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Spray-foam insulation is useful tool when sealing a space

Q. I recently read an answer you gave about attic ventilation. The part that caught my attention was, "But the first thing to do is to look for all possible convective paths. Sealing them would likely solve the moisture problem."

My question is: How should they be sealed? The obvious source of most of these convective paths would be from holes for bathroom vents, laundry vents, light fixtures, smoke/CO detectors and conduits connecting everything electrical together. Could an expanding spray foam be used? I believe that will work, but it might cause a problem for smoke/CO detectors if it expanded inside the unit.

A. Convective paths can also be found where drywall tape is separating, cracks in wall and ceiling joints, spaces around ceiling light fixtures and fans, folding attic stairways or access panels not properly weatherstripped, holes through which pipes and electric wires go through the top plates of walls into the attic, etc.

Canned foam is a good way to seal the larger spaces, and caulking works well to seal the smaller ones. You can buy canned foam in hardware and building-supply stores. There are several brands and types; choose the type that is for filling cracks and not the one that expands extensively. When carefully done, these procedures should not affect smoke/CO detectors.

The surest way to find all of these paths is to have a blow-door test performed by an energy auditor. It is best done when there is a substantial difference between indoor and outdoor temperatures so thermography can be performed effectively. The auditor will also have an electronic thermometer that will point out the changes in temperature where air leakage takes place.

Some of these firms can also do the necessary repairs.

Q. My 46-year-old house is primarily brick, but has some aluminum siding, redwood siding (both of which have been painted in the past), multipart cornices and wooden Anderson windows. All of these areas were last painted white about four or five years ago.

My problem: mildew! It's everywhere, and there's lots of it.

I plan on having it professionally power-washed. Do you have a product to recommend that should be used during the wash to do a good job of removal? Is there some kind of product that might be applied after the wash to prevent the mildew from coming back? Could that product be painted over on the next paint job? Lastly, do you have a favorite paint brand that fights mildew well?

A. The fact that you have so much mildew might be due to your environment or the use of a linseed oil paint.

Professional pressure-washing contractors will have a product to remove mildew.

You should use a latex paint to which a mildewcide can be added, and it would be best to repaint as soon as possible after the pressure-washing to prevent the growth of new mildew spores.

A good mildew-proof paint is Zinsser's Perma-White Mold & Mildew-Proof Exterior Paint. You should be able to find it in well-stocked paint stores. You can also go to the website www.rustoleum.com, find Zinsser listed under Select Brands, and click on Cleaners and Mold & Mildew Proof Paints. Then click on the exterior paint icon and on Find a Store. Perma-White can be tinted to the color of your choice.

Zinsser also makes mildew-proof primers.

Q. I've got a two-story garage with a concrete deck. For years, water has seeped through cracks in the upper side of the deck, rusting away the rebars and separating large chunks of concrete from the bottom of the deck down onto the floor below. Can the bottom of the concrete deck be patched so that it will hold onto the bottom of the deck with the rusted rebar in there, after I have sealed the top of the deck to keep further water from seeping in?

A. Yes, spalled concrete can be patched, but it will be very difficult, if not impossible, to do so overhead and make it stick without some way to hold the patches up while they cure.

Considering the length of time this problem has existed, I would strongly recommend that you have a structural engineer check your concrete deck to make sure it is sound. Rusting rebars do not sound healthy, and the structural strength of the deck may be compromised. It may be very risky to park cars or heavy equipment on the upper deck. The risk of damage and injury to anything or anyone on the lower deck may be high.

Q. We recently had engineered, dark brown wood floors from Lumber Liquidators installed throughout our house and have been unable to find a cleaner that doesn't leave footprints everywhere afterward.

The company suggested that we use only Bellawood Hardwood Floor Cleaner and shake it before applying to a terry-cloth mop cover, but to no avail. We were also told not to use other cleaners or a Shark cleaner that would clean and steam.

This has been extremely frustrating and has required us to clean floors almost daily. We do have an air conditioner running, but we're not sure if that has anything to do with it. We would appreciate any suggestions you might have.

A. Try Bona; it's the most recommended floor cleaner and polisher by wood-flooring professionals.

We have used it for years on bamboo floors, and it is great.

Q. I read your columns in the Daily Herald and I know I've seen some on gutter covers. But now that we're ready to replace the gutters, I can't find the columns. We are planning on putting up the slightly larger 6-inch gutters, but are unsure what the best gutter covers for this would be. The contractor quoted me Gutter Caps, which is a company out of Naperville. They are expensive and I can't find any reviews for them. Are you familiar with them, and if not, what do you recommend for gutter covers?

A. Gutter Cap is similar to other gutter covers, depending on the surface tension of the water to follow the lip of the guard into the gutter while presumably preventing leaves from getting into the gutter.

I have seen an installation where the leaves piled up onto the Gutter Topper (a similar concept) in sections protected from the wind, causing water to overflow the gutter onto the ground. Pine needles had also clogged the downspout. The owner had the guards removed and decided to depend on fall and spring gutter cleaning from her handyman.

I have tried a number of gutter guards over the years, and have not found one completely satisfactory. The one I settled on for our gutters is DCI's Flo-Free Leaf Guard. Its leaf guard can accommodate 6-inch commercial gutters, which you are smart to have chosen. I hope you have also decided on commercial downspouts, which have twice the surface of residential spouts.

Flo-Free gutter guards can be easily installed by anyone; the installation instructions are clear. They will require periodic removal of tree debris that accumulates on the guards. The manufacturer supplies a brush attached to a 2-inch-by-3-inch elbow that can be attached to a length of 2-inch-by-3-inch downspout in order to make cleaning from the ground possible for single-story gutters.

It's not the most practical option, but far less costly than any other commercially installed guard.

Q. I have a plaster ceiling in a lower-level family room that has a few cracks. It appears they were patched years ago. I have been in the home 10 years and they have not opened or increased in size, so they appear stable.

The ceiling has a rough finish - not a popcorn ceiling, but a texture that is a little rough. I was looking for options to cover the entire ceiling. I do not want to take the ceiling down. The ceiling is already low, so a traditional drop ceiling would not be practical.

I was wondering if there is any type of plaster or plaster-type product that could be applied directly over the ceiling? Are there other coverings, like sheets or tiles, that could be installed with an adhesive? The main goal is to hide the cracks without taking down the ceiling or lowering the ceiling height. Any suggestions would be appreciated.

A. If you want to keep the rough finish, an experienced plasterer (if you can find one of this disappearing breed) should be able to touch up the stable cracks and leave you with a similar finish.

If you want a smooth ceiling, an experienced drywall finisher can cover the ceiling with Durabond and leave you with a smooth surface ready to paint.

Another option is to screw 1/4-inch thick gypsum board over the existing ceiling for a very small loss of height in the room.

A drywall contractor can tell you which would give you the best end product and be the least expensive. I'd vote for adding a layer of thin drywall.

Q. I try to read your column every week and really enjoy it. My question is regarding a workshop and garage concrete floor. What is your opinion about staining concrete for these two places?

A. Staining concrete should work, but the concrete will have to be thoroughly cleaned to remove any oil stains, tire marks and whatever else is on its surface.

A good way to clean concrete is to wet it with hot water, sprinkle TSPPF crystals over the area and scrub it with a stiff brush. Then rinse with clear water. You may need to do it more than once to get an even stain application.

• Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. His book, "About the House," is available at www.upperaccess.com. His website is www.henridemarne.com. Email questions to henridemarne@gmavt.net, or mail First Aid for the Ailing House, Universal Uclick, 1130 Walnut St., Kansas City, MO 64106.

© 2015, United Feature Syndicate Inc.

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