Ceiling Insulation Question

cabinetman

We are in the process of re doing the ceilings in the front half of the house. The roof is a flat deck and the rafters are 2x6, 16"OC. The present situation is that inside there is a layer of 5/8" plasterboard and then a 12" square, 1/2" T&G ceiling tile.Our choices are first: To leave the existing two layers and add a third layer of 12" ceiling tile (new), OR-
Tear down the two layers, install R-19 fiberglass batts and add one layer of ceiling tile (new).
Which would offer the best insulation?

AtlanticWBConst.

....In your own words..., tho, I would add sheetrock on the ceiling...

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cabinetman

Thanks for the help. My question is relevant to the amount of isolation/separation in the two choices I've come up with. I'm concerned in maintaining an airway above the ceiling and provide air to the underside of the roof deck (it's a flat deck), and want to create a good layer of protection from heat/cooling loss. I could just add the new ceiling tiles to the existing layers giving me a layer of plasterboard, and two layers of gypsum based ceiling tiles, versus the R-19 and only one layer of ceiling tiles.

I hope my OP was clear on the two choices. If the best insulating method is to take down the two layers and install the batts and add one new layer of tiles, I'll go that route. It just seems like a fire drill in removing what's there. I'm thinking the air way plus one layer of sheetrock and two layers of ceiling tiles would seal off the ceiling fairly well. Am I correct?

AtlanticWBConst.

That has no R-value what-so-ever.

Yes and no, see below...

I don't understand what you mean by a "Fire Drill"...?

That would not seal off anything.

What you should do is:

1.) Rafter vent installed (stapled) against the underside of the roof sheathing (if you are concerend about airflow). This should vent horizontally out to the soffit areas with soffit venting installed.

2.) R-19 Insulation, kraft face on the inderside (facing warm environment)

3.) One layer of taped Sheetock for a complete 'seal'.

4.) Layer of what ever it is that you want to install for ceiling materials.

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cabinetman

That sounds like a good plan. It's talking LOML into it. We just had the roof re-done and as for the venting, I am concerned about venting instead of just having the insulation under deck.

Thanks again for the advice.

Brik

Atlantic has the right approach.

My question - What is the goal? A new ceiling? Improved venting to prolong the roof life? Improved insulation for comfort?

if its just aesthetic then just go ahead and add your new tiles. Improved venting to prolong your roof life and improved insulation go hand in hand. and are done like Atlantic suggests

cabinetman

I don't want to sound redundant in explaining the situation. I also understand that there is a "correct" way to do this remodel.

Since I would be doing the work by myself, hanging sheetrock on the ceiling is not an option. My question has to do with the two options I do have. The question being of the two if the differential between the two is minor enough not to take down the two layers that are there. Right now, there is an air space due to the 2x6 rafters. There is 5/8" sheetrock nailed to the bottom edge of those. Then there is furring strips nailed to the sheetrock. The ceiling tiles are attached to the furring strips. So, there is an airway above the sheetrock, and an airway between the sheetrock and the ceiling tiles.

My wife has worked for general contractors for over 20 years and she questions every detail of any repairs or projects. Our discussion of what to do hinges on whether going through all the work of taking down what's there, adding just R-19 and ceiling tiles would be better than adding the new ceiling tiles to what's already there.

Money is definitely an object and I'm not a young whipper snapper.