fixing improperly sistered beam

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Old 04-22-09, 11:03 AM
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fixing improperly sistered beam

After buying my A-frame w/addition home last May, I was repeatedly puzzled by a bow in the floor of on of the bedrooms that flexed somewhat alarmingly.

It's taken a while to get to it, but I've been in the process of gutting and rebuilding (better, faster, stronger-- I have the technogy!) the room below. I finally pulled down the old ceiling drywall to discovered a past weekend-carpenter had for inexplicable reasons cut a twenty inch gap in two of the beams holding up the second floor. (They also cut through a support truss in the framing around where a stair used to go up, but that's another matter entirely.)

They sistered each of their 20" beam cuts with a 60" pair of 2x6 and 2x4 boards. It is apparent that after cutting the beams, the structure sagged an inch or two, but they made no apparent effort to correct that prior to sistering (or, indeed, the sistering job was just so poor, the structural sagging occurred later).



Well, this sort of thing really sticks in the craw for me, and I hate to leave a problem like this in place once I uncover it. I'm thinking a single 2x10 or 2x12 that runs the full beam length, jacked up to level the floor being supported, and then bolted profusely to the compromised beam.

Thoughts/opinions?
 
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Old 04-22-09, 09:40 PM
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How long are the floor joists? Are they 2x10? What load is above them? How far apart are they spaced? Be safe, GBR
 
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Old 04-23-09, 09:10 AM
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Right.

So, this is a 16 foot span, beams are 24 inches OC. I assume because this section of the house was originally a 1961 A-frame, possibly assembled from a kit intended to be easily handled, the beams are 2x6 with 2x4s stacked on top. Subfloor is 20/32nds plyboard and underlayment is 3/4-inch particleboard.

Above that is padding and carpet and a bedroom-as-office. (I'm sitting almost directly above the cuts as I type this). I'd characterize the load as light, there's not much in this room, really.

I'd hate to see what would happen if someone tried to fill a queen-sized waterbed over these beams, though....
 
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Old 04-23-09, 01:05 PM
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I really don't see how that could pass an inspection.

The 2x6 with 2x4 on top, really only act as a 2x6 unless they are plated together, as per engineering, to act as one. With plates similar to those on the ends, in the picture. Pressed together under tons of pressure.

Are you certain the rooms above this floor are supposed to be lived in?

The 2x6 joists should be spanning only 8'6" maximum, UBC code.

For IRC code look here at the purple box, bottom right: http://www.google.com/url?sa=t&sourc...o2L4YXFmW1B3NQ

For 16' span, need [email protected]24"o.c. or [email protected]12"o.c. or [email protected]16o.c.

Is your floor bouncy, please don't try it. Be safe, GBR
 
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Old 04-23-09, 02:58 PM
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Well, it probably couldn't, especially the way it's been cut, eh? I think I mentioned that this was not visible until the drywall was pulled down, earlier this week.

Anyway, it was built in the early 1960s in Clear Creek County, CO. Take up code issues with the building inspector of the day.

Oh, I've jumped profusely over the spot already, in the past, trying to determine the nature of the squeaky floor there! I screwed down the underlayment and subfloor quite a bit, but obviously, it didn't stop the squeaking because the issue was structural in nature.

Uhm, yes, the room is intended to be habitable This is a 2.5 story A-frame. The top 0.5 floor isn't habitable, but the second floor consists of two bedrooms. The room in question was the master bedroom when the structure was originally built...
 
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Old 04-23-09, 03:16 PM
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Here's a shot of how the beams you see in the first picture are supported at their sides. You can see there are plates connecting the bottom frame elements and the top frame elements, but not interconnecting-- i'm not sure why that is; perhaps the 2x6 and 2x4s are pinned together somehow along their narrow edge?
 
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Old 04-23-09, 03:24 PM
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It appears to me that you have trusses that were cut for some reason. You may want an engineer to look at it to be sure, but you should be able to sandwich the old joist between two 2 x 10's and bolt them as you suggest. Since it is only two I think you would be OK.

Good luck,

Bill

Edit: After seeing the last picture I would definitley have an engineer look at it. There is nowhere for the 2 x 10 you would sister it with to bear .
 
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Old 04-23-09, 04:32 PM
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Yes, I agree. Someone was a complete moron at some point in this building's history.

I would probably support a sistered 2x10 by continuing some additional sistering down the diagonal 2x6 beam past the metal plate to support the underside of the sistered 2x10.

On the bright side, it's hard to imagine anything I could come up with making it worse than it already is. c_c
 
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Old 04-24-09, 01:54 PM
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I would have a Structural Engineer look, as Bill said. The supporting area would be my biggest concern. Be safe, GBR
 
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Old 04-24-09, 03:05 PM
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Hi chromal, do you know the definition of an elephant, it is a mouse built to engineering standards. Three joists, common sense, and as stated, it's got to be better than what is there. You sound like you have the common sense, I don't see the need for the extra expense. Not an engineer, thank goodness.

IMHO
Bud
 
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Old 04-24-09, 03:32 PM
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If I was doing it in my house I would do what I want and suffer the consequences later, if any. Since I am a contractor I would be doing any further repairs myself. For anyone who is not a contractor I would have them get an engineer to look at it so they can do it or have it done once and never have to worry about it again. jmho

Bill
 
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Old 04-24-09, 04:23 PM
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Repairs to trusses have to be designed by the manufacturer or a "registered design professional", usually a structural engineer.

IRC R802.10.4 Alterations to trusses. Truss members shall not be cut, notched, drilled, spliced or otherwise altered in any way without the approval of a registered design professional. Alterations resulting in the addition of load that exceeds the design load for the truss shall not be permitted without verification that the truss is capable of supporting such additional loading. .

My recommendation to clients is that they have the completed repair inspected and approved by the SE, and then staple a stamped copy of his/her approval letter to the truss(s) for future reference.

----------

Home Inspection: "A business with illogically high liability, slim profit margins and limited economies of scale. An incredibly diverse, multi-disciplined consulting service, delivered under difficult in-field circumstances, before a hostile audience in an impossibly short time frame, requiring the production of an extraordinarily detailed technical report, almost instantly, without benefit of research facilities or resources." - Alan Carson
 
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Old 04-24-09, 04:47 PM
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Well, I probably should. Goodness knows, I did get a stamped and signed structural engineer's letter when having roof beams sistered in (completely different story, same structure).

This would mostly be a resale value thing. With an SE's letter, I can say, "look, I added value to the house I bought." With a DIY fix, I quietly fail to mention the problem and the fix because no permit or SE letter raises eyebrows. c_c

I'll have to do some soul searching, because, quite frankly, I'm just skimming water financially, and cannot pay the $250 SE consultation and $150-250 design letter cost that I know our local SE will expect, indeed, that would exceed the cost of the raw materials of the repair... To make matters worse, I can't finish drywalling this room until the structural issue is addressed, and I need to finish it so I can have the house reappraised and take advantage of low interest rates with a refi later this summer...
 
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