"Fix" wet-basement grow room, or move to attic?

Question: Should I keep my grow room (veg + bloom) in the basement and fight the mildew, or move it to the attic, where temp fluctuates, but it's dry?

Background: In December, I was losing the battle against mildew and called the basement grow quits for a while. It's so wet down there that the water I left standing six months ago never evaporated. My set-up was a bit haphazard: I did not have a sufficient barrier against moisture from the fieldstone wall; and the air I brought in was the wet air from the basement itself. I doubt my exhaust was pulling well enough either.

Here are pictures of (1) mildew/mold on the back wall after a couple days without the dehumidifier; (2) the field-stone the basement is built out of, right behind the grow room's back wall; and (3) the water that hadn't evaporated over 6 months:



So it is time either to move to the attic, or to shore up the basement grow.

The Basement
I'm trying to fit veg + bloom inside this space. This is my more cramped and wet alternative: The basement is field-stone, not cement, so humidity, mold, and mildew are a constant battle. The room sits on a 3/4" lift so it will ride on top of the regular floods. But maybe I can tighten this up right.

• Dimensions: 7' 1-3/8" x 4' 8-1/2" height: 6' 5-1/2".
• Relative humidity: ~80% without dehumidifier.
• Insulation: 1" fiberglass (made from low-R-value drop-ceiling panels). Perhaps I would re-insulate with R-19 rolls?
• Ducting: I should probably add exhaust ducting for the heat from the 400W HPS bulb.
• Air: I just have a 4" duct-fan bringing air in from the basement (plus passive intake), and a homemade carbon filter attached to a 6" duct fan evacuating air from the grow room. I should probably get new fans(?), a good filter(?), and duct nice air from the house into my veg. side, then pull it over to bloom(?).
• Heat/cool: I am not sure I will have to add A/C once the HPS lamp-heat is vented out; but I will probably have to use a heater in the winter (it's "Vermont-cold" here; but perhaps I could mitigate this by ducting in some house air).
• Electric: I have a dedicated 20-amp circuit.
• Water: I have a spigot, but no drain.
• Door: I am not sure how to build a door for this (I was using a zipper-door). Do I need two doors, to form an "airlock" that keeps basement air out of the grow room? Or would that be too neurotic?

The Attic
This is my more spacious and expensive alternative: Unlike the basement, I have not implemented any of it. Although moisture is not a problem up here, temperature fluctuations are.

• Dimensions: I can carve out a 7'9" wide space, 40' high at the edges and 6'5" at the peak. I'm working inside of a 25' corridor; I was thinking of using between 10 and 16 feet of it.
• Insulation: I'll certainly have to insulate (probably R-19 rolls).
• Heat/cool: I'd need A/C in summer (the temp. probably ranges from 65 degrees Fahrenheit on cool nights to 120 on hot days), and a heater in winter (it's "Vermont-cold"; but I could duct-up some house air to mitigate that a bit).
• I can get a dedicated circuit up there, and - with the help of a friend - water + a drain.

My inclination: I am inclining toward the basement at this point (although I hate the battle with mildew and I'd like the extra elbow room available in the attic). But there's a lot of infrastructure already built in the basement, and I could try properly sealing it before abandoning the attempt.

What do you think?: What's my best bet?

By the way, if you have suggestions about air movement, it might help to know:

I think the room is 216.340 cubic feet (the dimensions, in feet: 7.114 x 4.708 x 6.458).

If you cannot resolve the moisture issue in the basement, move to attic until you can resolve the basement issues, mold and water fungi are not going to breathe or smoke, even if you don't see any on the plants do you really want to risk it?

with the probs ypu describe in the basement

personaly, I'd go to the attic, more room is always a plus
heat from the bulbs can offset AC usage in the winter.
trying to seal an old stonewall from moisture intrusion can be a major pita,
no matter what you do in the basement there's a good chance you'll need to run a large commercial dehuey 24/7

Isn't getting your basement drier something you need to do for structural or health reasons?

But if its maxing out at 80% that's not terrible. Improve air movement with more fans, and get the wall sealed up. If its over 75%, then I might throw an exhaust fan somewhere and get that air outside on a regular basis


That was weird. There's thebchart I was talking about.

Thanks for the feedback.

I'm going to shore up the basement room, and then if necessary, move up to the attic. I'm hopeful about setting-up like this, bringing nice air from the house:
(from http://dudegrows.com/grow-room-set-101-thecapn/)

Where's intake air coming from? What's the temp air going in? Looks good.

Good question, Sovereign! I'll pull air in from a living room; but I didn't notice that it's not shown here.

Good news: I found a grow space for veg. in the eaves.


I'll tighten up the basement grow room and use it for bloom (simplifying airflow), and clone/veg. up in the eaves, for which I'll insulate.

Nice. Thanks all.

upgrade airflow and keep dehumidifyer running ..atleast basement temps are stable usually .. attic grow have huge temp swings unless really insulated ....been there done that a few times.i have had to triple insulate attics before.foam inserts,pink panther,black plastic,reflectix/tek foil farmtek....yeehaw..my basement grows have always been been better than attic grows..my last basement grow my reservoir was in my bedroom closet upstairs..gravity took it down ..no pump..