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View Full Version : I want to finish my basement, where does vapor barrier go?



pOrk
01-18-2012, 11:07 AM
I've read it either goes against the concrete walls of the basement and I've also read it goes directly behind the drywall, which is it? Another suggestion I saw was to not use a moisture barrier at all, and to use foam board insulation because it also acts as a moisture barrier. If thats the case, do I use this against the basement walls and build the 2x4 wall after the board is up? One side of my basement has 2x3 metal beams to support the wall, so how do I get around this as well? Do I frame inside of each beam or do I build a wall infront of the beams? My basement is long and narrow so I'd like to use as much space as possible.

My basement walls do condensate a bit in spring time hence why I want to make sure I get this right. Working 2nd shift has me BORED as hell during the morning and I need to do something productive. Anybody else want to help? Haha.

Half of my basement is already finished, I want to frame up insulate and drywall the otherside. Any tips / pointers would be great, been googling all morning and seems like everyone does it differently and its hard to find the RIGHT way vs the other way.

88Nightmare
01-18-2012, 11:12 AM
I could give you a hand. What I did in my mothers basement was paint the walls and floor with a moisture blocking paint.

88Nightmare
01-18-2012, 11:25 AM
If I were to do it over again, I think I would do the paint, then extruded polystyrene foam board up against the block, then frame the wall, and then install the fiberglass insulation (R12). I believe code requires a vapor barrier installed in between the studs and drywall though.

77thor
01-18-2012, 01:38 PM
Moisture barriers always go on the back of the WARM side(e.g. the drywall).

jbiscuit
01-18-2012, 01:45 PM
^ This. Bleach the wall, then Drylok. Then frame the wall. Then choose your insulation: foam sheet or fiberglass. I used foam in my basement at the old house. Worked great. PL200 the sheet to the wall openings between the studs. Then vapor barrier. Then drywall. I would lay down a strip of foamor plastic under your sole plate or float the sole plate 1/8" off the floor in case of wetness. Some people recommend using a treated 2x4 sole. If you get dampness, make sure you do everything you can to get that wall dry and clean! Otherwise you WILL get mold

WickedSix
01-18-2012, 03:34 PM
http://www.nlcpr.com/BasementInsulation.pdf


taped foam insulation-->framing->insulation->loosely fitted vapor barrier->drywall

Lash
01-18-2012, 05:14 PM
I believe it's code to use treated lumber for the bottom plate in a basement.

05caddyext
01-18-2012, 08:20 PM
I did a lot of research before finishing my basement. More often than not people said not to use foam. The problem with it is that if you do get any moisture behind it, youll never know it, and never get it dry. If you are going to use foam, do not just put it between the studs, put it behind the studs and make sure to tape all the seams with foamboard sealing tape, it's red. When I did my basement, which seems to be very dry, I used the insulation that is actually encased in plastic. It's fiberglass insulation, but it isn't kraft faced, it's actually wrapped on all sides with plastic. The walls were already painted with drylok, so I just studded right up against them. I then put up a regular 4mil plastic vapor barrior over the top of the studs, so I have a double layer of protection. The biggest thing to remember is to have a plan before you start. Put in plenty of outlets, and run whatever other stuff you think you may ever use before you finish the walls. I ran monster speaker wire to do a 7.1 set-up. I also ran ethernet to 3 different locations. I realize everyone uses wireless but why not just have it there? Stuff was .17 a foot. Do you run a dehumidifier in the summer? If so, how often do you empty it, or do you have it run to a drain? If it goes to a drain, run it with a bucket for a while and see how often you have to empty it. This will give a good idea of how wet the basement actually is. You said that you have some condensate on the walls that you can actually see in the summer... This is a concern. Find the cause, or don't finish the walls, you will regret it later. If you aren't positive it's going to stay dry, don't waste your time and money going forward with it. I would absolutely not use the foamboard on the walls if you have seen condensate. You will get condensate on the walls behind the foam, and it will all run down to the floor where your carpet or whatever else is on the floor will soak it right up. Also, what's your plan for a ceiling? Make sure if you plan on drywalling that you don't hide junction boxes or shut-off valves up there, you need access. And lastly, make a budget and stick to it. Projects like this can get expensive real quick if you don't plan.

05caddyext
01-18-2012, 08:21 PM
The best thing to do would be to stud the walls, run your electrical, and then have someone come in that does spray foam. Costs a butt-load more than any other insulation, but it's 10x more effective. Had I done this all over again, i'd do that in a heartbeat.

05caddyext
01-18-2012, 08:22 PM
Post up some pics of what it looks like now, including the beams that are there, I'd like to see what you have to work with.

CATNHAT
01-18-2012, 08:56 PM
My basement walls do condensate a bit in spring time hence why I want to make sure I get this right. Working 2nd shift has me BORED as hell during the morning and I need to do something productive. Anybody else want to help? Haha.



HMMMM.... If only some wings and beer were paid up for on the other freebies..................

Vapor barrier ONLY on conditioned side of stud AT ABOVE GRADE CONDITIONS!

Always use treated lumber when in contact with concrete. You may experience diminishing returns with rigid foam, stud, R-13, drywall scenario. heat loss calcs will determine this. R13 batt actually only good for about R11 due to compression.

PL200 is caustic to rigid insulation (extruded polystyrene) and does more harm than good so dont do that. Mechanically fasten rigid insulation to your foundation.

20% of your energy losses are in your in your box sill and spray foam (icynene) is the best solution here. i believe you had regular fibergalss insulation here.

Will the HVAC be zoned?

There are literally thousands of things that need to be considered prior to starting this project. If your going to do it, do it right.

UnderPSI
01-20-2012, 07:28 PM
I wouldn't use drylock, you want your block to breath. The last thing you want to do is trap water in your block and have it freeze.