# 2x3 vs. 2x4 in basement?



## deepstuff

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!


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## stubborn1

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.


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## jaros bros.

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.


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## Ron6519

jaros bros. said:


> 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


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## jayharold

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


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## Scuba_Dave

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


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## jaros bros.

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.


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## Bob Mariani

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.


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## kickarse

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.


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## Mikey Palmice

Bob Mariani said:


> 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


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## Bob Mariani

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.


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## Mikey Palmice

Bob Mariani said:


> 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.


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## Bob Mariani

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


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## kickarse

Bob Mariani said:


> 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.


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## Bob Mariani

kickarse said:


> 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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## kickarse

Bob Mariani said:


> 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.


If you have the foam against the wall or not isn't necessarily the issue. It's if the foam will allow moisture to pass through it and not be trapped between the foam and the concrete. It really doesn't matter if it's a millimeter or 3 inches. Remember, too layering adds air between the layers. Air is a great cushion for slowing the transfer of heat or cold. Once you put a solid piece of material it against another adds a "conductor" of sorts. Same reason why fiberglass type insulation is "puffy" or airy.

I tend to disagree that if you keep the concrete "warm" by adding insulation to only one side, as you suggested the interior, it will keep condensation from forming. Moisture is wicked through both sides of the wall, not just the outside. Anywhere that there's a vapor barrier will incite moisture buildup, on one side or the other or both. The key is the ability to dry this moisture from the air in a timely fashion.

Remember warmth doesn't necessarily dictate a non humid basement. Just look at the tropics. Also, there can be moisture in a cold environment long as there's a source, ie a dryer, rain.

I agree though that if people don't understand the concepts of why moisture builds up there will be, are, many moldy houses.


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## Bob Mariani

The open cell insulation board allows the wall to breathe in both directions. Read the science on this, recommendations are to do it exactly as I stated. If the concrete wall is colder then the heated interior then condensation will occur. The foam will stop this from happening. The method I described contains no vapor barrier in either direction.


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## kickarse

Bob Mariani said:


> The open cell insulation board allows the wall to breathe in both directions. Read the science on this, recommendations are to do it exactly as I stated. If the concrete wall is colder then the heated interior then condensation will occur. The foam will stop this from happening. The method I described contains no vapor barrier in either direction.


That's why I prefaced it with that the real issue was "if the foam will allow moisture to pass through it and not be trapped between the foam and the concrete."

The science isn't that the foam will keep the concrete warm but it will keep the concrete at a similar temperature to the outside. Which will usually remedy condensation between the foam and the concrete wall. I mean, you'll have a certain amount of heat loss and cold leak.

I was just making a point about the spacing and that you could possibly do it either way. But I certainly agree that you can put the foam right up against the wall.


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## walkman

I wanted max space in my basement upgrade so I turned 2x4 on side and used slimline outlet boxes. 2x3 are usually too twisted to use around here.


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## Bob Mariani

walkman said:


> I wanted max space in my basement upgrade so I turned 2x4 on side and used slimline outlet boxes. 2x3 are usually too twisted to use around here.


Now you can enjoy a very wavy wall. That is no way to build a wall. Space should not be such a consideration that you will build something not structurally sound.


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## walkman

No wave at all, and structurally solid since that it's against cmu. 

This isn't a free standing load bearing wall so space was a consideration.


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## Mikrboro

Let's not forget to consider your situation. I built my home in 1965. My basement was dry as a bone until 1985. I installed furring strips, then plastic, board insulation between strips finally followed by drywall. I have replaced sections as late as 2006, and saw no signs of mold or mildew. If your basement is dry, don't go nuts. My opinion for what it's worth after 46 years of building.


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## Raiseace62

*Scuba _dave has it right, Follow his advice.*



Scuba_Dave said:


> 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


 This is the way to do it.


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## Raiseace62

*plate*

Bottom plate does not have to be rot resistant, need to have a insulating barrier between the plate and the concrete floor. They sell in in rolls just for this.


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## woodworkbykirk

it has to be either or. rot resistant or have a contact break between wood and concrete


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## mae-ling

Wow a 2009 thread revived with one post in 2011, then again yesterday.
Apparently some location say no Treated wood in basements.

Originally Posted by Scuba_Dave 
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"

Now isn't this want we are to do 2" styrofoam against concrete!


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