water permeating concete block

I would like to insulate and finish my basement but am concerned about moisture. IThe house is 39 years old with concrete block foundation. have never seen any liquid, but the brick is soft and flaking off in a few places. The block was painted before the previous owner sold the house, they said to conceal efluorescence. However the paint started coming off after less than a year. I repainted with eitter a thin primer or a thick "bathroom" paint. The bathroom paint is badly blistered but the primer is fine. I think this is because water is coming thru the wall, and the thick paint does not allow it to pass through. Question: 1) Is this condition anything to worry about, 2) Can I finish the wall with the usual studs and gypsum without causing mold problems? If not, is there a better way?

 

wetwall,

Here is some good links to look at and evaluate them accordingly.

http://www.jlcnet.com/banner/basep4.html

Sealers - These do require a clean surface so be preared for some elbow grease but they do work.

http://www.ugl.com/faq.html (better product)

http://drylock.com/H2Dry.html (better product)

http://www.radonseal.com/basement-waterproofing.htm (good product)

This may be fine for water penetrating through the block. However if other issues are present like at joint between wall/slab or on slab, other issues need to be addressed.

Good article on mildew and mold;

http://www.epa.gov/iaq/molds/images/moldguide.pdf

If you don't have the issue of moisture under control, I would not do any improvements to a basement. The investment that you put into all this will be destroyed! It's your choice.

Basement wall framing and insulation - my article for what it is worth!

I guess this is the best and most economical way to construct walls that would be placed on the exterior. I prefer to see 2x4 but as mentioned by others they can get 2x3's. You still need that W/T plate. Doing the framing 16" O.C. provides a solid base for your 1/2" drywall. If using traditional framing method, frame your new wall 1" from the vertical block/masonry surface if using R-13. The reason to keep the wood out from the walls is the moisture that could damage them. If using insulation like R-19 and only 2x4 studs, the insulation would touch the walls. I have stated before that if a homeowner did put thicker insulation in, and the wall was only 1" from the masonry surface, I have recommended hanging a vapor barrier between the back of the wall and masonry surface. This doesn't allow for the insulation to touch the wall and air movement is not restricted but at least you won't create damage to the insulation or wood. If you do want to increase the R value, move the wall out further or use the R-13 and then apply a rigid insulation over the studs (warm side) then drywall (not paneling) *Code advises a 15 minute fire rated material over any rigid insulation - 1/2" Drywall*..

Kraft Faced insulation is fine to use in the above scenario. No need for the poly and you can do everything easily. You may find this easier and I would do this versus unfaced and vapor barrier because I don't like to play with it any more than I have to.

Let me add one other thing, rigid insulation used on a concrete/masonry surface is fine. Considerations to make in using this is;

1. If you are just using 1 1/2" rigid and furring strips - A. You need W/T strips to protect the wood. B. The strips can be adhesively applied but they must be solid - mechanical anchors may have to be used to insure that if shelving is installed it will hold. Problem with this is, the penetration into a sealed concrete/masonry surface is damaged and subject to leaking. C. Any electrical boxes will have to be shallow - sometimes makes it hard to wire. D. You must use a fire retardant material over this as per Code.

(Most books, articles about rigid and furring strips fail to say anything about the use of W/T and this will get destroyed and be a good source for mold/mildew with the slightest hint of moisture)

2. Alternative which does add cost is to apply full rigid sheets to the concrete/masonry walls, adhesively applied, then place frame wall against the rigid, then insulate between studs and cover with drywall. The Rigid insulation does then act as a the vapor barrier. Do not tape/seal the seams. This allows it to breath and dry up any condensation that may form.

So here is some more stuff....

1. Vapor barrier should be placed directly under the drywall. The warm inside air containing water vapor can get past the wall finish and insulation and condense inside the colder wall cavity. If enough of this happens, and the water cannot escape, wood rot, mold, and other moisture-related problems are likely to occur. For this reason, building codes often require installing a vapor diffusion retarder on the warmest side of the wall cavity. This is what is required in Minnesota;

"A 4 mill poly vapor barrier must be placed against all concrete or block exterior foundation walls prior to applying furring strips for full height of the wall. Another 4 mill poly vapor barrier must be placed over furring strips and insulation prior to covering with finish materials. (State Energy Code Requirement)" - MINNESOTA CODE

***PLEASE NOTE THAT YOU MUST MAKE SMALL SLICES AT GRADE LEVEL ONLY FOR WEEPING IN THE POLY IF POLY IS PLACED AGAINST THE BLOCK - ATTACH THE POLY WITH STAPLES TO YOUR JOISTS/FOUNDATION SILL PLATE***

2. W/T is wood treated. International Residential Building Code says "it must be used whenever wood is in contact with concrete and/or masonry". Check it out with your local inspector. This would also include furring strips applied directly to a vertical block wall unless you use the vapor barrier behind it.

3. If you are considering using 2x2's as furring strips I can only give you my 2 cents worth and you decide.
A. Are you going to have electrical in the walls? Short depth boxes make it difficult to wire. 2x4's would be better. B. Are you planning or foresee hanging shelves or cabinets on the exterior walls? Not alot of strength and may be subject to splitting easier than 2x4's.
C. I personally can't seen how 2" will make a difference in conserving space when you consider the hassle of doing electrical or other carpentry issues.
D. Depending on what you are talking about when it comes to the pre-cut polystyrene, the white foam board, which is the molded expanded polystyrene (MEPS) only is available in R-2 - 3/4" thick, it only costs about $5 per 32 SF. The better quality with R-7.5 is the pink foam - extruded expanded polystyrene (XEPS). This is great stuff but costs more.

Just a note, when you use NON-W/T stock as the 2x2's or 1x3's as furring strips, you have to place a vapor barrier between that and the block wall - you have to attached the furring strips to wall somehow, right? You can't adhesively apply them, you have to use a ramset - this obviously has drawbacks...you just put a hole through the poly making it useless which in turn starts the problem with moisture touching the wood. Second, is if you used W/T or Non-W/T stock and have a waterproofing sealer on your block walls, you just penetrated the block, puncturing the seal coating that was suppose to stop water/moisture...creating possibly a worse problem....water that fills the concrete block cores starts to drain out or will leak in heavy rains. Just thought I'd bring this up. I would do 2x4 walls with R-11 or R-13, insulation would cost about $.02-$.03 more per square foot than the white foam and be better all around. Leave the walls out 1" from the block when framing, apply your poly over the studs apply the drywall and be done. You'll have no problems then.

Hope this helps!

 

Thanks for your advice. My experience has shown trying to seal the water out will not work. I would like to try and build a wall that will allow the moisture to evaporate. Your suggestion that the wall be built an inch or two from the block shows you agree. Before I build the wall, I would like to know if the construction will allow adequate air movement to keep the wall dry. I am thinking some sort of vents at the top and bottom might be best. Also, would it be prudent to apply a porous surface bonding mortar to the wall surface to keep if from flaking?

 

wetwall,

The 1 inch gap will provide for air - YOU DO NOT WANT TO INSTALL ANY VENTS WITHIN THIS WALL! Remember that the wall is not creating a vacuum void, air flow will be there naturally due to everything else that is not sealed in a "jar". What good is the poly for or use of Kraft Faced insulation if you are allowing moisture to travel back and forth? For that matter, what good would the insulation itself be?

If you are concerned about the moisture, which may seem to be more than you stated earlier, do the prep work as I mentioned and then procede with the walls. I'm worried that the moisture is a real issue that needs to be resolved.

Trying to apply another coating of whatever without getting down to a "clean substrate" is a waste of time. It would be a matter of time before this also would be coming off and it wouldn't or doesn't serve any purpose at all.

Hope this helps!