# Can I do this???  Post and beam question



## hondadrv24 (Feb 4, 2008)

I have a 12 year old Ranch style house, approx 24x44  with a beam down the middle of the basement to support the upstairs.  I know that the roof is truss, making the exterior walls the only load bearing surfaces for it.  so the beam with 3 posts spaced evenly underneath is only supporting the living area of the house.  

What I would like to do is turn the basement into a 24'x24' living room, one bath, one utility(furnace, waterheater), one bedroom, and a playroom connected to the living room.  

the beam is 8"x5" x5/16" I beam with 3" support posts.

My question is the living room, as i currently have it planned has 2 of the support beams out in the room.  I would like to remove one of the posts. and move the center one about 3 feet over to make the living room have no posts in it.  To support the upstairs I would weld 2 3/8" plates one on each side of the  beam to box it in.  the overall length of the span would be 24'  I could put a post in at 3' from the exterior wall to shorten the span, as the stairs are  right there, and I could put a heavier post in on the other side as it would be in the utility room.    Is this a plausable solution??  InspectorD would code allow something like this or do I need to consider putting a second beam in to support the floor joists??

upstairs above this area is the living room and kitchen.  thanks in advance for your replies.  
Justin


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## mudmixer (Feb 4, 2008)

You really need some engineering help to give you some options.

Where is the splice in the main beam or is it one continuous beam? An engineer can determine if it can go from 3 equal 14' spans to a 14' span, an 8' span and a 17' span (approximate). Usually, the beams for a house are not over-designed enough for major span changes.

Since you are moving the post, you will need a new footing under it. You cannot just sit it on the floor since you have absolutely no idea how thick or strong the floor is and if there really is any soil supporting the slab in the new location.

Having a beam fail or a post poking a hole in the slab is is major problem that will damage everything above.


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## CraigFL (Feb 4, 2008)

My quick calculations say that by extending the distance between supports from 11' to 24', increases the stress and deflection by 220%. By putting two 3/8" X 8" plates on the beam, one on each side, you only increase the stiffness and stress resistance to 150% of what it was which wouldn't be enough to make it as good as before. Without knowing your situation, it would be difficult to guess which way would be best for you to go but deeper( greater than 8") is alsways much better.


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## hondadrv24 (Feb 4, 2008)

Mudmixer,

I planned on digging down and putting a new footing under the post.  The beam is one continuous beam so no seams.  

CraigFL,  

thanks for the calculations,  if i went with a thicker plate would it make it stronger or would i be better off getting a couple of engineered wood or steel beams to go beside the existing.  The floor joists extend approximately 1 foot past the beam on either side.  I have a 9' poured wall basement and was planning on dropping the ceiling height to at least 8'.  Like I said last time I could  reduce the span from 24' to 21' by putting in a new post at the stair edge.


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## inspectorD (Feb 4, 2008)

How come I get thrown under the bus...what about the other guy's..... 

Create some scale drawings yourself...and walk them over to the nearest engineer. They will cost you 2-300 for a sizing.

I would guess you will just be told to go with a modification to the beam. The problem is not can it carry the load...it's how much deflection can you live with. Boing..Boing...trampoline style.
Trust me, when a piece of steel breaks...there is no creak. It just goes BANG...and its in many pieces.

Get the engineer, be safe and save the DIY for other stuff. 

Not to mention the headaches when you try to sell, with no engineered specs or building permits.


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## hondadrv24 (Feb 4, 2008)

I just figured since your an inspector and seem to be giving quite a bit of advice on similar questions that you would have some sort of an answer for me. 

 I plan to do it all legally, Every permit that I need will be gotten!!  I did something like this when I was working with a contractor in KC but the beam was only supporting the floor of a big living room upstairs, so i guess it didn't matter if it bounced a little.  In my house it matters, because my kitchen floor is wood and I cant stand squeaks.  I already have enough from where they missed the stud nailing down the sub-floor, (can't wait till i change carpet and put a screw into the stud every 6").  

I'll get it spec'd but all the work will be DIY.  just trying to get some preliminary answers before I proceed too much farther, hoping to start in about 2 months.


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## inspectorD (Feb 4, 2008)

Ouch.. 
Yea, I wish I could answer that one. The steel beams are easy to size...just costly to put in a new one. 
Usually we end up putting LVL bolted inside the beams. Other times we weld a 4 foot piece just under each post. It kind of makes a small cantilever into the room but puts the weight further out.

There are plenty of solutions, but I would just get the train guy ...haha...and sleep at night.

Sounds like a fun project, hope you take pictures and share with the others who are thinkin about what yer doin.


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## hondadrv24 (Feb 4, 2008)

what is LVL???  is it similar to what i originally suggested doing?  Dont think that a cantilever is what i want,  But i see the idea behind it.  

I'll take pictures dont worry, the wife and I do plenty of that.  when we moved in our kitchen had carpet and wallpaper.  
   But we quickly ripped that up and put down Oak hardwood. much better    the before/after pics show a huge difference between the oak and new paint.  

I'll be sure to get some pics before i start and post them for you all.


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## glennjanie (Feb 4, 2008)

Also visit a steel supplier. They normally have span tables and will advise on the beam to buy from them for free (the advice, that is).
Glenn


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## guyod (Feb 4, 2008)

To get an idea of what maximum span of the i beam you have now is check this chart out

http://www.toolbase.org/PDF/DesignGuides/ResidentialSteelLoad_SpanTables.pdf


The chart  shows that in your situation an 8" beam will span between 13' -21'
Depends on the width/thickness of the beam.  I know a w8-13 is 4" wide about 1/4'' thick and w8-28 is around 8'' wide.  The rest you will have to look up..


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## inspectorD (Feb 5, 2008)

Laminated veneered lumber, basisally the same as what you said.
There are other types of engineered beams, this is the one you need. It's the least expensive...and not for looks.

You could size your own beam ..like I said, however we don't know what the loads are on your home. 

Grand piano, fishtanks, or hot tubs...oh my... 

I guess when you start to see to many things done questionable...you start to be cynical.


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## CraigFL (Feb 5, 2008)

You guys are just too conservative and get worried too easily. He just wants some information to see what is possible. I know you don't know me from Adam but I can tell you I've been a registered Professional Engineer for over 30 years. My information is based on quickie calculations to try to keep the stiffness and stress of the new support beam equal to the old one so there will be no perceived difference felt on the floor above. Armed with this information and having thought about the alternatives, he should be able to help make decisions for the final design of this project...


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## inspectorD (Feb 5, 2008)

It's time to make some money on the side. 
I understand you completely Craig, folks can do alot of things themselves with lots of background. I just see to much not followed through on so I lean to the side of caution...expecially when I am not there to see it in person. Being an engineer, I did't mean anything by the train guy comment either, you've earned your right to give that advice which others should not. 
He can always just do what he wants. I just give my opinion.


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## guyod (Feb 5, 2008)

So thats what they are called.. They look like a 4"x8" chunk of plywood.. I price the 10" and it cost $10 a foot. The guy at the lumber yard said they are equivent in strength as the same thing in standard lumber (2 2x8). But have less deflection and come in longer and straighter cuts.. I was expecting them to be stronger and couldnt  justify the price difference and went with the standard lumber.. I dont know what you would need maybe 2  12x6 using my lumber yards guys advice. i think they are stronger than he is saying though. 

I dont know what access you have to your basement but getting a 24' piece of lumber in your basement and in place will be almost impossible 

I would use this idea as only a last resort.


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## hondadrv24 (Feb 5, 2008)

I dont see how LVL bolted into the beam would be stronger than welding plate steel.  I would think if anything I should put LVL on both sides of the  beam and go with deeper than the steel.  I have room to get the beam in as I need to cut a couple of windows into the basement, which is only about 3' from being able to  cut a walk-out.   But that is a different project all together  Basement first landscaping later  Thanks for all the input guys.  

btw I have no idea how to read the chart on that website you sent me, I had seen it before but it just confuses me.  Definitely going to have to get an architect on this one.


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## guyod (Feb 5, 2008)

I didnt notice you put the width of your i-beam in your post. an 8''X5'' i beam could either be an w8 -18 or w8-21 beam.. The chart says a  24' wide one story trusses home can span 17.6' or 18.8' accordingly

Using that number with craigs calculations are puts you at a 24' max span with the steel plates.. 

18' to 24' is an 150% increase.. 

I like your steel plate idea as long as your a good wielder. I would add a foot wide plate over the seams because that will be your weakest points. 

Hope this helps


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## hondadrv24 (Feb 6, 2008)

Awesome, glad to hear that my idea might work,  I'll still take it to a pro to be sized pry but its good to hear that my idea is plausable.   As far as the welding goes, my best friend from high school is a certified welder and a millwright.  Used to work for him, but then I went to college and eventually ended up in trucking.  I'd pry have him weld it for me as he is a far better welder (and he has a really nice miller bobcat portable stick welder that I'd need)   thanks for the help.


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## joeychgo (Mar 26, 2008)

CraigFL said:


> You guys are just too conservative and get worried too easily. He just wants some information to see what is possible. I know you don't know me from Adam but I can tell you I've been a registered Professional Engineer for over 30 years. My information is based on quickie calculations to try to keep the stiffness and stress of the new support beam equal to the old one so there will be no perceived difference felt on the floor above. Armed with this information and having thought about the alternatives, he should be able to help make decisions for the final design of this project...




While we're on the subject - let me toss out my similar question.

I have a question I hope you can answer. I have a 1926 built, 2 story home in Villa Park (with a full basement)

Currently, I have a wooden beam that supports the first floor. This beam is 8" x 6" (6" tall 8" wide). It runs approximately 35 feet. It is supported by the chimney and foundation on the ends and has 3 support columns placed approximately 8 feet apart along with a load carrying wall near the chimney.. 

My first concern is that the beam, although not broken, does have a lot of horizontal checking and cracking. 

My second concern is that I would like to remove 2 of the three support posts to allow better use of the basement space.

My question is this. What can I do to strengthen the beam so that first, it's safe and second, I can remove the 2 support poles closest to the foundation?

I am sure I could replace the beam with a steel beam, but would prefer instead to reinforce the beam with wood products if possible. (installation and fabrication costs are my concern here) My thinking is that I could sister several 2x8 dimension lumber or perhaps Parralam or LVL beams onto the existing beam. If I could keep the height of the additional beams to 8" I would be quite happy.

This is a preliminary question. Ultimately I would need drawings to get a permit to accomplish this, but I am first interested in figuring out what I would need to do so I can determine if it would be cost effective.


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## Square Eye (Mar 26, 2008)

Without seeing, and knowing what's being supported by that beam, It would be impossible to answer this. You need an engineer actually, or at the very least, a specialist in this type of structural modification. The manufacturer of the lam beams will send a rep to estimate the load and the required beam in most cases. I'd guess though that steel would be the best if you want to keep your headroom. No wood products that I know of will span 16' with a live load unless you go over 10" high. If you have load bearing walls above this beam, I'll bet you'll have to go even larger.
Removing posts changes the structural dynamics of a house. It's not a job to be taken lightly or to be experimented with.


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## joeychgo (Mar 26, 2008)

Well, my thinking is that if we know what's working now - then it can be figured from there. 

I know what your saying about wood - but what would happen if, lets say, I sistered 3 or 4  2x8s with plywood inbetween?


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## inspectorD (Mar 26, 2008)

Let me ponder that one....well, you would still need to ask the engineer. Every home is different, except for the ones that where built the same...hehe.
There are to many issues which are particular to that type of question, and without being there to see it we really should not give advice. 
Some questions that come to mind... 
How big is the joist span? Loads above, where do any point loads from above fall.
What condition are the joists and beam in? Checks, decay, bends, crushing points, plumber cuts in the right place. 
What type of footings are underneath the slab? Now all the weight is at one point instead of spread out over three.
What condition is the foundation in? Settlement, cracks....wet.

I could go on some more...but the best thing is as Square Eye suggested...the engineer, to see it up close.

It is doable...but the steel sounds about right with that headroom issue.


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## hondadrv24 (Apr 10, 2008)

I talked to my old boss, who runs a millwright company and based on the beam being a w 8x18 (it was stamped on the beam, just didn't look hard enough) the max span for the beam is where it is now 11',  He said that boxing in the beam would make it weaker.  the other problem that he saw would be in the deflection.   since the beam is already under pressure from the first floor, I would have to jack it up to preload the beam and new posts.  He didn't think that trying it was a good Idea and after talking it over with my wife we decided that we would leave them and start the framing.


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