Passive attic venting systems are the most efficient

Q. I live in a 100-year-old house in Atlanta - a very hot and humid climate. I am getting ready to re-roof, and each roofer I have gotten a bid from has suggested different exhaust vent options, even though I have no soffit/intake vents and no possibility of adding them without severely detracting from the aesthetics of the house. My eaves are just an extension of my 1-by-8-inch roof decking with exposed decorative rafter tails.

A couple of important things to note - I cannot install light-colored shingles and I have a "leaky" ceiling (attic floor) that I will not be able to seal completely, which allows air into the attic.

I have attached pictures of the roof from several angles.

A. Your email has been heavily edited because of its length, but all your questions have been answered.

You are right: The various roofers' suggestions are not helpful. I would not recommend power vents. Your research is correct: Powered exhaust fans, as well as passive exhaust vents (such as turtle vents, turbines, etc.) would draw air from the living area - especially when the power vents are activated - if there isn't an equal amount of CFM (cubic feet per minute) air intake. This would occur with any exhaust-only venting (ridge vents included), especially in the summer when superheated air will rise.

High heat buildup may affect the longevity of dark asphalt and fiberglass shingles. It would not affect light-colored shingles as much, which you say you cannot have. The heat buildup is not really dangerous, but certainly not good for any attic contents, either.

The most desirable, effective ventilation for attics is a passive system comprised of full-length low intake vents with full-length ridge vents.

Since the architectural feature of your eaves, as shown in one of your photos, will not allow soffit venting, you are fortunate in that you can provide eaves ventilation by using DCI SmartVent. It is a wedge-shaped strip that is installed at the eaves on top of the drip edge and is hardly visible. According to the manufacturer, it has passed hurricane and ice tests.

A small slot needs to be cut in the roof sheathing at the appropriate spot to allow the intake air to get into the attic below the roof sheathing. You can see it on the company's website: www.dciproducts.com.

An ice-and-water protective membrane is applied over the SmartVent, followed by the shingles. Be sure that your roofer installs a full-length, externally baffled ridge vent, such as Shinglevent II by Air Vent Inc., in order to provide the needed exhaust while preventing most of the potential weather intrusion from strong winds.

Q. We have an electric water heater that is about 6 years old. Two years ago, we began to get a strong sulfurous smell from our hot water taps. We have tried several recommended remedies. All worked for a short while. We put hydrogen peroxide into the tank, replaced the anode rod, and had it run without the anode rod for a while as well. We have to drain the tank twice a week to keep the smell at bay, because it comes back after three and a half days without fail. It doesn't seem to matter how much hot water we use. Our water comes from our own artesian well and is treated with a water softener. We have lived here for 28 years. We are wondering why this started, how to remedy the situation, and if an on-demand hot water tank makes sense for us.

A. There may be several causes for the sulfurous smell. If you replaced the magnesium anode rod with a similar one, the problem has recurred.

Magnesium sacrificial anodes, installed to protect glass-lined water heaters from corrosion, are corroding faster in systems with water softeners. Replacing a magnesium anode with an aluminum alloy rod (aluminum/zinc/tin) will delay the need for replacement.

Another choice is to replace the anode with a powered anode, which will last much longer and may not need replacing for the life of the heater. It uses very little current - in the milliamperes - but it must not be used in stainless steel or galvanized tanks, or the A.O. Smith Vertex.

The water heater may also be harboring hydrogen sulfide bacteria, which hydrogen peroxide will not destroy. To kill the bacteria, you need to pour chlorine into the rust and sediment filter housing, which is usually installed ahead of the water softener. Fill the housing halfway with chlorine.

Make sure you set the control valves to bypass the water softener, as chlorine should not go through it.

Run the hot water until you smell the chlorine, and stop using water overnight (12 hours are preferable) to give the chlorine time to kill the bacteria.

Flush out the system, preferably by draining the water heater if you can attach a garden hose to its drain faucet and discharge the hose into a floor drain (most codes no longer allow floor drains in basements) or outside. You should see a lot of black stuff coming out.

Have a licensed plumber install a mixing valve and raise the water heater tank temperature to 140 degrees Fahrenheit, which will prevent the growth of bacteria. The mixing valve reduces the temperature at the various faucets to 120 degrees Fahrenheit, which prevents scalding. These steps are now required by plumbing codes, and if they are not done now, they will have to be when you replace the water heater.

You haven't mentioned the state in which you live. If in Vermont, you may wish to call a Kinetico dealer and have it analyze your water to offer any new suggestions. Kinetico water analyses are free. If you live in another state, there are Kinetico dealers in most of them. Look for one online at www.kinetico.com.

On-demand water heaters are expensive to buy and to operate, as they use a lot of electricity or propane. They must also be sized properly to give a family all the hot water needed.

Q. This summer the road in front of my house was repaved. They put a topcoat of asphalt on the existing road without removing anything. Now the water, which used to flow past my house and sheet across the road to a storm drain, can't move across the road because of the grade and it sits in my yard and driveway. Prior to the paving, it was OK. A normal rain causes quite the pool of water at the foot of the driveway and a very soggy yard along the road. I am worried that with a big rain or winter thaw, it will back up into my garage and maybe house. The town has not been able to address the problem. Do you have any suggestions for steps we can take to prevent possible flooding into my house?

A. You haven't told me what town you live in. Was the repaving job done by your town or the state? If it was done under the auspices of the Vermont Agency of Transportation, call the agency and leave a message, giving the names of your town and road where the paving was done, for someone to call you back.

The person returning your call will need to have this information to determine the subcontractor involved, and to decide if the subcontractor is responsible to do whatever is necessary to alleviate your problem.

If the paving job was done by your town, you will have to deal with its officials.

Q. I have been a fan of your column for years. Our newspaper (Telegram & Gazette in Worcester, Massachusetts) runs a house plan/specs feature next to yours, and I have noticed a trend.

Walk-in closets are frequently placed inside a master suite bathroom. How does that square with moisture from the shower and tub? Have you had complaints from homeowners?

A. I have not heard from anyone about this trend. In older houses, and those not tightly built, I don't think this is much of a concern in the winter, as it helps keep the relative humidity (RH) in a healthy range, as long as there isn't a humidifier in use.

In the summer, people should always use a ventilating fan to remove the moisture from bathing or showering, unless the house is centrally air-conditioned - and even then, the fan may still need to be used.

In today's tightly built houses, there should be an air-to-air heat exchanger, and bathroom fans should be used whenever bathing or showering.

It is also a good idea for every home to have a moisture meter to keep track of the RH. They are not expensive, and some models also give you the current indoor and outdoor temperatures as well as the low and high in a 24-hour period - fun to check out.

Hardware stores and Radio Shack sell these digital instruments.

More holiday gift suggestions: I have several Skil cordless tools that I find very helpful. The four-tool kit came with a jigsaw, a drill/driver, an orbital sander that looks like a small iron with a pointed end that makes it so easy to get in tight corners, and a powerful light.

With only one battery, it's important to recharge it after each use to make sure you are fully charged when ready to use the next tool.

Also helpful is the Handy Camel Bag Clip. It clamps at the top of fertilizer, birdseed and any other heavy bags to make them easier to carry. After the bag is open, it can be set on a corner while you lift the bag by the bottom to pour out its contents. It makes these two steps so much easier. You can see how the clip works on the manufacturer's website: www.thehandycamel.com.

• Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. His website is www.henridemarne.com. Readers can send questions to Henri de Marne's email address at henridemarne@gmavt.net.

© 2014, United Feature Syndicate Inc.