5/8" wallboard max ceiling span

[59ctd]

My son and I are finishing the last basement bedroom and are building a box around the ductwork. Most wallboard will be 1/2" but I am wondering if we can get away with 5/8" wallboard spanning the main heat run in the center and the two air vent ducts on the right. Plan is to put a 2x4 or similar on the right wall where the flexible cold air duct is sagging in this pic. That would be about a 28-29" span between there and the I beam just left center by the heat duct. If 28-29" is too far then we would need to add a bunch of 2x4's at 90* orientation and loose another 1.5" of ceiling height.

 

[mike93lx]

24OC is what I have always seen as a limit. That said, if headroom is tight, I'd probably just send it at 28-29OC. Could also strap it with 1x and only lose 0.75"

 

[BillK]

I would be that even 1/2" will be fine. My entire house is 1/2" with trusses on 24" centers and there is not a bit of sag anywhere that I know of. I doubt that the extra couple of inches will make any difference. It almost looks like you could get a 1x laid flat across under the duct for some extra support.

 

[geneg]

Run your 2x4 nailer along the right hand side. Screw decent quality 1/2" plywood across the nailer & floor joists as far as you need to. Glue and screw your sheetrock to the plywood. Won't sag & you can trim it with a cove mold or 1/4 round painted ceiling color. Actually the 5/8 @ 29" probably wouldn't be an issue. But since it is a basement- I'd rather be safe than sorry.

 

[Nofries]

Similar solution, is to use metal furring channel.

Furring Channel / Hat Channel | ClarkDietrich Building Systems

www.clarkdietrich.com

These would run perpendicular to your ducts 24" oc max.

I'm a little biased since I work with metal framing everyday. I checked and or local Home Depot has it, not sure what is in your area.

 

[wssix99]

Run your 2x4 nailer along the right hand side. Screw decent quality 1/2" plywood across the nailer & floor joists as far as you need to. Glue and screw your sheetrock to the plywood. Won't sag & you can trim it with a cove mold or 1/4 round painted ceiling color. Actually the 5/8 @ 29" probably wouldn't be an issue. But since it is a basement- I'd rather be safe than sorry.

This is what I would do. Although, I would laminate plywood to the back of the drywall (with construction adhesive) before putting it up, so you don't need to put screws in the field and worry about piercing your ducts.

 

[59ctd]

My son put in the 2x4 nail board on the right. Ends up the two are roughly 27" apart so we are just going to wallboard over it. Neither of the vent pipes will put any pressure on the rock so it should be alright. There is a lot goin on above the gray flexi duct pipe above the doorway. That is where I ran all electrical, gas, phone, and 6x CAT6 cables from the basement utility room out to my shop addition back in 2006.

 

[mike93lx]

No idea if it will eventually leak, but I'd foil tape the seam on that duct

 

[59ctd]

Never had any drips from there in 27 years but maybe I will throw some poly on before the wallboard goes up below the ductwork.

 

[mike93lx]

Never had any drips from there in 27 years but maybe I will throw some poly on before the wallboard goes up below the ductwork.

I meant air leaks

 

[59ctd]

I meant air leaks

All the joints are foil taped

 

[mike93lx]

All the joints are foil taped

I saw. I was referring to the hemmed joint that runs the length of that large duct