The cause of cracks in ceramic tiles
December 14, 2012Steve Maxwell
SPECIAL TO THE STAR
“Concrete doesn’t expand in contact with water, so it sounds to me like your insurance company is making an excuse.”
Q: Can regular water contact cause ceramic tiles to crack and lift when they’re installed over concrete? Our trouble area is underneath a tub that’s been leaking slowly. The insurance company says they won’t cover the damage because the leaking caused the concrete to expand and damage the tile. Is this true?
A: Concrete doesn’t expand in contact with water, so it sounds like your insurance company is making an excuse. Something certainly caused the tiles to fail, but it’s obviously not the presence of water.
Showers have traditionally been built with ceramic tiles over a mortar bed for many decades and this was always regarded as the best way to do things. The presence of water in this application never caused cracking, and it’s not the cause in your case.
I suspect the problem goes back to different levels of expansion and contraction between the tiles and the underlying floor. If an uncoupling membrane had been installed underneath your tiles, you probably wouldn’t have any trouble now. I’ve had best results with a product called Ditra by Schluter. Check out my video on proper installation of uncoupling membranes at www.youtube.com/smaxwell1963. In it I cover essential details for optimal ceramic tile installations.
Insulating a pre-insulated basement
Q: How should I insulate the walls and floor of the basement in our new home? The builder left us with R12 blankets extending almost all the way to the floor. Is this sufficient?
A: Your question is both common and important. The building code only requires the simplest of basement insulation strategies for new homes, and since most homebuyers don’t recognize the value of better systems, it doesn’t pay for builders to invest the extra money for decent and durable stuff. The end result is the ubiquitous fiberglass wall blankets like you’ve got.
While you could leave the basement insulation in place, build a frame wall on the inside face, then cover it with drywall, this approach has two major flaws. First, the R12 worth of fiberglass doesn’t actually deliver a lot of warmth in the real world, especially if air leakage occurs through the above-ground part of your foundation wall.
And second, all forms of soft, fiber-based insulation are susceptible to moisture infiltration. Some are more vulnerable than others, but all lose their insulating value if they get wet, while also being a perfect breeding ground for mould in high-moisture situations.
The first thing I’d recommend is that you hold off finishing your basement until you’ve been through at least one complete spring thaw. Any finishing strategy depends on truly dry conditions all the time, and you haven’t spent enough time in the house to verify that. And even if a basement seems dry for years, future leaks are always a possibility. So is invisible moisture vapour coming through the masonry walls. All this is why I really like foam-based insulation products for basements.
The best strategy is to remove the fiberglass and use some kind of foam insulation instead. The insulation performance is better and resistance to moisture is superior, should that ever prove to be an issue.
As for the floor, there are many subfloor options and all work well. My preference is to go with versions that include no organic matter (so no chance of mould) along with high insulation values.
Stair Finishing Strategy
Q: How can I get an even colour of stain on wooden stairs I’m refinishing? I’ve stripped the old varnish, but the new stain I’m applying now is turning out uneven. Is sanding in lighter areas before restaining likely to work?
A: No, your plan probably won’t work. Besides being a lot of trouble, you’ll still have too much uneven colour. A better option involves using a coloured finishing oil, rather than the usual approach of stain followed by urethane. There are two reasons why.
First, coloured finishing oils build a thin surface layer after multiple coats. That’s why they’re less lightly to depend on even absorption for even colour. And second, finishing oils offer the option of easily and effectively repairing areas of wear.
Regular stained and sealed finishes are difficult, or impossible, to re-establish in worn areas without sanding completely back to bare wood. And by now you’ve probably had more than enough of that kind of work.
Oil, by contrast, is easy. Just wipe a new coat over the trouble spots at night, just before you go to bed. The stuff I use is called Deftoil and I buy it at Lee Valley Tools (leevalley.com, 1-800-267-8767). It’s dry enough to walk on by morning. Repeat for three or four nights and your stair treads will look as good as new.
The last set of wooden stairs I finished with Deftoil remains wear-free after more than three years of constant use.
Steve Maxwell, syndicated home improvement and woodworking columnist, has shared his DIY tips, how-to videos and product reviews since 1988. Send questions to firstname.lastname@example.org, connect with him at stevemaxwell.ca, on Facebook at Canada’s Handiest Man or follow him on Twitter at @Maxwells_Tips.
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