I am planning to finish my basement this winter and include a theater area but it won't be a dedicated theater room. My cousin who has some experience in construction has now scared my wife to death about mold after we put drywall up. The house is only 4 years old.

My question is, if I give in to my wife's hysterics, how would sound quality be affected if I didn't drywall the exterior walls and painted them? Is there anything I can do to the walls, such as acoustical tile or whatever, that would help? Or would that not really help with the mold concern as the wall would still be covered?

This is my wife freaking out about this so this is more to ease her mind. Our basement is very dry and has flooded only once, and that was because the rainfall was so fast that the city's storm sewer was full and thus the sump pump couldn't pump it anywhere. It wasn't a fault of our house. We plan to get a second pump that would pump water into the back yard. Theoretically that should keep that from happening again.

Thanks,
Karl

I am planning to finish my basement this winter and include a theater area but it won't be a dedicated theater room. My cousin who has some experience in construction has now scared my wife to death about mold after we put drywall up. The house is only 4 years old.

My question is, if I give in to my wife's hysterics, how would sound quality be affected if I didn't drywall the exterior walls and painted them? Is there anything I can do to the walls, such as acoustical tile or whatever, that would help? Or would that not really help with the mold concern as the wall would still be covered?

This is my wife freaking out about this so this is more to ease her mind. Our basement is very dry and has flooded only once, and that was because the rainfall was so fast that the city's storm sewer was full and thus the sump pump couldn't pump it anywhere. It wasn't a fault of our house. We plan to get a second pump that would pump water into the back yard. Theoretically that should keep that from happening again.

Thanks,
Karl

Hey Karl welcome to the board i am sure you will find answers to all your questions here as there are some very knowledgeable folks on the board. To answer your question what i am going to do on my exterior wall is apply 2 coats of drylok, then i am going to use that 1" blue styrofoam insulation and glue that right to the block, then i will build my stud wall and leave about a 1" gap between the wall and the foam insulation as an air gap and then i will fill the cavities with R13 insulation i think by leaving the gap all will be fine as far as mold is concerned. The other thing you can do is buy that dens armor which is a paperless drywall you can purchase this stuff at lowes here is a link to their site. http://www.gp.com/build/stopfeedingmold/default.html

hope this helps

Welcome to the forum!

I'm also very paranoid when it comes to mold in the basement.

Basement moisture is not only an issue with rain/flood water, but with condensation as well-- that is, moisture in the air (think warm, humid summer air) coming into contact with cool basement walls and floor. When the floor and walls aren't covered, this moisture can re-evaporate (i.e., dry) and you don't have a problem. However, when you cover the walls and floor without any sort of vapor barrier/retarder, humidity in the air can condense and not have sufficient space to dry, creating a better environment for mold growth.

The best thing you can do is to insulate the outside of your basement walls. However, this is difficult and expensive to do in a retrofit.

The next best thing is to spray closed-cell foam insulation on the basement walls, or by gluing extruded (not expanded) polystyrene (styrofoam) on the walls. You then build conventional un-insulated walls next to the insulated outside walls.

The next best thing to that is building a conventional insulated wall leaving an air gap next to the outside wall. A vapor barrier goes on the room side of the insulated wall.

For the floor, do not put carpeting directly over the concrete-- moisture in the air will condense in the carpeting, creating a better environment for mold. Use a product like Dricore (there is also a completely plastic product that is similar to Dricore, but I forget the name) to leave an airgap between the floor and carpet.

Never put a vapor barrier directly against the concrete-- this will trap moisture. You want the concrete to be able to breathe, so that if (i.e., when) it becomes wet/moist, it can dry.

Running a dehumidifier in the unfinished part of the basement will also help to prevent mold.

I used the paperless drywall for the walls in my basement build. It's about twice as heavy as regular drywall and cost about $2/sheet extra. It dimples differently; it's much easier to drive a screw all the way through the backing, so you have to be careful when hanging it. Because of the weight, and fragility of the backing, I wouldn't use it for a ceiling.

mold is an important and common topic of discussion. see the threads that showed up in that box when you entered the name for this thread:

http://www.avsforum.com/avs-vb/showthread.php?t=836272

http://www.avsforum.com/avs-vb/showthread.php?t=927404

http://www.avsforum.com/avs-vb/showthread.php?t=905226

Wow. Great stuff. Thanks guys.

I think my basement walls are insulated on the outside. I can see about 1" thick styrofoam or something or another peaking out past ground level at some points around the house. I assume this is insulation? Does this mean I don't have anything to worry about as far as the exterior walls go? Can I forgo the vapor barrier then? What about insulation on the inside? Will that still be needed? Drylok?

I've heard of dricore. I will also check into the paperless drywall.

Thanks,
Karl

Wow. Great stuff. Thanks guys.

I think my basement walls are insulated on the outside. I can see about 1" thick styrofoam or something or another peaking out past ground level at some points around the house. I assume this is insulation? Does this mean I don't have anything to worry about as far as the exterior walls go? Can I forgo the vapor barrier then? What about insulation on the inside? Will that still be needed? Drylok?

I've heard of dricore. I will also check into the paperless drywall.

Thanks,
Karl

I would not use a vapor barrier b/c as grey skies stated this will trap moisture. The drylok will help with moisture and condensation. i would still use some type of insulation on the inside like the spray foam or the blue styrofoam panels.

I used Certainteed MemBrain as a vapor barrier over unfaced batts in a steel stud wall. This is normally water impervious, but when humidity builds, allows moisture to pass through.

Another suggestion - steel studs.

db

All this talk of mold is starting to feak me out. Especially since my framing is all but done. Now granted I have a bone dry basement with well designed exterior drainage, but still I hadn't given condensation issues much thought up to now. My plan was to put up the foam board up between the joists, stuff the walls with unfaced R13 and run the dehumidifier year round.

All this talk about mold has me worried as well.

I didn't insulate my basement and the framing is about 1 inch away from the concrete wall, then sheet rocked. The ceiling is a suspended ceiling. I figured that with as much open areas between the walls and ceiling it would allow for air movement and mold wouldn't be an issue. My basement is dry as a bone (knock wood) and haven't had any mointure problems at all. I e ven did the moisture test by taping a piece of plastic to the basement floor to see if there was moisture in the basement. None.

All this talk about mold has me worried as well.


IIRC, I've heard of some mold due to groundwater seepage in Colorado, but that was also due to vapor barriers put directly against concrete. And with ambient humidity levels usually in the single digits there, I don't think you have to worry much about condensation. :)

All this talk of mold is starting to feak me out. Especially since my framing is all but done. Now granted I have a bone dry basement with well designed exterior drainage, but still I hadn't given condensation issues much thought up to now. My plan was to put up the foam board up between the joists, stuff the walls with unfaced R13 and run the dehumidifier year round.

All this talk about mold has me worried as well.

I didn't insulate my basement and the framing is about 1 inch away from the concrete wall, then sheet rocked. The ceiling is a suspended ceiling. I figured that with as much open areas between the walls and ceiling it would allow for air movement and mold wouldn't be an issue. My basement is dry as a bone (knock wood) and haven't had any mointure problems at all. I e ven did the moisture test by taping a piece of plastic to the basement floor to see if there was moisture in the basement. None.



I think the main thing is not use a vapor barrier that can trap moisture --allowing water to dry rather than be trapped by the vapor barrier.

a secondary strategy (and less important) is putting foam boards against the foundation which allows incoming moisture to pass as vapor through the board and is also helpful in preventing water vapor in the interior air of the basement from condensing on the cold foundation wall. (The foam board maintains a higher temp above the dew point -- or something like that).

As for foam board in the joists: I think the area in between joists is more of a sound isolation issue than a vapor/mold issue. I was planning for mineral wool btw the joists for better sound isolation.

(or do you mean in between the joists around only the perimeter of the basement? -- in the "band joist" or "rim joist" area? For that I had Draft Stop in Chantilly use spray foam in that area and that worked great. It wasn't too expensive at only $700 for the whole basement. Or you can do it yourself with the spray foam kits from efi.org (have to login to the commercial side of it to see the spray foam in the big canisters for doing a whole basement)

Also see: http://www.taunton.com/finehomebuilding/PDF/Free/021189072.pdf
http://img.photobucket.com/albums/v613/Kevin_5/Home%20Theater/3850374a.jpg

Like this from the Gingko thread:

Has anyone used ovrx instead of dricore?

As for foam board in the joists: I think the area in between joists is more of a sound isolation issue than a vapor/mold issue. I was planning for mineral wool btw the joists for better sound isolation.

(or do you mean in between the joists around only the perimeter of the basement? -- in the "band joist" or "rim joist" area? For that I had Draft Stop in Chantilly use spray foam in that area and that worked great. It wasn't too expensive at only $700 for the whole basement. Or you can do it yourself with the spray foam kits from efi.org (have to login to the commercial side of it to see the spray foam in the big canisters for doing a whole basement)



Actually I'm an idiot. I meant to say that I was going to put the foam board as the first layer against the cement in the WALL cavities. For the ceil joist cavities I will use mineral wool.

I have fire blocking rated foam sealer that I'll squirt in the rim joist area for the non-theater part of the construction. No clue how far the few cans I bought will go. In the theater it will be more likely be just mineral wool.

As far as vapor barrier goes, you have a cold concrete block wall, and you have a warm room. The only thing that separates them is drywall and some insulation, you need a vapor barrier between these two temperature extremes. You can do it one of several ways.

#1 - Frame out a 2x4 wall and fill it with batt insulation that has a kraft paper vapor barrier on it and cover that with drywall.

#2 - Frame out a 2x4 wall and fill it with batt insulation that doesn't have a vapor barrier, then cover that with a 6 mil plastic barrier and then cover that with drywall.

#3 - Frame out a 2x4 wall and shoot the insulating foam from the rim joist to the floor, this will insulate and act as your vapor barrier. Cover with drywall.

And as others have said, you can get paperless drywall or at least get the green board drywall that resists mold. Mold has to have something to grow on, so make sure you use pressure treated wood for any wood that touches the floor. Of course you could go with metal studs and paperless drywall, that would mean mold would have nowhere to grow.

And make sure you sweep up your construction debris. Mold can grow on it if it's left in the walls.

As far as vapor barrier goes, you have a cold concrete block wall, and you have a warm room. The only thing that separates them is drywall and some insulation, you need a vapor barrier between these two temperature extremes.

#1 - Frame out a 2x4 wall and fill it with batt insulation that has a kraft paper vapor barrier on it and cover that with drywall.

#2 - Frame out a 2x4 wall and fill it with batt insulation that doesn't have a vapor barrier, then cover that with a 6 mil plastic barrier and then cover that with drywall.

These are both recipes for mold.

see:

http://www.buildingscience.com/documents/primers/plonearticlemultipage.2006-12-05.5229931729/section-2-recommendations/ (very good!!)
http://www.buildingscience.com/documents/primers/plonearticlemultipage.2006-12-05.5229931729/section-2b-recommendations2014air ("One of the worst assemblies for basement walls from the perspective of mold and moisture problems is a foundation wall that is internally framed and insulated with fiberglass cavity insulation and covered with a plastic vapor barrier."
http://www.eere.energy.gov/buildings/building_america/pdfs/db/35398.pdf
http://www.eere.energy.gov/buildings/building_america/pdfs/db/35017.pdf
http://www.buildingscience.com/bsc/resources/foundations/Understanding_Foundations.pdf
http://www.buildingscience.com/bsc/resources/foundations/basement_insulation_systems.pdf
http://www.buildingfoundation.umn.edu/OCBasementSystem/ProjectReview.htm
http://ths.gardenweb.com/forums/load/basements/msg1013404110282.html?4
http://www.newsday.com/features/home/nyp-hsdr-082505,0,452831.column
http://www.housingzone.com/proremodeler/article/CA6358797.html
http://www.huduser.org/Publications/pdf/moisturehomes.pdf (p. 54, 84)
Fine Homebuilding No. 169 March 2005 p. 78
Fine Homebuilding No. 162, May 2004 p. 52
http://www.housingzone.com/topics/pr/build/pr04ca007.asp
http://www.housingzone.com/proremodeler/article/CA6404480.html
ICAA Technical Bulletin re vapor retarders "it is recommended that a vapor retarder not be used in a wall that is partially or fully below grade."]
http://www.buildingscienceseminars.com/2006/handouts/BSD-103_Understanding_Basements.pdf

#3 - Frame out a 2x4 wall and shoot the insulating foam from the rim joist to the floor, this will insulate and act as your vapor barrier. Cover with drywall.

Spray foam isn't a vapor barrier so this would be ok (but that much spray foam would be expensive -- foam boards are likely cheaper.)

My walls were preframed and pre-insulated when I moved in. I've looked at what they've done and its the concrete wall, a vapor barrier, the framing about an inch from the concrete with bat insulation and then another vapor barrier.

Currently, its still unfinished, but I'm starting electrical and will be starting to drywall fairly soon. From the articles linked above, it sounds like I should take the 2nd vapor barrier off before drywalling, is that correct?

Get rid of the vapor barrier that's against the concrete.

Guess I'll have to do some more reading. Didn't think the Bat insulation should be directly against the concrete and haven't budgeted for rigid insulation for the outside walls, plus, not really sure how I'd get it inbetween the studs and concrete wall except in pieces inside each stud cavity.

I went with the Buidling Sciences method: foam boards, studs, unfaced batts, drywall.

If you already have a 1 inch gap you could still get foam board in there. Use 1-inch foam board but you'll have to piece it in there to get inside the stud cavities. May want to seal the joints with tape since you will wind up with some non-tongue and groove joints.

It's money well spent to do it the right way as you only have one chance to do it.

Here is my scenario.

Cast in place concrete walls with fibreglass insulation to the frost line.
NOTE: The fibreglass insulation has a plastic vapour barrier. The walls are framed about an inch away fron the concrete walls.

Should I add more insulation and another layer of vapour barrier to the framed walls or should I just drywall the walls when I am ready?

By the way I live in an area with sandy soil and have had no water problems in the basement whatsoever. As always "knock on wood"

Any suggestions would be appreciated.

Eric

I recommend you take a look at post #16 above and check out the links. Zmist's 2nd link and quote pretty much sum up what you have, if I understand correctly.

Never use "double" vapor barriers. That traps moisure in the wall which is what you don't want.

Well, looked over the situation much closer and there isn't enough space to get the rigid foam inbetween the concrete and the framed wall. The frame is firmly against the concrete at the base and really only appears to have space in the middle of the framing.

Anyone have a good article on retro-fitting an external wall to prevent the mold problem?

Well, looked over the situation much closer and there isn't enough space to get the rigid foam inbetween the concrete and the framed wall. The frame is firmly against the concrete at the base and really only appears to have space in the middle of the framing.

Anyone have a good article on retro-fitting an external wall to prevent the mold problem?

You may want to look at the spray on foam solution.