Greatly appreciate if anyone out there would have an idea what to use to support a lift in the center of a 16 ft span, and have a 1500 lbs max load?

Thinking of maybe three stacked 2x8x16s??

  • 1
    What is the context, e.g. is this a backyard project or inside a structure? You may be able to use existing structure to help stabilize a beam or truss, but if you just stick two posts in the ground and a beam across the top it may topple over.
    – HABO
    Feb 12 at 20:25
  • 2
    I’m voting to close this question because there are so many conflicting opinions (from highly rated members of the community) that the only proper answer is for the OP to hire a local, licensed Structural Engineer to do the math, come up with a solution and sign off on it.
    – FreeMan
    Nov 10 at 13:15

An "I" beam. I have pulled engines from cars and see triple 2x8s bend over a 5-6' span. No way are you going to carry a dead load of that much weight right at the center with less than an I beam... I mean you could but the wood would be much much more expensive than a basic I beam.

  • 1
    You call it “a basic I-beam”. What size is that? Does that I-beam require steel columns?
    – Lee Sam
    Feb 12 at 7:20
  • A steel I beam does not require steel columns. My house, for example, includes an I-beam the support the center of the garage area. The I-beam was originally installed on posts made up of 4 2x4's nailed together. (I replaced one end with a steel post during a remodel.)
    – aghast
    Feb 12 at 14:54
  • @aghast How are you going to secure the I-beam to the end grain of the wood posts, unless you weld on side straps or provide steel columns?
    – Lee Sam
    Feb 12 at 17:33
  • @LeeSam - first you can use wood posts for i-beams. The reason you don't see it much is that the fasteners on each end make it cost prohibitive - meaning that if you buy the two fasteners you might as well buy a $60 post. You can get quality posts for $60. So $60x2 for posts and a new 4x4 i-beam around ~300 (used 100-150). SO looking at $420 and something that is done right with no long term issues. You use 2x12s and not only may the bend but they may take other structure with it.
    – DMoore
    Feb 12 at 17:38
  • @DMoore No, the reason wood columns are not used with steel beams is because they could easily fail. The smallest beam I could find in my manual is 10” high and will support 29,000 lbs. However, a 4x4 post will only support about 9,800 lbs. for a post that is 8’ tall. This is due to the “slenderness ratio”. (A heavy load will cause the post to buckle.) If you’re mixing structural materials, you’d better understand their properties, capacities, etc. (Never lay a beam on its side. Wow, no one would believe that one...)
    – Lee Sam
    Feb 12 at 18:06

You'll need to provide more information, or do more thinking, about the surroundings.

When you have a beam connecting two points, with no support in the middle, the measurement you are concerned with is "deflection." That is, how much does the beam bend or sag.

When a beam is installed in residential construction, there is concern because the beam might also be connected to drywall or plaster, and so there is a limit to the amount of permissible deflection. Typically this is a tiny fraction, like 1/240 or 1/360. (That is, one inch over 30 feet.)

If you are installing a beam that is not supporting a floor and not supporting a ceiling, but just exists to support a hoist, you don't need to worry about that. BUT you do need to worry about the other aspect of deflection: when a beam deflects, it becomes effectively shorter. If a beam is secured at the ends, the deflection of the beam translates into pulling the ends of the beam together.

If you secure your beam on a post, the deflection of the beam will pull the top of the post inwards. This could cause your entire structure (posts, beams, hoist, etc.) to collapse.

The solution to deflection is height-of-beam. The taller a beam is, the less deflection. An "I beam" is basically the perfected realization of a common wooden beam -- most beams don't carry enough load to worry about breaking the material, so much as the need to worry about deflecting the material. So the vertical part of the I is tall (to reduce deflection) but thin (because you aren't worried much about breakage). The flanges of the I are there to prevent the beam from twisting.

If you are going to build freestanding self-supporting posts that the beam will rest on with no connection, you can just use an 18 foot beam over your 16 foot span, and the deflection/shortening won't be much of a problem (as long as the beam can slide relatively freely). You'll have to worry about the beam falling over, though, so put some side supports in place.

If you don't have room for that, you'll need a beam that won't deflect very much. To get a wooden beam with (only) 1 inch of deflection across 16 feet of span with a 1500 lbs load would require 6 inches by 16 inches of cross section (4 laminated 2x16 or LVLs).

Most people are surprised by the height requirements. But there's a reason why those big warehouses have 3-foot girders across the ceiling.

This is one of those areas where steel is going to outperform wood, and where it actually matters. You may want to settle for a hoist on wheels, or an engine lift. If you insist on a beam hoist, you should absolutely talk to an engineer. It doesn't cost that much, and it is a real relief to be able to show an inspector (or your wife) a set of signed off plans.

  • Sorry...I’ve got to downvote this answer because there’s so much inaccurate information. 1) A 1 3/4” x 7 1/2” Versalam will support about 2,000 lbs. I don’t know where you got your information, but it’s wrong. In fact, Boise Cascade doesn’t even make a 6” wide Versalam...see attached chart. Scroll many pages to the Versalam calculator on attached: p.widencdn.net/acrjga.
    – Lee Sam
    Feb 12 at 17:16
  • Additional inaccurate information: 2) The reason the steel beams have flanges is NOT to keep the beam from rotating. It’s because of the extreme material (fiber)in bending. The closer you get to the center of the beam the less extreme fibers are in bending...until you reach the center and the material is not in compression or tension...it’s called the “neutral axis”.
    – Lee Sam
    Feb 12 at 17:22
  • Additional inaccurate info: 3) A 4x8 will deflect slightly less than 1/2” for a 16’ span and loaded with 1500 lbs. in the center of the span. I don’t know how you calculated the deflection to be 1”. Please explain.
    – Lee Sam
    Feb 12 at 17:26

A 4x8 wood beam can easily support 1900 lbs. located at the mid-span of a 16’ span of a beam using a mid-grade spruce, pine or fir (SPF) beam.

If you use a higher grade like “select structural”, then it will support 2200 lbs. or more.

Make sure you use adequate posts (4x4’s) and provide adequate connection (like Simpson connectors) to posts, walls, etc. Also, make sure it’s laterally braced.

  • I won't downvote but I just want other users to understand that this is a really flawed answer. Mainly because 4xs are basically the worst type of material to use as joists. 4xs are for vertical support - posts. Much much much better off buying 3 2x8s and flip them on their side laminated across the span - it would probably support 3-4 times the weight of the 4x. That being said this would not handle a high center load especially if that center load was constant.
    – DMoore
    Feb 12 at 17:42
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    @DMoore I don’t think you understand what the op is asking. This is a SINGLE beam NOT a JOIST. If you lay 3-2x8’s on their side you loose it’s strength. Beams are to be installed vertical not horizontal.
    – Lee Sam
    Feb 12 at 17:51
  • If the OP is meant to lift a 1500 weight positioned in the middle of the beam, I don't see anything wrong with Lee Sam's response, which suggests 4x8 beam with 4x4 posts. But I am not a wood person, so I reserve my commitment to use 4x8. Also, one shall address safety factor along with his/her recommendations.
    – r13
    Mar 15 at 0:12

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