by Jorge Cervantes
Step by Step Grow Room Construction
Step One: Design the room
Once you know how much you want to grow and where you want to grow, you are ready to design your grow room or purchase a ready-made room. I like to draw the room to scale on paper before constructing it.
Step Two: Assess electrical needs
The average small 1 or 2 room grow closet will need a single 15-20 amp electrical circuit at 120 volts and a 10-15 amp circuit at 240 volts. An electrical circuit is considered overloaded when it is at 80 percent capacity. For example, a 15-amp circuit is overloaded when it draws 12 amps and a 20-amp circuit is overloaded at 16 amps.
You will also need an easy-to-access electrical outlet. Ideally, the outlet should be inside the room. Remember to keep water away from the outlet. You also might want to install a ground fault interrupter (GFI) outlet with its own breaker switch. If you must run an extension cord from the outlet to the room, make sure the wire for the extension cord is at least 16/3 (16 gauge wire with 3 strands, one of which is grounded) or it will lose voltage enroute. Do not let the run of the electrical cord go more than 10 feet – the shorter the better.
Step Three: Enclose the room
Can’t make holes in the walls? Build a freestanding garden. If you are lucky, you already have a small, enclosed room; if not, it is easy to enclose a room so that you can control everything inside. However, many growers chose to set up a grow area in an unused corner of a larger room.
Enclose a grow room by framing it with boards, usually 2x4s, or use Mecalux. Once the superstructure is set up, cover it with Visqueen plastic, plywood, or Sheetrock. The room’s finish on the outside depends upon your security needs. Rooms covered with Visqueen are difficult to keep a secret. Rooms with rigid walls are generally easier t control and contain light and odors.
Enclose the room with white Visqueen plastic. Secure plastic to walls with staples, screw down 1×2 inch strips with Sheetrock screws, or duct tape. Join seams together with duct tape.
Insulating the room will help contain sound and help control temperature and humidity.
Cover the outside walls with Sheetrock once it is insulated.
Sheetrock will further deaden the sound and make the room blend in with the rest of the rooms in the home.
Install a door with a lock and key. Make sure to line the perimeter of the door with plastic or carpet to help contain light and sound inside the grow room.
Step Four: Divide Room
Divide the room to make a seedling / clone / mother / vegetative room on the bottom third and a flowering room on top. Install a plywood shelf t form a partition between the top and bottom of the grow closet.
Frame 1×2 inch boards or Mecalux, 3-3.5 feet from the floor around the walls of the room. Secure 1×2 inch boards with screws. Cut a 3×4 foot piece of 0.75 inch plywood with a 6×6 inch piece cut from the right rear corner from the duct vent. Set the plywood on the ledge of the 1×2 inch boards with the vent hole toward the back wall.
Install rigid 6 inch ducting through the hole to connect the vegetative and flowering rooms. Use small screws to install a small inline fan in the pipe to direct air up from the vegetative room to the flowering room.
Step Five: Whiteout Room and Line Floor with Plastic
Reflective walls increase light coverage on the perimeter of the garden about 10 percent. Paint the ceiling and walls white or cover them with white Visqueen plastic, reflective Mylar, or similar product. Use high-quality semigloss white latex paint. Do not use inexpensive paint because it takes longer to apply. Use a roller and paintbrush to apply paint.
Cover the floor with heavy plastic to form a large tray to protect the floor from dirt and water. Fold the plastic so that at least 6 inches run up the wall. Attach the plastic floor covering to the walls with duct tape or staples.
Step Six: Install a Vent Fan
A vent fan is necessary in virtually all grow rooms. Most grow rooms require some sort of odor control to keep it secure from cops and robbers. The fan will need to be more powerful to draw air through a charcoal filter if one is used to clean the air.
Often one of the biggest obstacles to constructing a grow room is where and how to run the exit ducting with a minimum of work and structural damage.
Normally you can run the vent out a window, chimney, sewer vent, or other pre-existing exit. Locate the vent in the ceiling or near the ceiling where hot air naturally accumulates. Carefully cut a hole in the wall or ceiling in the exact place you want it. Smart growers plan the entire project on paper before cutting holes in existing structures.
Use rigid ducting instead of flexible ducting if possible. The larger the ducting the more freely and quietly air will flow out.
If cutting into a ceiling with a crawl space, make sure you have a method to evacuate the grow room air from the crawl space. Install louvers below the rafters on the outside will of the house.
Cut the hole in the ceiling into the attic or directly through the rof. G into the attic and measure where the hole will come out. Make sure there are no wires or other impediments before cutting the hole. Pull back insulation above the hole if necessary. Use the ducting or the fan to mark a circle where you want to make the hole. Drill a 1 inch hole near the center of the circle. Use a hand hole saw to cut out the circle just outside the line. Install the vent fan and supply it with electricity. hide the fan with louvers attached to the ceiling.
Tap into ABS plastic sewer drain vents and insert the extraction vent. make sure that you are tapping into the ventilation pipe rather than the actual sewer pipe. Install a backflow vent in the extraction duct so that foul-smelling odors do not invade the grow room.
Step Seven: Neutralize Odors
Neutralize the fragrance of flowering marijuana before air is vented from the grow room so that odors do not cause security problems. The most popular and effective method is to use an activated charcoal filter attached to a vent fan.
Unless made from new lightweight carbon-impregnated material, carbon filters can be quite heavy and require stout mounting. Make sure to choose the right one for your grow area so you don’t have to mount a filter that is to heavy. For example, a carbon filter rated at 200 cfm is more than adequate for the average closet grow room.
Step Eight: Install a Circulation Fan
Air circulation is necessary in all grow rooms, especially during flowering. Usually air circulation must be increased with a circulation fan or fans. Small clip-on oscillating fans come in very handy to circulate air in small grow rooms. They are easy to use and direct air where needed. Or you can mount an inexpensive oscillating fan to the ceiling or buy an actual wall-mounted fan.
In general rooms require at least one 12-inch circulation fan for every 400 watts of light.
Step Nine: Install a Thermometer / Hygrometer
Install at least one maximum / minimum thermometer / hygrometer in your grow room to measure temperature and humidity. I prefer digital models because they are relatively accurate and easy to use. Calibrate them against 1 or 2 other thermometer / hygrometers so they remain accurate. Place the thermometer / hygrometer equidistant between the ceiling and floor, and fasten to the wall or hang from a string. Check the meter daily.
You can control the climate in most grow rooms with a vent fan attached to a timer or a rheostat. Personally inspecting the meter and plants daily will help you gain experience and learn exactly how much ventilation the room needs to keep the temperature about 75F day and 65-70F at night and the humidity below 50 percent (day/night) in the flowering room, and the vegetative room at 60 percent humidity both day and night.
Step Ten: Set Up Lights
Orient the reflective hood fixture so that light shines most efficiently. Less light shines from the ends of the fixture and more from the sides, thus throwing a rectangular foot-print of light below.
To install a lamp in the flowering room, insert 1 or 2 hooks depending upon light fixture requirements in a secure portion such as a beam or 2×4 bard of the ceiling. Mount the HID reflective hood/bulb fixture attaching it to the hooks with chain or cord. If using cord, attach the other end to a cleat on the wall so that it is easy to move the fixture up and down.
Set the remote ballast outside the grow room r on a shelf near the ceiling so that excess heat will stay high in the room and be easy to evacuate.
Step Eleven: Room Systems Check
Now the room is all set up, make a test to make sure that everything operates properly before introducing plants. Turn everything on – lights, fans, etc. t make sure they all work at the same time. Set a large pan of water out on the main growing beds to simulate plant transpiration. Close the doors of the grow room and let everything run for an hour or two. Open the doors and check the temperature and humidity in the room. Next turn off the fans and let the light run for 30 minutes with the doors closed. Check the temperature and humidity levels to see if the room is hotter and more humid with no ventilation.
Check the hydroponic garden before adding plants. Cycle all the systems to ensure that water flows from all emitters and runs back to the nutrient tank unobstructed. Check for leaks. Cycle the timer on/off function several times while you are watching the system to ensure everything works properly.
Step Twelve: Move in Plants
Move seedlings and rooted clones into the room. Huddle them closely together under the lamp. Make sure the HID is not so close to small plants that it burns their leaves. Position 400-watt lamps 18 inches above seedling and clones. Place a 600-watt lamp 24 inches away and a 1000-watt lamp 30 inches away. Check the distance daily. Hang a precut string from the hood to measure distance.