Steel Beam size vs Wood

[Spicycheesecake]

Hello,

I am looking at installing a much larger secondary beam to support the 20' 2x6 floor joist span at its mid point. Currently we only have a wood 4x4, and after some calculations by a structural engineer friend of mine, he says it should be replaced with a beam of either 3 2x8s, or 5x 2x6s, ideally of douglas fir. Note in the image attached there is a similar beam on the other side of the house but it isnt shown.

The beam would be 20' long, with support on both ends and a telepost in the middle.

Since my basement is only about 6' high I am wondering if there is an option for either replacing the 4x4 with a 4" tall steel beam, or instead drilling and through bolting a C channel beam onto each side of it. I'm also open to other solutions that could retain the existing headroom.

Is anyone able to help with the need steel beam size or spec that would be as strong or stronger than the wood beam options?

 

[SWComposites]

why can't your engineer friend design a steel beam or channel doublers? maybe you need to pay him or another structural engineer.

 

[Spicycheesecake]

why can't your engineer friend design a steel beam or channel doublers? maybe you need to pay him or another structural engineer.

He says his firm doesnt do that type of calc. He's just my buddy who took a look at it for free

 

[lexpatrie]

Teleposts aren't rated for permanent use anyway, unless that's changed lately.

 

[Greenalleycat]

Sounds like "your friend" has cooked up a scheme and now wants internet engineers to engineer it for free
Suggest that you pay "your friend" to do a professional job

 

[Eng16080]

I agree with the comments above. Your structural engineer should be able to answer these questions rather easily if they're any good.

Also, if I'm understanding the sketch, spanning nearly 14 ft with 2x6s spaced at 24" o.c. is rather questionable. Or is that the span you're trying to lessen? It's not that clear.

 

[will.sce]

This isn't a place to come get free structural engineering done for you

 

[Spicycheesecake]

I agree with the comments above. Your structural engineer should be able to answer these questions rather easily if they're any good.

Also, if I'm understanding the sketch, spanning nearly 14 ft with 2x6s spaced at 24" o.c. is rather questionable. Or is that the span you're trying to lessen? It's not that clear.

That longer spanned side already has an appropriate beam.

 

[Spicycheesecake]

This isn't a place to come get free structural engineering done for you

All I need is to know what size 4" steel beam can hold as much as a wood beam. Specifically it needs to meet or exceed 3x 2x8s or 5x 2x6s.

I originally didnt think it was that complicated and I'd find it on a table somewhere but it seems to be a pretty tricky question. Maybe I should try going to a place that sells steel beams?

 

[Spicycheesecake]

Sounds like "your friend" has cooked up a scheme and now wants internet engineers to engineer it for free
Suggest that you pay "your friend" to do a professional job

He came to my house and did a bunch of calcs and told me how to fix everything with wood beams for free?

I just want to know about using a steel beam equivalent to 3x 2x8 or 5x 2x6. Which from what im gathering is a lot of work to calculate?

 

[Spicycheesecake]

Teleposts aren't rated for permanent use anyway, unless that's changed lately.

Really? Is this In Canada? I see them in basically every house here.

 

[LittleInch]

The thing is that for residential floors the issue is not load capacity, but deflection and "bounce".

Your 25 psf looks very low for a kitchen. 40 seems more common.

But steel beam shape, thickness, flange size or C section dimensions makes a huge impact on its "strength" and flexibility.

But sag and comfort win out every time.

Also remember depth is everything. You could probably get away with one 2 x10....

 

[Luceid]

He came to my house and did a bunch of calcs and told me how to fix everything with wood beams for free?

I just want to know about using a steel beam equivalent to 3x 2x8 or 5x 2x6. Which from what im gathering is a lot of work to calculate?

So hire an engineer to do it. Or pick something based on strangers on the internet and run the risk...?

 

[milkshakelake]

I think if there were an easy solution, someone would've pointed it out by now. As it stands, it's a decent amount of work to calculate what you're saying. There's no table that has a 4x4 wood beam equivalency to 4" steel section. So nobody is willing to do that work for free. This is a place for professionals to help each other, not a place for free advice to homeowners - hence the backlash you're getting.

Besides that, there's also liability involved. Not in the traditional sense of money. But by ethical standards, we have to do the work and give a solid recommendation. Otherwise, you're looking at potential damage in the future. It's just not what we do. Contractors are fine giving free bad advice, but we can't. If your friend calculated 3 2x8, that's what you should use. A 4" steel beam is a far cry from that. Steel is stronger than wood, but it's not magically strong. The depth of the member makes a huge difference.

Telepost is a temporary shoring solution. People use it for permanent use sometimes, but it's not designed for that. Maybe it'll work, maybe not. It's like using a Toyota Camry on a racetrack.

 

[canwesteng]

Teleposts are allowed for permanent use in canada, though they required to be fastened.

 

[RWW0002]

I doubt you are going to get exactly the answer you are looking for around here, for the reasons pointed out above.

That being said, you might want to look into whether it would be possible or practical to construct your girder as a flush beam instead of a drop beam (i.e. cut the existing joists back as necessary to frame the 2x6 members into the side of it instead of over the top). You would have to use joist hangers @ each joist, but this would allow you ore room for something like a (3) 3x8 without losing head height. - There are many reasons why this might be impractical, but I thought I would throw it out there as food for thought.

Also, while many teleposts are labeled and intended for temporary use, there are some adjustable height posts (usually non telescoping but still allow adjustment) that are intended for permanent use. These should have an ICC Report associated with them (basically some testing that it is code compliant along with some tested and approved loading)

 

[Ron247]

First, I agree with others, hire a qualified engineer. But, briefly looking at your sketch, I see several things that bother me. I keep some general framing numbers in my head to help spot problems. 2x8s at 16" oc can span about 13'-8" and you have 2x6s at 24" spanning about that distance? Weaker and less of them? Not good. I also see a chance, you have a 2-span continuous beam condition by your sketch, that is another red flag. I also see 5 plys mentioned in your wood beam. In the back of my mind, I recall an issue with 4 or more layers.

If your friend is a registered engineer that does structures, they should have had a steel design course in college; regardless of what their firm does. We tend to take steel as mandatory in many locations, and can take Timber/wood as an optional course. I fail to see in the US (not sure about Canada) how you can take timber but not steel in college. As far as your friend, if they are not a licensed engineer, they absolutely should not be calling themselves one.

They truly are probably trying to help, but they are not if they are not fully qualified. Lastly, about using ANY kind of a chart or schedule. Most of us are taught we should not use a chart, schedule or even software that we could not reasonably reproduce the answer by hand if we had to. Maybe not a exact reproduction, but do we know the criteria and inputs needed along with the general process.

 

[Ron247]

You must be doing more than just replacing a beam. You must be removing some columns or you are currently having problems with the current system. If you are just swapping a 4x4 wood beam out, your friend should know which is stronger, a 4x4 wood or a W4x13 steel for example. Why does he size a 6" or 8" wood beam in other words?

 

[phamENG]

Which from what im gathering is a lot of work to calculate?

For us? No, it really isn't. But this is what we do to put food in our kids' mouths. Do you go to a lawyer, a doctor, or call out a plumber and expect them to give you their services for free? No. It's no different with us. I'm not going to charge somebody to size a beam for their house here in my city and then turn around and do it for free for some random person on the internet.

 

[Ron247]

Which from what im gathering is a lot of work to calculate?

Not hard to do if all I was doing is giving you a steel beam equal to (3) 2x8s. But if I was supposed to be giving you a beam that works for your actual conditions and based on your sketch, it would be 20 times more work. Literally, our ethics and code of conduct to my knowledge would question our involvement if something went wrong ANYWHERE in your remodel.

You list on Eng-Tips as an electrical engineer I assume. I think you would see our point if we asked you for a list of electrical services your firm provides for free over the internet that you would have liability for if something went wrong. Even if the wrong was created by me. You told me the breaker size for a wire size but I installed the breaker wrong or failed to notice the damaged place in the wire I used.