Insulating Basement???

[CycloneDaddy]

So after researching I think I'm more confused then ever on how to proceed with insulating my basement. The house was built last year and the builder put blanket insulation up (has vapor barrier on it). After talking with some people they said to leave the blanket insulation up and have the framers put the walls up over the blanket insulation so that is what I did. The 2x4 wood walls are 1 inch from the concrete foundation walls with the blanket insulation in between them. Vapor barrier is towards the 2x4.

I noticed the other day that there was condensation on the bottom of the vapor barrier where the barrier was in contact with the pressure treated lumber (only on the north side wall. Should this be a concerned? I asked a contractor and an engineer and they said once the drywall was up it shouldn't be an issue.

Also, should I seal the vapor barrier to the floor? I haven't been able to find an answer on this.

Thanks,

 

[mramseyISU]

I'm going to go all Mike Holmes on this but if you want it warm first lay down tongue and groove pink foam on the floor and walls. Lay a wood sub floor over that and secure it using tapcon screws. This is what you want to put the studs on. From there put the rolls or spray foam between the studs with the vapor barrier outside the insulation and then your drywall. Yeah that's overkill but when it's 20 below you'll be glad you did that.

 

[CycloneDaddy]

I love Holmes but he is building stuff in Canada so I would say our weather conditions here in Iowa aren't as extreme as theirs.

 

[CarolinaCy]

Forget doing anything to the concrete floor, just pad and carpet and you'll be fine. For the walls, you've done basically what I did. I took down the blanket insulation, built the exterior walls about 1" from the foundation walls, cut the blankets to fit the cavities and done.

 

[mramseyISU]

I think he builds around Toronto which isn't much farther north than Des Moines.

 

[CycloneDaddy]

Forget doing anything to the concrete floor, just pad and carpet and you'll be fine. For the walls, you've done basically what I did. I took down the blanket insulation, built the exterior walls about 1" from the foundation walls, cut the blankets to fit the cavities and done.

Thanks for the reassurance ... my neighbor told me I have watched to many tv shows and that I'm paranoid.

I'm thinking of adding another layer of R13 insulation on the north wall as well.

If I had to start from scratch I probably would have taken down the blanket insulation and put up the rigid foam (pink board) instead.

 

[mramseyISU]

I think I watch to many TV shows too, that any my basement was done in the late 70's so the only insulation is the 1/2" rigid foam the siding was nailed to so it's miserable down there. If I yanked the drywall down I'd be getting the rolls hung up.

 

[goldmember]

It was my understanding, the vapor barrier should be on the concrete side, because you want it between the cold and warm zones otherwise moisture will build up causing mold. If you set the studs an inch from the concrete wall and use spray foam, no vapor barrier is needed.

 

[leroycyclone]

It was my understanding, the vapor barrier should be on the concrete side, because you want it between the cold and warm zones otherwise moisture will build up causing mold.

That was the advise I got from a builder quite a few years ago.

Cover entire concrete wall with 4.00mil PE sheeting. Place the studs against the barrier and insulate with 1" polystyrene between the studs. It comes in 15" wide packs for this purpose. Don't insulate below the frost line. No need and it's good to have air movement.

Hold the bottom plates of pressure treated lumber off the floor with 1/4" - 3/8" blocks. Use concrete screws or a nail gun to hold the bottom plates in place.

Hold the drywall at least 1/2" off the floor so moisture doesn't wick up into the drywall. The baseboard will cover the gaps off the floor.

No need to use blueboard drywall with the drywall up off the floor.

No need to insulate the floor since it is below the frost line.

Holding the drywall and lumber off the floor is a good idea if water ever does get into the basement.

This will lead to a very warm basement.

 

[00clone]

I think he builds around Toronto which isn't much farther north than Des Moines.

He builds in Ames? I hadda couple of friends that lived out by North Dakota and Ontario. Not sure if it was Toronto for sure, but it was somewhere out there. And yeah, that's only 45 minutes or so north of Des Moines, but that's mostly in town driving.

 

[kingcy]

My basement was done with the vapor barrior over the studs. It was first finished 20 years ago. A few years ago I refinished it and the studs were basically rotted out becuse of the moisture that was being held behind them. I know if you get the basement companies to fix water issues in a basement they cover the block/concret walls with plastic. When I redid mind I used sheets of foil face, put the studs over that and screwed them both to the block.

 

[Three4Cy]

Forget doing anything to the concrete floor, just pad and carpet and you'll be fine. For the walls, you've done basically what I did. I took down the blanket insulation, built the exterior walls about 1" from the foundation walls, cut the blankets to fit the cavities and done.

This is what I have, a good carpet pad, and quality carpet is all you need.

 

[mkadl]

NEVER use fiberglass insulation it is junk. I have been in construction for over 25 years. Foam board, spray foam , sprayed cellulose are the way to go, air can not migrate through these products if installed correctly. Fill a foam cup full of hot coffee and pick it up, then try it with 1/16th of an inch of puffy fiberglass on a glass cup. (foam is neat that way) Also if your basement is walk out and exposed block, you can put 2" foamboard buried down to the frost line and cover it with a concrete stucco finish and paint. Use cement screws and big stainless washers and foam board adhesive to attach. If outside basement wall has siding on it, you are limited. I would then use as thick as possible foamboard insulation that has foil on both sides, on my interior wall, seal the seams, especially at the floor so no interior moisture can get to the cold wall. (your insulation should stay warm enough to prevent condensation) If you have moisture problems after all that, it is seeping from the outside.
Your condensation is warm moist air meeting much colder air. (I know that is obvious but....) Put a thermometer down where it condenses see the actual temperature, during cold spells I have seen frost where the wall meets the floor!!!

 

[mkadl]

I have a question. If a basement is not a walk out basement how is the wall 6 or more feet underground cold enough to allow condensation? There has to be very cold air inside the wall dropping down inside the wall. If this is the case the basement would be like a giant cooler all winter.

 

[CloneSt8]

So after researching I think I'm more confused then ever on how to proceed with insulating my basement. The house was built last year and the builder put blanket insulation up (has vapor barrier on it). After talking with some people they said to leave the blanket insulation up and have the framers put the walls up over the blanket insulation so that is what I did. The 2x4 wood walls are 1 inch from the concrete foundation walls with the blanket insulation in between them. Vapor barrier is towards the 2x4.

I noticed the other day that there was condensation on the bottom of the vapor barrier where the barrier was in contact with the pressure treated lumber (only on the north side wall. Should this be a concerned? I asked a contractor and an engineer and they said once the drywall was up it shouldn't be an issue.

Also, should I seal the vapor barrier to the floor? I haven't been able to find an answer on this.

Thanks,

Depends on where you are located. Answers are different for Iowa than Texas than Georgia than Arizona. It's not a simple problem with simple answers.

For Iowa and like states, some of the problems: 1) The concrete foundation wall contains moisture that takes time to cure and dry out. The vapor barrier traps this moisture trying to escape to the inside - not good as this can lead to mold growth. 2) If the house does not have a good air/moisture/vapor barrier on the outside of the foundation then water can migrate through the foundation wall resulting in a similar problem.

Best website that I have ever seen on problems with buildings and how best to construct in various parts of the country is buildingscience.com. Here are a series of articles on insulation for basements. An answer for you might be here:

Building Science Information

 

[CycloneDaddy]

I have a question. If a basement is not a walk out basement how is the wall 6 or more feet underground cold enough to allow condensation? There has to be very cold air inside the wall dropping down inside the wall. If this is the case the basement would be like a giant cooler all winter.

The middle of the room is at 59 degrees and below the egress window it is 57 degrees so not much different in temp. One thought I had was that the pressure treated wood might have some moisture in it and maybe that is causing some of the condensation on the barrier.

 

[imnclone]

I built my house in 2007. I pushed the builder to make sure mold would not be an issue. They ended up putting 1" Thermax sheathing in the basement taped with aluminum tape. This has been a good solution and I found out recently they now do this with all their homes. Stud wall was built inside the sheathing, but most of it isn't finished beyond that.

 

[leroycyclone]

The middle of the room is at 59 degrees and below the egress window it is 57 degrees so not much different in temp. One thought I had was that the pressure treated wood might have some moisture in it and maybe that is causing some of the condensation on the barrier.

There is a lot of moisture in a basement. In the summer, I run two dehumidifiers. The walls in winter are cold below the frost line but not nearly as cold as above the frost line. That's why it's important to allow some air movement in the area where the wall meets the basement floor, behind the drywall. Just install the drywall 1/2" or more off the floor and have the bottom pressure treated lumber plate off the floor also, using blocks to keep a gap.

Another method:

1. 4.00 mil PE sheeting against the wall. Tape the sheets together where necessary.
2. Tapcon horizontal strips to the wall to use as anchors for the studs.
3. Install bottom plate, keeping it off the floor with 1'4" to 3'8" blocks of pressure treated lumber. Tapcon screws or use a 22 caliber power actuated nail gun the nail to the bottom plate to the floor.
4. Put up studs, on the bottom plate and up to the top plate. Attach to the horizontal strips also.
5. Fill in the stud spacing with 1" polystyrene sheets, ceiling down to the frost line.

 

[mkadl]

The middle of the room is at 59 degrees and below the egress window it is 57 degrees so not much different in temp. One thought I had was that the pressure treated wood might have some moisture in it and maybe that is causing some of the condensation on the barrier.

what is the temp where there is condensation? Very warm moist air is meeting something much colder. I don't know how a board can get wet in a wall.

 

[mkadl]

I built my house in 2007. I pushed the builder to make sure mold would not be an issue. They ended up putting 1" Thermax sheathing in the basement taped with aluminum tape. This has been a good solution and I found out recently they now do this with all their homes. Stud wall was built inside the sheathing, but most of it isn't finished beyond that.

great solution.