanship and a flawed design still exist. If you really know what you are doing, then anything is possible. I'm just not a fan of pushing the envelope with light, small material when it's such a small increase in cost to buy larger lumber and not having to engineer a design using smaller lumber.

Eddie

 

[lovemytoys]

http://www.tractorbynet.com/forums/projects/255387-start-new-shed.html here mine

 

[matoyan]

I build a barn almost twice as big as yours and now I'm finding it not being big enough with tractor and all of the other attachments stored in it. Good luck.

 

[Verticaltrx]

There ya go! Using 2 by 4 stock for roof beams will never hold up. When we bought this place I was sure disappointed with the construction methods on the barn we inherited. The roof is all 2x4s and simple iron nails!
View attachment 359104
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I sure would like to have a long talk with the builder! The way things are going it won't make it another 70 years.

Bob

Then that gambrel roof of long 2x4s probably sawn locally and cured since last Tuesday when they built that roof 15 feet off the loft deck. And that lumber dimension is exactly 2x4, too, and not SPF but oak.

Bob

The full dimension 2x4 and the fact that they are oak is what allows them to get away with that. I have a barn on my farm that isn't quite as old (built in the 60's I believe) and it was framed entirely with rough cut oak 2x4's (doubled up oak 2x8's for the loft floor). Still holds 24,000lbs of hay in the loft just fine.

As a contractor I completely understand what Eddie is saying. I build barns for a living and use only the best materials made and overbuild everything, premium quality materials and premium quality craftsmanship. However, I'm also a farmer, and to make money farming you can't build barns and fences like that and expect to make any money.

The modern day lumber with its huge price tag is what drove me to buy my own saw mill. I'll be building a small 16x24 barn (one story) and I almost have all the lumber sawed. I'm using white pine which isn't as strong as oak, but much more plentiful on our farm. The poles will be locust, and anywhere that PT lumber would regularly be used I'll use locust or oak. I will build trusses with a 2x6 top cord, 2x4 bottom cord and 1x8 webbing, which on 4' centers should be plenty stout for our area.

 

[IHDiesel73L]

So I did a little more research (basically some creative Googling using the phrase "braced rafter") and found this:

http://pbis.okstate.edu/images/documents/6410_high.pdf

I've run across these old USDA plans before but this was the first time I had found a design that fit my needs. The drawing contains dimensions to build a truss or braced rafter system spanning anywhere from 20' all the way up to 34'. The 20' truss is built from four 2 x 6 x 8s, two 2 x 4 x 8s, fourteen gusset plates of 1/2" plywood, and a lot of nails. Glue is not mentioned, but I will definitely be gluing mine with a high strength construction adhesive in addition to nailing. Once I build a jig they should go together fast. Here's a section view of the new barn plan incorporating the braced rafter design:



The question now is whether or not this design requires the rafters to be tied together via a floor joist. The building is going to be 24' long and I'm thinking that I really only want the loft to cover half of it. So basically half the rafters will be tied together with 2 x 12 x 20 floor joists and half of them won't be. Any thoughts?