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posted: 6/29/2014 12:01 AM

Weather, clean surface key to asphalt sealant application

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Q. My problem is my blacktop sealer won't stay on. Originally, I thought this was because it was sprayed on and not brushed in, so last summer I cleaned the drive with my 1,300-psi power washer and applied Sealbest 400 to the drive when dry on a nice sunny day.

Now this spring, it is flaking off again after a tough winter with plenty of ice here in central Wisconsin.

What should I do now -- apply a petroleum-based sealer? Do the overhanging oak trees present a problem with their sap?

A. The adhesion failure of a seal coat on an asphalt driveway may be caused by a number of factors. Since you haven't given me enough details, I'll run through the gamut, hoping you will see your problem.

If the sealer was applied too soon after the installation of the driveway, before all the oils have a chance to evaporate, the oils will prevent proper adhesion. A newly laid asphalt driveway needs several years for the oils to dissipate. You can tell when it is time to put on a sealer when the driveway turns a light gray and feels "dry."

Sealer failure can also occur if the driveway was not thoroughly cleaned before applying it. All kinds of pollutants may be embedded in the asphalt, and need to be removed. A power washer used with care so as not to damage the surface is a good way to clean the driveway.

Applying the original sealer in too cool weather or too thickly can also affect adhesion, as can a pitted or cracked surface.

Flaking or peeling can also occur if the original coat of sealer has not aged enough before applying another one. This may take several years.

Q. We have a west-facing, poured foundation wall in the garage with a window. The garage is a tandem style located under two bedrooms and two bathrooms in a raised ranch-style townhouse. In the winter, we always clean off the cars of the snow and ice so they won't melt off in the garage (there is no drain in the garage).

The problem we have with the wall is that in the winter, the wall freezes and condensation causes mold to grow. We've found that by running a small fan on a shelf facing the wall helps a little to keep the frost from forming, but not completely. Our neighbor, whose unit is attached to ours with the same footprint, does not have this problem with his garage wall. Do you have any recommendations for rectifying this problem?

A. Is your poured concrete garage wall exposed to the elements or mostly underground? How about your neighbor's wall?

If your wall is mostly exposed, it gets very cold, and you are bringing cars with a lot of moisture in the undercarriage and on tire treads in spite of the snow and ice removal. The cars are also warm, which allows some of the remaining moisture to be absorbed in the slightly warmer air. Condensation occurs on the cold concrete wall.

If your concrete wall is mostly underground, although the same dynamics can play, (albeit in a slower time frame), the protection from the earth may prevent the condensation altogether.

This may explain why you have a problem and your neighbor does not. From the little information you gave me, this is the best I can come up with.

A solution might be to adhere rigid XPS insulation on the concrete wall after a good cleaning, using Styrobond or a polyurethane caulking compound, either of which you can buy in a building supply house. The insulation needs to be covered with a fire-resistant coating or material.

But insulating an underground foundation wall may risk causing it to crack unless the backfill was completed over a protected drainage system with coarse material, topped with loam sloping gently away to drain rain away from the foundation. The topsoil should grow grass or a ground cover.

Q. Our house was built in 1920 with a crawl space instead of a basement. Recently, I have suffered from a runny nose when I am home that disappears when I leave the house and go to other buildings. I assume I am reacting to mold or mildew and guessing it is from the crawl space. There are small vents to the space, but there is not enough distance between the sand and the floor joists for a person to get in and move about to do much. Do you have any suggestions?

A. Your allergic reaction can very well be from moisture in the crawl space. Even sand can exude considerable amounts of moisture, although it may seem dry.

The solution would be to get a small and agile person to crawl in there and lay 6-mil plastic thoroughly over the entire crawl space.

Once any mildew smell is gone, the vents should be closed because they introduce cold air in the winter and humidity in the summer.

Q. How do I properly vent a bathroom ceiling fan in a one-story hip-roof house? I have read several of your columns with venting advice, but never dealing with a hip roof, which has no gable or wall to exit the vent. I do have soffit vents 3 feet away, but you always say not to vent there or into the attic space.

It seems the only choice I have is to run 14 feet of 4-inch plastic vent tube (dryer type) up to the ridge vent. Is that too long a run? How far from the ridge opening should the tube end? And how do I keep condensation from running back down into the fan?

A. Several readers have asked the same question. Here is my answer to a previous reader, which applies to all hip roofs. It covers the subject as fully as I can.

"It is never a good idea to discharge a bathroom or kitchen fan through a soffit, gable or ridge vent, or the roof itself.

"The most efficient way to vent bathrooms is to do so downward through a basement or crawl space and outside through the rim joists.

"So if the fan is to be installed in a first-floor bathroom, see if this can be done in an inside wall, so as not to disturb any insulation in exterior walls. If need be, the vent can be run through a closet or in the corner of a room and boxed in. A bathroom fan does not need to be installed in a ceiling -- it can be installed on a wall.

"Venting downward respects the laws of physics, which allows us to save energy. When a fan is vented upward through an attic to the outside, the stack effect encourages warm, moist air to continually exhaust because the flap of the outside jack is not airtight, and is constantly pushed open by the exhausting air.

"When a fan is vented through the rim, or band, joists, the normal stack effect in the house seals the flap, thus preventing the loss of energy suffered by upward venting.

"But if the bathroom is on the second floor, and it cannot be vented down using the strategies outlined above, and you have a hip roof (thus no gable), you may have to vent it through a soffit.

"If you have soffit vents now, here is a possible solution: Have a metal piece about 2 feet wide and as deep as the overhang made up to cover the vented soffit above the fan's jack. It should have both ends bent down at a 90-degree angle and dropping about 3 inches. The far end at the roofline should flare out at a 45-degree angle and also extend out about 3 inches to deflect the exhausting air away from the roof fascia. If your soffits are white, use the white side of the metal; but if dark, use the other side. A contractor with a metal brake can easily fashion this.

"If your soffits are not vented, you can use a special jack that spreads the exhaust to each side. This may eventually cause paint problems from all that moisture unless you install a metal shield as described above.

"If the duct runs in the attic, it should be insulated by snugging R-15 batts on each side and on its top to reduce condensation.

"The best ducting to use is Schedule 20 bell-end PVC pipes. The bell-ends should face the fan, and it is best to slant the pipes slightly toward the outside by placing small blocks of diminishing size under the ducts. Any condensation will run to the outside. Insulate them as described above."

Q. I have a 15-year-old home here in South Burlington, Vermont, with vinyl siding. I have noticed I have a green fungus that is slowly spreading on the siding. It used to be on the sunless areas and now is spreading to the brighter areas. I do have a power washer. What do you suggest?

A. The best way to wash the siding and remove the green stains is to mix equal parts of EcoGeeks' Deck & Patio Cleaner and OXY-Boost in hot water. Apply it with a regular garden sprayer and brush it in, or just use a brush.

This is not only one of the most effective cleaners for siding, but it is also environmentally safe.

One of my clients had his painter use it with great results. His painter told him he had never seen anything work as well.

You can buy both products online at

• 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

© 2014, United Feature Syndicate Inc.

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