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2x10 Span

 
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Old 05-14-2019, 07:03 PM   #1
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2x10 Span


Well new one to me, started a new remodel of master bathroom, opened floor and found 2x10 joists spaced 12" o/c span 16' 10 1/2"

Doing tile over ditra heat membrane with nu heat cables. Freestanding tub with 90 gallons. Engineer wants to put a beam mid span, we have expansive soils so that means cutting or jack hammer into slab in finished basement.

I suggested hanging one end of beam off foundation wall or bolting post to wall.

Anyone have any other good ideas?

Client is aware the span is way too much I came up with L300. Impossible to sister full length, adding plywood I don't think will help bending or deflection of joist itself.

Last edited by kevjob; 05-14-2019 at 07:08 PM.
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Old 05-14-2019, 07:37 PM   #2
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Re: 2x10 Span


Is there room to sister? It's not as crazy long of a span as it sounds. The low end BCI/TGI joists calc out ok. LVLs surely would.

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Old 05-15-2019, 07:24 AM   #3
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Re: 2x10 Span


No way to sister, too many things in floor and no way to get the joists into house. Contacted a few helical pier companies and see what I can do versus having them do it all.
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Old 05-15-2019, 07:33 AM   #4
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Re: 2x10 Span


How old is the house, is there a grade stamp on the joists? Are you calculating deflection with #2 lumber?
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Old 05-15-2019, 07:36 AM   #5
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Re: 2x10 Span


The sizing of the joists is well within prescriptive limits, no worries. If you want to stiffen the floor you don't have to sister the joists by going 100% of the length of the existing joists.
Sistering them about 85% of the length would work just fine.
It is just my opinion but I think it would stiffen the floor as much as you need.

Andy.
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Old 05-15-2019, 07:42 AM   #6
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Re: 2x10 Span


Quote:
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How old is the house, is there a grade stamp on the joists? Are you calculating deflection with #2 lumber?
No stamp I was using the deflecto calculator form another forum.

Built in 1974.
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Old 05-15-2019, 07:44 AM   #7
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Re: 2x10 Span


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The sizing of the joists is well within prescriptive limits, no worries. If you want to stiffen the floor you don't have to sister the joists by going 100% of the length of the existing joists.
Sistering them about 85% of the length would work just fine.
It is just my opinion but I think it would stiffen the floor as much as you need.

Andy.
I can't sister anything now as I installed plumbing etc...my mistake, should have waited to hear from engineer.

Cant even go 50% with sistering.

I don't know the species or grade of joists house built in 1974.
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Old 05-16-2019, 05:26 PM   #8
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Re: 2x10 Span


I recently checked 2x10 span for something. If I recall the book maxed them out at 15'10" 16 o/c. So your going a foot longer and reducing the o/c. Without out looking it's got to be close to Max.

I would look for extra support or at least pay few hundred for someone else to stamp itm
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Old 05-16-2019, 05:39 PM   #9
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Re: 2x10 Span


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I recently checked 2x10 span for something. If I recall the book maxed them out at 15'10" 16 o/c. So your going a foot longer and reducing the o/c. Without out looking it's got to be close to Max.

I would look for extra support or at least pay few hundred for someone else to stamp itm
Yeah my other engineer coming out tomorrow, used this guy in past but was too busy a year or so ago to come look at a project. Every which way I run numbers, chart spans etc... I am at max and will be over with tile. Only one gives me a ray of hope is https://www.awc.org/codes-standards/...tware/spancalc

I am pulling drywall ceiling below for him to assess everything. This guy has 30 years experience and has helped me with some real head scatchers.

Big problem is our expansive soils, bentonite have to float basement walls makes putting a post in hard as hell in finished basement.

17 godamn feet....WTF...

Last edited by kevjob; 05-16-2019 at 06:10 PM.
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Old 05-16-2019, 06:16 PM   #10
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Re: 2x10 Span


Yeah, the AWC give Doug Fir #2 an elastic Modulus of about 1,600,000 which when you run the numbers gives you a span of about 20' for your application.
The other charts are conservative in the extreme with an elastic modulus of about 1,000,000 1,200,000.
If your AHJ allows for interpolation of the IRC then you are just barely good to go with your application as is.

That is my opinion anyway.

Andy.

Well I just ran their numbers on their website and they do not jibe with their own tables.

I give up.

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Old 05-16-2019, 09:31 PM   #11
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Re: 2x10 Span


Thanks Andy, I appreciate the answers here and in email!

I will update tomorrow once I have engineer on site. Hoping something other than beam mid span, PITA with expansive soils.
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Old 05-17-2019, 10:36 AM   #12
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Re: 2x10 Span


Did you reach out to Techno Metal Post for helical?
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Old 05-17-2019, 05:25 PM   #13
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Re: 2x10 Span


If you search some old posts on garden web which is now Houzz I think, there's a guy "Brickeyee" who's an engineer/contractor. There are a few threads where he talks about fastening steel straps to the bottom of joists that add a ton of stiffness. Other threads talked about adding a 2x4 to the bottom like half an "I" joist with adhesive and fasteners to a certain schedule which, if I recall correctly, functioned similar to sistering joists of the same size. I think the tile forums also had some discussions about this method. Engineer should be able to run the calcs and spec something like that for this application.
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Old 05-17-2019, 07:23 PM   #14
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Re: 2x10 Span


Quote:
Originally Posted by EricBrancard View Post
If you search some old posts on garden web which is now Houzz I think, there's a guy "Brickeyee" who's an engineer/contractor. There are a few threads where he talks about fastening steel straps to the bottom of joists that add a ton of stiffness. Other threads talked about adding a 2x4 to the bottom like half an "I" joist with adhesive and fasteners to a certain schedule which, if I recall correctly, functioned similar to sistering joists of the same size. I think the tile forums also had some discussions about this method. Engineer should be able to run the calcs and spec something like that for this application.
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Old 05-19-2019, 01:46 PM   #15
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Re: 2x10 Span


Okay exposed the joist they are DF #2 found a stamp on couple joists.

Licensed Engineer, I have used before, came out and so far has speced a double 9 1/2" LVL beam 11' wide, one end will bear on step foundation footer I exposed, no problem there.

Other side he proposed an adjustable steel monopost 3" OD bearing on slab in wall that is 11' away from other end in exterior wall. Bathroom is 90" wide and that is where I am calculating 60 lbs per sq ft over the 8'x17' area.

He seems to think the slab and soil which is expansive in our area will support the 2,200 lbs each post will need to support. Slab is 45 yrs old and I am assuming not reinforced.

My gut tells me to open floor 12" x 12" x 12" deep and do a pad under monopost for my peace of mind. Both rooms in basement are finished, the one I exposed the ceiling in is a work zone now.

Thoughts?
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Old 05-19-2019, 02:07 PM   #16
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Re: 2x10 Span


Is that 2200 lbs per post or 1100 per post?

Edit: I see where it says per post.

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Old 05-19-2019, 03:53 PM   #17
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Re: 2x10 Span


Tap the slab in those areas and make sure there aren't any hollow spots.
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Old 05-19-2019, 05:14 PM   #18
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Re: 2x10 Span


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Tap the slab in those areas and make sure there aren't any hollow spots.
Slab appears solid in all places. My big concern is our expansive soils very wet years it swells, droughts shrinks and can move a ton of weight.

To me it seems a no brainer to do it now versus after if tile cracks and then floor heat has to come up as well.

Half day now versus 1 week down the road.

The slab may hold fine, what if it doesn't.

Would you do it?
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Old 05-19-2019, 05:18 PM   #19
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Re: 2x10 Span


a 12x12" footing is quite possibly less strong than the 45 year old reinforced slab. That's a tiny footing. It'll have a cold joint to the slab and it's on the same expansive soils.
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Old 05-19-2019, 05:21 PM   #20
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Re: 2x10 Span


Well you consulted an engineer and anything you do beyond his beliefs is extra safe so go for it. Its bugging you and it would me too, just 1 event is very costly

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