# Sagging floor trusses



## joecaption (Nov 30, 2011)

A picture of what you have would be a big help.
Are there really trusses or are they engineered floor joist? 
Two differant products with two differant fixes.
Also is there just a sag in the middle of the spans, or is the middle settling causing the low area.


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## STANGER50 (Nov 2, 2011)

I believe they are trusses, they have top and bottom boards (2x4) with bracing in between up and down and at 45 degree angles (like pic attached not mine just a reference) not sure what the difference between and sagging and settling would be. when i take my level starting from 1st truss to next it is not level drops 1/4 to 1/2 inch, but only in middle they are level at the end and closer to the ends. floor above slopes down as well.


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## joecaption (Nov 30, 2011)

I would build a temperary beam out of 2X 8's screwed together and use jacks to lift it untill it was level, then attach 5/8 CDX plywood or OSB with constrution adhesive and 1-1/2 ceramic coated deck screws to the sides of them.


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## STANGER50 (Nov 2, 2011)

Thanks seems like a reasonably easy fix, would you plywood the sides of the entire truss end to end or more just in the center where the sagging is?


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## Bud Cline (Mar 12, 2006)

How old is this structure?
How about a photo?


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## Clutchcargo (Mar 31, 2007)

Just out of curiosity, what is the span and the dimensions of the truss?
Also, is anything significantly loading the truss (fishtank maybe)?


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## STANGER50 (Nov 2, 2011)

span is about 25 feet the truss height i will have to measure but approx 16in maybe? house was built in 1974. to significant loads like a fish tank, just a 1/2 bath and the kitchen but the only the fridge is toward the center.


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## Bud Cline (Mar 12, 2006)

> span is about 25 feet


Wow seems like a lot. Anyone have a Span Table handy?


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## zircon (Sep 24, 2007)

joecaption said:


> I would build a temperary beam out of 2X 8's screwed together and use jacks to lift it untill it was level, then attach 5/8 CDX plywood or OSB with constrution adhesive and 1-1/2 ceramic coated deck screws to the sides of them.


I assume you mean the temp beam is at right angles to the trusses. Could be too much pressure on the trusses at a point and they could crack? Like breaking a stick over your knee? Perhaps strap 3' or 4' lengths of 2x8 under each truss and place the beam to be jacked under that to spread the force out.


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## Bud Cline (Mar 12, 2006)

Or, under the circumstances you could seek advice from a legitimate structural engineer well versed in such matters and not take a bunch of conjured-up advice from us yay-hoos on an Internet forum. Some faulty structural situations are just too serious to be following advice from some guy with an imagination on the Internet.:thumbsup:


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## BigJim (Sep 2, 2008)

That is good advice to get a pro out there and look at it, maybe an engineer. If a truss is moving usually something is coming loose. and a good sign it needs to be taken care of soon. Hopefully there aren't any load bearing walls on the trusses but chances are they are, with a span that long.


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## Bud Cline (Mar 12, 2006)

Don't know for sure if this is the correct table but here it is...see for yourself. More criteria is required but seems that (as usual) you are just barely making minimums and obviously that isn't working well after all.

Call a pro.



http://www.square1truss.com/resources/sy42.pdf


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## Ironlight (Apr 13, 2011)

As noted by Bud you really should get a professional structural engineer to come out and take a look at your specific circumstances. They will be able to calculate the load, look at what is in place, and make a recommendation for a fix. Granted the house has stood for 35 years, but some fixes, if not properly engineered, can create their own set of problems.

Perhaps most important, if your house has this structural deficiency it stands to reason that there may be others. It would be worth having the engineer give the entire structure a quick survey.


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## AGWhitehouse (Jul 1, 2011)

That amount of deflection is to be expected for a 16" joist at 25' span. I don't feel you're in critical danger, but a bouncy floor and noise china cabinets are definately a daily affair for you. If you want to flatten and stiffen the floor I also suggest consulting a structural engineer to get the best fix.


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## Bud Cline (Mar 12, 2006)

> Granted the house has stood for 35 years, but some fixes, if not properly engineered, can create their own set of problems.


The right wind or seismic shift just hasn't come along yet.


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## STANGER50 (Nov 2, 2011)

I hear ya guys I do have someone coming out to look at it tomorow too look at it that specializes in this stuff was just looing for some feedback or ideas. I know whats it like when someone thinks thay can fix something themselves and turns out well they just cant, been a Ford technician for 20 years seen it all!


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## Daniel Holzman (Mar 10, 2009)

You state that the truss is 25 feet long, with a maximum sag in the middle of 1/2 inch. That works out to a deflection/span ratio of 1:600, which is well within standard deflection criteria for the average truss. So I am not sure why you believe there is a problem here. You need to be very careful messing with trusses, kind of like messing with the Zohan, generally a bad plan unless you know exactly what you are trying to accomplish, and have a good understanding of potential side effects.


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## woodworkbykirk (Sep 25, 2011)

with it being only a minimal amount of deflection i wouldnt really worry about it.. what kinda odd to me is a O.J.T spanning 25'. most of the houses ive been framing and putting additions on have been getting ojt's for a floor system yet our longest spans were 15'. T J I's on the other hand tend to span much greater distances

regarding putting plywood on the sides of the joists. this is only half of what should be done. when i have bearing walls sitting on top of double oj'ts i install plywood between the top and bottom chord first then on the outside. this greatly reduces the crush factor


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## STANGER50 (Nov 2, 2011)

well I wasnt sure what was normal and what was not, like I said I am a mechanic by trade not a carpenter. I guess my biggest concern was with whether or not I am leading in to bigger problmes down the road. I am only checking these things now because I have the basement apart for a remodel and figured now is the time if anything of the nature needs to be addresed. i do have a structural guy coming out toinight to look at it so I will see what he thinks. the only real concern that lead me to this was the floor above seems to be sloping downward. if 1/2 in is normal then so be it.


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## Bud Cline (Mar 12, 2006)

Hold on now, wait a minute.

When it comes to "deflection" the 1/2" sag may be within tolerances for deflection allowances measured with a point-load applied. Static loads and dynamic loads anticipated must also be considered when designing a floor system.

However, what you have is not deflection in an ordinary sense in my thinking. That is a "sag" plain and simple. The floor should be flat and level for the most part most all of the time. True, structures do go haywire but usually because they are built to minimums and things vary enough that sometimes minimums can be disastrous. If you walk across the room and the dishes rattle, that is not acceptable. If the pictures on the walls are always askew, that is not acceptable. If you feel the bounce with every footstep, that is not acceptable.

Who knows who built the trusses and if they are Hoyle. I would be investigating the truss assembly, each and every one.

You now have some ideas on what can be done if it were me I would do it before I proceeded too far into a basement remodeling project. At the very least the trusses should be raised and reinforced, and this time without any short cuts.


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