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Author Topic: post & beam design for load bearing interior wall; questions  (Read 8042 times)

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Offline thedarko

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Hey all

I'm hoping to hear some opinions or suggestions regarding my project. I'm tearing down a bedroom in my house and merging the space with my family room. The pictured stud wall is support the weight of the upper floor (12' spans in either direction, 2x8" joists 16OC) and I'm planning to replace it with 2 posts on either end, 8x8, and either an 8x10 beam across, or an engineering/laminated beam which I'll clad in wood to match the posts.

 

I'm looking for ideas for fastening/joinery, ideas for suitable wood species, and what folks think about using a single 8x10 timber beam as opposed to engineered beams. Any opinions, warnings, ideas are all welcomed... Im in the process now of finding the posts. I've found cedar, doug fir, and various reclaimed timber that I will be checking out tomorrow. Unfortunately its *DanG near impossible to find new dried 8x8s and I'm worried about warping and severe splitting after installation.

I'd like to avoid using any kind of angled support from the posts to the beam, as they will take up headroom and general space. Is there a specific way a beam should be set on top of a post? Ideas for fastening? Or is this a no-no?

For what its worth, Im a professional carpenter but my experience lies mostly in architectural and finishing millwork.. framing, especially the timber/heavy variety, is not exactly my forte.

Thanks

Offline thedarko

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Re: post & beam design for load bearing interior wall; questions
« Reply #1 on: July 06, 2012, 04:44:40 pm »
One more thing: Im considering making 2 of these (upper braces, wouldn't do that lower one)

 

Thoughts from a structural point of view?


Online beenthere

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Re: post & beam design for load bearing interior wall; questions
« Reply #2 on: July 06, 2012, 05:06:18 pm »
Welcome to the forum.

The length of the stud wall is ?

Looks like 24" o/c studs so maybe 16' ?

What load is expected above this wall?
south central Wisconsin
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Offline shelbycharger400

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Re: post & beam design for load bearing interior wall; questions
« Reply #3 on: July 06, 2012, 05:11:03 pm »
doin mostly the same deal here. a builder i know said that in time even a 6x6 will sag from heavy snow loads ect.
he said use a lam beam

Offline thedarko

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Re: post & beam design for load bearing interior wall; questions
« Reply #4 on: July 06, 2012, 05:16:46 pm »
The wall being demolished is 16 OC 2x4 stud. Its about 9-10' long. The top plate is carrying 2x8 joist ends 12' long. The span of the room will be 24', currently it was 2 rooms at 12' wide.

I wouldn't consider anything less than a 10" tall beam. I just don't know if a single 8x10 timber is advisable, or if I should be looking at laminated joists, dressed to look like whatever posts I wind up using.

Thanks

Online losttheplot

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Re: post & beam design for load bearing interior wall; questions
« Reply #5 on: July 06, 2012, 05:41:13 pm »
Check to see what the posts will be bearing on.

You are taking a load that is distributed over 12ft and concentrating it in two spots. (point loads)
If you have a "slab on grade" type foundation you may have to do some concrete work.
Are there any load bearing walls in the rooms above being carried by the existing wall, bath tub, fire place?

144sq ft of floor is 4- 6000lbs of load, depending what values you use.
An 8x10 #2 doug fir may work. use Don P's load calculations in the tool box at the bottom of the page.

That means 2-3000lbs for each post so check the load path to the ground.

If there was just drywall on the studs you may not need to worry about shear so you might not need the braces.

A simple tenon on the post and a mortise in the beam, with 1 inch pegs would likely be ok.
Simpson make lots of brackets that could be used on the bottom.


If that is a door on the right side of the picture ? the load from the header may also need to be included in the calculation.

Check to see what the posts will be bearing on.
DON'T BELIEVE EVERYTHING YOU THINK !

Offline thedarko

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Re: post & beam design for load bearing interior wall; questions
« Reply #6 on: July 06, 2012, 06:24:25 pm »
Thanks for the responses


The load is bearing on this:
 

Its 4 2x8s laminated together.
(A): they're resting (and cemented in place) on the foundation ledge
(C): these 2 spans are roughly 4-5 feet each
(B): this is the location where I will be placing the near post (8x8)

The far post will go near (A), about 12" in from the foundation wall.

I intend to place 3/4" steel plates, roughly 32"x32" onto the slab. I'll then place steel screw-type jackposts onto the plates, and brace them up tight against the existing laminated 2x8s in the photo. The posts will then sit directly on these 2x8s. I may add another 2x8 to bring it up to 5 total.

I think even this is overkill, and technically the structure currently in place would be able to bear the posts... but Im erring on the cautious side. Im no engineer though. Thoughts?

Regarding the floor above: yes, there is a load bearing wall directly above the wall that Im removing. Its the same length, and it supports the roof trusses in the attic I believe.


Online beenthere

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Re: post & beam design for load bearing interior wall; questions
« Reply #7 on: July 06, 2012, 07:45:10 pm »
Quote
Regarding the floor above: yes, there is a load bearing wall directly above the wall that Im removing. Its the same length, and it supports the roof trusses in the attic I believe.

Then likely you can consider that wall on the second floor a "beam" that (if no doorway in it) could conceivably span that distance. Then just hang the floor joists and 8x10 solid beam below from it.
Only would need to worry about it buckling.

I think of it as a bridge supporting the span from above, rather than below. Your additional steel posts in the basement looks good.

I'd be concerned that an 8x10 beam may sag under its own load over time which you may not like. But adding the stiffness and support from the second floor wall may work well. But that depends on the continuity of the wall above.
south central Wisconsin
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Offline thedarko

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Re: post & beam design for load bearing interior wall; questions
« Reply #8 on: July 06, 2012, 08:45:31 pm »
The wall on the 2nd floor essentially mirrors the one Im tearing out... so the load on top of my new beam will be evenly spread, from end to end.

Sag is also my worry, but I don't know if its justified. The 8x10 beam will carry an even load, but that doesn't necessarily mean it wont sag over time.

Are 4 2x10s stronger than a single 8x10? I'm under the assumption that the answer is yes. I could potentially have some old timber sawn down to 2x10 sizes and then either laminate or bolt them together. It really comes down to aesthetics in the end.. how will it look?

Regarding the 8x8 posts, they should be able to carry the load no problem right? Will species matter? I'll try to get the best grade that I can find, of course.

Offline shelbycharger400

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Re: post & beam design for load bearing interior wall; questions
« Reply #9 on: July 06, 2012, 10:07:48 pm »
laminating the board.. opposite grain patterns...same way they make the big ones.   bolting is always a better route as you can always tighten them up more.   

Offline thedarko

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Re: post & beam design for load bearing interior wall; questions
« Reply #10 on: July 06, 2012, 10:12:08 pm »
If I choose to bolt multiple 2x10s together, does anyone have references for proper placement and spacing of bolts?

Online losttheplot

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Re: post & beam design for load bearing interior wall; questions
« Reply #11 on: July 06, 2012, 10:21:15 pm »


I think you would be wise to consult with a qualified professional



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Offline thedarko

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Re: post & beam design for load bearing interior wall; questions
« Reply #12 on: July 06, 2012, 10:36:44 pm »
Im going well and beyond requirements... this will be over-built no matter which specific direction I choose to go. I don't feel the need to fork over $xxx for an engineer to come tell me "yeah this looks good" ;)

Online beenthere

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Re: post & beam design for load bearing interior wall; questions
« Reply #13 on: July 06, 2012, 11:31:09 pm »
I'd use good straight 2x, and glue it, clamp it, and screw it together. If you can do a light skip-plane on the glue faces and use a resorcinol glue you should be right there with the laminated beam manufacturers. Will be no need to tighten bolts, and the surface will be good to wrap with your boards for the beam look you want.
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Offline Piston

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Re: post & beam design for load bearing interior wall; questions
« Reply #14 on: July 09, 2012, 07:02:24 am »
Are you limited to an 8x10 due to headroom?  If not, you could increase the depth of the beam and certainly meet your "overbuilt" intentions  ;D

I would use a solid beam whenever possible, but that's mostly due to personal reasons. 

An 8x8 would be more than sufficient for supporting the vertical loads.  Just for reference, a 6x6 oak post, can support something like 46,000 pounds (it may be 64k? don't know for sure off the top of my head).  This is probably about the weight of your entire house.   :o

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Offline frwinks

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Re: post & beam design for load bearing interior wall; questions
« Reply #15 on: July 09, 2012, 04:16:02 pm »
I built a similar support for a good friend last winter.  16' span, supporting sagged (badly) second story 2x6 rough sawn joists.  Balloon framed, 100 year old cottage/home.   I used reclaimed doug fir, 8x11 reduced to 8x9 for head clearance with 8x8 gunstocked posts. Open concept master bed upstairs, and now they can safely move about their room ;D