How to build a grow room

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Before you rush into growing marijuana, it is important to do some research into grow room design, whether that is buying a grow tent or learning how to build a grow room.

A lot of people don’t grow their own marijuana because of the cost of the equipment needed for a grow room, however our guide on how to build your own grow room will prove that it doesn’t have to be expensive. Nowadays you can set up a basic DIY grow room on a budget for as little as $100 and if you really want to maximise your yields for around $300-$600 you can have a pro style setup with reusable equipment.

Where do I set up my DIY grow room?

First things first, you need to decide where you are going to set up your room, for this you need to take into consideration what a grow room needs to work well.

  • Enough space
  • Access to electricity
  • Easy access to water
  • Air ventilation
  • Light proof – If the area isn’t currently lightproof you can easily make it so.
  • Noiseproof – This isn’t a necessity, but take it from someone that has done multiple indoor grows, the sound of a fan running constantly can keep you up at night if your bedroom is adjacent.

Finding a suitable space​

This is arguably the most important step because without enough space to grow your plants you will never have big  yields. However, you can set up a grow space with as little as 1 square metre so don’t worry if you do not have space in abundance. This is why you should choose your grow space first, before you jump the gun and order any seeds, after all you don’t want to go ahead and buy a pack of ten tall sativas when you only have enough space to grow a couple of autoflowers.

Almost anywhere can be turned into a suitable grow space but you ideally want somewhere that has good access to electricity, or at least is close enough for you to use an extension lead with easy access to water.

You should also make sure that the area you choose is not carpeted, carpets can trap humidity and can also harvest bugs and bacteria which you definitely want to avoid. It is also very likely that at some point you will have a spill so if you have hard floor it is much easier to clean up.

Finally you want to choose a space that doesn’t interfere with your neighbours or yours and your family’s life too much. By this I mean that grow rooms give off lots of heat and can also be pretty noisy so ideally choose a room that isn’t adjacent to a bedroom and going to keep anyone up all night. An ideal space would be in a garage, basement or even a spare room. 

How to build a grow room in 6 steps

How you go about this will be massively dependant on how much space you have at your disposal, however all of this can easily be downsized or scaled up accordingly. Follow these simple 6 steps to build your own DIY grow room.

​Step 1: Flooring

​  diy grow room flooringHopefully the area you have chosen already has hard flooring, however if it doesn’t and you have carpet, I would advise either taking the carpet up or if this isn’t an option laying down some type of hard flooring over the top such as interlocking matts (right) to give you a stable surface and to minimise the contact with bacteria and moisture that can be absorbed by carpet.

Step 2: Light proofing

If you are using just a portion of a room to grow in you can buy a grow tent that will block out most light, however if you are using  whole room or would prefer to self construct your grow room then this is how. Block out any light source leading to your grow room, this is essential because it is the quality of light that dictates the size and quality of the yield, and when the plants go into bloom they will need 12 hours of undisturbed light followed by 12 hours of undisturbed darkness, this can only be attained by a room that is completely void of light leaks. 

To make sure that no light is leaking in or out of your room you will need to cover the walls, ceiling and floor with reflective material and some tape. Most grow tents already have a reflective foil lining the inside of them, so again if you buy a tent you are already covered here. Personally I use Orca grow film which is a specially designed bright white film for lining grow rooms and maximising evenly spread light across all of your plants, while also minimising light leaks with its thick black backing. Remember every 1% of light leaked equates to 10% less yield. Once you are confident any light leaks are covered, stand in your grow space in the dark and check to see if you can see any light leaking in, this is very important, any light that leaks in when the plants should be in darkness can confuse the plants and in some cases cause them to flower early completely ruining all of your effort.

Step 3: DIY grow room odor control and ventilation

Marijuana grow rooms can get very hot and humid, so to prevent any mould and mildew building up it is important that the grow is in a well ventilated area. However you will also want to make sure that the grow is somewhat airtight, marijuana plants when in full bloom can be very smelly, so to keep the smell from being noticed by neighbours you also need to make the grow space airtight.

diy grow room odor controlMaking it airtight: It is important to make the grow room as airtight as possible, firstly to reduce the amount of smell leaking out, however it is also beneficial to your plants. If you know that the room is completely airtight then it also massively reduces the risk of pests and plant diseases infiltrating the grow and also creates and environment that can be easily manipulated to get the most out of your plants. If you are using a tent then they are fairly airtight to start with, however if you are building your own grow room then try to make it as airtight as possible. You should have already covered any light leaks so you will be half way there, however it is a good idea to cover any small cracks or splits in the wall material with tape and to also purchase some airtight strips to put around the door leading into your grow room as well as an airtight under door sealer (image right).

Ventilation: You need to prevent hot humid air building up inside the grow room. To do this some of the air inside the grow room needs to be pumped out, this then allows you to regulate both the temperature and humidity of the room and provide ideal conditions for your plants. Firstly to provide good ventilation you need to get the air moving inside the grow room, now as you have made the room airtight you need to replicate the plants natural windy environment and put a fan or preferably a couple of fans inside the room, this is not only useful for preventing mould but also helps the plant stems grow thicker and stronger which will allow them to support the weight of the dense heavy buds at a later stage. Ideally you should place the fans on opposite sides of the room so that all of the plants are fanned evenly and the air will then circulate the room. Now that you have the air circulating the room you will want to remove some of the hot humid air, for this you need to install an extraction fan and carbon filter, the extraction fan will suck air out of the room that has already passed through the carbon filter so the smell will be limited by this. Next to get fresh air into the room you need to have an intake fan that will breath fresh air into the grow room and effectively replace the hot humid air that is removed by the extraction fan. Both the extraction and intake fans work in sync and will need to have ducting on the other end leading preferably outside the grow room, ideally you want them to lead outside the house/room completely via a window. 

Stealth growing? Read our top tips to stay under the radar.

Step 4: Climate control

Aside from ventilation and fans you also need to take into consideration how you are going to control and monitor the climate, for this you will need:

  • Humidifier and Dehumidifier
  • Thermostat or thermometer
  • Humidistat or hygrometer
  • Light timer

Not all of these are essential, if you are setting this up on a budget then at a bare minimum I would say you need a thermometer, hygrometer and light timer. However having a Humidistat and Thermostat will make the grow easier for you and more self sufficient.

Humidifier and dehumidifier: Using these allow you to manipulate how humid the grow room is, humidifiers usually come with a built in hydrometer so you probably wont need to shell out the extra cash on one of these. Marijuana plants love humid air, especially in the growth phase, it can massively speed up the vegging period and can in some cases allow plants to grow twice as fast. Again humidity can cause a greater risk of mould so having a dehumidifier is also important.

Thermostat or thermometer: Thermostats can be manually connected to the air ventilation system you have set up so that if the thermostat goes above the desired temperature then the fans will automatically kick in or speed up to cool down the room and this can also work vice versa. Having a thermostat is by no means essential and plenty of people just use and thermometer and manually speed up/turn off the fans as and when the temperature fluctuates. It is also very use full too connect a dimmer switch up to the fans so that you can easily reduce/increase the speed at which the air is ventilated.

Light Timer: This is possibly the most essential piece of equipment, as the name suggests you need to set this up on your desired light cycle so that the lights turn on and off at the desired times, without one of these indoor grows are almost impossible. 

Step 6: DIY Grow Room

how to build a grow roomNow that you have decided the best space to use it is time to learn how to build a grow room. You need to prepare the space and get all of the things required to start the build. It can also help to have a grow room design drawn up before you start so that you don’t lose track of where everything goes. 

  • Staple Gun
  • Saw
  • Orca plastic (or other reflective wall covering)
  • A drill
  • Screws
  • Nails
  • Scissors
  • Wood (planks and ply/chipboard sheets)
  • Hammer

You want to start by measuring the dimensions of your grow space, from this you can work out approximately how much build material you require. For example, I have now measured the dimensions of my space and it will be 2 meters x 2 meters with a height of 7 feet. The grow will be placed in the corner of my spare room (see right) and therefore I need to partition it off from the rest of the room by building the two other walls. I have worked out that I need approximately 8 lengths of wood that are 7 feet long, these will be the vertical studs and corner. I will also need 7 lengths of wood that are 2 meters in length for the horizontal top and bottom plates (see diagram below). I am going to use 2 x 4 pieces of wood, these are pretty standard for any type of internal wall building.

Simple Step by Step grow room design:

  1. grow room designLocate and mark out the area of the walls
  2. Attach the top plate to your ceiling using screws.
  3. Use a plum line to position the bottom plate directly below the top plate and nail it to the floor (before you do this be sure to leave room for a door/walkway if you plan on installing one).
  4. Install your vertical wall studs between the top and bottom plates evenly so that they will be able to support the ply boarding.
  5. Nail or screw the ply board to the studs for the wall (make sure you do this for the inside, the outside is not 100% necessary)
  6. Now that the physical structure is in place you need to staple your Orca plastic sheeting to the inside walls of the room to make sure that there are no light leaks.
  7. Finally you need to install 2-3 top beams that will run horizontally across the top of your room (see above image) between two of the walls. These will be used to hang lights and a carbon filter so need to be secured well enough to be able to take the weight of these. 

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