# Fixing overspanned floor joists



## jar546 (Feb 25, 2011)

This is the underside of a corridor for an office building.  It was a large, open bank building and the 2nd floor was added a few years ago.  Your are looking at 2x8s 16" oc and a 15'6" span.  This is the back corridor which leads to an stairwell.

As you can see they used 2x4 on the flat and placed solid blocking in this area to compensate for the over-span.  The width of the corridor is approximately 52" in this area.

Has anyone ever seen a setup like this?

My guess is that this still does not meet the loading requirement for a corridor in an office building.


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## jar546 (Feb 25, 2011)

No need to comment about the NM cable either. lol what a cluster


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## jar546 (Feb 25, 2011)

Just to clarify, I don't think this was a fix but part of the contractor's original installation method.


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## Yikes (Feb 25, 2011)

Wow.  Lots of room for improvement here.

Out of curiosity, how does the floor feel when you walk on it?


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## fatboy (Feb 25, 2011)

Probably like a trampoline. Yeah, I don't think the flat 2 X 4 adds much, haven't seen that in the span charts.


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## NH09 (Feb 25, 2011)

I've seen it before, but never seen the documentation to back it up.


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## dhengr (Feb 25, 2011)

2x8's at 16" o/c won’t span 15' - 6" in a residential bldg. (LL = 40#/sf) and meet any serviceability criteria, let alone in public bldg., office bldg., where if I recall correctly office space is (LL = 50#/sf) and corridors and exit spaces are (LL = 100#/sf).  This shows-to-go-ya that our design LL’s are fairly conservative some of the time.

The orientation of the corridor w.r.t. the span of the joists is really the more critical condition than the exact width.  The corridor crossing the joist span might work in part because all spaces are not fully loaded at the same time.  Also, none of the spaces have probably every seen their full design LL.  I would assume they have had questions about the bouncy floor system though.  The secretary sitting at her desk, on one side of the wall, bouncing up and down as someone on the other side walked down the corridor, might find that disconcerting... I started to say, but then others might find that interest.... I thought.  I need another drink, and it is after noon now.  The corridor running with the jst. spans would be a completely different criter.

The interior partitions and their orientation might help stiffen that floor system too.  The solid blocking looks kinda ill fitted, but the 2x4 under it, will stiffen it a bit, because it tends to prevent the blocking from parallelograming or the joists from spreading and rolling as the blocking does its thing.  The end nailing through the jst. into the solid blocking doesn’t prevent this blocking motion, while the 2x4 might help a bit.

This looks kinda like a two red flagger or does a black flag indicate a more serious situation?  I’d suggest, or insist, that the owner have an engineer send you a letter on this one.


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## Pcinspector1 (Mar 1, 2011)

I've seen poor framing before, IMO they wasted material. An LVL and hangers would reduce the span if the LVL can be supported, there appears to be room if they move the flex duct? unless I'm missing the point of the question?

Even a steel I-beam would correct this IMO.

pc1


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## TimNY (Mar 1, 2011)

That is mid-span pressure blocking.


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## Swerd (Aug 4, 2011)

jar546 said:
			
		

> Just to clarify, I don't think this was a fix but part of the contractor's original installation method.


Yes dude,.

I agree method was nice to fix it,.


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