Quoted:
The above info is great if you're going to be able to keep the place at least ventilated/conditioned to maintain steady temps and 'low' humidity.

If you just insulate and drywall with no climate control - it'll get damp at times which can cause probs with the drywall as it can get moldy and/or pop the seams from temp/humidity fluctuations.

And uncontrolled temp/humidity variations can cause moisture build up inside the walls that invite other pests, too, depending on the location.
The point is, there is no 'this is always the best answer because...' approach.
You have to decide what you need, how much you want to maintain it Vs nail it up and never spend another $ on it, and how long you plan on keeping it.

Quoted:
I have to first ask why?

Is there a source of heating or cooling inside?


The fucking twat that we bought our house from had insulated and drywalled the shed. Critters fucking love it. They get in the walls and have all the insulation they could want to make cozy little homes. It does a fantastic job of capturing their piss and shit and it smells like hell inside.

I don't know what his fucking deal is, he must have been retarded. The shed is about a foot off the ground. The walls are heavily insulated, but the floor and roof are just a layer of plywood (and shingles on the roof obviously. Completely fucking retarded.

Quoted:
The above info is great if you're going to be able to keep the place at least ventilated/conditioned to maintain steady temps and 'low' humidity.

If you just insulate and drywall with no climate control - it'll get damp at times which can cause probs with the drywall as it can get moldy and/or pop the seams from temp/humidity fluctuations.

And uncontrolled temp/humidity variations can cause moisture build up inside the walls that invite other pests, too, depending on the location.
The point is, there is no 'this is always the best answer because...' approach.
You have to decide what you need, how much you want to maintain it Vs nail it up and never spend another $ on it, and how long you plan on keeping it.

Quoted:

Besides some comfort heat/cool NOISE is the biggest  
My main concern is the siding is not 100% sealed so a driving rain it gets damp inside

Quoted:


If driving rain penetrates now, insulating without resolving the leak point will just result in a stinky moldy rot-inducing situation once you add insulation. Best to get the exterior leaks sealed before insulation or you'll be compounding your problems.

Quoted:

Yes I guess that's really my question if putting the vapor barrier inside would be enough to help with this or I should use a sealant outside first on the cedar it's just natural now

Quoted:
[color=#ff0000][ETA: Tyvek type products that are applied between the exterior sheathing and exterior finish are a breathable moisture barrier that are designed to keep water droplets from penetrating but allow moisture vapor to breathe through.
These help to keep the rain out but don't keep the dampness out, but it keeps the dampness from being sealed in.

Tyvek is also susceptible to clogging with dust.  If you live in an area with lots of dust/pollen/etc, the tyvek can act as an air filter and eventually stop passing moisure back out as it can't breathe thru any more.][/color]

Back on topic:
Vapor barrier is a tricky concept, even though everyone assumes it's not.

Vapor barrier is basically to keep moisture out of the insulation, and in habitable structures tended to focus on the moisture source as the human/animal life inside putting moisture into the 'warmer' air inside by respiration and sweat which would then be able to condense against the inner surface of the outside 'colder' walls/roof in winter, and by extension icing up inside the insulation which reduced the value of the insulation, and then melted when it got warmer which could cause a flood from inside in more extreme conditions.
So it made sense to install the vapor barrier between the inhabitants and the insulation.

But: In the summer - the moisture tends to be in the warmer outside air, (inside conditioned air tends to be dehumidified by the A/C) and when it migrates into the walls and insulation - it can condense on the 'outside' side of the vapor barrier which would be on the 'interior' side of the insulation - allowing moisture build up inside the walls/insulation in the summer months instead.

Conventional wisdom says vapor barrier between the people and the insulation.
But that only 'really' applies in the cold weather, and can reverse in the warmer weather.
Clearly, places like Arizona ( example) with 2% humidity don't follow the above for obvious reasons, but Arizona (example) doesn't have a comparatively large representative population.

You can use the rigid blue or pink Styrofoam insulation between the studs for a certain amount of thermal and acoustic barrier, but remember that it has gotten pricey because of the EPA rules on chlorofluorocarbons and such, but ants and termites don't mind tunneling into it like a big ant hill, and mice will mine it for habi-trails too in the right climates.

Again - no 'right' answer.
You make your choices based on where you live, what you want, and what you expect.