Strongback

[NJinspector]

Can someone give me some insight into strongbacks in floor framing.

I believe I have only seen one on a mentored inspection, but felt too stupid to ask what it was there for. I assume more support, but dont understand how their built, and why.

thanks

[chrisprickett]

"Strongback" is a somewhat vague term. Are you talking engineered I joists, conventional framing with added support, a remodel?

Something like this maybe?

http://www.ufpi.com/literature/ojguide- ... framing%22

[NJinspector]

I assume if I see this, it will be conventional framing in residential construction.

[hausdok]

Hi,

When I was coming up, my old man taught me that a strongback was used over wide-span ceilings to stop them from sagging under the weight of plaster and lath or drywall and the insulation above. They were typically secured to the top plate of bearing walls perpendicular to the ceiling joists at mid-span over either end of a room. They usually consisted of a couple of heavy planks secured right angles to one another in an L or T shape, so they'd be as rigid as possible and wood cleats or metal brackets completed the connection to the joists below. Sometimes they'd take the form of a fink or queen post truss that bore the weight on the lowest chord.

I see them a lot in older construction but not so much anymore because most everything is trussed these days.

ONE TEAM - ONE FIGHT!!!

Mike

[kurt]

In my world, they are exactly what Mike said; beams in the attic, usually over large LR or DR spaces, bearing on partitions or exterior walls, & w/the ceiling joists "hung" from them.

They keep the ceilings from sagging.

[charlieb]

In the south they work the same as the do in Chicago and Washington. So I'd agree with Kurt and Mike. Well most of Mike's response.

"Sometimes they'd take the form of a fink or queen post truss that bore the weight on the lowest chord."

Aint nver hered of dem!

[charlieb]

So,

What is a fink or queen post truss?

[Scottpat]

Do you really want to know what a "queen" is?

[Mike Lamb]

I was able to correct a seriously sagging ceiling by jacking it up fairly level and putting in a strong back after the fact. It worked.

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[hausdok]

Originally posted by charlieb

So,

What is a fink or queen post truss?

Go to the menu bar above, pass your cursor over 'resources' then choose 'downloads'. Scroll down to FM5-426 and download/save the Army carpentry manual and then look up those types of trusses.

OT - OF!!!

M.

[DonTx]

My version of strongbacks are the same of Mike Lambs.

I believe IRC 802.3.1 discusses their need in framing. It's a common problem in new construction here. Many trades do not understand them or do not care to use them properly.

BTW, Mike, what book is that illustration out of?

[Mike Lamb]

1986 John Feier and Gilbert Hutchings, "Carpentry and Building Constructuion"

[charlieb]

Go to the menu bar above, pass your cursor over 'resources' then choose 'downloads'. Scroll down to FM5-426 and download/save the Army carpentry manual and then look up those types of trusses.

Ok Ok

I'll see how many trees I can kill to print the thing. I KNOW those two truss designs will be the only thing in the manual I don't already know.

Wouldn't you rather spent 10 minutes typing an indepth description for me[?]

[hausdok]

Don't print it. Save it to your hard drive and then you can read it without printing it.

OT - OF!!!

M.

[Bob White]

trusses:

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from The Visual Handbook of Building and Remodeling

[hausdok]

Hmmm,

Yeah, well see, to do that I gotta figure out how to use the scanner. Since I've only used it about a dozen times in the last half dozen years, I'm not willing to expend that many brain cells trying to refigure it out.

Yep, I'm no account lazy. No question about it. [:-dunce]

OT - OF!!!

M.

[charlieb]

Mike,

I did a little ereading last night. Looking at the truss in the first picture I knew it was a well uh it's a .........

Kurt,

The rest are for you. These are the flattering shots. Folks in CA have to much $$$. Want to have a resturant to play with. The residential mkt has slowed a bit but the commercial is kicking. Booked a 192 unit apt today. It's a section 8 project. It's another CA client who plans to clean it up and make more $$.

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[charlieb]

It's a PRATT![^]

[Phillip]

I have been seeing a lot of strange things in stick frame attics these days. No purloins where I think they should be. They are use what looks like a knee wall sit up. The AHJ is passing them in their inspections. Could someone recommend a good book on framing.

Yes Mike I am down loading your manual.

[hausdok]

Hi,

Go to http://www.jlconline.com , choose bookstore from their menu, scroll down on the right side and choose 'structure & framing" and take your pick

OT - OF!!!

M.

[Phillip]

Thanks Mike,

After I posted I was looking in my JLC mag. and I found the add for Advanced Framing from the book store. I am going to get it as soon as my wife will let me have some money.[][:-dev3][:-censore

[kshepard]

If it is actually in the floor framing underneath the joists, it's a girder and it's purpose is to support floor joists that would otherwise be overspanned.

As stated before me, if it's fastened to the top of ceiling joists, it's a strongback installed to prevent ceiling sagging. This can work, but it can become a problem because carpenters are tempted to install roof bracing so that the braces bear on this strongback. This is a defect. Over time it will cause the ceiling to sag again, since the ceiling joists that originally couldn't carry the load of the ceiling without sagging are now being asked to carry the ceiling and roof loads.