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Chucker77 06-02-2010 10:54 PM

new here - re-finishing basement - questions
 
Hey all,
I just cam across this forum trying to get some info on insulating my basement. This is my second house, and one we'll likely stay in for a long time. Looks like some good info is given here, so here's my questions:

I just ripped down the panelling and old insulation in the basement. It's soaked. It has 1x2" strapping I believe on the wall and had rigid (fibre board of some sort) insulation with a foil over top. Looks like it's been there 20 years.
At this time, there is about a .75" thick plywood subfloor put down on strapping which is attached to the cement floor - thinking of leaving it and carpeting right on it when all said and done.
Here is my question(s) - What is the best way to re-insulate the walls? I have been told to tar-paper the walls, build a wall against that with 2x4's, add fibreglass insulation (keep about 12" from the floor), put a vapor barrier, and then re-apply panelling or drywall. I have also had people say to build the wall about 1" from the wall and some say directly on the wall.
I've been told to use a plastic board insulation of some sort, then build my wall and add fibreglass insulation, with no vapor barrier.
What is the most prefferred method to not get moisture at all? Vapor barrier good or bad? Can I leave the existing ceiling? At a stand still as this is new to me, along with many other projects I'm sure to undertake.
Cheers

Chucker77 06-04-2010 11:01 AM

Any ideas?

oh'mike 06-04-2010 05:39 PM

My first question is ,Why was the old insulation 'soaking'?

Now that the walls are stripped --are they dry?


Once you know that the water in the old insulation was only condensation--or a leak that you fixed--


I do not put a vapor barrier over the concrete foundation.---There are a lot of different opinions about vapor barriers.--

Build 2x4 stud walls an inch or more away from the foundation.

Insulate with craft faced insulation--floor to ceiling --with the vapor barrier facing the room.

Adding a couple of return air type grills to the walls will increase air circulation behind the insulation-

A sheet magnet could be used to close the vent in winter if cold air is coming in.


I've built a lot of basements this way,never had a call back---Mike----

jomama45 06-04-2010 07:43 PM

Quote:

Originally Posted by oh'mike (Post 451207)
Adding a couple of return air type grills to the walls will increase air circulation behind the insulation-

A sheet magnet could be used to close the vent in winter if cold air is coming in.


I've built a lot of basements this way,never had a call back---Mike----

If I'm reading this correctly, you are actually venting the foundation wall cavity into the conditioned air?

If that's correct, I really think that you're on to something. :thumbsup:

I've thought for a long time now that some kind of forced air circulation in this cavity will become code someday. I think your method of natural convection may be even better though.

Chucker77 06-05-2010 12:11 AM

Quote:

Originally Posted by oh'mike (Post 451207)
My first question is ,Why was the old insulation 'soaking'?

Now that the walls are stripped --are they dry?


Once you know that the water in the old insulation was only condensation--or a leak that you fixed--

I've built a lot of basements this way,never had a call back---Mike----

I have to believe it was just condensation. It was around all of the outside walls, but above the ground level. I would not vaour barrier against the concrete wall, but it has been suggested to me to put tar paper. I believe this would breath maybe more than vapor barrier, but prevent insulation and 2x4 wall from contacting cement wall? Ever heard of it being done this way?

I like the idea of return air grills, but would this create a space in the vapour barrier for moisture to condensate?

oh'mike 06-06-2010 07:13 AM

Your studs and insulation will not ever come in contact with the foundation if you leave an inch or more of space.

I do not put a vapor barrier against the foundation--tar paper is a vapor barrier.--Mike--

tim444 06-07-2010 01:04 AM

Are your walls concrete? If they are, building sciences recommends using XPS board directly against the foundation walls. Then build your 2x4 walls about 1" out from the concrete walls and use unfaced insulation inside your 2x4 walls:


http://www.buildingscience.com/docum...g-your-basment


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