need help to build a underground grow room

Well its not just a lump of concrete underground.. its a big ass lump.

Burn the house down?

Hey do what you want. Where i am though, hes prolly gonna make sure the foundation is alright after he puts a few holes in your chest

foundation ?

its not under the house lol
its at the end of the garden where I cleared
loads of weeds and broken up concreat

would never dig under somones house


yer a few loft grows when wrong round my area and court fire

Although a septic tank is a grand scheme, you'll have to pull permits if it was "legit". The wrong person see whats going on with the equipment and a tank then you'll have inspectors knocking on your door.

justugh said:

ohhh this is fun been awhile since i got one of these

first thing .......u are going to hate it but it is the truth .......u need at least 6 feet of soil over the roof ( 6 feet of dirt is the minimal requirement to hide the smell ) it is why bodies are buried 6 feet or deeper animals can smell it and could dig it up

the next with out renting a back hoe to dig this u are looking at some real work ........and by yourself months (it would be smarter to rent the gear get the hole done and then start the walls)

as for the walls and all the floor concrete will work ( rem to seal it ) but the walls u would be better off using cinder block ( in the concrete floor use rebar sticking up ) u stack the cinder block with the rebar in the center then pour concrete tho the holes on the cinder block filling it in incasing the rebar making it one solid wall

then your walls are going to need to be sealed from the inside

Click to expand...

I wouldn't use cinder blocks. Rebar reinforced poured wall is the way to go its more durable.

My opinion, I'd get a shed about twice the size of your grow make a "tent" inside for the actual grow for one to "insulate" the heat and two make it where you can actually store your yard stuff, kinda make it look like its functional from the front

If I saw a neighbor digging something like that and it wasn't an actual home improvement I'd be super suspicious.. that's just me tho.

Good luck!
Keep us posted

FlyBySoHigh said:

My opinion, I'd get a shed about twice the size of your grow make a "tent" inside for the actual grow for one to "insulate" the heat and two make it where you can actually store your yard stuff, kinda make it look like its functional from the front

If I saw a neighbor digging something like that and it wasn't an actual home improvement I'd be super suspicious.. that's just me tho.

Good luck!
Keep us posted

Click to expand...

thats the good thing I am on a corner, so only one neighbours can looks over the garden and hes always out

never seen him in the back garden

at the end of the garden there is wall that drops 5ft and alleyway by the side of the house, so there no windows and they can't look in the garden

going to keep a good 5ft gap between the wall and my room as I don't want the wall falling down and as the drops 5 ft I can go down 5 more, so there's going to be a 5ft drop 11ft from
the side of building to my grow room

can't see that being a problem.

a shed is a great ideal, may put one up over my room, so I can dig it out, the entrance to my room is going to be in a large green house so it looks like I check and water the plants every night

I guess I didn't catch the greenhouse over top part, that's freaking brilliant tho!
As for your under-bunker, presuming your water table is nowhere to be found you'll be fine with concert slab and rebar for floors and ceiling. I'd go with the celuar block reinforced with rebar "L'd" an tied in the floor rebar and long enough to lock in the ceiling web, literally enough for every cell. I'd even plant two 8"+ PVC pipes opposite corners in my ceiling of my "bunker" one for fresh air in and power/water and the other for an air scrubber or such for smell. All that could easily be hidden in your green house above.

Now, far as construction.
Mixing that much concrete by hand or even in a rented electric drum mixer fast enough to pour a quality slab is nearly impossible and will laterally beat you down physically and mentally, even if you had a buddy you could trust helping

Consider calling a cement truck when time comes for floor slab, filling the cells and ceiling. People get nosey and start asking questions tell them its a fallout/doomsday shelter, shits pretty common now a days.

Laying block is super easy and could possibly be done in a weekend given you could handle it physically and had proper scaffolding built.

Building the green house is pretty straight forward.

You'll want to pull power out there on its own breaker and depending on what your requirements are possibly even separate panel. That is something you'll want an electrician for. Super dangerous geting into power like that.

That being said.

I am a licenced contractor in the united states, have been for going on 7 years.

Buy me a plane ticket, cover the hotel cost and material cost, pay me by the hour and I'll have you ready to "move in" in three weeks.

Pay me cash and we'll never have to know each others names.

Love the crazy idea OP! I am going to keep an eye on this thread and watch your progress. Please post pics!

Personally, I think the shed idea is a great one. You also might consider a wood privacy fence to shield your yard activities from the neighbors. Consider leaving the top of the bunker plain concrete and make it look like a shed floor. Obviously this adventure is gonna cost you $$$$$$. So, take that extra step.

Love it man. Subbed.

Love the way you're thinking. The only worry is nosy neighbours or buildings control popping round if things start looking a bit to construction-y. Maybe say you're building a swimming pool lol.

FlyBySoHigh said:

I guess I didn't catch the greenhouse over top part, that's freaking brilliant tho!
As for your under-bunker, presuming your water table is nowhere to be found you'll be fine with concert slab and rebar for floors and ceiling. I'd go with the celuar block reinforced with rebar "L'd" an tied in the floor rebar and long enough to lock in the ceiling web, literally enough for every cell. I'd even plant two 8"+ PVC pipes opposite corners in my ceiling of my "bunker" one for fresh air in and power/water and the other for an air scrubber or such for smell. All that could easily be hidden in your green house above.

Now, far as construction.
Mixing that much concrete by hand or even in a rented electric drum mixer fast enough to pour a quality slab is nearly impossible and will laterally beat you down physically and mentally, even if you had a buddy you could trust helping

Consider calling a cement truck when time comes for floor slab, filling the cells and ceiling. People get nosey and start asking questions tell them its a fallout/doomsday shelter, shits pretty common now a days.

Laying block is super easy and could possibly be done in a weekend given you could handle it physically and had proper scaffolding built.

Building the green house is pretty straight forward.

You'll want to pull power out there on its own breaker and depending on what your requirements are possibly even separate panel. That is something you'll want an electrician for. Super dangerous geting into power like that.

That being said.

I am a licenced contractor in the united states, have been for going on 7 years.

Buy me a plane ticket, cover the hotel cost and material cost, pay me by the hour and I'll have you ready to "move in" in three weeks.

Pay me cash and we'll never have to know each others names.

Click to expand...

was going to buy ready mixed bags of concrete and do in stages making lots giant slabs instead of the hole room in one go
I am sure this would be very strong and I could handle this myself
still thinking about laying blocks Laying block or making the wall with concrete not sure yet

the green house is already up with plants in

with electric I am lucky, not sure why but the electric all sorted, there a thick main cable from my fuse box to the end of the garden, 20 amps at 230v that's 4.6 kw, have no ideal why he set this up

thanks for the offer but I am going to carry on thinking about this over the next few mouths

working on a new design to cut down the space but in a way I can see have 4X 600w lights on the go









this would save me a lot of work and money

first idea

room size (3m * 2.4 * 2.4) = 17 m2

soil needed to be removed (3.3* 2.7 * 2.7) = 24 m2


side walls 2.4m * 3m * 0.15m = 1.08 x 2 = 2.16 m2

end walls 2.4 * 2.70 * 0.15) = 0.97 x 2 = 1.94 m2

ceiling /base 3.3m * 2.7m * 0.2 = 1.78 X 2 = 3.56 m2

total concrete needed 7.66m2



second ideal

room size (3.2m x 2m x 1.7m) = 10.88 m2 soil

soil needed to be removed 3.5 x 2.3 x 2 = 16.1 m2 soil

side walls 2.25m x 1.7m x 0.125m = 0.478m x2 = 0.956

end walls 3.2m x 1.7m x 0.125 m = 0.68m x2 = 1.36

ceiling 3.45m x 2.25m x 0.15m = 1.16m
base 3.45m x 2.25m x 0.1m = 0.77m

total concrete needed 4.246 m2

thanks for reading what do you think

GrowUrOwnDank said:

Love the crazy idea OP! I am going to keep an eye on this thread and watch your progress. Please post pics!

Personally, I think the shed idea is a great one. You also might consider a wood privacy fence to shield your yard activities from the neighbors. Consider leaving the top of the bunker plain concrete and make it look like a shed floor. Obviously this adventure is gonna cost you $$$$$$. So, take that extra step.

Love it man. Subbed.

Click to expand...

thanks man some good ideal there, I am going spend a lot of time planning this to get it right and then I will start the work and put lots of pics up

beepotron said:

Love the way you're thinking. The only worry is nosy neighbours or buildings control popping round if things start looking a bit to construction-y. Maybe say you're building a swimming pool lol.

Click to expand...

if they start asking question, I have that covered, I had some ivy in the back of my garden and it what 20ft high and 15ft thick, I asked the landlord if I could remove it, it did a lot of damage to the shed and broke the concrete patio up , so I would say to them as I removed the ivy and it broke the patio up, I have replaced it as I did the damage with a thick soil patio base to stop any further damage

should do the trick, but its better if they don't ask questions

Having power already available is amazing.

Me personally, I'd go for the bigger plan. You'll appreciate it in the long run, yeah cost a lil more and takes a little more time. Well worth it..

All I'm working with is a garden tub in a master bathroom 7'L x 4'w x 8' t.. on the last leg of a super lemon haze now.. about 4-6 days I think.. litteraly watching the glands change over from clear to milky

You could use up a large part of the discard soil for planters around the house as well.

Breaking the slabs down into a manageable size is a good plan to minimize work load, but don't skimp on your "footer" slab with the wall rebar in it your wall are gonna be supporting a lot of weight that rebar alone won't distribute right and eventually, break down.

jacks, you know we're all coming over to see this thing (and smoke some bud), don't you?
Just be freakin careful man, neighbors know more than you think. They many not ask you anything directly, but gossip spreads at the speed of light sometimes. Just throwin' that out there, you know them better than we do.

FlyBySoHigh said:

Having power already available is amazing.

Me personally, I'd go for the bigger plan. You'll appreciate it in the long run, yeah cost a lil more and takes a little more time. Well worth it..

All I'm working with is a garden tub in a master bathroom 7'L x 4'w x 8' t.. on the last leg of a super lemon haze now.. about 4-6 days I think.. litteraly watching the glands change over from clear to milky

You could use up a large part of the discard soil for planters around the house as well.

Breaking the slabs down into a manageable size is a good plan to minimize work load, but don't skimp on your "footer" slab with the wall rebar in it your wall are gonna be supporting a lot of weight that rebar alone won't distribute right and eventually, break down.

Click to expand...

yer going to stick with the bigger room


super lemon haze is a great strain I rember growing that a few years back when it first cam out, but the flowering times was all over the place I had one plant that was done in 8 weeks from 12/12 and another took 12 weeks out the same pack, I took cutting and settled on a 9 weeker, large yield and a strong but mellow smoke, only problem I found with the strain over time it when Hermie,

took cutting from cuttings and about the 4-5 lot it would turn, it happened on two packs of seeds

how thick would you make the footer slab to be on the safe side ?

Lo Budget said:

jacks, you know we're all coming over to see this thing (and smoke some bud), don't you?
Just be freakin careful man, neighbors know more than you think. They many not ask you anything directly, but gossip spreads at the speed of light sometimes. Just throwin' that out there, you know them better than we do.

Click to expand...

I total agree with you fellow and that's why i am taking my time to get it right before I start work

jacksthc said:

yer going to stick with the bigger room


super lemon haze is a great strain I rember growing that a few years back when it first cam out, but the flowering times was all over the place I had one plant that was done in 8 weeks from 12/12 and another took 12 weeks out the same pack, I took cutting and settled on a 9 weeker, large yield and a strong but mellow smoke, only problem I found with the strain over time it when Hermie,

took cutting from cuttings and about the 4-5 lot it would turn, it happened on two packs of seeds

how thick would you make the footer slab to be on the safe side ?

Click to expand...

At least 16" wide and 1' deep if your soil is "loose or wet" you'll be safer in the long run with thicker

My lemon haze: germed two, both showed super vigorous early veg. I topped one twice and lst'd it, it loved it and actually finished a couple days after the LH that I didn't do anything to. That had about a 10" tall 3" across main cola.. that was under A.H. 300w cob and 4 - 150w full-spec CFL's.. can't wait to go full oblast super excited to smoke.. waiting on it to dry now . Gonna try an Ak48 when I get my room perfected

cheers fellow i

FlyBySoHigh said:

At least 16" wide and 1' deep if your soil is "loose or wet" you'll be safer in the long run with thicker

My lemon haze: germed two, both showed super vigorous early veg. I topped one twice and lst'd it, it loved it and actually finished a couple days after the LH that I didn't do anything to. That had about a 10" tall 3" across main cola.. that was under A.H. 300w cob and 4 - 150w full-spec CFL's.. can't wait to go full oblast super excited to smoke.. waiting on it to dry now . Gonna try an Ak48 when I get my room perfected

Click to expand...

that makes a lot of sense, 16" wide and 1' deep

so a 4" deep footing, 16" wide and 1" inch deep base should do the trick

been looking at re bar videos

there saying the strength is in the re bar not the concrete, so could i use 5" thick concrete for the walls and the roof as long as i have used re bar in the right places

ak48 sounds great fellow, good knock out stone

Hey mate check my profile out you'll see my underground room every bit done by hand if you need any advice giz a shout