Wet Attic Floorboards - HELP!!!

[Richard Niemiec]

OK, this is the situation. In the center of the attic, when humidity is high, generally in the summer (Northeast NJ), the floorboards and the ceiling joists become saturated with water. This only occurs in a small area in the center of the attic, far from any windows, right in the middle of the attic floor. This tends to dry out in the winter, but results in moisture damage to the ceiling below.

The roof is tight, no water enters the attic from the outside (confirmed by three different roofers, a home inspector and a structural engineer, all of which had moisture meters and actually sprayed down the roof to create leaks.) The wet area is not anywhere near the chimney. There is no plumbing in the attic at all. No mechanicals in the attic, no drain lines, nothing. Insulation is clear of the soffit vents and there is excellent air flow from them. Homeowner had previously installed all new soffit vents, new windows, and now most recently a roof attic fan with temp and humidity controls.

The new roof fan has been operating for two days now, and what is occuring is the wet area is growing, water actually pooling on the floorboards and joists, and running along them to increase the wet area.

Nobody can figure this out. I'm trying to help a coworker with this problem and the only thing I can come up with to tell her is that the increased air flow is drawing the moisture from the floorboards, wicking it to the surface. She shut off the fan, and I am going to advise her to put it on and leave it running for several weeks to see if this is in fact the case.

She called the manufacturer and they couldn't figure it out, and told her to shut the fan off. I think that they are simply worried about a lawsuit or claim and don't want to get involved so the safest thing is to tell her to shut it off.

Does anyone have any other ideas here?

Thanks to all. RN

[Joe Pelonio]

It seems unlikely that if the professionals couldn't solve this that one of us could, but here goes my idea anyway. Do they have bathroom and kitchen fans, venting to the outside? If not, even if so, if they are insufficient or there's a really high humidity, it could be traveling through the ceiling. Also,
do they run A/C in the home? That would make it even worse.

Warmer air (attic) absorbs more moisture than cooler air. The top side of the ceiling be cooler than the attic air, so would cause the warm moist air to condense on it.

If I'm right, a moisture barrier of kraft paper, foil, plastic or tyvek on the top of the ceiling wallboard should help. You'd have to remove all of the insulation, then put it back. Messy job I'd think.

[Brian Weick]

Rich,
Rather odd situation,but not uncommon If, and I do mean if, she doesn't have proper ventilation :ie soffit vent- ridge vent combined- that can cause high humidity and high moisture content and buildup. If the venting system is a baffle in between the roof rafters~ then insulation, then 4 mil vapor barrier combined with a full length ridge vent - she should have no problems. If this is the case- I would check to see if the ridge vent-is in fact , open at the top (3" gap) . with out knowing what she has for roof venting - it's hard to determine the problem. She may not have eve soffiting at all and has to use a gable end and ridge vent system- if that has been done at all. Even if she has a power fan installed , if there is no way for the fan to draw the outside air in - it is useless. something is not set up write (if it is the ventilation that is causing this problm) with the ventilation.- can you be a little more specific as to what ventilation system she has for the roof?
thank you
Brian

[Richard Niemiec]

Brian: She has soffit vents (new) and a roof mounted attic fan with "humidistat" and temperature automatic control switches. The air ventilates well from the soffits when the attic fan is on. Air circulation is not the problem, its just when the air circulates the water beads, then pools on top of the floorboards making the wet area larger.

Do you think my "wicking" theory holds water (pun intended!)?

[Brian Weick]

It seems unlikely that if the professionals couldn't solve this that one of us could, but here goes my idea anyway. Do they have bathroom and kitchen fans, venting to the outside? If not, even if so, if they are insufficient or there's a really high humidity, it could be traveling through the ceiling. Also,
do they run A/C in the home? That would make it even worse.

Warmer air (attic) absorbs more moisture than cooler air. The top side of the ceiling be cooler than the attic air, so would cause the warm moist air to condense on it.

If I'm right, a moisture barrier of kraft paper, foil, plastic or tyvek on the top of the ceiling wallboard should help. You'd have to remove all of the insulation, then put it back. Messy job I'd think.


Joe is correct,
That could be the problem and sounds like it may be the culprate , but who knows~ I don't know any of the specifics.
Brian

[David Epperson]

Warmer air (attic) absorbs more moisture than cooler air. The top side of the ceiling be cooler than the attic air, so would cause the warm moist air to condense on it.

I would think that a very quick test of the condensation theory ( And I happen to agree is probably the case) would be to rent a dehumidifier, set it up in the middle of the wet area and measure the collection for a few hours both with and without the fan running. One day with and one day without should provide a workable answer to the condensation question in less than a weekend. If it is a condensation problem, then it is also an insulation problem with the attic floor being cool enough (losing heat to the AC room below) to cause this level of condensation. Warmer flooring should not condense the moisture out of the air.

[Lee Schierer]

I suspect the problem is A/C related. Pulling in warm moist air from outside made the prblem worse. Turning off the attic fan is treating the symptom, but not curing the problem. Somewhere near the wet area there is and A/C duct that is either poorly insulated or has an air leak. Uninsulated drywall or wood can do the same thing. The cool air (or duct) is condensing moisture out of the air and it is running onto the ceiling or floor boards.

The fan increased the air flow through the attic which brought in a fresh supply of humid air. Stopping the fan will slow down the problem but not cure it.

What you need is a temperature probe to check the temp of the floor boards and air near the wet spot. I suspect the temp will closely mimic the a/c thermostat set point.

The problem will also go away if they don't run the A/C.

[Brian Weick]

Couple of questions:
Joe brought up a good point- bath fan/kitchen- is it running out through the ceiling and through the roof properly?
Does she have the Baffle/insulation/4 mil Polly combined with the full length ridge vent system?
If so - why did she have a power vent installed on the roof- that will not draw air from the sofffits (they are sealed off- if that system is applied correctly) it will only draw air from the ridge vent-(if she had that installed)
can you tell me exactly what has been done with the ventilation system- in detail.
Brian

[Brian Weick]

Brian: She has soffit vents (new) and a roof mounted attic fan with "humidistat" and temperature automatic control switches. The air ventilates well from the soffits when the attic fan is on. Air circulation is not the problem, its just when the air circulates the water beads, then pools on top of the floorboards making the wet area larger.

Do you think my "wicking" theory holds water (pun intended!)?


wicking, I don't think so - That power fan is adding to the problem- like I said - if she has had that roof venting system applied correctly and the roof joists and gable ends (if she has that roof system)insulated properly- there should be no problems. A proper ventilation system , if installed correctly works incredibly well and there should be no problem of moisture collecting anywhere in the attic. Someone mentioned A/C ductwork - that could be a definite possibility as well-absolutely. If it is leaking or poorly insulated around the ductwork - that could be the culprit.
Brian

[Brian Weick]

OK, this is the situation. In the center of the attic, when humidity is high, generally in the summer (Northeast NJ), the floorboards and the ceiling joists become saturated with water. This only occurs in a small area in the center of the attic, far from any windows, right in the middle of the attic floor. This tends to dry out in the winter, but results in moisture damage to the ceiling below.

The roof is tight, no water enters the attic from the outside (confirmed by three different roofers, a home inspector and a structural engineer, all of which had moisture meters and actually sprayed down the roof to create leaks.) The wet area is not anywhere near the chimney. There is no plumbing in the attic at all. No mechanicals in the attic, no drain lines, nothing. Insulation is clear of the soffit vents and there is excellent air flow from them. Homeowner had previously installed all new soffit vents, new windows, and now most recently a roof attic fan with temp and humidity controls.

The new roof fan has been operating for two days now, and what is occuring is the wet area is growing, water actually pooling on the floorboards and joists, and running along them to increase the wet area.

Nobody can figure this out. I'm trying to help a coworker with this problem and the only thing I can come up with to tell her is that the increased air flow is drawing the moisture from the floorboards, wicking it to the surface. She shut off the fan, and I am going to advise her to put it on and leave it running for several weeks to see if this is in fact the case.

She called the manufacturer and they couldn't figure it out, and told her to shut the fan off. I think that they are simply worried about a lawsuit or claim and don't want to get involved so the safest thing is to tell her to shut it off.

Does anyone have any other ideas here?

Thanks to all. RN

normally,
you don't use a power vent fan in conjunction with soffit venting-that application is usually used in conjunction with gable end venting- the home may not have soffiting and the joists are square to the wall ends with no hang over.It sounds to me that there is no insulation in the roof joists at all. If she has vented soffiting and the proper ridge vent installed - with baffles/insulation/ and 4 mil poly barrier on the roof joists- the movement of air occurs through the vented soffiting,into the roof joists through the baffles and out through the ridge vent. something doesn't sound write to me. If she doesn't have this venting system properly applied she is just bringing in the air from outside into the whole cavity of the attic and creating more problems.
Brian

[Richard Niemiec]

Brian: We have a one story ranch house, 50 years old. Nothing fancy, just a straight roof with soffits on front and back. New soffit vents were installed on both sides. Clear air flow from the soffit vents, e.g., the insulation is not blocking air flow. She first tried gable vents, no effect on the wet boards; she had new windows installed and left them open, again no help. She installed the roof fan with the humidity and temp switches (and was advised to put plastic over the gable vents so the air flow would come from the soffit vents, and I agree with that advice). She tells me you can feel the air circulating from the soffit vents.

After two days of using the roof fan, the boards are beading water, and she is fearful this is making the problem worse. Again, there are no other mechanicals in the attic, no pipes, vents, conduits and no ductwork (the house has no central AC, she uses window units, and then only when really needed.) The house has no kitchen or bath fans.

I have told her to sponge up the water that beads on the boards and keep track of how much volume she gets each day, and that could indicate if the boards are drying out with the new attic fan.

[Richard Niemiec]

Brian: Oh, I know you make a good point about the soffit venting acting in concert with the ridge vent, and there is no ridge vent, that's why they suggested a roof fan.

What I can't get over is why the immediate beading of water on the floor boards once the airflow was substantially improved. Again, this wetness only occurs in the virtual center of the attic floor and nowhere else. All the roof rafters are bone dry, as is the sheathing.

regards.rn

[Brian Weick]

Rich,
This hyperlink has 2 examples of how it should have been installed- left side is one example the right is the other. the right side diagram is using a strip but in your case you are using the vented soffit- makes no difference- the cavity has to be open. I think the reason it is getting worse is that fan is drawing moisture into the whole attic. Obviously you know if the air being drawn in is the opposite temperature of what is inside ~ your going to get moisture and possibly condensation and it will go to the place where that meeting is most abundant between the two temperatures ~ My point is , I hate to say this- but that fan has been applied to the wrong ventilation system in this case- based on what you have explained, make sure the baffles are in the roof joists, the insulation is applied over that and the 4 mil ploy barrier is installed from the eve to the ridge. the insulation and baffles should go write down into the cavity of the soffiting (ceiling the cavity off) ~ Then install a ridge vent system- that should have been done in this case. There will know be air movement inside the joists cavities- and should be unnoticeable if you are standing inside the attic.

http://imgs.ebuild.com/xCat/ebuildWebB/15?ObjectID=35295&Variant=Original

[Ben Grunow]

Hard to imagine that there is not a shower below with an exhaust fan that is not ducted outside or a recessed light in the bathroom that lets shower steam up into the attic.

You sure the water is not driipping from above? Place a piece of paper on a chair over the spot to see.

Just some thoughts.

[Brian Weick]

So is the verdict in as to the problem? :confused:
Brian