Author Topic: Need lots of help lol.....  (Read 1899 times)

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Offline yankeeredneck

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Need lots of help lol.....
« on: March 02, 2019, 06:19:02 AM »
I am beating my head over this. As I have mentioned before in some of my posts, I am basically remodeling the family farm house. And boy am I running into some walls understanding a few things. Some history of the house......

House was built with 2x8 floor joists spaced 16 on center. The house is 30widex42long. The center girder is basically double 2x8 with a 2x8 on the bottom with posts every 10 feet. I know from basic structural engineering that it is not strong enough. Shoot....you can already tell that the floors are not even and the basic floor is like that of a bowl....sinking towards the center. My question is that if I add (4) 2x12 LVL together and put the posts at every 10ft, under the existing 2x8 structure, will it be strong enough. And basically do the same for right under the 14.5 ft of single 2x8 floor joists.

I have done a lot of searches and research but I am confused by the online calculators and stuff. I like things in plain English lol.
I will add pics in a moment to make sense of things.
« Last Edit: March 02, 2019, 06:38:09 AM by yankeeredneck »
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Offline yankeeredneck

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Re: Need lots of help lol.....
« Reply #1 on: March 02, 2019, 06:31:47 AM »
Here are the pics I have.....more to come with more of a pictorial of what I am looking to do





« Last Edit: March 13, 2019, 12:03:56 PM by hpinson »
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Offline Nate R

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Re: Need lots of help lol.....
« Reply #2 on: March 02, 2019, 06:36:41 PM »
We need more info. Is it a single story? 2 story? More? Snow loading?

Offline yankeeredneck

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Re: Need lots of help lol.....
« Reply #3 on: March 03, 2019, 04:12:33 AM »
Single story with a 5/12 roof on a not quite 8ft center block foundation. From what I see in code snow load is 20. The house is in Watauga county in western NC.  I am working getting more pics today. And the diagram of what I think I need to do but wanted other eyes looking just in case I missed something.
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Offline NathanS

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Re: Need lots of help lol.....
« Reply #4 on: March 03, 2019, 04:19:10 AM »
Trying to keep the initial response simple,

You don't need calculators or LVLs (at least for now).

You need to spend a little time learning about the prescriptive tables in the code. They will give you max spans for joists (which yours are over span by a couple feet), and max spans for a girder (your double 2x8 beam).

Table R502.3.1 gives you living area spans for joists. By the book, you should have a girder midspan-ish under those joists.

Girder sizing is given in section 602. Provided that your girder is only supporting the floor, a double 2x8 can really only span around 5'. So you would either need posts every 4 or 5 feet, or simply frame a wall underneath it.

The worst part here is that you need a footing for either the posts or the wall to bear on.

There are tons of solutions to the problem, the question is what's the least back breaking. :)

If you want to jack the floor back up go very very slow, maybe over the course of weeks. I have never done anything like that, but if I was going through the effort of mixing concrete and pouring footings, and all that carpentry, I would jack that floor back up as close to level as I could get it.

Offline NathanS

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Re: Need lots of help lol.....
« Reply #5 on: March 03, 2019, 04:24:49 AM »
Code: https://up.codes/viewer/new_york/irc-2015/chapter/6/wall-construction#R602

WFCM: https://awc.org/pdf/codes-standards/publications/wfcm/AWC-WFCM2015-ViewOnly-1510.pdf

Post a diagram of the floor as you understand it. It is also important to know whether the roof is full span (outside wall to outside wall) or if some of the load is transferred down inside the building.

Offline yankeeredneck

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Re: Need lots of help lol.....
« Reply #6 on: March 03, 2019, 04:32:08 AM »
Thank you so much for the explanations!  That is what I was needing. I will get some plans down later this afternoon. I just want to make sure I am not over thinking the solution(s).
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Offline Nate R

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Re: Need lots of help lol.....
« Reply #7 on: March 03, 2019, 05:00:50 AM »
Now you're getting there! I was going to go through the exercise of figuring out max loads on the girder and sizing it from there after adding up all the actual pounds of possible weight....But Nathan S's way is easier/better.

Offline Don_P

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Re: Need lots of help lol.....
« Reply #8 on: March 03, 2019, 09:15:19 AM »
Back out and take some general overview pics of the house to help give an idea of the building and foundation, you're in too tight for me to get oriented yet. I think I would use 30 psf snow in Watauga Co. If I'm understanding correctly the 2x8 floor joists are spanning about 15', that is also part of the deflection problem, they really shouldn't span more than about 12' so you are probably looking at a couple more girder lines under there to solve that problem. Back in the day it was very common for carpenters to use 2x8's for joists no matter what the span which leads to some pretty soft floors. Which way and how far from Boone are you?

Offline yankeeredneck

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Re: Need lots of help lol.....
« Reply #9 on: March 03, 2019, 09:30:38 AM »
You would be right on that. The single 2x8s are spanning around 14.5 to the double 2x8 center girder. What I am thinking is that about the 7ft mark on both sides of the center girder is to basically make 2 double 2x12 girder and put a 12inchx12inchx5ft sono-tube with  4 #4rebar in them every 10ft and a post on top of the sono-tubes. And I would then replace the center double 2x8 girder with the same double 2x12 set up as on the left and right side of that.


Please note that the flue will be coming out as they notched the girder to fit it in. I will be moving the wood stove to attach with the current HVAC system.


More images:
https://imgur.com/B2ewCaC
https://imgur.com/S3qsF7K
https://imgur.com/CbESlLE
https://imgur.com/BqJnamL
https://imgur.com/G6vXeLd

Drawing coming up soon


And Don....I am about 15 minutes outside of Boone....Valley Crucis  area
« Last Edit: March 13, 2019, 12:05:47 PM by hpinson »
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Offline yankeeredneck

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Re: Need lots of help lol.....
« Reply #10 on: March 03, 2019, 10:04:19 AM »


This might help some
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Offline yankeeredneck

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Re: Need lots of help lol.....
« Reply #11 on: March 03, 2019, 10:16:32 AM »
Reason for all this is not only for the existing house but I plan on adding on a 16ft extension. Plus it just needs to be brought up to date some. This is my wife's family home and we both want it to last for the next generation and beyond.
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Offline NathanS

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Re: Need lots of help lol.....
« Reply #12 on: March 03, 2019, 10:24:14 AM »
It's unnecessary to remove the doubled 2x8 girder. All you need to do is add more supports underneath it and it will be plenty strong enough.

Offline yankeeredneck

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Re: Need lots of help lol.....
« Reply #13 on: March 03, 2019, 10:30:40 AM »
An what about the 2x8 floor joists? Add a girder for them as well?
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Offline akwoodchuck

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Re: Need lots of help lol.....
« Reply #14 on: March 03, 2019, 11:49:29 AM »
First, eat a good balanced breakfast....second, cut notches in block wall with a propane saw, run a couple steel I-beams through, jack up and shim in place....third, go eat lunch, you're done  :D
"The lyf so short, the craft so long to lerne."

Offline yankeeredneck

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Re: Need lots of help lol.....
« Reply #15 on: March 03, 2019, 12:01:24 PM »
lol I actually have been debating that. The problem is.....what size I-beam if I go that route? Can I stay with a basic 10 or 12 inch I beam with 1/2 inch web or something different.

I guess that's the fun part of all this. I know either way I go.... it just needs to be done.
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Offline Don_P

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Re: Need lots of help lol.....
« Reply #16 on: March 03, 2019, 06:53:42 PM »
If you can tolerate steel posts on 8' centers under the existing girder... Measure from slab to the underside of the girder and go get some steel posts at Lowes, or Parker Tie in W Jeff, not the telescoping ones but the type with a solid post and an adjustment screw. They come in various length ranges so just match up to your height range. Install those on 8' or closer centers.

You also need the 2 new runs of girders, they can be either 2 ply 2x8's with posts at 8' centers or 4 ply 2x8's with posts at 10' centers. This is going to be quicker and easier to adjust than the sonotubes and has plenty of strength for the application, I've just done something similar in an underbuilt commercial building.

If the slab is not capable of supporting 2800 lbs per post @8' or 3500 lbs @10' then you need to spread the footprint over a larger area. I poured 18" square x 8" thick pads on top of the slab and put the posts on those, I had significantly higher loads. I suspect 8x8x1/2" steel plate between the slab and post would be plenty here to distribute the load. I ran the numbers using #2 southern yellow pine which it appears you have and is readily available. Anyway, install, snug them up and then slowly apply pressure till you get to the happiest place you can. I ended up lifting the center girder off those posts slightly in an attempt to get the floor's deflection set to flatten some on our project.

I'd be willing to bet the chimney does not notch into the girder, simply into that worthless plate under the girder. There was a thinking problem going on there. They were using that plate to "support" the joists framing into the girder rather than joist hangers. If that is the case it wouldn't hurt to check to see that none of the joists have slid downward, look at the top of the girder and the top of the joist up against the subfloor at each location. If the nailing was good and it is in plane don't worry about it, you are picking up more support here. If things have drifted then it needs to be addressed. Anyway that is all a quick and simple fix.

We were married in Valle Crucis, the old St Johns Church. I'm about 70-80 miles north but can see Grandfather from the peaks here on a clear day. I heard they clocked 124 mph for 3 seconds there last week.

Offline yankeeredneck

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Re: Need lots of help lol.....
« Reply #17 on: March 04, 2019, 03:11:21 AM »
Don,

Thank you for the solution you have presented. I just might do it since I was leaning toward that way but with 2x10 or 2x12 doubled up. The girder has drifted just a little....like by a half inch. My plan was to add a steel I-beam under the existing girder and create basically the same thing on the mid way points of both sides to make sure I am even all the way.


Yes, Grandfather MTN did set a record that day of just slightly over 124mph. I am about 20 -30 minutes from there on the Foscoe side of Valley Crucis. And yes, I know the church you guys were married in. Nice to know I have someone close by me


I will update when I can on the progress of this project. Many more to come lol


And thank you all for the responses. I have learned a lot from everyone here.

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Offline Don_P

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Re: Need lots of help lol.....
« Reply #18 on: March 05, 2019, 05:59:08 PM »
Ah, back up, I made an assumption I shouldn't have. Is there a load bearing wall above that girder running the length of the house that in turn supports part of the roof?

Offline yankeeredneck

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Re: Need lots of help lol.....
« Reply #19 on: March 06, 2019, 03:04:54 AM »
There seems to be. I have been up in the attic area and it looks like it.

Am I going back to the 2x12 scenario?lol
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Offline Don_P

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Re: Need lots of help lol.....
« Reply #20 on: March 06, 2019, 03:41:02 AM »
Go back up into the attic. Are there ceiling joists lapped over that center wall? If so the girder is picking up an additional ~10 psf. Next are there vertical or canted posts or studs holding up the rafters or ridge from over that center wall? If so the girder is also supporting roof weight ~30-40 psf.

Offline yankeeredneck

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Re: Need lots of help lol.....
« Reply #21 on: March 06, 2019, 03:47:24 AM »
I can tell you that yes, the roof is connecting to the center wall. And yes, there are vertical 2x8s as well on the center wall. The 2x8s run vertical and angled every 16 on center I believe.

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Offline Don_P

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Re: Need lots of help lol.....
« Reply #22 on: March 06, 2019, 06:30:34 PM »
Well that's not good for the basement problem.  I'd say you ought to count on at least 16' of the roof width bearing on the girder x 10' post spacing x 40 psf= 6400 lbs plus the 3500 pound floor load, we're at 10,000 lbs per 10' span, and I would reuse the post locations, there should be a footing under the slab there, you can drill to confirm that but they have worked in those locations thus far. So the center girder needs something more substantial. You also need a way of getting it in, door or window in that axis with it or remove a few blocks, you'll probably be bringing it in in 20' pieces. I believe a W8x13 should do it in an I beam, that is 8" deep and 13 lbs per foot. A W8x10 barely works, I think I'd go a little heavier. In LVL a triple 9-1/4" deep would work. The supplier can check the engineering on that, I think that would be the easier solution and can come with an engineers stamp.

For that raising script, you are installing the new girders and taking some of the load, bring in the lvl's and set them on the floor beside the existing posts. Then build shoring on each side of the existing girder to take the load off the existing posts, drop the old posts, raise the new girder under the old and replace the posts. I'll try to get some pics of one way to do the lateral bracing of all of the new dropped girders, they need to be laterally braced to prevent rolling over each post.

 

Offline yankeeredneck

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Re: Need lots of help lol.....
« Reply #23 on: March 07, 2019, 03:00:30 AM »
I figured I would have to replace the center girder. Gut feeling.

And I appreciate the help on this Don. And again thanks to everyone here on the forum. You guys are some of the best out there!
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Offline Don_P

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Re: Need lots of help lol.....
« Reply #24 on: March 07, 2019, 05:22:09 PM »
That does bring up another way. If you can tolerate a wall under the existing girder that would also work, another way of thinking about the old saying "many hands make light work". A treated plate bolted to the slab, run a stringline 1-1/2" below the girder as a straight reference and cut studs that measure from top of plate to string + 1-1/2" and knock them in to vertical would flatten and support the girder. Header any openings and then sheath the wall to prevent the studs from bowing. Just one more option.

 

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