Sizing ceiling joists

ZoSos

Have a 15ft span that I need to install 24oc ceiling joists with .5 inch drywall. What size joists are going to get the job done.

woodworkbykirk

the only thing that will span 15' with todays materials are engineered joists

another option is to set a flush beam that runs down the middle of the space and then run joists that are just under 7'6" off of the beam, however consult an engineer first as what exactly to use and whats accepted by your local building authority as per codes

sixeightten

If it si truly just a ceiling joist, I think you can still get by with dimensional lumber. Ceiling joist spans are much longer than floor spans.

ddawg16

Not sure where you get that....

Cuz...according to the span tables used by Los Angeles County Building code....

24" OC would require a 2x6 ceiling joists to span up to 15' 6".

With a 2x8, you could go 20' 5".

Personally....I would go 2x6 on 16" OC. Makes doing the drywall a lot easier....remember, your going to be stagering those sheets.

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woodworkbykirk

with the weight of the drywall hanging on a 2x6 spanned almost 16' whats going to keep it from sagging. i have used 14' 2x6 to create a dropped ceiling but the 2x6's were also anchored to floor joists above with 2x4's to keep the ceiling from sagging

DannyT

in western ny the maximum for 2x6 ceiling joist is 12 feet. dont know what it is where you are. also if you go 24 inch centers you will need 5/8 drywall, 1/2 inch drywall will sag between the joists at 2 feet apart.

Gary in WA

Check locally with your AHJ.

Species, grade and storage/no is the deciding factor: http://publicecodes.citation.com/ico...002_par023.htm

1/2" drywall 24" oc, perpendicular application is fine without a water-based texture is fine, chart: http://gypsum.org/pdf/GA-216-2010.html

Garage or carport application?

Gary

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