Help please with insulation

[New guy joe]

Normally in building science it's agreed that the placement of the vapor barrier within the wall assembly doesn't matter in regards to which side of the insulation it's placed. But given that we prefer negative pressure inside our growing space and all the issues covered in the article I linked, I think depending on your outside environment that having the vapor barrier on the outside might be beneficial. All that being said the only true way to find out is through testing and measuring the conditions that you will be exposed to. All the mold resistant building materials won't do jack if the conditions are right, hell our bodies sluff off millions of mold spores & bacteria every day. I guess my point is based on budget I wouldn't get to crazy worried about it cause rebuilding parts and correcting issues might be cheaper in the long run than going hog wild and over budget on gestamating. Warning I'm high so this may all sound stupid in 3 hours.

Totally makes sense man. A vapor barrier for the outside would only be about 15$ per room.

 

[UncleBuck]

what part of oregon are you in?

in portland, an insulated room inside a large glorified tent would be misery during the winter. could work in the higher country.

might as well build a shed with a really nice door. not really in your budget range though.

 

[New guy joe]

Eugene area.

 

[UncleBuck]

it's wet there for many moon. wet as shit. and i don't even know what a "portable garage" is. got a picture of what one looks like?

 

[New guy joe]

it's wet there for many moon. wet as shit. and i don't even know what a "portable garage" is. got a picture of what one looks like?

This isn't the one I'm working with exactly ( different color) but this is what it is.
Size is roughy , 20'x10'x10' 10' highest point of the roof , 7' is the lowest.

 

[New guy joe]

Very aware of the rain I've lived here for 22 years . Stays very dry inside this.

 

[CanadianONE]

Yes panda film is a vapor barrier

 

[Rrog]

So how's the mouth surgery healing up? That's gotta be uncomfortable

 

[New guy joe]

So how's the mouth surgery healing up? That's gotta be uncomfortable

Slowly and painfully. Had a root canal get infected and had to be surgically removed.
Btw I posted another thread about room size and plants number. If anyone could go over to it and give some expertise I would be thankful.

 

[Rrog]

That sounds pretty awful. Glad you're feeling better

 

[New guy joe]

What is your budget like? Are you building wall panels like you would a normal home or just making a frame out of 2" x 4" lumber and sheeting it with plywood or similar? What are the high/low temps like there summer/winter? Closed cell polyurethane would be number one choice if budget calls for it because it will give you the insulation along with vapor barrier in one application and an R-value around 5-6/inch. Extruded polystyrene rigid insulation (Foam board) would probably be second choice. Just make sure to tape all seams with sheathing house wrap tape to achieve the required vapor barrier. This will give you R-5/inch also. After that would be regular batt (Fiberglass/Stonewool) which will achieve around R-4/inch but you will also need to install a 6 mil vapor barrier ( Polyethylene) over this and tape all seams. These would be listed from most expensive to cheapest.

Would the fiberglass insulation be blowin into the room of the only thing between the plants and it was a layer of panda film?

 

[Rrog]

Yes at some level that's possible

 

[New guy joe]

Yes at some level that's possible

Okay would osb be the cheapest for the inside panels? I'm trying to keep the weight of the rooms down for easier transport and initially didn't want that much wood. But if fiberglass gets on the smoke I might as well junk it all

 

[Rrog]

Plywood is lighter than OSB which is lighter than drywall.

The cost is the opposite. Drywall cheapest, ply is priciest

Plywood holds a screw better than OSB, and drywall is brittle.

So OSB is in the middle of all the decisions, and would keep walls more stable than drywall if you needed to transport. You could use 2x3 frames at 24" spacing to cut weight and cost also

Hope you're feeling great these days!

 

[CanadianONE]

Plywood is lighter than OSB which is lighter than drywall.

The cost is the opposite. Drywall cheapest, ply is priciest

Plywood holds a screw better than OSB, and drywall is brittle.

So OSB is in the middle of all the decisions, and would keep walls more stable than drywall if you needed to transport. You could use 2x3 frames at 24" spacing to cut weight and cost also

Hope you're feeling great these days!

First off if you use pandafilm as the only barrier inside but you tape all the joints to prevent any air from bypassing the film then you will have no issues at all and no fiberglass will get into the room. Putting up any vapor barrier (6 mil or panda film) is useless if it isn't 100% sealed. The entire vapor system is to prevent any moisture/air from getting into the building envelope.

 

[Merkin Donor]

OSB is also a moisture magnet plus who knows what kind of off gassing is going on with it, really not something I'd personally want connected to my grow room that's under negative pressure.

 

[CanadianONE]

OSB is also a moisture magnet plus who knows what kind of off gassing is going on with it, really not something I'd personally want connected to my grow room that's under negative pressure.

What would you use plywood? Any engineered product that contains glue will off gas formaldehyde (Including plywood) As far as moisture goes plywood will wick up moisture quicker then OSB but OSB will take longer to dry out. Plywood is more permeable then OSB at higher relative humidity which means more water can pass through plywood over OSB. Both products are commonly used in building construction (roofs, walls etc) One way to protect both of them from wicking up moisture is to make sure the wood does not run all the way to the floor, Keep a small 1/2 gap at the bottom where it would meet the floor and you can also use a good moisture barrier paint like something you would use in kitchens and bathrooms.