Need advise building a grow room in cold outside temps

Discussion in 'Grow Room Design & Setup' started by corbin5754, Jan 2, 2017.


    corbin5754 Well-Known Member

    Hey great to be back. Haven't grown since 2014. Have since moved and want to start again. I just built a 18x30 ft steel garage non insulated in my backyard and would like to section off a enclosed grow area mabe 6-7 ft wide 7ft long and mabe 8-9 ft tall.
    If temps outside are 10-30 degrees what do you think temps will be in my grow room if I fully insulate it and have 2 400w hps lights in cool tubes. Can you help me out on what I need to do to control temps.. I imagine they will be fine when lights are on but when timer kicks lights off it will be 2 cold. Could I place a space heater inside room to kick on when lights go off?? Any help would be appricated thanks.

    Jaybodankly Well-Known Member

    You are going to need to start with insulation- floor, walls and ceiling. Insulation will be a lot cheaper than running a heater all winter and AC all summer to cool it off. Low Depot and places sells 4x8 sheets of foil faced insulation. Plants love consistent temps. Making a grow room is about controlling the environmental factors. Insulation is the first step.
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    thumper60 Well-Known Member

    for starters I would dump the cool tubes u gonna want the heat.
    house34, Shroominnm and Tim Fox like this.

    corbin5754 Well-Known Member

    So if I fully insulate it I should be fine with temps when the lights shut off?

    NewGrow15 Member

    Possibly. You may consider breaking up the light cycle so lights out isn't too long for temps to drop. I also hear alot of people that do garage grows running autos come winter
    corbin5754 likes this.

    texasjack Well-Known Member

    I have a oil radiator heater that has a thermostat for my unheated garage grow space. Works great.
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    brimck325 Well-Known Member

    might be better off building 1 big room with smaller flower n veg inside that room with plenty left for a lung room. it will be cheaper heating an insulated lung room then whole un-insulated garage.
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    Tim Fox

    Tim Fox Well-Known Member

    insulation for sure,,, do not use the cool tubes in winter,,
    you have to trail run a few days without plants, using meters and sensors to get a feeel for how temps run with lights on and off
    I use a variac thermostate and a baseboard heater,, it only kicks on if temps get to low,, so during lights on the heater may stay off,, but if some heat is needed it will kick on,,, during lights off the heater is always on to some degree,,,
    IF your humidity is in range,, you can recycle the air, my buddy made a cheapo box out of cardboard and feeds his exhaust into the box, and his intake is on the other side of thebox, then he just spreads the two hoses together or apart as needed to adjust the temp inside the grow space,, simple but really effective
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    Aeroknow Well-Known Member

    Environment controller and a properly sized dehu.
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    GreenParty Member

    I have pretty much the same set up as you describe. My grow room in my unheated metal shed is built with 2x6s and insulated with fiberglass. As @texasjack describes, I too have an oil-filled radiator type electric heater plugged into a LUX LUX WIN100. My temps actually get colder than what you described. Dealing with the humidity is a little tricky at times...yes I do have a dehumidifier. But, to answer your question, yes, your room will need some added heat.
    corbin5754 likes this.

    Mr.BrightLights Member

    Just my two cents.. id do away with the cool tubes on your hps until it gets warm out again. Do your insulation and get a general sense of your temp range after. Shouldnt have a problem at all with insulation + hps at the rate they produce heat but I would suggest getting a space heater with adjustable thermostat to compensate for the heat lost when your lights kick off. Just run it on a seperate timer accordingly. Shouldnt cost but about 50-60 bucks for a heater that will fit your needs n 10 bux for an extra timer. All around no more than 80$ to fix your problem. I had the same problem with my grows last winter when my central heat & ac went out.. if humidity is an issue just use humidifier/dehumidifier or run a few extra fans. That usually takes my humidity temps down.

    Jaybodankly Well-Known Member

    After insulating as much as you can. Add as much thermal mass as you can. Thermal mass is the ability of a material to absorb and store heat energy. A lot of heat energy is required to change the temperature of high density materials like concrete, bricks and tiles. Water can hold twice as much as concrete. Once the room starts to cool off. It will release that heat back into the room. It works both ways by absorbing heat it keeps the room from getting to hot. By releasing heat it keeps it from getting to cold. It clips the temp peaks and creates more of a temp wave. Plants appreciate consistent day and night temps. I had 9 - 5gal buckets in a 3x3 tent one winter in my basement. A soil cable could also be useful. Soil biology slows down rapidly below 50 degrees.

    GreenParty Member

    My wall and ceiling insulation is R19. The shed floor is cement. My room first covers the floor with linoleum and then in winter I put down a board of 2" hardboard insulation under the plant area. You are going to have to consider your intake and exhaust as of course bringing in cold air can cause condensation. My first winter when I was trying to figure things out had my room just dripping at times. I now never exhaust during lights out and do very little of it even during flower.
    thumper60 likes this.

    fandango Well-Known Member

    If you can use a bit more space in the 2 twin rooms in there...use a wooden platform an insulate the floor...lights will be on 24/7...flip from room to the heat from room to room...that takes care of the 12/12...really you will need a veg room as well...24/7

    Alwayslearnin Well-Known Member

    Hello all,
    I live in the northeast and it gets pretty cold up here in ME. Mine is also in my shed only my shed is made of wood to start but it was falling apart until i revampted it. Anyway my room is 7×16×9 and im running 1000watt hps without the cooling tubes, in fact they are all open hoods which i wouldnt suggest for lights with such a high amount of heat they produce unless you have a good air intake of cold air.
    It is also insulated with r13 rated pink panther insulation built in place with 2×4framing. I choose whiteboard for the walls they are thin but i find that 3 lights puts out enough heat to control as long as outside temps are below 30 degrees. Winters here are dry believe it or not for the most part. I acually have a humidifier in mine instead of a dehumidifier. My sugestion is to just build yo7r room like any other wood structure only inside you steel garage. Idk how much carpendry skills you have ive been doing it for a good while so i shouldnt assume everyone knows how to build. But its certainly not roket science right. Lol. What are your plans for power? I had to run a seperate box out to mine and put each individule plug in to its own 20amp fuse at the breaker so i have 5 outlets with 10 seperate 20 amp plugins as apposed to one breaker per outlet box. And it aint enough! So be sure you have plenty of outlets.
    I have 2 6" can fans for intakes pulling air in from inside the shed so i didnt have 3 seperate exaust ports on my shed one is bad enough and that one is my outake exaust. Which is an 8" can with a 22 inch carbon filter. Make sure you put some kind of filter on your intakes also. I tried a dyi filter but you would be wise to invest in ones that you know will work to keep out outside pest that will most likely be dormant this time of year but as soon as they get in the heat they wake up. Pm spidermites ect.

    GreenParty Member

    Concerning an intake filter....I found this here while lurking and copied it.

    Works super. Replace the hepa filter every grow and I have a bug screen on the intake pipe in addition.
    a senile fungus

    a senile fungus Well-Known Member exactly what I do, lil bit smaller building though. I use a duct system around the building to keep air constantly circulating in.the rooms, and a motorized damper on a thermostat brings in cold air when the room gets to about 75 humidifier to add moisture when needed. Works perfectly so far LOL
    fandango likes this.

    fandango Well-Known Member

    You could build the 12/12 rooms in the center of the 18x30 building and use the rest of the building for the veg section.Control the temps of the entire building and have intakes in the 12/12 rooms that have exhaust fans in them to circulate the cool air from the lung area and expell the hot air back out to the conditioned area.
    But the cost for this grower would be huge and he would need to move about 50 lbs a year to recoup the investment

    corbin5754 Well-Known Member

    Thanks for the replies guys. How big of a sub panel box do you think I'll need ran to my building for 3- 400 watt hps lights and a few inline fans and mabe a few other outlets?

    Alwayslearnin Well-Known Member

    I have up to 4 1000wat hps and ibhaveva 100amp main hooked up an ran 20 amps to each idividual outlet plug. So 4 outlets with 8 20 amp inlets. Uf you do something like that i did it to save money. I should have just spent the extra. But i still owe a friend for running the cable out.that wasn't cheap. He is a good guy, rusdian fella name of oleg.i call him the mad Russian, so fo my kids but hes the nicest person u know. Anyway i wouldnt cheap out i did and now i realize just how many i really need.
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