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-   -   2x3 vs. 2x4 in basement? (http://www.diychatroom.com/f15/2x3-vs-2x4-basement-38809/)

deepstuff 02-21-2009 08:01 AM

2x3 vs. 2x4 in basement?
 
HI,

I'm ready to start framing out the inside of my 8' concrete basement walls. Is ther any reason why I should use 2x4 instead odf 2x3? Would either be easier to work with etc??
I do not need the added strenght of the 2x4's since my walls are 8-foot concrete. Just making a space for wires and added insulation. I will be finishing with batt insulation, vapor barrier and drywall. I will be adding this to the 1.5" styrofoam already on the concrete.


Thanks!

stubborn1 02-21-2009 08:09 AM

I would go 2x4 just for the reasons you mention - space for electrical boxes and insulation. As long as you aren't tight on space, I wouldn't consider the 2x3s.

jaros bros. 02-21-2009 08:34 AM

You'll want to omit your vapor barrier as this will trap moisture in the wall as it migrates from the concrete to the interior. A basement wall dries to the interior not to the exterior.

Ron6519 02-21-2009 10:03 AM

Quote:

Originally Posted by jaros bros. (Post 234018)
You'll want to omit your vapor barrier as this will trap moisture in the wall as it migrates from the concrete to the interior. A basement wall dries to the interior not to the exterior.

I don't think this approach is correct. I think you would definitely need a vapor barrier for your climate.
Ron

jayharold 02-21-2009 10:30 AM

You could use 2x4 on the walls with the block and 2x3 on the rest of the walls.

Scuba_Dave 02-21-2009 10:55 AM

2x3 is fine, bottom plate should be rot resistant - PT or similar
You do not want 2 vapor barriers, it will trap moisture between the wall & the concrete = MOLD
Most houses (even my 60 year old house) has tar on the outside basement wall. This acts as a vapor barrier. Most moisture comes into the basement as vapor thru the concrete - you don;t have to see it. I have a humidity gauge in my basement & kick a dehumidifier on any time I see humidity rising

The wall along the concrete MUST be out approx 2-3" to allow moisture to be eradicated. That is why you can use 2x3 = you will have enough room for boxes & wire

Who put the styrofoam on the concrete?
You will most likely have mold growing between the styrofoam & the cement wall. A lot of the styrofoam has a vapor barrier built in - a cover on one side

jaros bros. 02-21-2009 11:05 AM

Scuba, I think that you are going to confuse a lot of people. First of all, moisture does not enter the concrete just from the outside horizontal face, it enters from wherever it can, including via the footing. Tar does not prevent moisture from entering concrete except where it is applied. All concrete will be moisture laden. Secondly, you seem unaware of the different properties of styrofoam. There is open cell and closed cell. One is semivapor impermeable and one isn't. True, foil facing is a vapor barrier. You seem unconvinced, even though all evidence points to concrete holding vast amounts of moisture. You also seem dissuaded to agree with huge amounts of scientific evidence to support this. I think everyone appreciates you wanting to help people out but you are in over your head in this particular area and people might take your advice and end up regretting it. Procedure is to apply foam to the interior or exterior of the wall, both sides is better, and then to stud up a wall inside without a vapor barrier. Any other method is asking for trouble because those systems have failed. On a previous thread you had suggested using a vapor barrier on the interior under the drywall...I then posted a picture showing what would happen and you have since retracted that advice. There is so much advice out there about insulating basements and a lot of it is wrong.

Bob Mariani 02-21-2009 11:24 AM

Jaros... most of it is wrong. (OTHERS NOT YOU) Best advise is that DIYer do not do there own basements. Above ground moisture moves out of the basement, below it moves into the basement like you said. many if not all basements have this to deal with. And almost all posts do not point this out. And open cell or closed cell or foil backed or spray foam... too much for them to follow. You are correct Scuba gets it wrong. And he reads and tries.. so how can a homeowner get it right? Moisture problems will happen in the life time of a basement wall. Vapor barriers are not going to address this. You need to consider how to the wall componets will dry out.? Batt insulation is less effective after mositure damage. So I never reccommend this at all.A spray polyurehtane followed by Dens-glass sheathing will perform best. Followed by Owens Corning's bsement wall finishing system which has removable panels for periodic inspections. These use a vinyl frame covered by a polyester fabric. The worst possible system to use is wood framing poly sheets, batt insulation and drywall. The poly stops one component of the other from drying out. The others cannot handle moisture and dry out poorly.

kickarse 05-03-2009 01:00 PM

If you don't have the option to use a spray foam insulation, could we use sheet type extruded styrene. Provided its open cell to allow moisture to wick through and dry properly? While still leaving around 2" of clearance between the backside of the sheet and the concrete wall?

Also, instead of using a treated piece of lumber is it acceptable to use a strip of poly foam insulation, the stuff they use for sill plates?

And, tar's applied to form a water barrier on the exterior of the basement walls, more so for leaks, not so much for moisture.

Mikey Palmice 05-03-2009 07:58 PM

Quote:

Originally Posted by Bob Mariani (Post 234084)
Jaros... most of it is wrong. (OTHERS NOT YOU) Best advise is that DIYer do not do there own basements. Above ground moisture moves out of the basement, below it moves into the basement like you said. many if not all basements have this to deal with. And almost all posts do not point this out. And open cell or closed cell or foil backed or spray foam... too much for them to follow. You are correct Scuba gets it wrong. And he reads and tries.. so how can a homeowner get it right? Moisture problems will happen in the life time of a basement wall. Vapor barriers are not going to address this. You need to consider how to the wall componets will dry out.? Batt insulation is less effective after mositure damage. So I never reccommend this at all.A spray polyurehtane followed by Dens-glass sheathing will perform best. Followed by Owens Corning's bsement wall finishing system which has removable panels for periodic inspections. These use a vinyl frame covered by a polyester fabric. The worst possible system to use is wood framing poly sheets, batt insulation and drywall. The poly stops one component of the other from drying out. The others cannot handle moisture and dry out poorly.

Bob, does an Owens Corning Basement System installer have to do this? Or can anybody get the material and put it in themselves? I have heard the Owens system is a great way to go, but it's very expensive.

Is there a tool online where you can estimate costs associated with this technique?

thanks

Bob Mariani 05-04-2009 06:51 AM

It is only done by their installers. A good system, but expensive as you note. Other similar systems are also expensive. Whether you need to go to this extent depends on the moisture problem you may or may not have now. When I do basements, I use foam directly over the concrete walls where the walls are below grade. Leave a 1" airspace to allow any wet conditions the ability to dry. I use sill insulation under the sole plate as a capillary break on the stud wall. I use metal studs with 2" foam between the studs, sealing seams with foam insulation. Use closed cell foam to seal the rim joist and the floor joist bays along the outside perimeter. No vapor barriers! Mold resistant drywall and a good dehumidifier that is plumbed to the drain for automatic water removal. Only use latex paint to allow the wall to breathe.

Mikey Palmice 05-04-2009 07:45 AM

Quote:

Originally Posted by Bob Mariani (Post 269140)
It is only done by their installers. A good system, but expensive as you note. Other similar systems are also expensive. Whether you need to go to this extent depends on the moisture problem you may or may not have now. When I do basements, I use foam directly over the concrete walls where the walls are below grade. Leave a 1" airspace to allow any wet conditions the ability to dry. I use sill insulation under the sole plate as a capillary break on the stud wall. I use metal studs with 2" foam between the studs, sealing seams with foam insulation. Use closed cell foam to seal the rim joist and the floor joist bays along the outside perimeter. No vapor barriers! Mold resistant drywall and a good dehumidifier that is plumbed to the drain for automatic water removal. Only use latex paint to allow the wall to breathe.

thanks. I have bee very dry since getting french drains put in around the house.

Bob Mariani 05-04-2009 11:55 AM

That does not mean much. Moisture issues happen AFTER insulation. Still needs to be done right.

kickarse 05-04-2009 12:46 PM

Quote:

Originally Posted by Bob Mariani (Post 269250)
That does not mean much. Moisture issues happen AFTER insulation. Still needs to be done right.

What does not mean much? The drains around the house?

I'm planning on finishing my basement as well. 2x4 walls, 2" styrene, 2-3" from the concrete wall, pressure treated 2x4's for the pieces touching the concrete, ramset the studs, mildew resistant drywall.

Bob Mariani 05-04-2009 03:17 PM

Quote:

Originally Posted by kickarse (Post 269266)
What does not mean much? The drains around the house?

I'm planning on finishing my basement as well. 2x4 walls, 2" styrene, 2-3" from the concrete wall, pressure treated 2x4's for the pieces touching the concrete, ramset the studs, mildew resistant drywall.

You need some foam board directly attached to the concrete wall. (glued and sealed with foam and/or tape at the seams. This acts as a capillary break to stop moisture coming from the concrete wall as well as keeping the concrete wall warm thus avoiding condensation that occurs when warmer air moves towards this wall from the basement. Also add sill insulation under the sole plate for the same capillary break from the slab.

It means that a basement can appear to be and be dry while not finished. The moisture that is always moving through the concrete can dry to the open air in a basement. BUT... people add finished walls that are constructed wrong and/or add an vapor barrier and now you have a wet wall. Moisture no longer can dry to the basement.


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