New Attic Grow Room Design - Need Advice

I've been lurking for months, got a lot of good data here but need some advice.

I'm making an attic grow, as the person who built my home used every nook and cranny in the house aside from this small sliver of space I need a ladder to get to. I'm handy with a hammer and saw so I'm building a room (or two) for my medical grow. I know attic grows can be difficult because of the extreme fluctuation in temperatures between winter and summer, but I'm using R19 insulation in the walls, drawing cold air from a closet inside the house (below the attic) that is around 70-degrees F as shown on the left hand side of my diagram. My thought is that this air feeds into the other room through a simple non-charcoal filter, just to keep dust particles and bugs out that may get into my house.

The mother/clone area isn't two separate rooms, i just drew a line to separate them in space. I'm handy with circuitry and am building an arduino to monitor room temp, relative humidity, etc. Its eventually going to control the watering schedule, but I still have to collect more data. The flower room has a 2x4 wall separating it from the mother clone area, more R19 insulation and a sealed door. I want to know your opinions on how to either ventilate or scrub the air in the flower room. I see I can either:

1) Lug a 20 lbs CO2 tank up a ladder every few weeks (or however long that lasts for a 700 cu ft grow space), have a carbon filter with a fan to scrub the air of odors and dirt (DON'T WANT MY HOUSE SMELLING). Have an inline fan to push air through the hoods and circulate that air back into the house through another carbon filter/booster fan, or just keep it in the attic to keep positive pressure around my grow space.

2) Push air from the closet, into the mother/clone room, then push that air in two directions (one over the hoods, the other just into the room), use a Y connector and push air from the hoods and scrubbed air from the grow room out of the house. I think this would keep CO2 at nominal levels and keep odor out of my house.

Anything inherently wrong with this design aside from the hand watering until I get it automated? I'm concerned that sending the air out of the house pretty much non-stop (to keep negative pressure in the grow space so smell doesn't creep into house) will cause my heater and air conditioner to also have to run non-stop. I know the drying/curing is the really smelly part, but I think I can manage that by burping the odor into the grow room, which is then scrubbed by the filter. I was going to place the dry/cure cabinet in between the clone table and the flower room. Once I store it in vacuum bags for later use, I won't worry about odor.

Things I (think) I have taken care of:

• The arduino will control the flower room lights, putting a 30 minute delay on them if I lose power, which isn't often, but it only has to happen once.
• Fire/carbon monoxide detector with a fire extinguisher quick at hand.
• I had an electrician come and run 3 separate 20 amp service lines into the attic.
• Can you tell I'm really cautious about potential fire hazards?
• I have 9 temperature and humidity sensors monitoring every corner of the grow space.
• Closed circuit video camera so I don't have to run up a ladder constantly to check things out.

My grow material consists of:

• various strain seeds, to see which one(s) like the environment I'm building.
• coco coir
• 5 gallon fabric pots
• General Organics line of nutrients
• about 2400 watts of HPS grow lights
• T5 lights from mothers and clones
• Rockwool cubes to propagate the clones in.

Forgot to mention, total grow space dimensions is 7 ft across, 40 ft long, 7 ft high, however the roof tapers it down to about 700 cubic feet in the flower area.

Thank you for reading my first post. I appreciate any help you might offer.

I've only seen 2-3 maybe 4 successful attic grows, at all times the good attic grows were in BIG houses, that really should not be there, if you can afford a big luxury house then you can afford a proper grow room, otherwise as you will find accidents with water do happen, and the temps swing too much ....relocate to a cellar

If I had a cellar, that's what I'd do. Integral garage takes up pretty much all the space. I think this attic space has a good chance because I'm building like a real room, running duct work to cool it and it's on the nouth side of the building, hence it's never getting hit with the hottest sun rays. I ran sensors in there before and with just an attic fan the temps never went above 95 degrees. Putting in 6 inch walls with r19 insulation and running duct work, I'm pretty sure I can keep the temp and humidity where I want it. Just trying to get the whole negative pressure thing right.

Its not gonna be easy.. all i can say is get an enviroment controller. Make sute you put the co2 and temperature probes in the flower room,. Then just recirculate the air between the 3 rooms. I would replace the t5's for 150w mh for clones and a 250-400w for mothers. Put each light in coolable hoods (something slim for aerodynamics).
Then i would run insulated ducting between all the lights, drawing air from outside the tent, and expelling the ducting outside the grow room. Preferably out of the attic. Youll need air conditioning im sure. My attic room was 90'f and the temp outside was only 55'f .
Its going to take a lot of energy to keep that big of a grow space (in an attic) with that many lights.
It might be a better idea if you relocate the room and/ downsize it.. but if you dont mind the hassle and expenses,...

notacrook said:

If I had a cellar, that's what I'd do. Integral garage takes up pretty much all the space. I think this attic space has a good chance because I'm building like a real room, running duct work to cool it and it's on the South side of the building, hence it's never getting hit with the hottest sun rays. I ran sensors in there before and with just an attic fan the temps never went above 95 degrees. Putting in 6 inch walls with r19 insulation and running duct work, I'm pretty sure I can keep the temp and humidity where I want it. Just trying to get the whole negative pressure thing right.

Click to expand...

And from your diagram, if you pull air from outside the tent, run through the light hoods then echaust that air into any of the three rooms, you will have positive pressure in that room. I just think each room should share circulation through venting. Get a dual hose portable air conditioner and hook it up to your enviroment controller, along with your co2. This way,when your,a/c runs, it will shut off your co2 to prevent excessive usage of the co2..
I just dont think intaking air from the house will cool that many light in an attic

Just my thoughts

I'm definitely putting a dual port a/c up there. I see what you mean about positive pressure though. That's Where I need the guidance. Maybe I should consider venting outside. I'm on 20 acres, but a shed would draw more attention and then running power to it, etc. In the house was easier.

So, sealed with co2, then scrubbing the air in the grow room. Taking air from the closet to the mother/clone tent, passing that through the hoods, then sending that into the house. That would keep it negative pressure in the mother tent.

You can try it like that. But my thing is,if you draw air from outisde the grow tent/room into the mother and clone, you will no longer be in control of your mother and cloning rooms . The fan pulling air from the closet would have to be mighty strong. Even then i dont think itll be enough to keep cool.

Just try to make every room 100% sealed. But have fans that move air between each room. This way each room is ran off 1 controller and share commin enviromeny conditions. If the whole attic is insulated, i would draw air from within the house into the attic to keep ambient temperatures at a reasonable number.

Its hard to explain without a a picture, so im sorry if i dont make much sense..

Ok... I think I got it. Seal the tents in and of themselves. Use an attic fan to keep the ambient temperature around the tent at a reasonable temp (like 90 degrees). That way the tent isn't trying to regulate with 100+ degrees just outside the walls.

Then just seal up the room, which isn't tough, but then you need CO2. Since the area is big enough, I can regulate the heat easy enough. Ok... I think I got my ideas. I'll take pics when I get this done.

Right. You can draw air from your house like you originally stated, but draw that air into the attic, not into the grow room(s). This will help with ambient temp.
And by using all hid lighting in veg and flower, you can run air through all the hoods without changing the pressure of the rooms. You should definitely exhaust the hot air out of the attic, but not into the same room you intake air into the attic. This way you dont just draw your hot air back into the attic.
Then of course your air,conditioner. If you set up your ventilation correctly for the lights, then your a/c unit shouldnt have to work real hard. But just be sure you have fans and duct work connecting the rooms so they share equal enviroment conditions.

This limits you in terms of flexability but going this route will save you headaches. You may want to set your co2 to stay around 600~900ppm since it will be providing for the veg rooms as well, and thats about all veg plants need.
I know im being repetitive but,i want to make sure im painting an acurrate image.

This has bad idea written all over it. But a few tips....

First of all attics just plain suck, I would do anything but.

Is it feasible to extract all that air from your house considering home heating and cooling costs?

Second , dont dump any air into the attic, directly vent outside.

And insulate the vent or else you will be leaking condensation and introducing mold in a short time.

I wouldn't use Co2 in that setup. Sealed scrubbed rooms don't hide the smell as well as you think. Smell would be outside though.

Sounds familiar, very familiar. I am finishing up an attic room myself, as I have no basement nor a big enough space other than the attic.

I filled the roof rafters with R-13 fiberglass insulation then faced them 1-1/2" R-7.5 board insulation. A total of R-20.5 on the roof proves one problem, the snow melts off the roof except for a perfect 8' x 10' area! lmfao Might as well just put a huge red X on my roof! The walls of the room are built with 2"x2" and sheeted with 1" R-6.5 foil faced board insulation. If this proves to not be enough for the walls, then I will double up 3/4" R-4.9 foil faced board in between the studs, which should give me close to R-16 walls.

I have 2x 8" fans pulling air out of my closet and into the room. I have 1x 8" fan exhausting my flower room through a cool tube. I have an additional 6" fan exhausting my veg room. A small fortune in duct tape ensures the only air entering/leaving the room is through my fans, and should keep positive pressure with the more intake than exhaust.

Hey JSJ,

Ya, sounds like we are in the same boat. I found a guy's YouTube channel, DudeGrows, and it's exactly what I'm looking to setup and he seems to be doing well with it. You should check it out. I'm feeling very confident about my sealed setup now. Just wondering how long a 20# cylinder of co2 will last in about 700 cu ft at 900 ppm.

Hope all goes well. Feel free to message.