Deteriorating shingles put reader's patience through the roof

Q. We are having our cedar shingles replaced at the end of this month on the lake side (southeast) of the house where weathering has been the most prominent. The existing shingles are falling off in increasing numbers. The north side is holding its own. A friend said we should consider laying down some sort of a "membrane" sheath under the new shingles, which supposedly would help prevent the accumulation of moisture. Is there anything to this? Do you have any other recommendations? We never had a preservative sprayed on, as I feared that the treading on the steep, pitched roof would cause more damage.

A. Your friend is referring to Cedar Breather, a matrix applied over the felt (or ice and water protective membrane that should cover the roof sheathing at the eaves, valleys and all other vulnerable areas). It allows the underside of the cedar shingles to dry and claims to lengthen their life. It would be a good idea to coat the roof shingles with Amteco TWP, 200 series (amteco.com) every five years to ensure a much longer life. It contains oils that replenish those depleted by the elements, protecting the wood from cupping, curling and splitting. The north-side roof can also greatly benefit from this treatment. Unless the roof is too large to allow it, TWP can be applied with a garden sprayer from a ladder. You can buy TWP in ICI Dulux paint stores (formerly Glidden) and you can find other dealers by navigating Amteco's store locator.

Q. I did a bunch of Internet research before insulating our then-unfinished basement about four years ago. I just discovered your column and have been reading back columns. We live in northern Illinois (near Chicago). I insulated the walls - floor to ceiling - with rigid pink Owens Corning foam boards. The basement is now finished - drywall, carpet, etc.

So I just read your recommendation to leave the bottom of the walls uninsulated. I don't recall seeing that anywhere previously. How much of a problem can this be - and is there any retrofit way to deal with this short of removing wallboard and removing some of the insulation?

A. The recommendation to insulate foundation walls to a depth of only 2 feet below grade will allow some heat transfer from the basement to the soil outside through the lower part of the walls. This will prevent deep frost that can crack the walls but only applies to buildings in areas where the soils are clay and/or silt and with backfill that is unknown.

In sandy and gravelly soils that drain well, this is not usually an issue. This is also not an issue if the foundation meets all of the following criteria: 1) a drainage system consisting of a stone bed, into which a perforated pipe is buried and is adequately protected by filter fabric; 2) the perforated pipe is connected to a solid pipe daylighting in a lower area or is connected to a sump pump; 3) the backfill done with coarse sand or bank run gravel to within a foot of the final grade; 4) final grading consists of native soil sloping away from the building at a rate of about 2 inches per horizontal foot; and 5) a healthy stand of grass is maintained from the foundation to at least 2 feet away. I always try to discourage people from planting flowers and shrubs against the foundation of any buildings, as this usually results in flat or negative grade that can lead to cracking or leaking problems caused by deep penetration of frost or water. Plantings can be set in beds several feet away from the building and enjoyed from inside - another plus.

Q. The 1960s mosaic-tile bathroom floor in my rental is a mess and a source of great embarrassment. The landlord doesn't want to change it because there appears to be a separated under-floor plate creating a slight surface unevenness. I am looking for a simple, affordable, fix. I came across something that looks interesting called SnapLock (www.snaplockdancefloors.com). The tiles are designed for quick set up and are waterproof (not watertight). Do you think I can place this over the mosaic-tile floor for a better look without problem? Can you recommend something else?

A. The Snap Lock Dance Floor will be fine as long as you never intend to use the bathroom as a bathroom. This system is water-resistant, but it is certainly not designed as waterproofing. In fact, placing this system over your existing bathroom floor will guarantee that the space between the dance floor and the existing tiles will become waterlogged, and filled with germs, mold, mildew and unwanted pathogens, as well as emit foul odors. Covering a ceramic-tile bathroom floor with carpet or other finishing materials will have the same undesirable results.

Your letter indicates there is a problem with the existing floor, but it is not clear whether the problem is cosmetic or structural. No doubt your landlord would love to have you fix the floor properly at your expense. But generally, any necessary repairs should be done by the landlord or building owner.

If the problem is cosmetic, and was pointed out when you inspected the space before moving in, about the only thing you can do is cover the floor with a throw rug. But if the tiles are cracked, unsanitary conditions exist that make cleaning and sanitizing the bathroom impossible. Cracking of the tiles or shifting of the floor are usually good indications of a structural problem. If this is the case, you, members of your family, or your guests may be subject to injury should the condition worsen. (A waterproofing membrane installed on such a floor will most likely be damaged and allow more water to pass through to the structure, accelerating its destruction.) Neither grout nor tiles are capable of repairing a structural problem.

If your bathroom floor is merely cosmetic, you will have to find a way to live with it. If the problem is structural, you and your landlord should expect the situation to continue to get worse.

Q. A home improvement book suggested that I paint the window frames with primer before I putty the windows to prevent the wood from sucking the linseed oil out of the putty. Should this also be done if I am using the new silicone sealer to putty the windows? If I should prime the window frames, should I use oil-based or latex-based primer? - Bound Brook, N.J.

A. The advice from the home-improvement book is for when you use regular oil-based glazing putty. Synthetic glazing compounds that do not contain oil can be applied directly to unpainted wood. But there is no reason why you can't prime the sashes before applying the glazing compound. Raw wood should be coated with an oil-based primer, be it linseed oil or a synthetic alkyd.

Q. I have a 40-year-old tile bathroom floor, which is in good physical shape. I scrub it with a product called Clorox Cleanup and water. I add extra bleach. The tile cleans pretty good, but the mortar between the tiles always looks dirty. How can I improve the appearance of this tile floor?

A. Clorox Cleanup is more of a disinfectant than a cleaner. In fact, the label instructions call for "pre-cleaning" surfaces that are very dirty. The instructions also call for the cleaner to sit on the surface 30 seconds before wiping it off. Assuming your grout is white, try letting the Clorox Cleaner sit on the surface for several minutes or longer before heading off to the store for more cleaner. Spray on your cleaner, then cover the affected area with plastic food wrap so the cleaner will not evaporate. After three to five minutes, remove the food wrap, wipe off the excess and rinse the surface with freshwater.

If the stain persists, I suggest you purchase a heavy-duty cleaner made specifically for use with ceramic tile. A made-for-tile cleaner could make the grout spotless. At 40 years old, the joints between the tiles were most likely filled with regular white grout, and unless you have used a combination of sealer/impregnator and cleaning, the grout may be deeply stained, and it may require restoration by a professional. Once the old grout is clean, allow the installation to dry completely, then treat both the tiles and the grout with a quality impregnator, such as Miracle 511 (miraclesealants.com), to reduce the incidence of staining.

Q. In an attempt to conserve energy and lower our heating and cooling bills, we are ready to add insulation to our attic. The house was built in 1975. We live in central New Jersey. Is there any advantage to removing the original insulation? If not, we'd like to avoid this messy and time-consuming work. Most of what I've heard and read talks about laying new insulation over old. Also, would insulating the crawl space in the basement be advisable?

A. There is no need to remove the old insulation, regardless of its type. If your roof is built with trusses, the most efficient way to add insulation is to have cellulose blown in, as it can fill difficult areas that would not be easily filled with fiberglass batts without extra caution. If you intend to do the work yourself, it will still be worthwhile comparing the cost of the fiberglass, time and effort against having an insulation contractor blow in the cellulose. Aim for a total depth of at least 12 inches.

I am not sure what you mean by the crawl space in the basement. A crawl space is a foundation that is not high enough to stand up in and often does not have a finished floor - only bare soil. A basement is a foundation with enough headroom to stand upright comfortably, usually with a concrete floor. It is definitely advisable to insulate the walls of a crawl space or basement, but it needs to be done cautiously. Make sure that there is no leakage, there is a functioning drain system at the base of the foundation walls, that the backfill is done with coarse, well-draining material and the grade slopes away from the foundation. If these criteria aren't met, the walls should not be insulated any lower than 2 feet below grade to allow some heat loss in order to prevent deep frost that could crack them.

• Henri de Marne's column appears Sundays. He was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. Write to him in care of the Daily Herald, P.O. Box 280, Arlington Heights, IL 60006, or via e-mail at henridemarne@gmavt.net.

© 2009, United Feature Syndicate Inc.