Q. In a recent column, someone had bird droppings problems and wanted to know if the cleaning technique (12 percent hydrogen peroxide to 1 cup of ammonia) could clean a natural bluestone patio. Your answer said it works on bricks and you saw no reason why it would not work on bluestones.

I am sending photos of my front steps that I paid a mason to do. One year later this is what I have. Frankly, at this time it is an eyesore.

Could this cleaning technique work on my bricks and mortar? It was not like that right after he did the work. If this cleaning technique will not work, could you suggest one that I could use?

A. The photos clearly show efflorescence, which is caused by water dissolving the salts that are part of all masonry products.

Rain ran off the stoop and penetrated the bricks and mortar joints, and when the water evaporated, the salts were left on the surface of the masonry.

This is very easy to fix. You can simply brush the efflorescence off with a stiff-bristle brush. If it does not completely remove all salts, you can wet the brush and brush the remaining salt off.

You may have to repeat the process as more salts get dissolved over time.

Q. I only recently learned about PVC roof trim, which seems to address the dream of not having to paint and replace rotten lumber over time. With the understanding that it does cost more, it sounds like a good investment. KOMA was recommended; what is your opinion and possible recommendation?

A. PVC trim is revolutionizing the construction industry. Most of these products can be left unpainted, but can take paint well as long as the manufacturer’s instructions are carefully followed.

I have no reason to recommend one brand over another.

Q. I was just in the crawl space putting down plastic, and looked over to the sump pump setup. I am just wondering if there is a better way, other than just a backup battery, into which we pour distilled water now and then, to ensure the sump pump continues working when the electricity is out? We are out of town a lot. I was actually in Cleveland when a storm hit, and my husband could not get to the house for more than an hour due to flooded streets. Our electricity did not go out, but many in the area lost power. I use the crawl space as storage and have a lot of stuff that would get ruined if the sump pump stops working. Just something I think about during a storm!

A. I can’t think of a better system to ensure that the sump pump will continue to function during a power outage.

If you make sure the battery backup is kept in good operating order, it should offer you the protection you need.

If you are really concerned about a lengthier power outage than the battery backup can cover, you might want to ask a licensed electrician if he or she can install a second battery backup that would only come on when the first one is running out of juice.

I assume everything you store in the crawl space is off the ground, set on boards resting on masonry blocks or pressure-treated wood, or pallets, which you can get from home goods stores or construction supply firms.

I also assume that since you are applying plastic, the soil may be bare and not covered with concrete.

Q. I’ve recently noticed my hot water is not as hot as it used to be. I haven’t adjusted the temperature setting.

I wondered if this could mean the hot water heater is nearing the end of its life? It’s about 9 years old.

A. It is possible that the dip tube, which delivers cold water to the bottom of the tank, is cracked or broken, in which case cold water is delivered at the top of the tank, mixing with the hot water drawn when faucets are opened.

The heating elements may also have accumulated some calcium deposits, in which

case one or both will need to be replaced.

The lower element is the one used the most and if it fails, the top element takes over, but only heats up a small amount of water.

There may also be heavy deposits on the bottom of the tank. You can draw a gallon or more of water from the heater by attaching a hose to the drain faucet at its base as long as there is a drain nearby; see if that helps.

Depending on the heater’s warranty, it may be worth considering its replacement with a more efficient model rather than spending money on a plumber to check all the possibilities and fix the problem.

Q. Thanks for your column. It’s great. I have a 1960 frame house 20 miles west of Chicago. On the outside is steel siding with ?-inch black cardboard underneath. I would like to remove the siding and leave the black cardboard. Over the black cardboard I would like to install ½-inch plywood and 1½-inch XPS panels and then vinyl siding. Should the plywood be tongue and groove? Do I need housewrap? How do I install everything? Do I use screws or nails and what size?

A. Consider a much better system. If you are going to the effort of replacing the siding and installing XPS to improve the energy efficiency of your home, look into the Huber Zip system, which has an excellent record.

The Zip system consists of various thicknesses of foam insulation from 1 inch to 2½ inches integral to an OSB board. The panels are 4-by-8 feet.

You have probably seen buildings in your area sheathed with it; its green finish seems to be everywhere.

Consider removing the old Celotex and what must be ?-inch plywood at the house’s corners that provide structural rigidity to it. Since Zip panels are structural, do the removal in sequence so as not to cause problems.

Remove the plywood structural panels one at a time and replace each immediately with a Zip panel.

Apply the Zip system with the proper size nails. If you choose the 2½-inch foam (as you are proposing), the nails will need to be 4 inches long (20 penny) and will need to be driven with pneumatic guns that can take 4-inch nails. You may be able to rent one or work with a contractor who has one. Hand-nailing following the manufacturer’s instructions would be very tedious.

Be careful that the nails penetrate close to the center of the studs, which will take some care, having to go through 3 inches of material before entering the studs.

Regardless of whether or not you decide to use the Zip-system or choose to proceed with your original plan, you will still have to deal with the windows. They are a large component of heat loss in a house and you should consider replacing them with top-of-the-line efficient windows.

Why spend a considerable amount of money on the walls if you decide to keep the old 1960s vintage windows?

If you want to look into the Huber Zip system, go to www.huberwood.com, click on Products, then Wall Sheathing in the drop down menu, followed by clicking on Insulated R-sheathing. Scroll down to the illustrations of the wall thicknesses.

Be sure to follow installation instructions, including taping of the joints. Your best bet is to hire a contractor experienced in the installation of the Zip system.

The vinyl siding is best installed with 1½-inch large headed nails. Be sure you do not nail the siding tightly; stop short to allow the siding to move as it expands and shrinks following outdoor temperature swings.

If you insist on following your original plan, let me know and I’ll provide instructions.

• Henri de Marne, a former remodeling contractor turned columnist and consultant, is the author of “About the House with Henri de Marne” (Upper Access Publishing). He continues to take questions from readers for this column and his website, www.henridemarne.com. Email questions to aboutthehouse@gmavt.net.