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hondadrv24 02-04-2008 10:16 AM

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

mudmixer 02-04-2008 01:03 PM

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.

CraigFL 02-04-2008 01:58 PM

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.

hondadrv24 02-04-2008 05:22 PM


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


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.

inspectorD 02-04-2008 06:36 PM

Why me????
How come I get thrown under the bus...what about the other guy's.....:D

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'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.:D

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

hondadrv24 02-04-2008 06:46 PM

Your an Inspector!!
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.

inspectorD 02-04-2008 06:52 PM

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.:D

hondadrv24 02-04-2008 07:32 PM

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:D :D 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.

glennjanie 02-04-2008 08:01 PM

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).

guyod 02-04-2008 09:51 PM

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

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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