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what to do? 1950 uninsulated ranch w/ moisture problem

My house is a 1950 uninsulated block ranch. Attic is well insulated and
vented. Windows are double paned.
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?) put in 1/2 " styrofoam
insulation and then sheet rocked the walls. That did take care of the mold
on wall issue but not the condensation problem on the windows.

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 vapor 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

Re: what to do? 1950 uninsulated ranch w/ moisture problem

You don't need a vapor barrier. You just need insulation and putting it on the outside of the wall is a good idea in your case. Strip off the stucco, apply 2-4" thick foam wall boards, house wrap over this and then furring strips, nailed or screwed to the concrete block walls through the foam insulation and finally your vinyl siding or a new layer of stucco. House wrap is not a vapor barrier, it is a moisture barrier and that is what you need.

But all of that will not solve your problem. It will make your house warmer, save some on utilities, maybe 10% of your heating bill, but your problem is the windows. Are they aluminum framed? Is there good weatherstripping around them? The frame on metal framed windows conducts the outside cold to their inside surfaces where condensation will surly occur. Even the double paned glass is significantly colder than the inside air so condensation is going to occur.

You can reduce the condensation on your windows by reducing the interior humidity with a dehumidifier and you can upgrade your windows to better insulated models. The warmer the surfaces of the windows and window frames, the less condensation you will have.

Re: what to do? 1950 uninsulated ranch w/ moisture problem

Keith thank you for your reply.

1. We did not want to remove the stucco.....big job. Would it matter if you left it on?
In order to do this on top of the stucco. A contractor wanted to put furring strips attached to the stucco and in between them foam insulation, then wrap the house with a moisture barrier and finally the vinyl siding.

2. 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.

3. You said you thought it was the windows, but do you think the moisture barrier would also help with this?

4. Since siding the house would be a pretty big investment I want to be confident that this would solve my problem, since the stucco is in good shape.

Thank you. Lori

Re: what to do? 1950 uninsulated ranch w/ moisture problem

You can leave the existing stucco in place. I would put a continuous foam exterior and then nail the furring strips on top of the foam, with longer nails to compensate for the thickness of the foam. This makes a thermal break between the block wall and the vinyl siding.

You said the moisture was on the windows, if that is so, then insulating the walls will not help. If your walls have condensation on them, then it will.

Re: what to do? 1950 uninsulated ranch w/ moisture problem


The essential problem is that you haven't yet determined the source of the moisture getting into the interior of the building; I would hold off contracting to do any costly siding projects or similar work until you have had a chance to do some DETECTIVE WORK, or hire someone to do the DETECTIVE WORK to find out exactly where the moisture is coming from----I can think of any one of 5 or 6 different possibilities, but you have to nail it down to the MAJOR CAUSE in order to resolve the problem.

For example, is the moisture on the windows/walls present in summer as well as winter??? Do you use an AC in the summer, & does the AC minimize the problem??

What kind of heating system do you have??? If it's forced hot air, there's a real possibility that there is a crack in the furnace's combustion chamber/heat exchanger that's allowing the moisture-laden partially burned combustion products to mix with the heated air entering the living space---this would contain carbon monoxide which is dangerous, and produces physical symptoms like headaches, watery eyes, breathing problems and frequent colds among the occupants; a $6 carbon monoxide monitor/alarm should be in place in the living quarters now and during the heating season to check this out.

Do you have any moisture in the cellar/crawl space due to water getting inside the foundation due to foundation leaks??? As the article below notes, faulty roof gutters and downspouts that don't direct the runoff away from the foundation could be the problem. Do you have a stone/brick chimney??? check out the roof flashing on the chimney for leaks that can wash down the inside chimney all the way to the basement and cause a buildup of inside moisture; check any under-cabinet leaks in plumbing fixtures in the kitchen, bath & cellar; the article mentions other sources of moisture, such as an excessive number of house plants, or a blocked vent on a clothes dryer, or venting the dryer directly into the house instead of outside; a lack small exhaust fans in the bathroom to expel moisture after showers, or in the kitchen to expel moisture produced by cooking/cleaning/washing should also be checked.

Do you have a cellar/crawl space?? Builders are required to spray or paint the exterior of the foundation with a waterproof membrane, but many times it just isn't done, through ignorance or cost-cutting measures.

See what I mean??? you can waste a lot of $$$ assuming it's the stucco walls, or something else, until you have nailed down exactly what is the cause.

If you don't now own one, purchase a good dehumidifier for the coming heating season to reduce water vapor inside the house until you find the real culprit.


Re: what to do? 1950 uninsulated ranch w/ moisture problem

Dodsworth, thank you for your reply. In answer to your questions.

1. No, there is no moisture on the windows/walls in the summer, only in winter.

2. we have forced air, furnace is inspected each year. No problem there and we do have a CO2 detector.

3. We have gutters and the chimney is OK. No blocked vents. Partial 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 spot 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.

Do you think that the inside basement sealing that a company who specializes in "dry basements" would be sufficient in keeping the moisture out of the basement?

Thank you. Lori

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