Silicone fails bathroom in multiple ways
Q. We have a shower stall, with ceramic tiles on the walls and floor, which was installed by the previous homeowner about seven years ago. Within a year of moving in, some of the grout started to come loose in various places in the shower. We assumed that it hadn't been properly sealed, so we had a company called The Grout Doctor come out to patch it up. At that time, the company filled in the grout and then placed some kind of silicon-type clear caulk at the joint where the wall and floor come together.
We continued to have grout come loose in other places that had not been repaired, so we had the same company come out again. It re-grouted and replaced the silicone caulk — this time putting the caulk in all of the joints — where the walls meet, where the walls and floor meet, and where the shower door meets walls and floor.
After about one year, black mold started growing in multiple spots underneath the clear silicone caulk. I assume water is getting trapped beneath the caulk. There is no way to clean it, as using a grout brush causes the caulk to peel. Is it necessary to use this type of caulk on the joints because it just seems to cause mold to grow? Can't we just use grout in the joints and that's it? Thank you for your time.
A. You are a victim of the silicone craze. Many people in the construction trade view silicone as a panacea for all problems. Unfortunately, you have firsthand experience with two major issues: It mildews, and it comes off easily. Advanced silicone caulks have additives to help with these problems, but it seems as if this is not what The Grout Doctor used.
You should have The Grout Doctor return at its own expense and remove all the silicone, replacing it with a better product. If you have another shower, and can avoid using this one for a week, use Sikaflex-1a polyurethane caulking, which needs a week to air-cure properly. If you can't keep it dry for a week, it will turn a dirty yellow/pink. If you cannot wait a week, try DAP Kwik Seal Plus Premium Kitchen & Bath Adhesive Caulk with Microban.
For that reason, I tried DAP some time ago and wrote that it seemed to work well. It remained sparkling white and did not mildew. Then I noticed that it began peeling off the wall on the long and faucet sides of the tub, whereas the Sikaflex-1a left on the opposite short side of the tub is as solidly attached to the wall as it was when I put it on years ago. The DAP is still white, while the Sikaflex-1a is slightly gray. So the choice is Sikaflex-1a with minor discoloration and tough adhesion or DAP's color retention and loss of adhesion, which means that it will need to be replaced. Choose your poison. But for me, I will stick to Sikaflex-1a from now on.
Q. We have a 24-by-42-foot ranch with aluminum siding. About 40 years ago, I added poured insulation in the attic to the depth of the ceiling joists. About eight years ago, we installed vinyl replacement windows and five years ago a new natural-gas forced-air furnace with central air. The basement is finished.
In 1961, we added a 16-by-16-foot family room with a crawl space. It has a flat roof with a two-inch slope and 15-year-old membrane roofing that is still in good condition. The ceiling has two-inch white-spruce planking supported by 6-by-8-inch western fir beams. There is one panel of Homasote under the membrane roofing. The room has an 8-foot Pella bay window and a rough-slate fireplace with a 34-inch Heatilator with glass doors that has not been used for more than 10 years.
We have not been at home during the winter for 20 years until this past winter. We were shocked to see 4- to 5-foot icicles hanging from the eaves of both the main house and the family room. While we probably will not own the home for more than five more years, we should do something to save energy. Any advice will be welcome.
A. If I understand correctly, the family-room addition only has the Homasote fiberboard as insulation; if so, no wonder you have icicles! The combination of the two-inch-thick planking with an R-factor of approximately 3 and the Homasote with about R-3 per inch is not providing the R-factor needed to slow down the melting of snow.
As for the icicles on the main house, if they are occurring next to the addition, there may be heat-loss transmission, or you may either not have enough insulation in the attic or there is convection of warm air into the attic through some openings in the living area. To determine the root of the icicles on the main roof, if they are not related in some way to heat loss from the new addition, an infrared and blower-door energy audit should point out what the problem is and guide you to the solution.
As far as the addition is concerned, to increase its insulation, the choices are to add a significant amount of rigid insulation to the roof system and put on a new roof or add rigid insulation to the ceiling below and cover it with new drywall or paneling.
Q. I have a 15-year-old cedar deck, which I stain every two to three years. There is another deck below it. I would like to seal the spaces between the boards with caulk so water will not wet the lower deck. What would you recommend to do this job, so I won't have a problem later?
A. Caulking the joints between the deck boards is likely to give you headaches over time. The caulking is unlikely to hold in the long run, and water will start leaking through the joints again. A better solution is to screw fiberglass, vinyl or metal panels below the top deck to shed the water to the outside of the lower deck. The process is somewhat complicated because you must make sure that all parts are properly flashed. Unless you are thoroughly skilled in carpentry and know how to flash, find a contractor familiar with this type of construction. An alternative is to look on the Internet for a contractor who installs under-deck systems by Googling “Vinyl Panels for Under Decks.”
Q. I need to insulate the back wall of my masonry house. The wall is built with 6-inch blocks, which I filled with vermiculite last year. Inside, the wall is strapped, to which is applied drywall on a vapor barrier. I propose to glue 1-inch or 2-inch-thick Styrofoam on the exterior of the walls and cover the insulation with T-111 plywood. What are your thoughts?
A. The issue is how to fasten the plywood through the insulation onto the block wall. I think the best way to accomplish your plan is to try to glue the two-inch-thick Styrofoam to the block wall and hope that the glue will hold temporarily onto the paint without losing its bond, as they may not be chemically compatible. Next, nail 1-inch by 3-inch strapping vertically to the block wall 16 inches on center, which will be the tricky part. You should use rawl nails of the proper length to go through the 5/8th T-111 plywood, two inches of foam insulation, and penetrate the mortar joints by 1½ inches.
These nails have a deformed tip that holds into solid masonry, and that is where the trick lies. You should nail the strapping into the horizontal mortar joints, starting with the first joint that is between the bottom and the next course of blocks. Then apply a nail every other joint — 16 inches — going up the wall. If you feel that any nail is not holding, add another one in the free mortar joint below. This system will provide what I dubbed “the rain screen” when I first devised it in the 1970s, to solve siding and paint problems.
Next, you will need to get a mesh material similar to the type used for ridge venting (the type I don't approve of for ridge vents) that comes in a roll to seal the spaces between the strapping to keep insects and vermin from nesting in them. Now you are ready to nail the plywood through the groove in the T-111 if you laid out the strapping correctly.
Q. I had a new driveway put in last year. What is the best sealer? What do you think of this acrylic sealer? Is it reliable? What do you recommend?
A. Acrylic sealers — first developed for use on tennis courts and now available for asphalt driveways — are the best sealers to apply to them. The Home Depot advertisement you sent me says “Acrylic Grade” sealer. You would have to go to Home Depot and read the label to make sure that it is a true acrylic sealer, and not an imitation. The ad does mention that it is manufactured by Dalton Enterprises, and it lists the product as Latexite, so it may be the genuine article. Please also note that it is for application over previously sealed asphalt driveways to rejuvenate them. So you will first need to coat your driveway with a coal-tar pitch or asphalt-based emulsion and let it weather for several years before applying an acrylic sealer. Asphalt driveways must not be coated too frequently, as the buildup can cause problems. Please keep in mind that it is best to wait a minimum of two years before applying a sealer on a new asphalt driveway if it is in a sunny location. It is best to wait even longer if the driveway is in a shady spot. The oils in the mix must be allowed to dry before the asphalt is sealed.
Ÿ Henri de Marne 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.
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