Home repair: Moss loves a damp roof

Q. A friend from Vermont suggested I write to you regarding a problem I am having with the shingles on my house roof, which has a number of annoying small clumps of moss on it. Some look green while others, I assume, have died there and now are brown. The moss is on the shingles on the north side of the house. The south side has no problem. I have tried spraying them with a solution that does not seem to dissolve the small clumps (about the size of 50-cent pieces).

Would you know of any solution to such a problem? The liquid I tried is called Safer Brand Moss and Algae Killer and Surface Cleaner. Suggested use is on fences, roofs and lawns. It is nonstaining, but it has not solved my problem. I appreciate greatly any suggestion you may offer.

A. It may take awhile to see results with the product you used. I have not had the opportunity to try it and have not heard from anyone who has. You may want to give it a chance to work before trying something else; all these materials take time to work.

The north side of your roof is affected because it does not dry from rain and dew as quickly. Moss, lichens, mildew and mold will grow on any shingle roof that remains wet or damp for an extended time.

Moss and lichens can be killed with a mixture of three parts white vinegar and one part water. Apply it in warm weather, but be prepared for a long wait before the moss turns brown. The moss will not fall off the roof easily; it will take strong rains or manual plucking to remove the clumps. Moss does not materially affect the life of asphalt and fiberglass shingles.

Q. We are buying a 20-year-old double-wide with the intention of renting it. The carpet has a very bad odor due to many indoor cats. We intend to pull up the carpet and padding. Is laminate flooring the best bet for wear and price? We definitely do not want carpeting. Any suggestions for odor removal prior to putting down a new floor?

A. Faced with a similar situation many years ago, I washed the subfloor with Pine-Sol, and it did a great job.

Laminate flooring is relatively less expensive than other floor finishes, and it is very durable if properly maintained. Since it is possible that tenants would not keep the floor clean of dirt and sand or wipe spills quickly (which may cause the planks to warp), you may end up with a scratched or buckled surface that cannot be repaired, short of replacement.

Most laminate flooring is manufactured using formaldehyde. This may present a health hazard to sensitive persons, and its outgassing is certainly not conducive to a healthy environment in the house.

Engineered flooring may be a better option in a rental property. But be sure to choose one that has a thick enough top layer so it can be sanded lightly if needed in case of tenant turnover.

Engineered floors are more expensive than laminate flooring, but they may end up costing you less in the long run.

Q. We had structural support work done in the basement last year that caused slight resettling throughout the three floors of our 1898 wooden home. We’re waiting until the building has stabilized before we repair the many cracks in the original plaster/lath walls and some ceilings that have resulted from this work. My question is, what time of year would be ideal to do these repairs? In midsummer when the humidity is highest, or in midwinter when the humidity is lowest? Or some other time of year? I’m thinking about the normal expansion and contraction of a balloon-framed building.

A. Sometimes the best time to do this type of work is when workers are available. Technically speaking, in my opinion, it is best to do it in the early spring, after the heating season, when the house has dried up from summer moisture, which takes several months, and before the high humidity of summer loads up the house again.

Q. I have a particular problem with my dining room chairs. When guests are seated and shift position, the chairs make a lot of squeaking sounds, which is a little embarrassing, I’m sure, to my guests. It is an old set that once belonged to my grandmother. I am 67, so this set has been around awhile.

Is there anything I can do to wooden chairs that will eliminate the squeak? I read your column all the time and have received such valuable information in the past that I hope you can help me with this problem.

A. You may be making too big a deal of this. The glue of the joints of old furniture may dry up and the parts loosen. Probably, your best solution is to take the chairs to a furniture restorer and refinisher.

Q. I recently had my attic reinsulated, and the installer sold me on installing a dehumidifier on the existing attic fan. The fan was there when we bought the house. He set the control at 40 percent. Since that time, the fan has constantly run. Bathroom fans are vented through the roof. Is there any proper setting for this unit? The answers I found on the Internet are quite confusing.

A. It sounds as if you have been sold a bill of goods! There is no need for a dehumidifier in an attic. It would be highly ineffective at low winter temperatures and cost you a bundle in electricity, and it is not needed in the summer, either. An attic fan is also a robber of energy, as it draws conditioned air to satisfy its CFM rating, since most attic ventilation is insufficient to provide it. It is best not to depend on an attic fan to ventilate an attic and instead get it done with an effective soffit and ridge venting system.

Bathroom and kitchen fans should not be run through roofs in cold climates, as condensation forms in the vents and runs down the ducts where it can stain ceilings, wet insulation and rust the fans. These fans should be ducted to a gable wall; the ducts should be kept as low as possible and be covered with insulation.

Q. I believe I saw an article written by you about Sikaflex-1a. My problem is a shower basin that has some mildew growing where it was caulked against the stone tile walls. Is this product a better solution than recaulking? Since they charge shipping and handling, I want to be sure this is a correct product for my intended use.

A. If the mildew cannot be removed with a Clorox bleach solution, the caulking is probably silicone because the mildew penetrates it deeply. In that case, you will have to remove it, which should be relatively easy, as silicone peels off like a rubber band.

To be successful with Sikaflex-1a, you need to allow it to air-cure at least seven days, otherwise it will turn pink if in contact with water. So this is not practical for people with only one bathroom. Over time, white Sikaflex-1a will turn slightly gray, which has not been objectionable to me, but is to some people.

I have also used DAP Kwik Seal PLUS Premium kitchen and bath adhesive caulk with Microban because of its claim that it is mildew-proof. It seemed to work very well. It remained sparkling white and did not mildew. Unfortunately, I found that it began to peel off the wall in about a year. So I prefer to stick to Sikaflex-1a and its slight graying.

Sikaflex-1a tubes sell for less than $5 in A.H. Harris stores (www.ahharris.com), found throughout the Northeast. You can also buy it from DHC Supplies, www.dhcsupplies.com. Home Depot stores do not carry Sikaflex-1a but do carry Sika Construction Sealant, which looks quite the same to me.

Q. I have two questions. First, I am installing vinyl siding on my house and I want to put 1-inch blue board insulation over house wrap and then install the vinyl. Do you see any problems? Second, I have built a new chimney with masonry block and insulated it with vermiculite between the flue and block. I want to know if there is any problem with painting the exterior of the block so it will match the house.

A. There is no problem with either one of your projects, as long as you make sure the chimney cap is very tight so water will not wet the insulation or the blocks and cause your paint to peel.

You sound like a very handy person, great to have around!

Q. I have just treated my newly installed (six months ago) deck with a mixture of half paint thinner and half boiled linseed oil. I saw somewhere that this was the best treatment for a wooden deck. 1) In your opinion, is this true? 2) How many times should I apply the mixture on this initial treatment? Could I apply today and do it again tomorrow; would it help significantly? 3) How often do you recommend treating the deck? What can I look for that would indicate a reapplication? 4) What, in your opinion, is the best way to clean the deck? 5) If I wanted to color the treatment solution, what would you suggest?

A. The solution you used may work for a while, but it is best to apply a coating specially made for what I assume is a pressure-treated deck. I haven’t used a mixture of boiled linseed oil and paint thinner on a wood deck before, but I know that it is a recommended sealant for exterior concrete surfaces (not recommended for indoor or garage floors because it would not effectively dry).

On a new deck, you should use a product, such as Wolman, made especially for new pressure-treated wood. On a 6-month-old deck, you can use a preservative stain such as Amteco TWP (www.amteco.com). These products come in several hues. Stay away from solid-body products and paints that would not penetrate the wood and eventually would peel off. A proper coating should last two to three years before needing to be reapplied. But that depends on the wear and tear.

The best way to clean a wooden deck is with a low-pressure power washer.

Ÿ 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. His book, “About the House,” is available at www.upperaccess.com and in bookstores.

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