foil board insulation vs panda wrap

xIPhobiaIx

xIPhobiaIx

Active Member
Hello all,

Building out a grow room and trying to decide on the insulation and lighting strategy.
I have a shed in Michigan I am outfitting and am in a Zone 5 climate.
Everything is being insulated up to recommended Zone 5 R values.
Walls will be R-19 and ceilings will be R-42.

I am spray foaming using Great Value Pestblocker first to air seal the room against the plywood exterior walls. Mind you I am not using it to spray foam the entire thing just seal off cracks, exposures, etc. AKA create the seal.
This will be followed by the fiberglass insulation than from here is where my questions begin.

Out of these order which one would give me the best environment/light reflectivity with the least amount of moisture issues, etc.

  1. Vinyl siding -> Plywood walls -> Spray foam -> Fiberglass -> Plastic wrap -> Polyiso foam bard with foil on each side -> Panda wrap
  2. Vinyl siding -> Plywood walls -> Spray foam -> Fiberglass -> Polyiso foam bard with foil on each side -> Panda wrap
  3. Vinyl siding -> Plywood walls -> Spray foam -> Fiberglass -> Plastic wrap -> Polyiso foam bard with foil on each side
As the polyiso has the foil facing that will reflect light and IR heat it is a great product. However, I am not sure if its light reflectivity vs panda wrap.
I know panda has great light diffusion aka no hotspots and reflects around 90% light. Not sure on polyiso and also not sure if panda ontop of polyiso will be to hot for the panda plastic.

Anyways, any help on this would be much appreciated!
 
TintEastwood

TintEastwood

Well-Known Member
Polyiso..Same as rigid foam?
I found out after starting to use it...

The foil on my 1 1/2" rigid foam does not block 100% of light.
I use panda/orca to lightproof and for high performance reflectivity.

Before panda.
20190419_075949_HDR.jpg
 
lakesidegrower

lakesidegrower

Well-Known Member
You have the right wall build for exterior wall construction - just make sure you use acoustic caulking around your vapour barrier (plastic sheet - use at least 6mil) then you could use rigid board for further insulation on the inside but don’t bother with the foil faced variety, go with anything between 1” and 2” depending on how much r value you want, use foam board caulking to seal where boards meet and where it meets the floor and ceiling. Then cover with either Mylar or panda wrap, whichever your preference.
 
Piper84

Piper84

Well-Known Member
I am in a shed in the mid Atlantic and I put up r19in ceiling and r13 in walls then put panda film over also sealed all cracks and everything , I run dehumidifier 24/7 now because the weather outside and the difference in shed temp caused my shed to sweat like a fucking cave. Had friend come over tell me to wipe down the walls dry them out then put back insulation and then put up something other then drywall and it will keep my shed from getting like cave again.
 
thumper60

thumper60

Well-Known Member
xIPhobiaIx said:
Hello all,

Building out a grow room and trying to decide on the insulation and lighting strategy.
I have a shed in Michigan I am outfitting and am in a Zone 5 climate.
Everything is being insulated up to recommended Zone 5 R values.
Walls will be R-19 and ceilings will be R-42.

I am spray foaming using Great Value Pestblocker first to air seal the room against the plywood exterior walls. Mind you I am not using it to spray foam the entire thing just seal off cracks, exposures, etc. AKA create the seal.
This will be followed by the fiberglass insulation than from here is where my questions begin.

Out of these order which one would give me the best environment/light reflectivity with the least amount of moisture issues, etc.

  1. Vinyl siding -> Plywood walls -> Spray foam -> Fiberglass -> Plastic wrap -> Polyiso foam bard with foil on each side -> Panda wrap
  2. Vinyl siding -> Plywood walls -> Spray foam -> Fiberglass -> Polyiso foam bard with foil on each side -> Panda wrap
  3. Vinyl siding -> Plywood walls -> Spray foam -> Fiberglass -> Plastic wrap -> Polyiso foam bard with foil on each side
As the polyiso has the foil facing that will reflect light and IR heat it is a great product. However, I am not sure if its light reflectivity vs panda wrap.
I know panda has great light diffusion aka no hotspots and reflects around 90% light. Not sure on polyiso and also not sure if panda ontop of polyiso will be to hot for the panda plastic.

Anyways, any help on this would be much appreciated!
Click to expand...
3 looks good the poly wrap is the most important thing when growing in out building where it gets for real cold= Below freezing for weeks at a time. I have seen exterior walls an roofs warp out in 1 winter from moisture excaping from warm fully insulated growrooms then you get mold after that. gotta stop that vaper from condensing in the wall.
 
xIPhobiaIx

xIPhobiaIx

Active Member
lakesidegrower said:
You have the right wall build for exterior wall construction - just make sure you use acoustic caulking around your vapour barrier (plastic sheet - use at least 6mil) then you could use rigid board for further insulation on the inside but don’t bother with the foil faced variety, go with anything between 1” and 2” depending on how much r value you want, use foam board caulking to seal where boards meet and where it meets the floor and ceiling. Then cover with either Mylar or panda wrap, whichever your preference.
Click to expand...
are you saying vinyl, plywood, plastic with acoustic caulk, foam board with foam board caulk, than lastly panda wrap?
 
xIPhobiaIx

xIPhobiaIx

Active Member
Piper84 said:
To answer your original question I would go with option 2 minus the polyiso board
Click to expand...
my concern is with harsh winters out here that taking the foam board out will leave me with less than desired insulative capabilities. walls are recommended to be r19 out here and with just fiberglass your getting r13.
 
xIPhobiaIx

xIPhobiaIx

Active Member
thumper60 said:
3 looks good the poly wrap is the most important thing when growing in out building where it gets for real cold= Below freezing for weeks at a time. I have seen exterior walls an roofs warp out in 1 winter from moisture excaping from warm fully insulated growrooms then you get mold after that. gotta stop that vaper from condensing in the wall.
Click to expand...
my concern here would be the foil insulation would not bring as good reflectivity as the panda wrap and also that the board overtime would be exposed to moisture.
 
lakesidegrower

lakesidegrower

Well-Known Member
xIPhobiaIx said:
are you saying vinyl, plywood, plastic with acoustic caulk, foam board with foam board caulk, than lastly panda wrap?
Click to expand...
Right - I live in northern Canada, so super harsh winters, so I’d go with 2” styro, you can also put this on the outside in between the siding and the plywood, it would honestly be the best bet, but putting it in the inside is fine if you can spare the space. Then it’s whatever you want on the inside, so panda wrap would be great, but don’t rely on it to be your vapour barrier. I wouldn’t even seal up the panda wrap, you want to avoid creating a ‘double vapour barrier’ which will trap moisture and eventually cause problems. I’d install furring strips (you can rip 2x4 lumber into 1/2” strips) on top of the styro board (if it’s on the inside) by screwing then into the studs behind the styro board, then hang the wrap on the furring strips, leaving like a 1/2” gap at the bottom. You’d then have an air gap between the panda wrap and the styro board that would allow some air movement behind the wrap and prevent moisture issues. Would be pretty sweet actually lol
 
xIPhobiaIx

xIPhobiaIx

Active Member
lakesidegrower said:
Right - I live in northern Canada, so super harsh winters, so I’d go with 2” styro, you can also put this on the outside in between the siding and the plywood, it would honestly be the best bet, but putting it in the inside is fine if you can spare the space. Then it’s whatever you want on the inside, so panda wrap would be great, but don’t rely on it to be your vapour barrier. I wouldn’t even seal up the panda wrap, you want to avoid creating a ‘double vapour barrier’ which will trap moisture and eventually cause problems. I’d install furring strips (you can rip 2x4 lumber into 1/2” strips) on top of the styro board (if it’s on the inside) by screwing then into the studs behind the styro board, then hang the wrap on the furring strips, leaving like a 1/2” gap at the bottom. You’d then have an air gap between the panda wrap and the styro board that would allow some air movement behind the wrap and prevent moisture issues. Would be pretty sweet actually lol
Click to expand...
So, you would just not do fiberglass at all behind the plastic? would the plastic go against the plywood? also, the design for this room is a closed loop system and air sealed with CO2 injection. there is no air coming in or goin out... well only exhausted if need be to reduce temps, etc but the CO2 keeps the air fresh and the closed design allows the CO2 to hit the right PPM requirements. my concern is that it being a shed with only foam board it will not retain enough heat in the cold. and i dont want it to breath because i dont want moisture getting to the fiberglass or really even the foam board. i am concerned with a double vapor barrier as well as i dont want to lock in any moisture which in this case would be the foam board if plastic behind and panda in front. so maybe just the panda in front as the vaport barrier along with the light reflection?
 
Star Dog

Star Dog

Well-Known Member
The 1st room I built was ply and flat white paint built in an attic, I can't ever recall having moisture gather, my 1st recollections of moisture gathering was my 1st grow tent.
 
TintEastwood

TintEastwood

Well-Known Member
From my experience, the eps foam is just one step above tent material.
I'm only using it because it's so light and easy to work with.

This is the type I"m referring to...
www.homedepot.com

R-Tech 1 1/2 in x 48 in. x 8 ft. R-5.78 EPS Rigid Foam Board Insulation 320817 - The Home Depot

Henry R-Tech is a cost-effective way to increase your project's energy efficiency. R-Tech is an engineered rigid insulation consisting of a superior closed-cell, lightweight and resilient expanded polystyrene
www.homedepot.com
 
lakesidegrower

lakesidegrower

Well-Known Member
Th
TintEastwood said:
From my experience, the eps foam is just one step above tent material.
I'm only using it because it's so light and easy to work with.

This is the type I"m referring to...
www.homedepot.com

R-Tech 1 1/2 in x 48 in. x 8 ft. R-5.78 EPS Rigid Foam Board Insulation 320817 - The Home Depot

Henry R-Tech is a cost-effective way to increase your project's energy efficiency. R-Tech is an engineered rigid insulation consisting of a superior closed-cell, lightweight and resilient expanded polystyrene
www.homedepot.com
Click to expand...
That looks like a perfect rigid board material, in Canada so we have different brands, same basic stuff
 
lakesidegrower

lakesidegrower

Well-Known Member
xIPhobiaIx said:
So, you would just not do fiberglass at all behind the plastic? would the plastic go against the plywood? also, the design for this room is a closed loop system and air sealed with CO2 injection. there is no air coming in or goin out... well only exhausted if need be to reduce temps, etc but the CO2 keeps the air fresh and the closed design allows the CO2 to hit the right PPM requirements. my concern is that it being a shed with only foam board it will not retain enough heat in the cold. and i dont want it to breath because i dont want moisture getting to the fiberglass or really even the foam board. i am concerned with a double vapor barrier as well as i dont want to lock in any moisture which in this case would be the foam board if plastic behind and panda in front. so maybe just the panda in front as the vaport barrier along with the light reflection?
Click to expand...
There are a few different options on how to do it properly, but the idea is that the building should either dry to the inside or dry to the outside - the addition of the styro board in addition to a grow inside makes that hard to accomplish whether you put the styro on the outside or the inside. In a perfect system you would styro the outside and used closed cell spray foam in the stud bays then no plastic sheeting because the spray foam would be your insulation and vapour barrier, then you drywall etc, you could just put up the panda wrap on the studs you wanted.
But that’s expensive and you probably already have the building. Just fill the studs bays with roxul insulation bats, take your time with the plastic sheeting (buy the thicker grade, don’t cheap out lol), caulk it well, buy the special vapour boots for the electrical receptacles and make that barrier as tight as possible. Tape the staples, tape every seam well. Then you could fairly safely install styro board on top of that - then strapping on the styro board, then tack the panda to that but allow it to breath behind by gap at bottom etc.
 
lakesidegrower

lakesidegrower

Well-Known Member
There technically is a ‘double vapour barrierm between the styro board and the plastic sheeting but I don’t think that would be a big deal. Then IF any vapour got behind the plastic sheeting the, the wall system would be able to breath to the outside (ie. through the insulation, through the plywood, then to outside). But this is only for a very minimal amount of diffusion. The key here is a very tight vapor barrier chested by the plastic sheeting system.
Hope this helps!
 
N

newbplantgrower420

Well-Known Member
TintEastwood said:
From my experience, the eps foam is just one step above tent material.
I'm only using it because it's so light and easy to work with.

This is the type I"m referring to...
www.homedepot.com

R-Tech 1 1/2 in x 48 in. x 8 ft. R-5.78 EPS Rigid Foam Board Insulation 320817 - The Home Depot

Henry R-Tech is a cost-effective way to increase your project's energy efficiency. R-Tech is an engineered rigid insulation consisting of a superior closed-cell, lightweight and resilient expanded polystyrene
www.homedepot.com
Click to expand...
these reflect a ton of light with the reflective material right? im in the process of putting these ones up right now.

im using the 2 inch thick ones with the reflective facing inside the grow room. i do like them too cause theyre not stiff
 
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