Wet & forget products will kill moss and stop mold

Q. A couple of years ago, you mentioned in your column a method to spray shingles to get rid of moss. Moss is becoming quite apparent on an area about 4 feet wide by 10 feet long.

What combo should I mix to spray the moss and get rid of it?

A. The easiest way to kill moss is to spray it with Wet & Forget, www.wetandforget.com. The manufacturer claims that it will get rid of mildew and algae, and kill lichen and moss - and that it is environmentally friendly.

A solution of equal parts water and white vinegar has also been suggested, but I have never tried it. It will also take a long time before you see results.

Q. During a free home energy audit, I was told that the program was unable to provide additional insulation in my small 1949 Cape Cod-style attic crawl space because there is vermiculite. The two upper bedrooms do not have built-in heating elements, so we use electric oil radiators. The auditor twice promised more information about the process that would be involved in adding insulation, but never followed through. Can you explain this process and the estimated cost?

Also, I just had my oil-burning furnace cleaned for the second time. They told me I should not switch the furnace off in the summer. I did this last summer because I have an electric water heater and do not see the purpose in keeping water used to circulate in the radiators hot for seven months when not needed. He said that condensation inside the furnace will eventually render it unusable. I'd never heard this before -- do you agree?

A. Vermiculite may contain asbestos fibers, but according to the CPSC, any asbestos product in good shape should not be disturbed. It is best to encapsulate it.

In the case of vermiculite insulation, if your attic is open and does not have floorboards (since you mention that it is a small crawl space, I assume it doesn't), you can have cellulose blown in to cover the vermiculite and increase the R-factor of your attic. As for the cost, you will need to get estimates from two or three local contractors.

Many boilers are shut off during the summer period without any problems. But if you want to make sure, call the manufacturer and ask what is recommended.

My longtime plumber friend just replaced his 37-year-old boiler with a more efficient one and told me that the interior of his old boiler was in perfect shape after so many years of being shut off during the summers. He just sold it to a neighbor.

Q. I am currently cleaning our porch ceiling in preparation for staining and sealing. As you can see by the first photo I sent, we have plenty of mold and mildew. It is unknown as to whether the wood had been sitting on the ground, unprotected, before being installed, or whether the problem occurred in the intervening years since its installation.

I have been using a product called, "Krud Kutter House and Siding" cleaner, and it has worked very, very well in taking the stains out of the wood, as shown in the second photo. The ceiling is raw wood.

I realized this morning, after cleaning about two-thirds of the ceiling with this cleaner and a scrub brush (brutal work), that the cleaner doesn't state on the label that it kills mold and mildew. However, in researching this question of needing to kill the spores before sealing, I read that it wasn't necessary as long as the surface was well-scrubbed and that trying to do more can "drive the spores deeper into the wood."

Other sources report that oxalic acid should be used to clean the wood and kill the spores before staining and sealing. I'm also wondering if a fungicide could be added to a staining and/or sealing product as well, to keep the mold and mildew from returning.

Is there an oxalic acid product I could simply spray on and rinse off in order to achieve the killing of the spores? Or is this even necessary? I sure don't want to apply any more product by hand if I can avoid it!

A. Are you sure that you do not have a roof leak? The photo showing the ceiling boards after cleaning also shows water stains where two boards join. That's not mold. A roof leak would also contribute to the heavy infestation on the boards that haven't been cleaned yet, and recurrence is likely. This needs to be checked and taken care of.

A simple way to make sure that all mold spores are killed is to wash the ceiling boards with white vinegar, or a solution containing borax or boric acid. You can also spray the boards with Wet & Forget Indoor. You can find out more about Wet & Forget on the product's website: www.wetandforget.com.

Once you have cleaned the mildew and the mold off, you can apply a new coating of your choice, but have mildewcide added to the coating.

Q. I have a 110-year-old home -- a three-decker apartment building where I live in the middle apartment and rent out the other two floors. I've been trying to keep the place in good shape and, in better financial times, had three energy-star gas boilers installed with hot water baseboard (HWBB) heating, blown-in cellulose wall insulation, and .30 energy-star windows installed.

Right now, however, times are tough, and I know I should try to do something with the dirt-floored cellar. Two-thirds of the cellar is 6 1/2 feet high and is walkable. Half of this walkable dirt floor had been asphalted by my late uncle, but the other half is still dirt, onto which my uncle applied thick plastic sheeting held in place by bricks every so many feet. The foundation is fieldstone with a cement mortar compound of some sort.

When summer would begin, my uncle's tradition was to open all three cellar windows (screened-in) and leave them open through sunny and rainy weather to "aerate" the cellar. When the cool weather would begin in the fall, he would shut/lock all the cellar windows, remove the screens and put storm windows back in.

• I have continued this "tradition," but after reading your recent column, and in view of all the other insulating/heating improvements I've had done, I'm not sure if I'm doing the right thing by keeping those windows open all summer long. Should I keep them closed always?

• The tenant lives above the cellar and the cellar ceiling is not insulated at all. Should I have someone place fiberglass insulation in between the cellar ceiling joists to keep it warmer for my tenant? (Average winter temperature in the unheated cellar that has the three gas boilers and three gas-fired water heaters is 65 degrees.) I sure don't want any mold to grow. I have had no mold problems ever. Your response is greatly appreciated!

A. Congratulations on all you have done to improve the energy efficiency of your building. If everyone took advantage of the credits available or even paid out of pocket to improve the energy efficiency of buildings, not only would they save money on their utility bills and be more comfortable, but they would also reduce the CO2 build-up in the atmosphere and reduce the need for more power plants, fracking and importation of oil from unsettled countries.

And now that I have expressed my personal opinions about the ecological and financial benefits of energy conservation, let's get to your question.

I wonder how the asphalted portion of the crawl space was accomplished; it can't have been easy, and is it really controlling moisture from the soil? You can check this out by tightly taping two-foot-square pieces of plastic to the asphalt in several places. If condensation forms under the plastic in a couple of days, the asphalt is not very effective. You may need to have it coated with an emulsion sealer. If the plastic is OK in the other half of the crawl space, you are fine.

Once you have made sure that moisture is effectively controlled, there will no longer be a need to have the windows open during the warmer weather. Open basement and crawl space windows and other forms of venting admit large amounts of outside summer moisture in these spaces, which take a long time to dissipate over the heating season.

Every summer, you should give the crawl space the "nose test"; if it smells fine, you are OK. But if you detect a musty smell, you may need a dehumidifier to run during the summer months.

There is no reason to add insulation between the floor joists. The heat from the boilers and water heaters keeping the temperature at 65 degrees Fahrenheit is all you need to keep the floor of the first-floor apartment comfortable.

Q. I've attached the latest pictures showing some improvement to my driveway, but by no means did the treatments you suggested for surface rust stains remove them; these are truly deeply embedded. The wet pictures have had three attempts; the other two pictures have had two attempts. Please advise the next method you offered to remove the remaining rust stains.

A. If several oxalic acid treatments have not completely taken care of the rust on your concrete driveway, the rust stains may have been there a long time and are deeply embedded in the concrete.

There are several stronger methods to attempt to remove deeply embedded stains from concrete, but they are quite complicated and may best be done by experienced concrete contractors.

Here is one from an article in Concrete Construction magazine: Dissolve 11 ounces by weight of sodium citrate in two quarts of lukewarm water, and then add two quarts and 12 ounces (a total of 76 fluid ounces) of glycerol. Make a stiff poultice of the solution with diatomaceous earth or talc. Apply it to the stains and leave it on for two to three days. If a stain remains, repeat.

The other methods are even more difficult and should not be attempted by untrained people.

• 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.