# Deflection Track



## Mlg (Sep 2, 2015)

Hello
I'm new to the site . I wanted to see if anybody could give me their insight on the question and architect is telling me to do on the building I'm doing. The architect is having me use the defection track on A 11' exterior wall framed from the concrete deck to a structural beam. It's calls for 18 gauge 6"'studs Framed up to the metal structural beam. But y deflection track and not just screws to connect studs to top track the beam will not deflect it's an ibeam?


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## MrWillys (Mar 10, 2014)

http://www.clarkdietrich.com/products/head-wall-deflection-systems/deep-leg-deflection-track-system

http://www.steeler.com/catalog/exterior-framing/deflection-track


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## Aussiecontractor (Oct 6, 2014)

I know what deflection track is......lbut as soon as you guys start spitting your imperial measurement mambo jumbo I get lost lol 


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## Aussiecontractor (Oct 6, 2014)

Do you have any red book installation guides on hand mr willys ? I'd like to see how your commercial differs from over here 


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## MrWillys (Mar 10, 2014)

The best I can do would be this?

http://www.ssma.com/filebin/pdf/SSMA_Technical_Guide_10-14.pdf

https://www.usg.com/content/usgcom/en.html

The USG site will have installation guides on all of their products.

http://scotthansen.net/altabates 

http://scotthansen.net/altabates2


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## Aussiecontractor (Oct 6, 2014)

I'll have a look on on My downtime cheers 


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## JohnNeggere (Oct 22, 2015)

What exactley is that?


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## endo_alley (Nov 2, 2013)

I have never used deflection track on exterior walls. It seems that this would negate structural headers over doors and windows. And might compromise wind loading at exterior walls. Most exterior finishes do not allow for excessive movement of exterior walls in relation to floor decks and building structure. I would bring this detail up with the structural engineer. There must be a good reason behind it. Occasionally, an architect just cuts and pastes a wall detail onto the plans that isn't always appropriate for every specific application.


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## MrWillys (Mar 10, 2014)

I've built deflection track in heavy gauge for exteriors? A box header or ProX is required anytime 2 or more studs are cut. I don't know why the engineer choose this method but it has been done. Back in 1981 I worked on a 41 story in SF and they wouldn't let us fasten the CH studs or panels in Shaftwall to the top track. I've yet to see a deflection system for Shaftwall. I even wrote to USG about this, but I'm not high enough on the food chain to deserve an answer.


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## WIdrywaller (Mar 6, 2012)

With the high cost of steel, and building designs changing as a result; we are seeing more allowable deflection designed into buildings. Also, depending on your seismic category and occupancy rating, the building design will change drastically for "earthquake resistance". For example a Class A/Category I building in Iowa is not going to have near the movement capabilities as a Class F/Category IV hospital in California; hospitals have the most stringent design requirement because they need to stay standing and functional when an earthquake hits.

Bottom line is that all buildings move, all floors deflect; how much depends on height, locale, environmental events, etc... Building that are built rigid will tear themselves apart when exposed to movement, so the building designs/codes require movement in the building construction. The plans/specs should always indicate the required deflection for the 05400 Cold-rolled Stud Framing, bear in mind that the figure given is total movement; for example if the deflection requirement is 2", that means the walls need to accommodate 2" overall movement (+1" and -1") ie: 1" up and 1" down, NOT 2" up and 2" down. In this case, your studs would need to be a minimum 1" shorter than the overall wall height to allow for the 1" space without imparting a force on the studs as the structure above compresses down on the wall. The use of deflection track or slide clips/deep leg track; allows the studs to be positively attached so that as the floors above/below deflect, the wall will remain rigid without being compressed/stretched.

The use of deflection tracks and slide clips is necessary for long term survivability of a building, as well as to preserve the integrity of the exterior building envelope. The allowable deflection for the exterior cladding also comes into play when designing the exterior CFMF stud wall design requirements; an exterior finish material like masonry, will only allow for an L/720 versus say an Aluminum Composite Panel system that can handle L/240 deflection; if not accommodated for properly you would have brick cracking or possibly failure of the brick ties and delamination. If you don't allow for deflection in your stud framed assemblies whether floor to floor infill or floor bypass construction at each floor line; then you will be imparting the load of the floor slab deflection on your stud framed assembly and as a result will eventually have failures on exterior finishes, interior drywall cracking, possibly even exterior glass cracking. Worse case scenario would be a building that rips itself apart in an earthquake because it can't move enough if the exterior walls can't accommodate the allowable deflection required in the building design.

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## JDPugh (Oct 26, 2015)

Yep hard to believe that big hunk of steel will deflect, but it will. Not a big fan of track in track in an exterior wall. With a standard track system the studs are cut pretty tight and screwed to the track flange and the track is fastened to the deck or beam in this case. With Track in track there is that gap between inner and outer track, depending on how much deflection they have designed for and the studs are tied to the inner track only. Puts a lot more horizontal wind load into the leg of the outer track and I have not seen a lot of data on that. Here we generally saw a vertical slide clip in this type situation. Used these head clips a lot here, but also used a lot of Clark Dietrich depending on which distributor I bought framing materials from.

http://www.steelnetwork.com/Product/VertiClipSL
http://www.steelnetwork.com/Product/VertiClipSL_s3lgb2d

Have also used a lot of that V-Flex track on interior walls but again not sure how much horizontal wind load that leg of the track can take. Whatever you use be sure and verify how much overall travel they expect in that beam deflection. There will be both up and down movement and that will effect the leg length of the deflection track or the length of the slots in the clips.


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