Suggestions for outside and inside walls of grow room?

So I'm building a grow room using pvc as a frame. For the outside and inside wall of the grow room I was thinking of just using all mylar. I'm also debating on using mylar just for the inside, and that black/white vinyl stuff for the outside. IDK. Anyone have any suggestions on what would work best? My main goal is to keep all heat and light on the inside. I don't care if it's air tight cuz I'm not doing Co2 yet. I will divert the heat with exhaust fans. Oh yeah keep in mind that there are no walls, just the frame. Whatever material I use will be the walls. Thanks everyone.

Mylar is expensive, difficult to work with, has to be cleaned regularly and if it wrinkles it's worthless. Seems like a good idea, in practice, not so much. Panda film will work well. Less maintenance and the difference in reflectivity is minimal.
Fred

Mylar does nothing but piss me off. Get Panda film.

http://www.lowes.com/pd_13358-56291-BP48025_4294858104_4294937087_?productId=3011906&Ns=p_product_prd_lis_ord_nbr|0||p_product_quantity_sold|1&pl=1&currentURL=%2Fpl_Foil%2BInsulation_4294858104_4294937087_%3FNs%3Dp_product_prd_lis_ord_nbr|0||p_product_quantity_sold|1

I have wanted to know about this as well. While at lowes shopping and thinking about the grow room I came across this and wanted to know if anyone used it. I think it would also be an IR blocker as well.

I hate mylar as well it crumbles like foil, I haven't tried panda film but I want to. I am either going to use the Reflectix double reflective foil insulation or the panda film next this.

i'm using reflectix in my grow room inside of a shed, if you're going to use this i would recommend using 2 layers or using a styrofoam insulation on the sides that are going to be hit by the sun cause with one layer my grow room gets about 90F early in the day when the sun is hitting the main wall. im also getting quite a bit of consinsation on the reflectix when its really cold outside and the grow room is 80-85, so i would really recommend using 2 layers or using stryfoam insulation and then the reflectix. home depot has stryfoam insulation in 4ft x 8 ft sections for fairly cheap. if i remember correctly it was like $18 a sheet

https://www.rollitup.org/grow-room-design-setup/355071-new-grow-room-rep-3.html theres a few pics here too show you

Reflectix is great. I use it to wrap buckets, ducting and pipes. Definitely eases the load on the chiller-less $$ spent on power.
Not sure if its economically feasible for walls though. I just picked up a new 10x100 roll of Panda for $80. One fourth the price of Reflectix. Certainly has no insulating properties though.
Speaking of insulation, don't underestimate the importance of this. The panels that silasx suggested work very well and can help lower overall heat load in some cases.
Fred

Got a shit load of mylar so I'd like to use it so....I'm thinking mylar inside, pink panther foam insul sheets middle, and reflectix on the outside. As the mylar degrades, I'll replace with reflectix. Does this seem like a pretty good way to achieve what I'm after? Also, I want to go daul 600 hps in this grow room, but I'm only at a 250hps and 400hps right now. What do you guys think of venting? Where should I vent to so I'm "invisible." I was thinking of constructing a room to run the exhaust ducting into. A room that's insulated with some of that heavy duty r-60 insul and completely sealed shut. This room would will have an exhaust fan (very small duty one) to exhaust out into the outside of the grow room at a timed basis. Does this seem too far fetched? Let me know what ya think. Bump for any1 with a good idea on this other than something retarded like tying it into your chimney or plumbing vents (man that looks too funny on an infrared when this is done, super obvious).

panda film!
http://cgi.ebay.com/25-x-10-POLY-FILM-PANDA-FILM-6-MIL-BLACK-AND-WHITE-/170537354947?pt=LH_DefaultDomain_0&hash=item27b4d186c3#ht_1155wt_911