Hog Barns: Why Slats & Beams Fail

( Sara Brown )

Tally up the years your livestock barn has been in use—and keep that number in mind as you step inside.

Now tally up the number of head of livestock, hogs or cattle and the people that pass in and out each day. If the concrete floor underneath fails, the injury and potential loss is hard to measure. That is a situation, Andy Altenburg, owner of Altenburg Construction, never wants a farmer to face.

“The No. 1 reason slats go bad is age,” Altenburg said during the 2019 Missouri Pork Expo in Columbia, Mo., Tuesday. After more than 20 years building and repairing livestock barns for hog and cattle producers, he’s seen about every situation-gone-wrong that you can imagine.

Good slats could last up to 30 years in hog barns and 40 years in cattle barns, he said, but slats can also fail from poor construction and poor quality materials. Which means that farmers need to regularly inspect their facilities to see the warning signs.

Here’s what to look for:

1. Cracks along the top and bottom of slats

Imagine the rebar inside each concrete slat. All rebar will rust eventually. As the materials are exposed to manure, water, etc., the rebar expands, pushes and cracks the concrete and the concrete falls off the slat. Anytime you have that, it compromises the integrity of the slat.”

Monitor the cracks in your slats to investigate further.

“The main thing you want to pay attention to is the bottom portion of your structure,” he added. “The top is a telltale sign to look deeper.”

2. Cracks along the header beams and on the ends.

One potential cause is improper construction, although it’s hard to see from the top of a pit. Incorrect placement of slats on header or lentil beams is a common reason why slats fail, he said.

cracks 2
Cracks at the header are often indicators to look at the slat's placement on the lentils or wall edges.

“There's certain minimum requirements that all slat companies should tell you openly,” he adds. One is that slats should be bearing, meaning that they should be sitting on 2” of your slat ledge or 2” of your beam or lentils.

The beams or lentils need to be sitting on a minimum of 3” on the post or end pocket.

“There's a lot of people in the industry that recommend putting posts on the end wall, rather than putting that end pocket in there. It’s just cheap insurance,” he said.

Quality of materials is another factor.

“Rebar should be placed 1” to 1.5” up from the bottom of the structure. Unfortunately, none of us can tell where the rebar is placed when that stuff is delivered, unless we cut them apart and look. And it isn’t a guarantee that that all the pieces are made the same,” Altenburg said.

Instead of going into a pit (which no one should do for safety), Altenburg rests on his construction knowledge.

3. Bowing or tripping on “kicker” slats. 

Slats that are too “green,” meaning they haven’t completed the curing process, are something to watch for in new construction.

“Beams and slats are taking tension—they do flex. I’ve seen slats flex as much as ½” to ¾” of an inch under a load,” he said. Posts, however are in compression mode.

If you build a new barn, you expect it to last for quite some time. “So if you're doing chores at a bar every day and then all of a sudden you're tripping over a slat—pay really close attention to that.”

Often it’s a placement issue with the slat on the end walls, he explained, and a post would prevent that issue. 

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