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Roof/moisture in house issues

Billsnogo | Posted in General Questions on

Lots of info before the question. I have a low pitched (around 3/12) rambler manufactured home built in 1969 that has cathedral ceilings, looks like some paneling similar to sheetrock is attached to the bottom of the roof RAFTERS (no trusses). The kitchen area, the area above the bathroom, central hallway and the closet at the house entryway have closed in dropped (not sure if that is the proper term)ceilings that allow dead air space. Roof was supposed to be two years old when we bought the house (as-is from hack home flipper), but the roof was rotted and spongy after 12 years, mainly around the bathroom. The house flipper remodeled it and never hooked up the bathroom vent and just let it vent into the dead airspace above the bathroom and into the roof thru the hole in the paneling attached to the paneling under the rafters. Two years ago I had chose a contractor that suggested ripping off the decking and use closed cell foam insulation as it will act as a vapor barrier since the only one I had was crumpling away on the fiberglass insulation in the ceiling. They ripped off the decking and added 2×2 strips on the 2×6 rafters to get me in the r30 range after spraying. Then they added a ridge vent instead of the three turtle vents we had. 

Fast forward to this late spring and a couple of issues exist. First showed up last year that a few areas have the 2×2 sections slightly lifted, one more so, and that one is likely due to a vent (likely was an old range vent) that was never pulled and sealed up and the roofers put a turtle over it. I asked what that vent was for and they said there had been a vent pipe. I had no idea what it could have been for, so I shrugged it off. Well, last year (roof one year old) called the contractor and told them about the raised section and they looked at it and didnt know why it was raised like that. They said they would fix it, but they first wanted to find out why this happened. Winter came and it was obvious there had been heat loss in this area along with the area by my front entrance. There is dropped ceiling with dead air space by my entrace, but maybe also could be a door not the best sealed leaking warm air up into the soffit?

Anyway, fast forward to about a month ago I noticed mold growing on an interior wall in my main hallway, the bathroom shares this wall, and damp to the touch on the bottom 10 inches in parts of that wall. I freaked out thinking it was a roof leak, called the contractor, they came out and looked things over. The one area that is obviously raised on the roof looks to be an old range vent that was never pulled out or sealed off properly, so he is thinking that is what caused the roof issue, and needed to be removed. Then he asked if the damp wall occurred before the roof and spray foam insulation, and I said no. He suggested using a dehumidifier for the time being. I used vinegar to clean up the mold and put the dehumidifier in the hall for two days, then moved it into the bedroom across the hall and set it to 60% and have not had any damp feeling to the wall in the hall since. The wall opposite in the hall had no damp feel to it, and that wall is shared by a bedroom with no dropped ceiling with dead air space, but the damp wall is the side shared with the bathroom with the dead air space. Funny thing is my bedroom shares a wall with the bathroom, and in my closet ceiling there is open space that is the dead air space above the bathroom, in other words the wall of my closet does not go all the way up to the cathedral ceiling , it is open from the top of the framing of the false ceiling up to the cathederal ceiling. I don’t have a closet door so it is always open, but mind you the opening to the dead air space is not much more than maybe 12″ tall at the edge of the closet opening.

The contractor told me they want to spray insulation foam in the dead air spaces and any of the dead air spaces that they add insulation to, he will need to cut out the foam at the ridge to allow the heat to vent through the ridge vent.  All the vaulted ceilings will stay as they are.  It’s just the dead air spaces they need to insulate and vent out at the peak.

My concern is two things, one is if they fill the area with foam, will that not create two vapor barriers if it is not completely filled up? If they fill it all up, will it be a non issue? I asked if they planned to fill it completely up and am waiting for a reply. My house is full electric so we do not have a furnace, but previous owners had central air installed at one point and I have ducting up in that area above the bathroom, and might want one again and need that space to run the ducting so I might have to cut access to those areas and hook up all the ducting again (has been moved around and disconnected since it has not been used). But one concern is how safe is it to spray foam all around the bathroom vent fan and wiring up there.

Does what the contractor plans on doing sound like a sound choice? Is the dead air space likely causing the damp wall? Has anyone seen anything like this before? Also any idea why a few of the firred out 2×2’s on the roof would of lifted?
Need some advice before I let him proceed.
thanks in advance to anyone with the knowledge that is willing to give your views/opinions on what might be happening.

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  1. GBA Editor
    Brian Pontolilo | | #1

    Hi Bill.

    Let's clarify a few things to help folks who may want to reply to your question:

    -Where is your house?
    -It sounds like you have a vented cathedral ceiling, meaning that there are soffit to ridge vent channels between the roof sheathing and the spray foam insulation. Is that correct?
    -The entire roof was insulated, not just the cathedral sections. Is that correct?
    -Do you now have bathroom and kitchen exhaust fans ducted to the outside? Do you use them?
    -Are you running A/C regularly?
    -It sounds like the dehumidifier solved the problem. Is that correct?

    1. Billsnogo | | #2

      Twin cities, minnesota.

      Yes, vented soffits, ridge vent, and air gap between the top of the foam and roof deck provided by the 2x2's nailed on top of the rafters.

      Yes the entire roof was isulated that way

      Kitchen has a ventless hood, bathroom fan is vented thru the roof. That bathroom is my wife's, and just found out she only uses it to vent out smells when on the toilet not when bathing (she only does baths, not showers)

      We do not run a/c regularly, only window air in bedrooms but thinking about having the central air setup fixed

      Seems better with the dehumidifier set at 60%, or at least no mold, but walls MIGHT feel damp at times BUT could be me over nervous as several walls throughout the house feel that way when touching them. Thinking more that it is in my head


  2. Billsnogo | | #3

    Not sure if I should start a new topic or just add on to this one?

    Okay, walls felt pretty damp on the bottoms again, weird that the most damp are interior walls on the bottom, so is it possible the cooler air from my finished basement causing this? I do not cool the upstairs other than two bedrooms. Weather gauges said 86 degrees and 72 percent humidity in the living room. I moved the dehumidifier into the living room for now. I know I need to work on two things that are probably causing interior moisture, the bathroom downstairs does not have a fan that vents outside, and out oven has a ventless hood. I am trying to get quotes to get these both vented outside. I do run a dehumidifier all year round down the the basement, but never did upstairs until I discovered the wet bottom of the walls.

    So I had a hvac contractor come out and give me an estimate to add a ductless mini-split system. I heat with electric baseboard heating, nice as my wife likes her room warmer than mine year round. Sounds like the system, a Hyper Mitsubishi 3 head unit (inside unit in two different bedrooms and one in the kitchen/living room area), that way we can control the temp differences that my wife and I like. He said it should remove any humidity troubles, BUT I forgot to ask if it also draws out the humidity during the winter, I assume not. Should help reduce the amount we use our baseboard electric heaters also, but starting to wonder if it is worth the extra for the heating option as it looks like our cost for electricity is .09 cents kWh winter and .13 cents summer rate. Cost for a 15k unit in living room, and 6k in each room would be $12,000. Trying to decide if this is a good option, or spend the money else where. Thinking about getting an energy audit to see if any bad leaking or if insulation is bad in the walls.

    So, penny for your thoughts? am I MAYBE right thinking the bottom of the walls being wet are because the humidity coming from the basement, or is that false logic. Trying to get some progress without just having to pay a contractor and not getting much for results..... and more late nights with little sleep thinking about my house having issues that need addressing.

    thanks as always :/

  3. creativedestruction | | #4

    Hi Bill,
    Lots of info there. I think you're on the right track with getting a bath fan in the basement and a vented range hood. I can't be sure without seeing the full picture, but I don't think more foam will solve your issues.

    The previously-installed ceiling foam made your house tighter, which is good apart from increasing the likelihood of elevated moisture. That can easily warp 2x2's. Less energy loss, infiltration and exfiltration means the A/C runs less and uses less energy, but then it dehumidifies less.

    I would put bath fans on timer switches to run them for 10-15 minutes during every shower and bath. Humidity-sensing switches are another option. Dehumidifier can be run in the basement during summer for good measure.

    Best of luck!

  4. Billsnogo | | #5

    Thanks for the reply :D
    I am guessing since I didn't know what I was dealing with, and still am needing to watch to know what is happening and why, but think I allowed too much moisture to build up in the house in the late winter/early spring without venting out the bathroom and kitchen and keeping windows/doors closed up. I have been keeping the windows and doors closed now for the last week and a half because we have had a long spell, and at minimum another week of pretty humid weather. If I open the windows in the morning to let the cooler air in, it gets very sticky as we have 66-70 dew points in the morning, EVERY morning for quite a while.

    But even without air conditioning in the house other than two bedrooms with window air, it stays between 80-85 degrees, and had been showing 60-65 for humidity, UNTIL today when I used a hygrometer I just bought off amazon instead of our "weather station" (temp/barameter/humidity gauge set). I had taken the hygrometer outside to check it against what they are reporting for weather. Then had taken it to the basement and check both ends that each have there own dehumidifier as the basement is pretty well split in half due to the stairs. Each side shows 47 percent and 79 degrees (been using a box fan to steal the cooler air to move it upstairs), which sounds pretty good percent of humidity, then the main floor (excluding the two a/c rooms) is 86 degrees (three degrees higher than outside) and 47% humidity (outside is 55% with 65 dewpoint), so with the lower humidity it is slightly better than outside.

    So looks like I have been freaking out looking at the weather station showing 60-65 percent humidity with keep the house closed up, but right now it shows 61%, compared to the new digital hygrometer showing 47%, which from what I read is acceptable and have been freaking out for nothing........
    Still going forward with adding a vented hood and bathroom fan, and replacing a few windows, AND making sure my front door is sealed up better. Huge load off my mind until winter, then need to make sure the humidity stays reasonable, and if it does, install a 3 or 4 head mini-split to help drop our heating cost, or at least allow us to up the heat to a more comfortable level (we use electric baseboard heat) and cool the house off on the hottest days.
    I will ask more questions later about the Mini-split if you guys are willing to put up with my endless questions. :D

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