TEK Screws In Deflection Track / Slip Connection 1

[BSVBD]

I see CFS (Cold Formed Steel) studs fastened to deflection top tracks with TEK screws.

In a deflection situation, where the TEK screw will experience frequent movement, wouldn't the typical TEK screw (without washer, nut and deformed threads) work its way loose over a short period of time?

 

[Ron]

A deflection track rarely gets exercised. It is primarily there "just in case".

 

[wannabeSE]

On a side note, many (most, all?) of the UL rated head of wall assemblies with slotted tracks require wafer head screws. Also, some of the deflection track manufactures have ESR reports that require wafer heads whether or not the wall is rated.

 

[XR250]

I assume you are talking about slotted deflection track? I have never used that because the premise seems sketchy to me. I only specify heavy gage track with no screws or deflection clips.
I agree with Ron, it likely rarely gets used, but we have to specify it since it is now standard practice.

 

[KootK]

A deflection track rarely gets exercised. It is primarily there "just in case".

I agree with Ron, it likely rarely gets used, but we have to specify it since it is now standard practice.

This surprises me. You guys don't expect to see real differential movement taking place in the primary structure above?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[jayrod12]

Deflection tracks around here gt exercised often enough. And I've seen too many situations where they weren't installed and it has caused significant damage to finishes.

 

[BSVBD]

My studs are 40' tall, by-passing OWSJ (Open-Web Steel Joists) spanning 58'.

With potential joist deflections of 1.9", i certainly expect some vertical movement.

wannabe... what benefit would a wafer head have? Are they unable to reverse direction and work their way out?

XR250... I considered the deep deflection track with no screws or clips, but, with potential lateral deflection of 1.25" along with potential uplift, I definitely want some positive connection.

Thank you all...

 

[sandman21]

Are you using the TEK's in the slotted holes? You should be using the deflection screws that came with the product or be spec'ing a shouldered screws or wafer head if the manufacturer allows it. The wafer head has a small shoulder vs. a TEK which has threads full length, the TEK may catch the deflection clip and not let it deflect.

 

[Ron]

KootK....the most common application is for the deflection track to be installed to the underside of a concrete floor above. That floor will likely never see its design live load, thus little deflection of the track. The track is usually installed after most of the dead load is already there.

Further, the exterior finishes are usually attached rigidly to the CFS framing system, thus if there were much deflection in the track you would see evidence of distress in the finish/cladding system (except brick veneer)

 

[jayrod12]

In these parts, the most common application is for the tops of demising walls that are sitting on grade-supported slabs.

 

[OldBldgGuy]

I see deflection track specified all the time in all sorts of locations, including below windows sitting on structural girts. If a window or row of windows is deflecting to that extent, what is happening to the glass? Despite repeated requests to architects & EORs of these projects, I have never had a single legitimate response to or example of an interior finish or exterior envelope detail that actually carries through with the concept of movement. I don't doubt that many finishes or envelopes could and would be compromised by this type of deflection, however I cannot recall ever seeing it happen and I can unequivocally say I have never seen anyone detail for it properly. The "in thing" is to specify slotted track, it gets done, and no thought is given to it.

 

[XR250]

XR250... I considered the deep deflection track with no screws or clips, but, with potential lateral deflection of 1.25" along with potential uplift, I definitely want some positive connection.

With that much deflection allowance you have alot of eccentricity on the track legs which causes a moment in the legs, and in the track web where it is shot to the structure. Make sure you take this into account when sizing your track - especially at window and door jambs. I would be using deflection clips in this instance such as an SL600.

As far as the deflection track getting exercised, I agree with Ron and OldBldgGuy. I never see any details for the interior or exterior finishes that address the potential movement across the joints and have never heard of any issues in my 25 years.

 

[sandman21]

The window top connection is a two-piece construction to allow for movement typically in two directions. The architect places an expansion joints at the locations with the deflection track. Proper detail for a spandrel system for exterior applications. Interior finishes are typical stopped above ceiling framing or if not an expansion joint is provided.