Ohh.....FFFFFFFFudge!

[JSUPreston]

A couple of weeks ago, SWMBO and I noticed some bubbling in the linoleum flooring in our study/office. I initially didn't think much of it, since it was put down in the mid to late '60s, and is ugly as sin anyway. However, the bubbles in a couple of areas continued to grow until last week, I pierced one of the bubbles and found moisture between the flooring and the plywood. The ply has delaminated in those areas and was sticking up pretty high. After a couple of more tests, we thought we might have a roofing leak.

Insurance sent out a leak detector inspector man and I just got the initial results. No leaks, which is good except for the fact that now this isn't covered under insurance. He said that the issue was caused by condensation in the subfloor caused by a lack of vapor barrier in the crawl space and no insulation under the floor. There are a few recommendations that he made, but the lack of the barrier and insulation was the main culprit in his opinion.

As most of you know, we are in an informal lease to own on the house with my FIL. He's going to foot the bill on this. However, in frustration (which I completely understand) he tried to say it was cause by us keeping the house too cold in the summer. During the nights, we keep the temp around 70 so that I can sleep. I get very hot very easily and have to have a room cool and a fan blowing to stand a chance of sleep. During summer days, the temp is usually 71 to 73. During the winter, we actually have to bump the temps up. We do this mainly because of a lack of insulation in most of the house.

I've offered to do a lot of the work myself to help save money, but I'm wondering if our A/C usage could have actually caused it. Obviously it could have contributed, but I doubt it was the main cause. Remember, I live in Alabama, so we have high temps and humidity during the summer.

[leehljp]

I have to agree with your FIL as to the cause. Cool does attract condensation. I am not without blame as we also live in an older house that was not built for AC, but rather window air circulation. The alternatives are: moisture barriers and or powered vents. This last one makes me think you have air vents around the base of the house, is this correct? If so, powered vents to draw more air and pull out moisture would probably be needed.

Also, you probably should get the sub flooring inspected for mold. Our termite inspector told us last month that even though we were termite free, we had some mold under a couple of rooms (that we keep cooler than the rest of the house). He said it is not bad yet, but it could increase if we did't do something about it. He recommended some spray ($350) and a couple of electric fan vents. (I had two new ones given to me about 10 years ago and I need to install them.) The mold, by the way, was tested and it is not the dangerous kind, but still we are about to get it sprayed.

BTW, I sweat considerably when temps get above 75, unless there is a lot of air movement. We keep our night time (from around 10 PM) AC down to about 68°. The programmable thermostats do a good job of keeping the temps at the right setting at the right times of day/night for us and it has reduced our electric consumption from when we had one temp all the time. The programmable thermostats are not that expensive compared to "smart thermostats".

I am not an expert on the above, but it is my observation. I draw my conclusions from the best I know how - from the observations and experiences. They are not scientific, so I welcome the more experienced ones to give better advice.

[capncarl]

Want to really see condensation and mold in Alabama? Turn your thermostat up. Operating the ac at a lower temp should be keeping the Rh lower and moisture under control better. Installing a moisture barrier in the crawl space requires simply spreading out poly. Not fun but not that expensive to have an insulation companies laborers do it. It is curious that after 55 years this problem shows up. You are probably not the first person living in that house that keeps the house cool.
I'd take a peek under the house myself and see if you have a small pipe leak causing the problem. It could be a pin hole in the pipe spraying a mist on the wood.

[Kristofor]

Want to really see condensation and mold in Alabama? Turn your thermostat up. Operating the ac at a lower temp should be keeping the Rh lower and moisture under control better.

Nah, for condensation to form the surface needs to be at/under the dew point. Turning the temperature up would reduce or eliminate the condensation (though it still may be plenty damp under the house).

If the moisture is coming from the ground then a vapor barrier or powered venting would help, but if it's from simply high ambient humidity that's not going to help. Pushing more air would help dry things out during the warmer part of the day but would exacerbate the problem when the floor temperature is below the dew point.

[capncarl]

Kris is correct about the dew forming on the colder wood, but I have not been able to distinguish between moisture under a house because of the living area temp being at or around 72 vrs where persons not living in it want it! (My observations are based on only 7-8 houses, not a whole city though) If the thermostat setting was causing the problem I would expect other areas of the floor to be rotting out as well. I still stick by my 1st forecast that there is a pipe leak spraying water on that board.
if you could get the floor insulated it would be nice, and your utility bill would drop a bit.

[leehljp]

Old houses not originally made for 24/7 central A/C:
When I was in college in the mid to late 60's, my parents moved from a farm into a small community of about 1500 people. They bought a then 30+ year old house (built in the early 30's. At that time, A/C was not around and cooling was done by fans and windows open. Mom and Dad grew up this way. This house, and probably JSU-s house were not built for A/C. These types of houses were meant for window and fan air circulation as much as anything else. Heating in the winter did not draw moisture UNDER the house, but some rooms inside the house would draw moisture (from gas heat) on one wall in some specific circumstances.

Humidity drawn to cool:
However the O.P. was addressing the humidity under the house. Many old farm houses were built up on blocks to allow free circulation (and dogs stayed there as well ) The purpose as much as anything else was that moisture trapped was what drew termites. For aesthetic reasons as well as to keep varmints out, the underside was skirted in with either tin or concrete or bricks and "air vents" placed in. This is probably the situation in the O.P.

This situation will allow humidity in fast but not out very fast. Now, with a cooling of two or three rooms more than others, the cool inside floors draw the humidity to those spots. This is what is happening to our house now - since LOML and I moved back from Japan. It did not occur before.

Why did it not occur before? Simple, My mom and dad grew up without AC and only used it in the hottest parts of the day (in the hottest part of the summer when the humidity level was 50% or less. And they used it mostly when company was here. Without company, they relied on fans. The previous owners relied on open windows and fans also. No A/C cooling. My daughter lived in this house from 2006 - 2010 (for free, house sitting) and she liked her privacy. She stayed in the one bedroom without central AC, but it had a window unit which was never used 24/7.

Without continuous cooling (24/7), the floors underneath did not draw moisture. Its like a glass of fresh done water with ice in it. Fill with ice, fill with water and the outside is dry. Set it on the table and in 3 minutes, moisture is running down to the table. The cold is on the inside. The outside walls (and in this case the underside of the "continuously cool room's" floors draw moisture to it. This doesn't usually happen with window units that are on 6 to 8 hours, or overnight only. It happens much more when the AC is on continuously. These houses and floors were not built for 24/7 A/C cooling. The need for a moisture barrier was discovered/realized - for that very purpose - to prevent moisture from going to the wood and condensing on the cooler wood. Our two rooms that need to be treated are the ones in which we have the AC registers fully open - our bedroom and den. The kitchen does get cool air but two under-house vents are located at the kitchen. They stay dry.

I am willing to bet before I hear the answer - that JSUPreston has several shade trees around his house, and maybe even bushes around the sides of the house, particularly the sides facing the sun. This will slow air from circulating and moisture from escaping.

A moisture barrier attached to the floor joists will stop this under the house - IF this is THE problem.

LEAKS: IF Bubbles form, as he mentioned - Carl, You probably are right about that too. Especially IF they have copper pipes, a pin hole would be the problem. It could be a combination of both.

My daughter's '50s house had copper pipes and it sprang a leak two years ago. Had to replace floors in two rooms and the hall. She had to replace joists in one room. It had leaked for several months with a pin hole, and for about a week heavily before they realized what was happening.

The organization that I work with now - has had some old houses donated to us over the years, and one house (nearly 100 years old) has been used to let people live in temporarily in emergencies and also for volunteer teams from churches to come and work in the area. The water pipes are the old iron pipes. Recently, after not being used for about 6 months, a lady from a church went to clean it up and prepare it for use for a week. She turned on the washing machine to clean some linen. The force of the washing machine stopping the flow of water, caused the water pipe to break - about 18 inches underground just at edge of the house. Old pipes can cause problems too!

[pelligrini]

I'm sure the low temp settings on the AC contributed to much of your problems, as well as the lack of insulation. The condensation might not have been as much with a vapor barrier, but there still would be moisture issues.

It wouldn't be the cheapest fix, but insulating the underside of the house (after you fix the subfloor) with closed cell foam would be the best solution. The closed cell will also act as a vapor barrier. Hopefully there is enough room in the crawlspace to do the work.

[cwsmith]

It's not clear to me whether this house is on a slab or whether it is raised with floor joists on some kind of footer or supports and an actual air space between the floor and ground. (Perhaps I've missed something.)

My maternal grandparents lived in Enfield, NC in one of those typical dumpy-looking shacks built in the late 1800's and for the first third of the 20th century. Lapboard siding, tin roof, and brick pillars holding the whole thing up about two or three foot off the ground. No insulation anywhere and certainly no A/C. But, there was plenty of ventilation, so no rot or moisture built up either.

I know for a while a lot of homes in the south (and up north too) were built on concrete slabs. No moisture barrier many times, and I imagine ground moisture would have been seriously disturbing over time. Termites and other insect infestations were too often a problem too. How you go about fixing a house like that I have no idea... just a serious building problem all around.

I have a house in Painted Post, NY with serious moisture problems, even though it has a full basement. The surroundin ground is fraught with springs and subsequently the poured concrete walls are always cold, summer or winter. When we first bought the house, more than 35 years ago, we thought that opening the basement windows would be the thing. Totally wrong, as the humid air condensed on the walls, and within days the basement became a mold factory. Only cure was to run a dehumidifier during those warm humid times (about eight months out of the year).

Here in Binghamton we have an old (1887) house with about 2800 sq. ft. We also have central air and heat, but no moisture problems. I have the basement and walk-up attic insulated, but the first and second floor walls are not. We run a dehumidifier in the basement, keeping the humidity down to 60%. We only run it for about six months, about eight hours a day. It is electronically controlled so it cycles on and off during that time. The central air keeps the moisture (humidity) down in the rest of the house. We only use it on days when the outside temperatures are in the mid-80's and above. (I too cannot tolerate the heat very well, and as I get older it bothers me more and more.) While it is not ideal, we don't have any mold, mildew or insect problems.

During the summer, moisture poses a problem from the general humidity of the area. Here in NY's Southern Tier, the humidity is very bad in the warmer months. In the winter, temperatures drop well below freezing and moisture poses a problem if it is allowed to build up within the house (showers, washing, cooking, etc.). So in the winter, you can tell improper venting by the moisture that will build up on the inside of the windows. A properly built/maintained house needs to be ventilated, but also maintain a certain level of humidity while doing so. Dry winter air isn't good for long periods either. In our particular case, we have a high-efficiency, forced-air furnace which maintains the internal humidity, while at the same time ventilating excess.

Warm air holds moisture quite well, and that humidity can cause problems with a house, and certainly discomfort for many of us. When a house is air-conditioned that moisture will condense on colder surfaces. Cold air simply won't hold moisture, so as the humid air is chilled, the moisture drops out... that is what happens when the humid air touches the side of a cold beverage glass; the air cools at it contacts that cold surface and the moisture condenses on the surface of the glass. Likewise, will be the warm humid air that penetrates the underside of the floor or outside of the walls. Condensation will form on the underside of a cold floor covering or the exterior of whatever vapor barrier it encounters if there is a drastic temperature difference. In the winter, the paint will peel on the outside walls and in the summer, from the inside walls. Proper vapor barriers and insulation is absolutely essential almost every where you live, otherwise ventilation is a necessity to fully equalize interior/exterior spaces.

CWS

[dbhost]

I couldn't disagree more. Yes cold does tend to attract moisture, which means the cold AC coils are going to suck the moisture out of the air before it has a chance to even come in contact with a wooden floor.

There are TONS of old structures here with plenty of exposed wood where the AC is kept at around 68 deg during the summer with no ill effect.

[Kristofor]

I couldn't disagree more. Yes cold does tend to attract moisture, which means the cold AC coils are going to suck the moisture out of the air before it has a chance to even come in contact with a wooden floor.

This would be true if they were running the A/C to cool and dry the air underneath the house. The damp air down there never gets near the cold A/C coils but it does come in contact with the (relatively) cool floor. This is assuming the water is coming from condensation under the house, if it is a pipe leak under the floor or in a wall then all bets are off of course.

[leehljp]

This would be true if they were running the A/C to cool and dry the air underneath the house. The damp air down there never gets near the cold A/C coils but it does come in contact with the (relatively) cool floor. This is assuming the water is coming from condensation under the house, if it is a pipe leak under the floor or in a wall then all bets are off of course.

What Kristofor said: "The damp air down there never gets near the cold A/C coils but it does come in contact with the (relatively) cool floor."

dbhost: Yes cold does tend to attract moisture, which means the cold AC coils are going to suck the moisture out of the air before it has a chance to even come in contact with a wooden floor.

Doesn't work this way. The A/C coils are not under the floor where the moisture is.

[atgcpaul]

We had a similar problem in my old lab. Our seed storage room was cooled to around 50degF. Underneath it was another lab's zebrafish tanks which they kept warm. All the condensation on the ceiling (and underside) of our floor rotted it out. The whole thing had to be redone to essentially encapsulate the fish tanks and provide A LOT more ventilation.

[All Thumbs]

How could a problem like this be localized to just that area? Is this room of the house particularly cold or something? Something doesn't make sense.

[Stytooner]

Well today's temps should be more appealing to you. It say's 64 F on my back porch right now.

[leehljp]

How could a problem like this be localized to just that area? Is this room of the house particularly cold or something? Something doesn't make sense.

JSU has't responded yet for his specific situation. But for me, in which we have central air, we have the vents closed in most of the house (well, a bare minimal opening to allow a tad of circulation. But for the kitchen, den and bedroom, we keep the air at 68 at night and 73-74 in the day. The rest of the house is at about 78 - 82. Two of my daughters hate cold, so when they visit, they get the bedrooms with the vents almost closed. The third daughter loves Alaska weather!

So, yes, different parts of the house are different temps! We don't find this unusual as we lived in Japan for 25 years and in the last 15, most houses had what is known here as the split A/C units - to cool and heat specific rooms according to the need - from one central outside unit.