Hi, Im converting my 2-car garage into a music studio and…

Question

Hi, I'm converting my 2-car garage into a music studio and I'm trying to figure
out if I need to strengthen the current ceiling joists in order to support the
weight I'm planning to put on it.

The ceiling has s 24' span, and is constructed of 2x8 douglas fir spaced 12" OC.
There is also 2x8 between each joist in the middle of the span.

I am planning to add a layer of 1/2" OSB on top of the joists, and 2 layers of
5/8" drywall (type X) beneath the joists, with R-13 insulation in between.

Will this ceiling be able to support that mass? If not, how should I go about
strengthening it so that it will?

Thanks for your help!

walkereng · Accepted Answer

walkereng :

I can help

Customer:

Hello

walkereng :

Let me read your question a bit closer

Customer:

No problem. I can give more details if needed.

Customer:

I also have some SketchUp screenshots if that helps.

walkereng :

let me look up the weights of your new material

walkereng :

If you can attach a screen shot, that would be great. Use the paperclip in the
toolbar

Customer:

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[//f01.justanswer.com/JACUSTOMERwyd4m28a/2013-11-05_211904_current_ceiling.tiff]Full
Size Image
[//f01.justanswer.com/JACUSTOMERwyd4m28a/2013-11-05_211904_current_ceiling.tiff]

walkereng :

Your existing 2x8's are know where close to working

walkereng :

I am using a Dead Load of 7 psf for your material

Customer:

That's what I was expecting

walkereng :

The code requires that I also use a Live Load of 10 psf

walkereng :

That is for someone walking around up there

Customer:

Yep, that makes sense.

walkereng :

You would need triple 2x8's at 12" o.c.

Customer:

Hmmmm... sistered?

walkereng :

You will need to sister a larger 2x member next to each 2x8

Customer:

Okay, that might be doable.

walkereng :

DF-L 2x10 (#1 grade) would work

Customer:

Okay, so just a single 2x10 fastened to each joist. I guess I should remove the
blocking, then do the work, then replace the blocking?

walkereng :

Correct

Customer:

How should I attach the 2x10's?

Customer:

Nails?

walkereng :

nails are fine, just alternate nails up and down at 12" o.c.

Customer:

Okay, that should be easy enough. What will the load capacity be once this is
done? Will I be barely there, or is it a fairly comfortable support system?

walkereng :

hold on

walkereng :

you will be at approx. 75% of the bending capacity

walkereng :

with approx. 3/4" of Total Load Deflection at midspan

walkereng :

That is if you have 10 psf od Live Load over the whole ceiling, which you will
most likely never have

walkereng :

I’d like to point out that a Professional Engineer’s standard of care typically
includes a site visit to assess field conditions and get an overall
understanding of the structure. This can obviously not be accomplished through
the internet. The information provided here is meant for planning purposes only
(general sizing and budgeting) and is based on the information provided by you.
All loading cases considered are for vertical loads only, no lateral analysis
has been completed. The information should be verified by a professional
engineer who can visit the site to ensure that potentially important information
has not been overlooked or omitted.

Customer:

And could you describe deflection a bit for me? Is that mean to say that the
ceiling would be bending down literally 3/4"?

walkereng :

It would be 3/4" lower at the middle of the span then at the supports

walkereng :

That is 3/4" over 12'

Customer:

And that would be true if there were a live load of 10psf.

walkereng :

yes, over every square foot above the ceiling

Customer:

Ah, okay

walkereng :

on top of the Dead Load of 7 psf

Customer:

Is that a reasonable amount of deflection? Is this common?

walkereng :

Try to keep to about 1/2", but the max is usually 1", so you are right in the
middle.

Customer:

Okay, cool that totally makes sense. This is working well, I actually have more
questions. Is there a time limit or something? Or can I ask away? :-)

walkereng :

remember that is only 1/16" of deflection very foot till you get to the center
of the ceiling

walkereng :

no time limit, ask away

walkereng :

typo "every"

Customer:

Okay, great. So this ceiling we are discussing is potentially the outer leaf of
a two leaf ceiling system....

walkereng :

not sure what that means

Customer:

I would be building a room inside of a room. Let me get a pic here....

Customer:

THis is it with some walls removed. Hope it makes sense... the sketchup is a
little rough at the moment.

Customer:

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Size Image
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Customer:

So the existing ceiling is there but the walls you are seeing are new walls that
I will be framing that will be completely inside the garage

Customer:

There would be a new ceiling on top of these framed walls

Customer:

That ceiling would be 14' span, 16" OC, and ideally done with 2x6's

walkereng :

tried to open and got the following "

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Customer:

okay, lemme try again

walkereng :

I was able to open the 1st one

Customer:

It won't let me upload now.

walkereng :

try sending toXXX@XXXXXX.XXX

Customer:

Okay, just sent a couple pics

Customer:

via email

Customer:

IN this version the details of my existing ceiling mass additions would change a
bit, but mostly in terms of location -- might even be less load. My question,
though is re: the new inner ceiling.

walkereng :

no pictures yet

walkereng :

just came in, hold on

walkereng :

OK, what is the question

Customer:

Basically comes down to this question: will a 14' 8 3/4" span, 16" OC, made of
2x6's support a similar load? The live load would be even less important since
there's no space.

Customer:

Or do I need 2x8's for this?

walkereng :

ok, same 7 psf Dead Load and no Live Load since you have a small space between
the two, correct?

Customer:

correct

walkereng :

2x6 (#1 grade) will work fine

walkereng :

for a 15' span and spacing of 16" o.c.

Customer:

Does that allow for a 10psf live load (per code)?

Customer:

Just curious

walkereng :

I did not add that since there is no way to have 10 psf Live Load

walkereng :

you would need 2x8"s if I added the 10 psf Live Load

Customer:

Okay, great.

Customer:

Thank you so much! This has really worked out for me. helps a lot.

walkereng :

Good Luck with your project!

walkereng :

If you feel you have received a satisfactory answer to your question, click the
Accept button that is appropriate. Experts are credited for each Accepted answer
they provide. If you have additional questions, please let me know. Thanks

Customer:

Will do. Thanks again!

Hi, Im converting my 2-car garage into a music studio and…

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