Beam design

[Mr.Ratbastard]

Our house is right at 100 years old. Back then it was common to build the kitchen seperate from the main structure. Somewhere down the line there was a porch added that connected to 2 then later it was enclosed. We had planned on pulling the low porch ceiling down to expose the cooler looking taller ceiling anyway but due to a crappy roofer and leaks I had to tear it out yesterday.
There is an opening between the living room and the porch room about the size of a garage door, (13'wX8't) it has a post in the middle and ridiculous beam design and framing above it. This is built into the original side wall of the main structure. I have also torn out a drop ceiling from the livingroom side.
I am hoing to put a new beam in and raise it as high as I can. One restriction is a new rigid spiral duct for the a/c. I can put in a laminated beam below the duct but I was wondering about the strength of a beam like this. https://images.app.goo.gl/SkFjo9PbJDAUSNwPA
I could build it in place (around the duct)and strengthen it further by sheathing both sides with plywood. Is this realistic? I imagine it would be substantionaly stronger than what is here now. The center post is probaly carrying the load now and I want to lose it.

 

[Dejeeper]

That link is a truss not a beam.

There r way too many considerations that need to be checked for u to trust anyone on the internets guesses. At least start posting a bunch of pics of the inside and outside so we can see what we r dealing with.

Best thing would to hire an engineer, would probably be under $1k and install the correct product so u dont drop your house on your family

 

[larboc]

A picture or diagram would be worth 10,000 words here. Nobody can figure out what you're asking.
1) Draw a free body diagram of what you're trying to ask. Include anything that is going to be loading this beam/truss and figure out what the live/dead loads are, PSF of snow load rating if this is supporting a roof, and if L/360 is sufficient.
2) Beams/trusses can be as strong as you need them to be so you first need to figure out the load you need to support, then find a member that will support that.

 

[junkytj]

pics/drawings at a min here and that will at least tell us if we can swag it or recommend you pay an engineer some money. No idea where you are or what the market is in your area. If you can find a semi retired eng working out of his house, it may be a grand or less and will be something easy to follow and build from even if it's on the back of an envelope. If you have to walk into an office with a receptionist and accountants and marketing, you are not going to get their attention for less than 5K and ti will be 20 pages of full size drawings most of which are standard details and have nothing to do with your house or plans.

 

[Mr.Ratbastard]

I was waiting on google photos to sync with my tablet, not sure why it took so long.
Here are a couple pictures. I will know more about what has been holding it up when I peel back the siding.
The house is getting rewired by the way. Crazy stuff going on in the wiring dept.

The edge of the foundation runs under the center post the same direction as the beam thing that is there now. Right now it looks like a 2x4 laid flat on top of a 2x10 als laid flat on top of the post and a 2x12 standing up on edge making a L shape.

 

[bgaidan]

What's beneath the walls at the end that will be supporting it?

 

[Mr.Ratbastard]

What's beneath the walls at the end that will be supporting it?

The edge of the origional foundation will be supporting the post I was planning on a 6x6 or 8x8 post at each end. The ceiling in the living room likely be rough sawn lumber, the duct is staying exposed. I can set what ever laminated beam on top of the post. I would like to figure out a way to stay as tight as possible to the duct or even have it pass through a structure like the truss in the link above.I was curious about tge liad carrying ability of a truss vs a beam or any other ideas out there.

 

[Splib]

you first need to figure out the load you need to support, then find a member that will support that.

The classics never go out of style :rolleyes:

 

[junkytj]

From those pics, it looks like they used a wall frame construction as a beam to the center support and down and the load is the roof.

Has the roof sagged any?

I was under the impression that the current outside wall was enclosing an old porch from the OP, if that is the case, how is it founded out there?

 

[larboc]

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I was waiting on google photos to sync with my tablet, not sure why it took so long.
Here are a couple pictures. I will know more about what has been holding it up when I peel back the siding.
The house is getting rewired by the way. Crazy stuff going on in the wiring dept.

The edge of the foundation runs under the center post the same direction as the beam thing that is there now. Right now it looks like a 2x4 laid flat on top of a 2x10 als laid flat on top of the post and a 2x12 standing up on edge making a L shape.

Looks like that existing beam is supporting the gable end of a roof so not much roof load? Floor joists setting on it from a floor above? How many square feet of floor are supported by it and what is that space used for?

What are you going to support the ends with? Setting the ends of it on 8"x8" columns setting on 3/4" plywood in the middle of a 16" span between floor joists isn't going to work. Setting on block probably will.
This is easy to engineer but you need to provide the loading details of what you want to do.

 

[jpmassey]

I'm a licensed engineer....go hire one and don't ask strangers on the internet. There are tons of individuals out there that will do a simple design for <$1000. Ask a builder in your area for references.

 

[Mr.Ratbastard]

Looks like that existing beam is supporting the gable end of a roof so not much roof load? Floor joists setting on it from a floor above? How many square feet of floor are supported by it and what is that space used for?

What are you going to support the ends with? Setting the ends of it on 8"x8" columns setting on 3/4" plywood in the middle of a 16" span between floor joists isn't going to work. Setting on block probably will.
This is easy to engineer but you need to provide the loading details of what you want to do.

The gable end is on the same wall as the tv. Upstairs floor joist end above the beam that is there now. The joist will be sitting fully on top of the new beam. The mention of plywood was to box in a truss for additional strength but I don't know the load a truss can carry vs a beam of similar size 4x12 or so.

 

[Mr.Ratbastard]

I'm a licensed engineer....go hire one and don't ask strangers on the internet. There are tons of individuals out there that will do a simple design for <$1000. Ask a builder in your area for references.

A simple beam on post would be much stronger than what is here now.

 

[larboc]

The gable end is on the same wall as the tv. Upstairs floor joist end above the beam that is there now. The joist will be sitting fully on top of the new beam. The mention of plywood was to box in a truss for additional strength but I don't know the load a truss can carry vs a beam of similar size 4x12 or so.

You need to calculate the PLF loading you need the beam to support. Do that by calculating how many square feet of floor it's supporting x PSF needs for that space. Also need to add up the side wall loading from the roof loads.
Sounds like you're talking about a lot of load on that beam, and based on you glossing over some of my questions I'm thinking you're out of your element.

 

[evernoob]

1) Draw a free body diagram of what you're trying to ask.

Well, that's what they pay Engineers to do after training. No offense to OP or all of the many skilled craftsmen here, but whether you come from it swining a hammer or a calculator, whipping out a Free Body Diagram is a cultivated skill, not a basic tool.

That's why PE Engineer offices charge contract minimums. Just sayin'.....


"Hey, shrink that body panel a bit with your hammer and dolly then let us have a look again..." is not an entry-level skill around here you see.

 

[non-OP]

Looks like that existing beam is supporting the gable end of a roof so not much roof load? Floor joists setting on it from a floor above? How many square feet of floor are supported by it and what is that space used for?

That may have been the case originally, but as soon as that "porch roof" from the space having been enclosed was added, the load went up a bunch.

What are you going to support the ends with? Setting the ends of it on 8"x8" columns setting on 3/4" plywood in the middle of a 16" span between floor joists isn't going to work. Setting on block probably will.
This is easy to engineer but you need to provide the loading details of what you want to do.

Since its the gable end of the original home there is likely foundation he can put the posts on (well squash block from floor down to the foundation) but at 100 years old, he has to make sure the foundation itself can handle point loads.

13ft is a decent span for load bearing onto old foundation. I'd pay the few bucks and hire an engineer. Technically you'd need a permit for the structural change and they'd want a stamp anyway.

 

[Mr.Ratbastard]

The perimeter is cinder block and what looks like the occasional big slab of stone or concrete. I forgot to answer the upstairs is approximately 600 sq feet and it will be a office or bonus room. I am not 100 percent against keeping a center post but it would be nice to get rid of it. And here is a picture of the sillyness that is there now. In the left corner of the picture is a dark 2x6 I believe this is the plate the floor joist are sitting on.

 

[jpmassey]

A simple beam on post would be much stronger than what is here now.

Stronger doesn't mean strong enough. One thing I've learned the hard way is just because it hasn't fallen down doesn't mean it won't tomorrow. My buddy had a 'microburst' at his house last month that pushed down 100 year old pines.

It's cheap insurance to have a engineer give you a design with a good safety factor.

 

[Eric]

That link is a truss not a beam.

Not exactly. A beam is designed to resist bending. A truss only resists axial forces. The picture shows a "composite" beam constructed from trusses. Basically.

 

[Cryptictoy]

This is glue lam in my house , span is 20ft-9 in , dimensions are 5"x16" this was the max span for length and able to have minimum head clearance. But if raise up can get others. And you can get with arcs as well . If you want to keep exposed this is the way to go . Beam is the dark with vine on it.

 

[Splib]

Mr Rat. It's the internet. You get internet answers. It's fun.

It's YOUR house. But think about this simple platitude. "You get what you pay for"

 

[Mr.Ratbastard]

Stronger doesn't mean strong enough. One thing I've learned the hard way is just because it hasn't fallen down doesn't mean it won't tomorrow. My buddy had a 'microburst' at his house last month that pushed down 100 year old pines.

It's cheap insurance to have a engineer give you a design with a good safety factor.

This is from 2 months ago. The Cedar tree is laying on the valley above this beam. The house has probably been through 25 hurricanes minimum. It doesn't mean the next one won't get it but the existing design as poor as it is has held up.
We just got back from out of town, it was when we were about 80 miles from home when we started seeing trees down. There are more trees broken in 1/2 and pushed over than you can imagine. It's crazy the destruction.
Anyway, not arguing your point, it's valid.

 

[2big bronco]

Download an I beam schedule and put in the biggest one you can fit in the space you have (height>width). Cut a hole in the web and plate around it for your duct to pass through.

 

[junkytj]

https://www.huduser.gov/Publications/pdf/res2000_2.pdf

These loads should get you close enough to design around.

I hesitate to post stuff like this in these threads, I'm an engineer and can do a free body diagram all day long. I'm not in a hurricane area, so I'm not confident how those are taken into affect. I do know we are looking at a sheer load from an exterior upstairs wall coming through the interior of the downstairs. I'm also not even a structural guy outside of tanks and retaining walls in concrete occasionally. So I'm not confident how uplift uplift on one side is translated across the structure of your roof. I'm pretty confident I could do a static check in this situation, but not confident with a dynamic load like a hurricane.

If it were my house, I'd check with someone who was more confident than I am.

 

[sdmuleman]

https://www.huduser.gov/Publications/pdf/res2000_2.pdf

These loads should get you close enough to design around.

I hesitate to post stuff like this in these threads, I'm an engineer and can do a free body diagram all day long. I'm not in a hurricane area, so I'm not confident how those are taken into affect. I do know we are looking at a sheer load from an exterior upstairs wall coming through the interior of the downstairs. I'm also not even a structural guy outside of tanks and retaining walls in concrete occasionally. So I'm not confident how uplift uplift on one side is translated across the structure of your roof. I'm pretty confident I could do a static check in this situation, but not confident with a dynamic load like a hurricane.

If it were my house, I'd check with someone who was more confident than I am.

Nor do we really have any good idea of what the loads are or how bracing/foundation/load distribution factor in. Someone who knows structural engineering really needs to look at that in person to give you a good answer.

 

[Mr.Ratbastard]

Nor do we really have any good idea of what the loads are or how bracing/foundation/load distribution factor in. Someone who knows structural engineering really needs to look at that in person to give you a good answer.

Can you not use the existing structure as a basis for what is sufficient proven by many years in use? I think it's pretty safe to do so.If it were failing you would need to know why. It seams to me with suffecient support for the post you now need to know post and beam size able to replace what is here less the center post.

 

[2big bronco]

Can you not use the existing structure as a basis for what is sufficient proven by many years in use? I think it's pretty safe to do so.If it were failing you would need to know why. It seams to me with suffecient support for the post you now need to know post and beam size able to replace what is here less the center post.

I think you could by "assuming" it was under its maximum load.... but we dont really know what the actual load is at all.

 

[Mr.Ratbastard]

Download an I beam schedule and put in the biggest one you can fit in the space you have (height>width). Cut a hole in the web and plate around it for your duct to pass through.

I think you could downsize a ibeam enough to just go under the duct. The duct is 12" so it would be a big s.o.b. to get in place.

 

[Mr.Ratbastard]

I think you could by "assuming" it was under its maximum load.... but we dont really know what the actual load is at all.

But we know what is capable of holding it.

 

[Stuck]

https://www.huduser.gov/Publications/pdf/res2000_2.pdf

These loads should get you close enough to design around.

I hesitate to post stuff like this in these threads, I'm an engineer and can do a free body diagram all day long. I'm not in a hurricane area, so I'm not confident how those are taken into affect. I do know we are looking at a sheer load from an exterior upstairs wall coming through the interior of the downstairs. I'm also not even a structural guy outside of tanks and retaining walls in concrete occasionally. So I'm not confident how uplift uplift on one side is translated across the structure of your roof. I'm pretty confident I could do a static check in this situation, but not confident with a dynamic load like a hurricane.

If it were my house, I'd check with someone who was more confident than I am.

Just my opinion and not a suggestion.

That house is a hundred years old and from the pictures I doubt it was built to withstand any kind of uplift. I dont see any hurricane clips or brackets and Im sure there are no foundation tie downs. Any laminated beam built for that span on 6x6s set to the foundation is going to be worlds stronger than what is there.

One issue you will have if you go to a Licensed PE and youre in a hurricane zone, they are going to design it to meet current hurricane standards. Tie downs brackets and whatever else local requirements are. Its not going to be slap a few posts and beam in there to equate or be stronger than what you have. Again Im not suggesting anything just stating what will happen.