Cautious homebuyers worry about potential foundation issues

Q. My wife and I are looking at a house (to possibly buy) that seems to perhaps have had some issues with the block foundation in the basement in the past.

It seems at one time they must have had pressure from outside of the wall, so they had a contractor install several vertical "carbon armor" strips along the wall three years ago. The strips start toward the top (maybe a foot from the top) of the block wall and run to close to the bottom. The strips almost look like an adhesive.

Have you ever heard/seen this approach, and is it an effective way to treat the issue long-term? We're on the fence about this house for that reason. I have sent you an excerpt from the paperwork that describes the product.

A. Yes, I am familiar with these strips, and they are one of the best ways to deal with the problem you see in the basement.

You are correct, outside frost pressure caused the buckling, and there are several reasons for this to have happened. When houses are built, the excavation is several feet wider than the footprint of the house so work can be performed on both sides of the planned walls.

If the excavation is backfilled with native soil, as is often done, and the soil happens to be heavy, the fluid pressure that the deeper soil exercises on the foundation wall as it gets wet can cause the wall to crack. This is particularly the case with block walls, especially if they were constructed with 8-inch-thick blocks. Any block wall over 5 feet tall should be built with 12-inch blocks.

Concrete walls resist this fluid pressure somewhat better, but can also crack, and do so in a different manner. Block walls usually crack horizontally, often three to four courses below grade, while the cracks on concrete walls are generally vertical.

Also important are a foundation drain, well-protected by filter fabric to prevent infiltration and eventual clogging by soil particles, as well as backfilling with coarse, well-draining material, capped with proper final grading.

Grading is the most important final feature of a backfill operation in order to ensure a problem-free wall, and it must consider inevitable settlement over time. The grade should gently slope away from the foundation to prevent deep water penetration and keep the soil fairly dry below a few inches - even if the backfill is made of better draining soil.

Prospective buyers and their home inspector can only visually see the grading. If the grading all around the foundation slopes gently away from the foundation, it is a good sign.

Good luck with the purchase.

Q. I enjoy your weekly articles in the Daily Herald in the Chicago area. I find them very informative. My question to you today may help many who are thinking of roof repairs. My roofing contractors are suggesting ridge or turtle vents. I would like your recommendation. I have a mansard-style roof. With the mansard style, which would be best for my roof?

A. Ridge vents are the most effective way to ventilate attics as long as there are soffit vents of equal or greater net free ventilation area (NFVA) and an unrestricted air space of at least two inches between soffits and ridge.

The benefits of this combination are its cooling effect on the attic in the summer and the control of ambient air moisture in cooler and cold weather. But the combination of ridge and soffit vents cannot counter excessive winter moisture from conditioned air that convects into the attic from the living spaces via open pathways. All such paths need to be identified and sealed.

In the case of a mansard roof, the soffit vents should be in a soffit provided in the upper (shallow-sloped) roof. If this is not feasible, there are soffit venting products that can be installed on the roof itself. One such product is DCI's SmartVent. There are others; check building-supply firms.

In your case, the product would be installed at the eaves and be covered with shingles.

Be sure that an unrestricted air space is provided.

Q. A recent column of yours that appeared in the Daily Herald about ceiling fans stated "that the fan should be blowing up - both winter and summer."

Internet columns and manufacturer's instructions all say that in the winter you should blow down, to circulate the risen heated air from the ceiling.

Incidentally, I have central air and a fan in every room. Am I reading the last sentence in your column incorrectly? I look forward to reading your column every Sunday.

A. Having a ceiling fan blow down in the winter subjects people to unpleasant air currents. Having the fan blow upward moves the stratified air down along the walls, mixing it pleasantly with the cooler air.

In non-air-conditioned homes, the fan is best blowing downward in the summer to cool the occupants, but in air-conditioned homes, it is best to have the fan blow upward for the same reason as during the winter, thus avoiding a "draft" on people sitting below the fan.

Q. The floor in my 31-year-old attached garage is generally smooth but has some pocked areas caused by winter road salt. The floor has never been painted or treated in any way following the linseed oil treatment after initial construction.

What do you recommend in the way of a sealant to prevent further salt damage? I am not terribly concerned about aesthetics, but just want to prevent further deterioration of the concrete surface.

A. The pocked areas can be filled with a vinyl-reinforced mix, which you can find in hardware and building-supply stores. The entire floor will have to be thoroughly cleaned.

Building-supply specialty stores also can sell you a clear topical sealer, which you will need to reapply every few years, depending on traffic.

The better penetrating sealers may not be absorbed by a garage floor, as it may not be porous enough to allow penetration. You can test it by pouring water on the floor to see if it is absorbed or just stays on top.

Q. I was told to get your Milsek product by Gary Sullivan, who has a very helpful radio talk show on the weekends for people with home improvement questions to call in for help.

My question to him was about our new skylight that leaked water onto my dining room table. I didn't notice it for a few days after the rainwater had been on the table, and it now has a water ring and some of the grain is a bit raised.

I used a very fine sandpaper to smooth the ridges, but the water stain remained. I applied my Cabinet Makers 18th Century Natural Wax (beeswax, lemon and other natural oils), but it left the wood without a shiny finish to match the rest of the table.

Then I applied Rustic Touch With Natural Moisturizers, but it also did not put the shine back into the table.

Gary Sullivan recommended your product. I located it at the fourth hardware store in my area. I didn't buy it because it comes in lemon oil and in orange oil, and the hardware man wasn't sure which one I should use. I am writing you to see which product I should buy. I have an oak table that is 35 years old. Which product would be the better one for me to purchase?

A. First, Milsek is not my product. It is a furniture cleaner and polisher, which was recommended to me by a Pennsylvania reader a number of years ago. I tried it and found it remarkable, so we have been using it regularly and I have been recommending it ever since.

You should use Milsek Antique & Restoration. You can order it online at www.milsek.com, or perhaps find another store closer to you that carries it by clicking on the Store Locator bar.

It may also help eradicate the water spot, if it is still visible, and it should leave a nice shine on your table.

Q. What alternative do I have other than a French drain to eliminate or deter water coming in my cellar at the foundation? It does not happen during a short, light rain, but when it pours over a lengthy time.

A. If possible, it is always preferable to solve foundation water problems from outside with minimal disturbance to what exists. This involves proper grading gently sloping away from the foundation and protected by a healthy grass stand or ground cover in order to drain water away and prevent deep penetration.

It is best to avoid flower beds and mulched plantings close to the house, as they encourage deep water penetration and moisture retention. Keep those a few feet away.

All appendages must be checked to ensure that patios, walks, stoops and driveways do not direct water against the foundation. If any of those are not allowing water to drain away, corrections need to be made. They may include pouring a new topping on concrete, laying flagstones or bricks on a sloping mortar bed, etc.

Follow-up: A few weeks ago, I answered a reader's question by pleading ignorance about DaVinci roof tiles. I have since received the following information, which may be of interest:

DaVinci tiles are polymer slate and shake roofing tiles manufactured in Lenexa, Kansas. They have a lifetime, limited warranty and resist moisture, impact, insects, fire and high winds.

DaVinci's website is www.davinciroofscapes.com, where you'll find everything, including a Color Designer Tool showing 50 standard colors to choose from.

• 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.