View Full Version : Preping Fish Room Walls

12/14/2016, 11:18 AM
So I am in the process of setting up a 475ish reef tank. The tank was custom built by AGE and is a beast of a tank. I am still on hold for setting it up because I am not done with the fish room yet. I have a few questions to keep the project going. First the room is ~250 square feet. Two walls are internal walls that are insulated with R13 insulation. The other two walls are external basement walls that are part cement and part framing. I kept the existing insulation in place whish is R19 in the 2x6 walls and the pink fiberglass secured to the cement portion. Over this I put R30 faced insulation to help with insulation. My questions comes in how to finish those walls and the ceiling.
1. As of right now I plan to use vapor barrier but I started to think about this. The electrical in the external walls do not have vapor tight gang boxes. Would this be a problem with humid air making it through and then condensing somewhere in the wall cavity and causing mold issues. Should I seal the boxes with caulk (inside perforated holes). I was able to get a good tape seal around the parameter of the box. If this is going to be an issue should I just not use vapor barrier and cover the walls with green board.

2. Will vapor barrier be enough or should I drywall and possibly FRP the walls as well to help with water resistance.

3. Should I vapor barrier the ceiling to seal up the room if I don't put drywall up?

I guess I just want some ideas or examples of what people have done to help seal their fish room.

Additionally will likely be using a room vent and a dehumidifier to deal with humidity.

My house is 6 months old so I need to take precautions to help protect my home.

Thanks in advance.


12/14/2016, 01:01 PM
Having proper automated venting in the fish room is the single most significant step you can take to protect your home from excessive humidity. Depending on how big a difference there is in the temperature you keep the fish room at versus the temperature you keep your tank and sump at you may want to consider some sort of covering on your water vessels to reduce evaporation while not interfering too much with gas exchange.

If you are concerned about your electrical boxes you can always change them out for plastic ones. Be sure to insulate and install vapour barrier around the outside of the boxes.

Most people go with vapour barrier and water resistant wall/gypsum board. Make sure you do at least two layers of paint to waterproof the walls and ceiling. I like the enamel floor coverings available for basements and garages, but if you want you can go with tile, also. Fibre reinforced plastic (FRP) is really expensive. I don't know too many people who can afford to do a whole room in it. If you can, congrats.


12/14/2016, 02:21 PM
So I looked everywhere to get the vapor boxes to go behind the gang boxes and couldn't find them. What I did was vapor barrier up to the gang box and did a good tape job around the box. I also used foam to seal the wire at the inlet. This still leaves several holes where vapor can get through. My options are to fill them from the back or caulk from the inside to seal them up. Do you think this would be sufficient?

Planed on green board for the entire basement with a good paint as you recommended. For the FRP that would only be used in "splash zones" that are at high risk of continuous splash. I am putting a lot of thought into the plumbing to avoid splash anywhere in the system but I know I will get splashes somewhere.

12/14/2016, 02:25 PM
Also for the vent that is a must and I am going to have a construction friend do that for me. My biggest concern there is negative pressure and CO from the furnace. My fresh gas intake for the furnace is in the utility room just next to my fish room. I don't want the negative pressure in that room being transferred to that pipe and pulling CO back into the house. May need to invest in moving the fresh gas intake outside as well.

12/14/2016, 02:30 PM
The fresh air inlet for the furnace should be coming from outside, not in the house, and preferably via an air-to-air heat exchanger if you're in a cold climate. If you're doing one outdoor vent you may as well do two at the same time.


12/14/2016, 02:32 PM
Unfortunately in Indiana it's common for the air for the furnace to just come from the house. It was extra during building to add it and I skipped. In hindsight should have added it then. Not sure I will create enough negative pressure but CO isn't something I wanna play around with.

12/19/2016, 04:11 PM
Use exhaust fans not a dehumidfier. Humidity will be your biggest enemy. I have a 400sq room i built on with pretty much the same insulation as you. It first was sweating from where the old roof met the new room because i didnt insulate my old roof inside all the way to the end where the new addition started so the cold air in the attic and warm humid room made a rain forest. In summer i just ran 2 window fans pulling out but when it gets cold i had to close the windows. I ended up with a tjerlund 2 fan ehaust setup and no longer have an issue. It was so bad in there before that my smoke detector started beeping one night and when i pulled it off the ceiling water ran out. I can get some pics of what it looked like before the fans when i getto my computer at home if you wanted to see

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12/23/2016, 03:56 PM
I would like to see pictures. At least I think, haha. May make me too nervous to fill the tank. I have a friend that is going to install the vent fan for me to help with the humidity. Thanks for the input.

12/27/2016, 07:51 PM
I used a whole house heat recovery ventilator. Nothing in the room yet but the humidity in the basement is the same as outdoor and the basement smells fresh. Can already tell a major improvement from last year.

I got a Honeywell hrv and it's dual fans make balancing the unit easy. Took less than a minute to balance.

I used drywall, 2 coats of primer, and 2 layers of premium semi gloss enamel. Did the floors in linoleum. Commercial wall base. Siliconed top and bottom of the wallbase. Accidentally tested the water resistance and it worked great. I plan on using frp for back splashes.