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posted: 3/23/2014 12:01 AM

Bathroom fans are creating a soggy mess in the attic

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Q. I have a two-story colonial built in the late 1970s in Shelburne, Vt. The two full baths upstairs have fans that just vent into the attic, which has blown-in insulation and a vent on each gable end.

In the winter, if we have a warm period, we will sometimes get a couple of water spots on the upstairs ceilings in a couple of different areas. I believe this is being caused when frozen condensation from the upstairs bathrooms melts and drips onto the ceiling Sheetrock. The roof was replaced about 10 years ago. We paid extra and had the ice and rain membrane put on the lower part of the roof at that time. There are no leaks that I have ever seen in the roof, even in the heaviest rain, so I can only assume the upstairs bathroom fans are bringing this moisture into the attic.

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I am looking to vent the bathroom fans outside. They are about 8 feet apart from each other. I have considered putting in a soffit vent for each fan, but I have heard some negatives about it causing mold problems in the attic. (I think this may be the case if the soffit is already vented and this allows the warm air to exit the bathroom soffit vent and rise back up into the attic through the vented soffit.)

The other option would be a roof vent, but I have heard negatives about cold air blowing into the bathroom from outside in addition to being a leak potential. Also, if you think a roof jack is best, can both fans be vented out the same jack?

A: You are right: The exhaust from the bathroom vents condenses on the roof sheathing and freezes. When the weather warms up, the ice melts and wets the cellulose insulation and the ceilings. The wet insulation loses its effectiveness and should be replaced if it does not dry naturally once the problem has been solved.

Gable vents in connection with soffit vents are not the best attic venting combination, but if no problems are found, which is not the case in your attic, there is no need to do anything about it.

It is unfortunate that when the roof was replaced 10 years ago, the gable vents were not closed off and an externally baffled ridge vent installed. It can still be done. A clear space between the soffit and ridge vents is essential for proper functioning.

The bathroom fans should be vented outside, but not through the roof, gable vents or soffits, as you have correctly found out.

Soffit vents are intake vents; any moisture discharged through them will be returned in the attic -- not much of an improvement over what you now have. Gable vents are both intakes and exhausts, depending on the wind direction. Roof vents in heating climates will produce condensation that will run down into the fan, causing some eventual rusting, and will also wet ceilings.

Each bath fan should be vented separately. Combining them into one exhaust vent can result in the discharge of the moisture from one bathroom into the other one. I once inspected an apartment building where this was done; one unit's bathroom was black with mold from the adjacent unit.

The best way to vent bathroom and kitchen fans is horizontally with the appropriate type of ducting. For bathrooms, schedule 20, 4-inch, 10-foot long PVC bell-end drainage pipes are best. The bell end should be facing the fan. A transition connects the fan outlet to the first section of the pipe. Additional full or partial sections of pipe are connected to the first one until the pipe exhausts through a gable wall and is capped with an aluminum or plastic hooded jack with a flap. Avoid louvered caps; I have seen too many of them with broken vanes.

It is best to set two small wood blocks of diminishing thickness under each section of pipe on top of several joists to allow the condensate to drain to the outside. If you have a lot of insulation covering the floor joist, add pieces of batts of decreasing thickness to achieve the same goal.

Snuggle 4-inch thick fiberglass batts on each side of the pipe and lay another strip on top to reduce the risk of the moisture condensing and freezing on its way out.

Q. It seems as if I know you because I read all your columns and save many for reference. My current question is about noise reduction methods in a 2-by-6-inch wall between my utility room and a future family room, which will also be the TV room for the house. The house is a 2-year-old, five-stars-plus home. The noise comes from the hot-air furnace room, but most is from the Rinnai wall-mount water heater. When running, it is noisy (I think it is the exhaust fan).

I am contemplating what to put in the 2-by-6-inch wall.

• Should I use the spray foam as they did in the joist pocket ends and fill it as much as possible?

• Should I dry fit foil-faced rigid foam panels, caulking after each one?

• Should I have the damp dense-pack cellulose or cotton sprayed in?

Which would afford me the best resistance to noise transmission (no thermal insulation is needed). Cost is also a consideration.

A. I assume that at least one side of the 2-by-6-inch wall is open. Or do you plan on opening one side up to have access?

The most effective way to soundproof the wall, since it is in the basement and weight should be no consideration on a concrete slab, would be to stack bricks or lightweight blocks to fill the space between the studs, as dense masonry is the best soundproofing method. But that is not too practical.

An alternative is to use sound-deadening blanket insulation, such as Quiet Batt friction-fit soundproofing insulation (www.soundproofcow.com), which is made of 80 percent natural cotton fibers, has an A rating for fire resistance and a sound rating of 1.00, which means it absorbs 100 percent of the sound. It is also ecological.

But where is the door to the utility space in relation to the Rinnai heater? If it is close to it, you will need to do something to increase the door's soundproofing, such as adding sound deadening board to one or both sides and weatherstripping it on all sides.

The ceiling may also need some soundproofing, which can be done with Quiet Batt insulation.

Q: I read your column every week and always find it helpful. I live in a 35-year-old house outside Chicago and find it is time for new windows. I have 31 windows that need to be replaced, so this will be a substantial investment. I would like your opinion as to which would be the best type of window and best manufacturer for the money.

A. If you want wood or fiberglass windows, Marvin windows are a good choice. You can check their line at www.marvin.com. If you prefer to use vinyl windows, you should research it locally and ask for references from several dealers. Ask for the names of customers who have had the windows for a couple of years, so they will be able to tell you if they are satisfied with their performance in the winter. When you call them, also ask these customers if they were satisfied with the installation and any needed follow-up.

Q. I have a problem with a new home. We are getting condensation on the inside of the windows and ice on the windows and frames in the really cold, single-digit temperatures. Even in summer with the air conditioning on, we have to wipe the edge of every window in the morning to prevent puddling on the window sill. The builder says it's a humidity problem, but I think it's either an installation or window quality problem. Humidity is reading 35 percent. What's your opinion on this problem? The builder says it's our responsibility to correct the humidity. Many people in our development of patio homes have the same problem.

A. It is not unusual to experience high humidity levels in a new home, and it may take a couple of heating seasons to get the relative humidity down to acceptable levels.

Be sure not to use a humidifier if you have one on your furnace. Use bath and kitchen fans every time you shower and cook.

If the house is built tightly to today's standards, you may need to have an air-to-air heat exchanger installed.

Q. We turned our basement into an apartment for my mother-in-law. The problem is sound is being transmitted upstairs through the ductwork for the heating system, which is shared by both levels of the house. We insulated and drywalled the ceilings, but the sound is magnified like a microphone from the ductwork between both levels.

A. You can buy magnetic vent covers in hardware, big-box and building supply stores.

Helpful suggestion from a reader: "I noticed in your column a few of your readers wrote about what to use to clean the shower area. I never have a problem keeping my shower stall clean. Every time I take a shower, I wipe the walls down with the same towel after I have wiped myself. I have also had a walker in my shower for 12 years, as I have a walk-in shower enclosure and cannot have any grab bars installed. I also wipe down the walker each time and it is still in perfect condition. No cleaners needed."

• Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. Write to him in care of the Daily Herald, P.O. Box 280, Arlington Heights, IL 60006, or via email at henridemarne@gmavt.net.

© 2014, United Feature Syndicate Inc.

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