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  1. #1
    Join Date
    Aug 2012
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    10

    Default HELP - moisture problem in a uninsulated block/stucco ranch

    We live in NY and my house is a 1950 uninsulated block ranch. Attic is well insulated and
    vented. We have a problem with moisture. Once it gets cold, we have heavy window condensation, spots of mold will form in the corners of our plaster walls and behind pictures, etc. In one room we took down the plaster to the bare block and painted it with a sealer (dry lock?) we put in 1/2 " styrofoam
    insulation and then sheet rocked the walls. That did take care of the mold
    on the wall issue for that room, but not the condensation problem on the windows. Our windows are vinyl, double hung, and double paned, maybe 8 years old. Their quality is probably middle of the road. During the winter the glass is not unusually cold to touch and there is no condensation on the window frame. There is no moisture on the windows in the summer, only in winter.
    We have a forced air furnace and it is inspected each year. No problem there. We have gutters and the chimney is OK. No blocked dryer vents. Partial (small) crawl space has a plastic vapor barrier on floor and ceiling is insulated. Basement is unfinished and if we have a lot of rain we may get some water, but only like a puddle in 1 or 2 spots, not a flood. We also keep a dehumidifier on in the basement. We painted the walls with a basement sealer?? paint (not sure of the name). I'm sure digging and putting in more drainage outside and sealing the wall would help a lot.

    What should I do about this? This is what we are considering doing.
    Installing furring strips over the stucco, then styrofoam insulation, then
    wrapping the house with a house wrap, then siding with vinyl siding. Do
    you think this is the way to go? Would there be a problem installing the
    house wrap on the exterior of the house? If not, would there be a problem placing the barrier over the insulation rather than in front of it? If the moisture barrier was installed on the stucco then the nails for the furring strips would poke holes in the vapor barrier. The
    house is cement block under the stucco I don't think there is another way? We don't want to have to gut the interior of the whole house.

    I would appreciate your expert advice, thank you in advance. Lori

  2. #2
    Join Date
    Aug 2007
    Location
    Portland, Oregon, formerly of Chicago
    Posts
    1,609

    Default Re: HELP - moisture problem in a uninsulated block/stucco ranch

    Ihort,

    Just curious, have you actually taken a humidity reading? It sounds to me as if your problem is a house withvirtually uninsulated walls. In a cold climate like New York State, even relatively low humidty would condensate on these cold walls. I think your problems would largely disappear if the walls were insulated, either from the interior or the exterior. From a heat transfer perspective, foam insulation on the outside is the most advantageous. The cement blocks then become a favorable heat sink on the interior, evening out the swings of heat and cold. Presently they only expedite the transfer of cold to the interior in winter.

  3. #3
    Join Date
    Jun 2009
    Posts
    271

    Default Re: HELP - moisture problem in a uninsulated block/stucco ranch

    Follow Ordjen's advice.
    Maybe contact an EIFS manufactures Rep. and ask for an wall Analyzes which will tell you how much insulation would be required on the exterior and where the dew point will occur.

  4. #4
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,418

    Default Re: HELP - moisture problem in a uninsulated block/stucco ranch

    I think you need to understand how this condensation takes place in the first place. A block house actually doesn't breath very well so the absolute humidity can be very high inside them. The water vapor in the air comes from living in the house, showers, cooking washing, toilet bowls and perspiration and breathing.

    First is to understand the relationship between absolute humidity (AH), relative humidity (RH) and dew point. Here is a link to an absolute humidity (AH) vs, relative humidity (RH) vs temperature (C). It comes from the German government so its in Celsius instead of Fahrenheit.

    http://www.tis-gdv.de/tis_e/misc/klima.htm

    Since a concrete block house is pretty air tight, at least the walls are, the moisture in the air tends to stay inside the house. The more moisture in the, the higher the AH. The RH also goes up, but RH has a temperature component. For a given AH, which is measured in grams of water per cubic meter, g/m3, the RH, measured in % varies by temperature.

    For example, if the winter temperature in your house is 20C or 68F and the water vapor is 12.1g/m3, the RH is 70%. Under the 12.1 on the chart is +14 which means that at 14C or about 57F, the AH of 12.1g/m3 becomes 100% RH and condensation begins, this is the dew point. So if the surfaces of the glass are 57F or lower, you will have condensation. If the walls are dry, then no amount of extra insulation on the walls will help.

    You will need to lower the humidity inside the house or increase the surface temperature of the windows. One trick is to have a heat vent under each window. You could add storm windows to the outside or a low emissive coating to the glass you currently have.

    You can lower your humidity with more de-humidifiers, but I would look into increasing the ventilation inside the house through a Lossney converter, aka energy recovery system.

    http://www.mitsubishielectric.com/bu...s/lossnay.html

    This unit draws in fresh outside air, runs it through a heat exchanger with the inside air being expelled and transfers a percentage of the heat from the outgoing to the incoming.

    I'm not sure that drylock in the basement or more dehumidifying down there is going to help you with the problems at the upstairs windows. A dry basement would be a good thing, as would additional insulation on the walls upstairs, though 1/2" foam is not very much considering the expense, but these may not solve the problem that you want to solve. You need to focus on that and remember that many contractors that you seek advice from will want to sell you what they install. They may not really understand what you are trying to achieve.

    I think this would be a really good project for "Ask This Old House". I hope they are seeing this and look into it.

  5. #5
    Join Date
    Aug 2007
    Location
    Portland, Oregon, formerly of Chicago
    Posts
    1,609

    Default Re: HELP - moisture problem in a uninsulated block/stucco ranch

    Ihort,

    Your original post does not mention what type of ventilation you have in your baths, kitchen and laundry areas.

    A 1950's house with a window in the bath would not typically have had a powered ceiling vent. If you don't have one in there, do get a good one installed, also have it powered by a timer switch that keeps it running for a few minutes after you leave the shower.

    The kitchen also generates alot of moisture. Just think of that pot of spaghetti boiling away or the sweet corn! Again, a good exhaust fan locate close to the source of steam and fumes - your stove. Likewise, if your laundry is enclosed, try to ventilate that area too.

    Do you have a high efficiency furnace that draws outside air for combustion? This contributes to high household humidity by virtue of the fact that they do not draw household air and send it up the chimney, as did older furnaces. Older furnaces drew air from household air leakage, bringing in bone dry outside winter air to replace the air which was going up the flue.

    Keith's suggestion for an air exchanger does somewhat the same thing. It draws in the bone dry outside winter air and salvages some of the heat from the warm, humid air going out.

    I would suggest that in winter, you consider letting your furnace fan run at least during the cold nighttime hours in an effort to keep air moving. Moving air discourages condensation and mildew. A slow moving ceiling fan might also help in this regard. As Keith suggests, it is not by accident that hot air heat vents are normally placed under windows. It keeps warm air moving over the cold window and exterior walls.

    One word of caution about putting an exterior storm window over your vinyl windows - DON'T. PVC can distort at as little as 130 degrees, a temp easily reachable between the primary window and the storm window during the summer when the sun is beating on that window. I have seen decorative PVC moldings literally sag on exterior doors which have had full glass storm doors put over them.

  6. #6
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,418

    Default Re: HELP - moisture problem in a uninsulated block/stucco ranch

    Quote Originally Posted by ordjen View Post
    Ihort,
    One word of caution about putting an exterior storm window over your vinyl windows - DON'T. PVC can distort at as little as 130 degrees, a temp easily reachable between the primary window and the storm window during the summer when the sun is beating on that window. I have seen decorative PVC moldings literally sag on exterior doors which have had full glass storm doors put over them.
    I would expect that the exterior storms would be removed in summer. But when I lived in VA, I built interior storm windows from 1x1 with weather stripping around the edges and covered with clear 8 mil vinyl on both sides of the frame. The project didn't cost me much and it stopped condensation on the windows (single pane) and kept them much warmer in the winter. Saved me a lot of money on heating as well. The house was a conventional brick house built in the 50's.

  7. #7
    Join Date
    Aug 2012
    Posts
    10

    Default Re: HELP - moisture problem in a uninsulated block/stucco ranch

    ***, I see, a lot of factors can contribute to my problem. First, thank you all for your input on this. I am now a very big fan of this discussion board and boy do I have a lot of other question!

    To answer some questions:
    1. We have a fan vented outside and a window in the bathroom. No exhaust in the kitchen w/ a LP gas range.

    2. We have taken humidity readings in the past , I remember it was on the high side but not exactly sure of the %. It was a while ago. I will take another humidity reading once the it's cool and the windows are closed.

    3. Not sure about the furnace,. I don't think it is getting air from outside?? Furnace is a Williamson w/forced hot air, purchased about 28 years ago. I think it was a high efficiency in the day....although that was a long time ago. Many technicians have commented on what a good furnace and that it should last a long time. We get it tuned-up every year.

    4. Someone mentioned that the minimum foam insulation should be 2". Any other thoughts on this?
    Our windows are not even with the outside of the house they are "set in" approx. 4". I would hate to have them "set in" too far for obvious reasons.

  8. #8
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,418

    Default Re: HELP - moisture problem in a uninsulated block/stucco ranch

    To see if the furnace is using outside air for combustion, location is a key. If it is located in an attic or garage, it is using outside air for combustion. If it is in a closet inside the house, see if the closet is open to the attic or if it has a ceiling. If it has a ceiling it is probably using interior air, if it is open, then it is using outside air and depending on the degree of weather stripping around the door, it may be using a mix of inside/outside air.

    If it has a ceiling, it could still be using outside air. It would get this air from a separate duct to the combustion chamber or the vent duct could have a double wall with outside air coming down between the walls and exhaust going up the center.

  9. #9
    Join Date
    May 2011
    Posts
    251

    Default Re: HELP - moisture problem in a uninsulated block/stucco ranch

    A stucco, block home is going to be very tight. You probably need more fresh air year round. A good solution would be a whole house a ventilating dehumidifier. They aren't cheap, but cheaper than adding insulation, or other major changes. You likely not only have high moisture levels but also high CO2 levels just from breathing and using the stove.

    Another option for fresh air can be using a higher end bath fan that has a continuous fan option to continuously exhaust indoor air.

    NExt I'd look at adding an exhaust vent for the kitchen range hood.

    You problems likely god bad after adding the new windows. The original windows, especially being 50 years old at the time. probably weren't as tight, and allowed more air leakage. OF course you can wait 10-15 years and you new windows will no longer be tight and will leak plenty of air too.
    1925 Two-Story Stucco Beaux Arts Neoclassical

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