Enclosing a 29" space in the ceiling

toddjb

Hi All,

I have a bit of a problem spot in finishing my basement. I have a 29" gap that I need to cover with drywall that runs the entire (30') length of the basement.

Here is what I'm dealing with. My trunk line was installed directly against the the main support beam for the basement. My ceiling is very low so I do not have the option of adding support beams under the trunk line (so please no suggestions about adding support beams under the trunk line).

I know that 24in OC is the recommended maximum distance to not get sag out of drywall, so here is what my plan is, please let me know if it will work.

On the outside of the trunk line build a standard soffit wall, on the other side where the trunk and support beam meet I plan on fastening a piece of angle iron to the side of the beam. This will give me something to screw into.

Then take a piece of plywood/osb to screw up to the soffit wall and angle iron. Then screw a piece of 1/4 drywall to the plywood/osb.

First question, will this work without sagging?
Second question, what do you think is the thinnest plywood/osb I could get away with without sagging?

Again, my objective is to have the thinnest result possible. Any thoughts are welcome.

brockmiera

Do you have any pictures?

toddjb

So angle iron on the left side and soffit wall on the right. Sorry I don't know how to flip it

Attached Thumbnails

 

coupe

can you get a picture from other side?

toddjb

Which side specifically would you like a picture of?

coupe

side with the beam

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as always, just my thoughts
good luck....coupe/Larry
take what helps? ignore the rest.

toddjb

That is the side with the beam. The top plate is fastened to bottom of the beam. The side of the duct and pressed right up to the beam.

kwikfishron

You’re just going to have to frame around it just like you have above that opening. Then you’ll have to block between the studs at the top of the wall for nailing.

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toddjb

I understand that framing around it is the ideal thing. But this is not an ideal situation. That opening is a doorway. It would look bad for the doorway and the ceiling to be at the same height. That is why I'm trying to come up with an alternative. Again, these are low ceilings so every inch counts.

Would a 1/4" piece of drywall drilled to 3/8" plywood sag over a 29" span? If so, what thickness of of ply would I have to use to avoid sag?

kwikfishron

3/8” ply and ¼” rock will sag in a 29” span imo. ¾”ply would be fine but you should have attached the ply to the bottom of the beam before framing the wall if you wanted to save space.

How tall is the door opening?

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toddjb

The door way as is is 6'2". When finished will be closer to 6'1". Fixing the plywood to the beam first would have been a better idea, but I did not see this issue coming. That is where the angle iron idea comes into play, which will only add about an 1/8th of an inch. So 3/4 would be the thinnest you think I could go? Is there any sag resistance difference between plywood and osb?

toddjb

Or, are there any thoughts on a different combination of thicknesses for maximum deflection strength. Like if I used 1/2" drywall and 1/2" ply. Or 5/8" drywall and 3/8 ply? Any thoughts?

mae-ling

the thicker the ply the better. 3/4 would be best.

To attach it to the wall use the L shaped track you can get for metal framing, if you can't get the L shaped one get a bottom track and rip it in half. Attach one leg to wall and set the plywood on top of the other leg. screw in with 3/4" screws. Then drywall.

mae-ling

May need to cut your door down an inch or 2

toddjb

mae-ling, do you have a link to the metal track product you're speaking of?