removed some metal T system drop ceilings now I want sheetrock but not sure best way to run ceiling joists across 15' room if I go with 8' 2x4 how do I tie them together towards center of room to prevent slag Edit if room is only like 14' can I just run a 15' 2x4 across span of room or do I have to buy engineered joists even though only weight I'll be making them hold is sheetrock

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    Have you looked at the relevant building codes to see what they require? Typically there are requirements stating what size lumber to use as joists for a given span, and how the walls the ends rest on must be constructed (load-bearing walls). Hint: 2x4 will never be an acceptable joist size. – user4302 Jan 19 '18 at 5:16
  • no nothing is load bearing it's on a first story literally only weight it'll have to take is the sheetrock being attached to it... I'm just curious as what is the best way to mend 2x8s together at meeting points in wide room or should i just go with longer 2x4s – user80572 Jan 19 '18 at 5:19
  • You can't span that with less than engineered joists. You can shorten the span with intermediate connections to the existing ceiling, though. Edit your post to add more information about the structure. There's not enough to provide an answer. – isherwood Jan 19 '18 at 5:21
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    @user80572 do NOT use 2x4s for this purpose and do NOT try to "mend" joists in the middle. You will be very sorry later on if you do. As in, "ceiling fell on my head" sorry. You really need to look up the relevant building codes for this and follow them. – user4302 Jan 19 '18 at 5:39
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    The use of the term joist is confusing the issue. Joists are for supporting a floor or ceiling, If you had a suspended ceiling than presumably it was suspended from something and that something is still in place and you want to cover it with Sheetrock, not build new structure. Perhaps you need to ad furring strips to attach the new Sheetrock to? WHAT KIND OF CEILING/STRUCTURE DO YOU HAVE NOW? Please explain your situation better and be very descriptive as to what your actual space is and how it is constructed. – Alaska Man Jan 19 '18 at 18:24

To span 14' or more with a ceiling joist with an uninhabited attic with no storage, you need 2x6s or larger. If you want something smaller, you need an engineeered product rated for the span.

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  • Thx so much for answer!!!! I went with 2x6 for joists before on another Diy but was curious why not 2x4s but I guess 2x4s across that span is a no go... was just curious.... But everyone's replies were really insightful I will still read and interact with any new comments because I find this really useful – user80572 Jan 19 '18 at 17:01
  • Have you picked up a #2. 2×4 lately? When I built my last shop back in 2000 I used 2×6 and some of those scared me (were taken back) hold the 2x4 at 1 end and flex it you would be surprised how many snap now add a hundred pounds of sheetrock and mud it is just asking to fail this is why everyone said no. – Ed Beal Jan 19 '18 at 18:08
  • @EdBeal I deal with 2x4s alot I just figured they had better sheer strength then that judging by all the replies I'm more than likely mistaken lol – user80572 Jan 19 '18 at 20:58

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