Please help with insulation of workshop project

Hello,
We have a 20' x 20' workshop detached from our house. I'm converting it to an office/studio.
The workshop had plywood nailed to the frame for the walls with no insulation. I don't have a large budget for his project, so I have pried the plywood panels off and added batt insulation in the walls, then nailed the plywood panels back up.
I've completed that phase. And instead of sheet rocking the walls, I found a tip where you can take a roller and cover the walls with sheetrock joint compound. It worked amazingly well. The walls look like they are sheetrocked and finished.
The reason for the concern with the insulation, is that I want the place to be able to be cooled effectively with a window unit AC. We are in Texas.
The joists in the ceiling are exposed. A friend of mine who is a home builder suggested that I put Celetex foam on the bottom of the joists with drywall screws. I would then blow in Cellulose in the attic cavity.
Question 1) How do I preserve access to the attic with a hatch of some kind?
I'm thinking that I would like to use luan or OSB to put underneath the celetex foam. And then possibly glue acoustic tile to the wood.
This is the plan so far. Is it misdirected or will it work?
Thanks!
KL
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E/K Littlefield wrote:

Do you mean Celotex?
In any case, check the requirements to cover this material with a fire resistant material. Most foams can not be used with direct exposure due to the problems if they are exposed to fire. Drywall may be enough.

Yes, a hatch of some kind.

--
Joseph E. Meehan

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snipped-for-privacy@hotmail.com (E/K Littlefield) wrote in message

Sounds like you plan to use the attic for storage. If that is true, I suggest you look at the Building Science web site for your climate. Typical attic spaces above insulation and vented are very hard on paper and other materails.
If you do place the insulation at the ceiling level, it's not hard to make a removable frame with insulation in it as an attic hatch.
Tom Baker
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Tom Baker wrote:

....
Good point, I might add that there may be some concern about the existing framing being able to safely support the weight of the storage, if that be the case.
--
Joseph E. Meehan

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