# Partition wall bracing and grid ceiling



## BWB (Jun 30, 2018)

hello all....I recently found this forum, so far it’s been very helpful! What does the code say in regards to bracing walls attached to a grid ceiling? From what I have read so far...a steel stud attached to top of wall and run at 45* to ceiling truss or bottom cord is acceptable...how often is a ceiling brace required?


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## cda (Jun 30, 2018)

Welcome!!

Heard the amount of salmon that can be caught this year is down??

Man the prices are high down here in the small states.

Give it a day or Monday for some great replies to your question

Which edition of the I Codes does Alaska use


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## RLGA (Jun 30, 2018)

The 2012 IBC requires that interior partitions greater than 6 feet in height have the ability to resist a lateral load of not less than 5 psf (Section 1607.14). Table 1604.3 indicates that exterior and interior walls need to have a deflection limit of l/120 with flexible finishes unless they have brittle (l/240) or stucco/plaster (l/360) finishes, but this is limited only to seismic and wind loads. However, footnote "b" states that the deflection for interior partitions is based on the horizontal load in Section 1607.14 (i.e., actual load but not less than 5 psf). Gypsum board could be interpreted as being either "flexible" or "brittle."

That was clarified in the 2015 IBC when Table 1604.3 was revised to create a separate category for interior partitions and move the deflection criteria to the live load column. The footnote "b" remains, pointing back to the minimum load in Section 1607.14.

Thus, metal stud wall design depends on the actual loading of the wall (but not less than 5 psf), the height of the wall, and the materials applied to the wall. ASTM C 754 will give you some height limitations for each of the deflection limits based on metal stud depths, thicknesses, and spacing with 1/2-inch gypsum board on each side. Metal stud organizations, such as SFIA and SSMA, publish technical documents that also provide greater information about loading of partitions with various applied gypsum board finishes.

Now, to answer your question (finally), these all assume that the wall is braced at the top and bottom; thus, the greatest deflection would be at mid-height. If a wall is not supported at the top, then the greatest deflection would be at the top of the wall. Suspended acoustical ceilings may provide some lateral support, but I wouldn't count on the building department allowing that as the only means of support. According to ASTM C 754, runners attached to concrete are required to have fasteners at 24 inches o.c. Thus, if the top runner is not attached to a surface above, then I would expect that bracing should be provided at the same spacing that fasteners would be required. ASTM C 754 also mentions attachement to suspended ceilings, but I suspect that the reference is to suspended gypsum board ceilings and not acoustical panel ceilings.

In the end, I would suggest talking to your structural engineer.


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## classicT (Jul 2, 2018)

Typical is 4-ft on-center alternating directions.


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## BWB (Jul 2, 2018)

Yes...so far the salmon returns are low...we couldn’t fish at all for kings until a couple weeks ago...hopefully things will pick up for Coho’s.
 Thanks for the reply’s!


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