Cleaning and sealing a concrete driveway

Q.    About 10 years ago, I had a concrete driveway put in. The company put a concrete sealer on the driveway, then told me it was saturated and needed no more treatment for a few years. Since then, the driveway has become stained with organic things (mold, crab apples, leaves, etc.) and non-organic things (black tires marks, etc.)

Last summer, I power-washed the driveway using a concrete and driveway cleaner with little in the way of results. Later, I accidentally spilled some chlorine bleach on one section of the driveway and it looked great.

Dirty driveway
Concrete driveway with dirt and stains

Can I use a hand tank sprayer and spray a water/bleach solution on the rest of the driveway? Would it ruin the sealant? If not, what percentage water/bleach should I use? How often can I use this solution safely? Thank you for any help you can give me.

A.    The sealant applied was topical; it forms a film and needs to be re-applied every year or two. The other type of sealer is penetrating, which needs to be applied only once, as it seals the pores of the concrete.
Nature does a great job of cleaning concrete from organic matter stains, and of tire marks as well. Snow over the winter will bleach the concrete very effectively in your climate (Pennsylvania).

But if it doesn’t to your satisfaction, go ahead and spray the concrete with a mixture a water and bleach. Start with 1/3rd bleach to 2/3rd water, and increase the bleach proportion if it does not satisfactorily do the job. Once clean, rinse well with your garden hose or pressure washer.

Once clean, if you decide to apply a penetrating sealer, wet the concrete to see if water penetrates it or beads on its surface. If the water penetrates, a penetrating sealer should work.

Cleaning and re-treating cedar clapboards

Q.  The cedar clapboards on our house were installed about 23 years ago. A year or two after they were put up, a bleaching agent was applied to help maintain the color. I have no idea what product was used. The south-facing clapboards have become quite dark.

I am wondering if another coat of something should be applied to keep the clapboards from drying out and cracking. If so, what should I use, and how is it applied? If it is sprayed on, do I need to protect the plantings at the base of the house? Do I need to protect the windows which are vinyl-clad?

A.    If the clapboards have not received any new treatment for the last 20 years or so, it is a good idea to do so this coming warm season. Buy Oxy-Boost and Deck & Patio Cleaner from Mix them in equal parts in warm water and wash the siding with a stiff brush. Rinse with a garden hose when done.

Before spraying the solution on, you should soak the plantings and cover them with plastic.

Hose the plastic off, remove it, and soak the plantings again. Once the siding has thoroughly dried, apply Amteco TWP Series 101 Cedartone Natural or Series 1500 Low Voc Cedar, slightly darker and less orangy than 101 Cedartone. Considering how long it has been since you applied a wood preservative on the clapboards, they might need two coats. You can apply Amteco by brush or by spraying it on. Be sure to follow the directions on the Amteco container for either brushing or spraying.

Removing mildew from cedar siding

Q.    We have been using an Olympic stain on our cedar siding for about 15 years but not in the last few years. A significant mold has developed on the north-facing side of the house and garage. We need advice as to how to get rid of the mold without killing the extensive foundation plantings we have.

A.    The way to remove mildew is by means of washing the siding with a solution made of one quart fresh Clorox bleach and three quarts water (if you need more than a gallon, respect these proportions).

If the siding is also compromised by other pollutants, add a cup of TSPPF to the solution. The application of the solution is best done with a pressure-washer, but it is obvious that this is not possible in your case.

The alternative is to soak the plantings and cover them with plastic sheeting, and to wash the siding by hand, using a stiff-bristle brush, and wearing heavy rubber gloves and expendable old clothing (or buy a Tyvek suit). Avoid splashing as much as you can. Do not rinse the siding unless you have added TSPPF to the mix (in that case, rinse the siding with your garden hose and flood the plantings and the soil to dilute the solution – TSPPF is injurious to plants).

Removing mildew from vinyl siding

Q.    I need to know if I can get mildew off of my white vinyl siding. We are pressure-washing it using a solution of mild soap and Clorox, then rinsing it with more water. I realize the Clorox is not good for the siding but the mild soap does not work. We are doing it sections at a time as the house is large. It is not that successful and I was hoping that you have a better solution. It is time consuming as well.

A.    The best way to remove mildew — and other pollutants that are sure to be present as well — from your siding is to wash the siding with a solution of 1-cup TSPPF, 1-quart fresh Clorox bleach and 3-quarts water. Keep the proportions the same if you need more than a gallon of the mix. Be sure to cover all vegetation with plastic after soaking it thoroughly. Rinse the siding and soak the vegetation again when you are done. Instead of pressure-washing the siding, try using a car-washing brush that is screwed onto a garden hose; its soft bristles are ideal for cleaning vinyl siding.

Cleaning soot from aluminum siding

Q.    We had a pellet stove installed in our basement two seasons ago. When the stove is running, the soot comes from the stove pipe which goes through the wall outside and colors the white aluminum siding.

I contacted Alcoa and they are sending me a manual showing different solutions for cleaning various stains. I described the problem but am not sure if they have an adequate answer for cleaning and I am concerned about removing the “powder” with the wrong cleaner. Do you have any suggestions? I really enjoy your column and read it religiously.

A.    The successful cleaning of the soot from your aluminum siding depends on how old the siding is. If it has weathered a lot over the years, the soot may be hard to get off completely. If you haven’t tried already, mix the following solution: one cup detergent (such as Tide) and two-third of a cup TSPPF in one gallon water, apply it using a soft-bristle brush and gentle strokes — a car-washing brush is ideal.

Fungus on siding comes from mulch

Q.    I hope you can help me. I have shotgun mold or fungus all over my white vinyl fence and house siding. I have been told it is from my mulch. We will be removing the mulch this spring. I tried everything I could think of to remove it. Nothing seems to work. It is so sticky and the little dots are everywhere! Do you have any ideas for me to try?

A.    You are referring to the spores of artillery fungus which develop in the decomposition of most organic mulches. These spores explode and are deposited on nearby surfaces; they prefer light-colored ones. They cannot be removed without risking some damage to the surfaces to which they adhere.

This is a spring and fall problem as these spores do not develop in cold or hot weather. The solution is to get rid of all organic mulch and replace it with new rubber mulch or other materials such as grass or ground cover or apply new mulch yearly over the old one to contain the spores.

Two readers have offered other solutions, which I can’t personally vouch for:

  • “Use cypress mulch to prevent this problem. To remove the spores, wait till freezing weather and they scrape off as they are now very hard.”
  • “Mix mushroom compost in with your hardwood mulch to prevent the fungus. This does prevent the growth.”

Worth a try anyway.

Asphalt spilled onto vinyl siding

Q.    We had our driveway black-topped recently. Some of the black stuff got on my white vinyl siding. Are there solutions to remove it without damaging the siding?

A.    Too bad the installers were not more careful. You should have them come and clean your siding. If that is not your choice, you should be able to remove the asphalt with mineral spirits (paint and hardware stores) or auto-tar remover (auto parts supply stores). Use a soft cloth without too much pressure, as it would “polish” the vinyl. Rinse with your garden hose.

Cleaning aluminum siding

Q.    My house is a cape with white aluminum siding. How do I clean the siding after 37 years? The surrounding area is covered with evergreen bushes and lawn.

A.    The best way to clean aluminum siding is with a solution made of 1 cup TSP-PF, 1 quart of fresh Clorox bleach and 3 quarts of warm water. You’ll need more than 1 gallon, but keep the same proportions.

If need be, tie back the vegetation that is too close to the siding so you have room to work. Soak the vegetation and grass with water and cover it with plastic before you begin cleaning the siding. Use a soft bristle brush such as the type used to wash cars with. Rinse thoroughly and flush the plastic cover and the ground with plenty of water as TSP-PF is injurious to vegetation.

You can also buy siding cleaners in hardware stores and home centers, but it will be costlier.