Preventing fibergalss from getting wet ...

[howz]

I'm finishing my basement. I plan to build 2x4 walls with r12 fiberglass. I will place my 2x4 walls 2" out from the cement walls to create a 2" dead air space. I know I need to vapor barrier the side facing the interior of my home (between the drywall and the studs), but I'm thinking I should vapor barrier both sides. I'm concerned that the fiberglass could fall back or slouch and then sit up against the cement walls. This would create a breading ground for mold. Other than a little extra cost, is there any reason I shouldn't vapor barrier both side.

Thanks for the help ...

[Stevetra]

Well the main reason you don’t want to put up 2 vapor barriers is you will only be exchanging one problem for another.
The dead air space is to allow both the walls you build and the concrete to dissipate their moisture. Sure placing a vapor barrier on both sides will hold the insulation in place, but it will also trap any moisture that gets into the wall.

They make wires that sit between the studs to stop the insulation from falling in, I would suggest that. (I can’t remember the building term for them)
They are normally used under floor joist to hold the insulation up.

:coffee:

[Ed Imeduc]

In all homes we always hang a 6 mil poly from the sill plate down on the cement wall. like you said set wall out 1" . Use a R13 paper back insulation paperside to the room. Staple the paper lip just inside the studs so you dont have a bump in the wall. Then put a 4 mile poly over the studs then the drywall or panel. Have did this in many many homes even earth contact. Have been back to many and no trouble at all.

ED ;)

[howz]

In all homes we always hang a 6 mil poly from the sill plate down on the cement wall. ED ;)

What is the purpose of doing this ???

[Ed Imeduc]

This stops any water pesay or humidity from the cement wall from going into the insulation. Dont forget the bottom plate has to be P/T wood. also make sure you put a piece of R19 insulation up tight in each joist space there on the sill plate. Been doing it this way for 30 years.

ED ;)

[jas_usn]

Ed,

My unfinished basement has insulation from the main floor joists half way down the cement walls. It is in direct contact with the cement and covered with a foil type sheet connected with button like fasteners. I just purchased the home and not sure how long it's been there. If I finish the basement, do you recommend getting rid of this and going with your previous method above or is there a way I can salvage what I have and go from there?

[Ed Imeduc]

Id say yes for sure. But dont know where you are and I do know some codes up in Canada call for it that way. Id say check code there for sure and see what they say.

ED ;)

[jas_usn]

I'm in Virginia. My concern was even if I could keep it like it is (upper half insulated), how would I go about studding for drywall. The insulation (and foil) are at least 2 inches thick up against the wall. Placing my studs up against that would shrink my room space and then I would have a gap between the studs. Doesn't seem right that way but I figured that there must be some logic as to why they did it that way to begin with (unless they were never planning on finishing it and just wanted to insulate the above ground portion).

[Blizzard]

I'm in Virginia. My concern was even if I could keep it like it is (upper half insulated), how would I go about studding for drywall. The insulation (and foil) are at least 2 inches thick up against the wall. Placing my studs up against that would shrink my room space and then I would have a gap between the studs. Doesn't seem right that way but I figured that there must be some logic as to why they did it that way to begin with (unless they were never planning on finishing it and just wanted to insulate the above ground portion).

Yep, it is a code requirement that all walls above the ground have to be insulated. 99% of the unfinished basements in VA are done just like yours.

What you do with the insulation after you decide to finish the basement is up to you. I have seen folks leave it and frame the wall out away from it. I saw one guy that took it down and cut it into strips that he put between the studs. I even know one family that put it up in the floor joists so that it would help control the noise from when their teenagers were in the basement. I really probably comes down to how much time an effort you want to put into reusing it or trashing it.

[Ed Imeduc]

Then like said Id take it down hang a 6 mil poly on the wall from the sill plate down build the 2X4 wall an put the insulation in it if you can and add more to cover the bottom there. with paper to the room side.


ED ;)

[jas_usn]

Thanks guys! I stopped by the code administration office yesterday to ask a few questions and found another roadblock before I can even think of starting. Seems that as of Oct 2003 you need to have an egress (5 sf) in ANY habitable room in the basement. I wasn't planning a bedroom and only have a small window. Talking to the guy at the office, on average it will cost around $2000 to have someone get my egress situation within code. Thanks for the info.

[howz]

Jas unn, couldn't you just put in an "office" that conveniently has a double bed for when you get sleepy. I understand the logic behind egress but honestly, my basement has 3 three escape routes, 4 if you count the window that that doesn't quite make egress.

Just a thought ....

[jas_usn]

Howz,

I don't even want a bedroom in the basement. All I really want to do is to put up perimeter walls, some outlets and a half bath. I was planning on sectioning a third off and leaving it unfinished (except walls) for storage. From what I gather, I can do anything down there unless I have the egress window. If I went ahead and "just did it" without the permits, I would have to rip everything back down prior to selling the house. I have spoke to people who say that I can go ahead with my plans and bypass the permit but I don't see how that would work when/if I decide to sell.

[howz]

Hmmm ...

That sounds bezaar. Who is going to make you tear everything down, the realtor?

Maybe the return will be less than upstairs but extra living space is an add on in my books any day.

[jas_usn]

Maybe I have gotten bad information. First let me say that this is our first home and also my first attempt at finishing a basement. If I don't get the egress window within code, when it comes time to sell, the home inspection will not pass. It would be obvious that no permit was obtained because they will see the finished basement with no proper egress. If I did just do it, I would have to bring it back to unfinished to sell or bring in back to just framing, rough elec and plumbing, fix the egress, get my permit and schedule the first inspection.

I didn't want to spend a lot of money on the basement (but really need to use the space). I thought that I could finish a portion of it and when it came time to sell, just list it as unfinished...but I don't think that is the case. If I am correct, I need to fix the egress situation or leave it unfinished. I wish I were incorrect but I don't think so.

[Stevetra]

There are acceptions to every rule.
Some areas have a grandfather rule, and only if the value of your improvements exceed a certain percentage of the house value, do you need to meet current codes. If this is the case, the windows and egresses that passed code when your house was built, will not have to be updated.
I was told by my building department that I did not need to pull a permit, because I am only repairing.
Now my repair job has me removing almost everything and replacing it, and at the same time fixing areas that were never to any code to begin with.
But I have a signed letter from the Code inforcement dept.

Whats more, when I purchased my house, I had it inspected.....
Never was there any mention of code violations that needed to be fixed, there were just areas that didnt meet current code. So I doubt you will have issues with selling your house.

[ERIKGENE]

Check out Johns Manville Poly-Encapsulated insultaion. Think insulation iside a plastic bag. This takes care of your vapor barriers on both sides. And elminates the problem of mosture between the block wall and the poly. the function of the dead airspace is exactly to absorb excess mosture. Mosture depending on the time of the year will either move into or out of the house.

[Robskins]

I had the same problem with not having an egress and showing a "bedroom" on my submitted plan to the inspectors office. They suggested that I not call any room a bedroom in the basement and that I could pass all inspections as long as I did not place doors on the room. I did this and got approval on the basement plan and passed my first electrical and framing insections.

Also I had the silver insulation on the basement walls and just put the studded walls over this insulation instead of removing it.