Sealing grouts will make grout joints easier to clean and more resistant to water penetration and staining. When water penetrates grout joints, it makes them susceptible to mold and bacterial growth. Even grouts containing mil — dewcides can eventually become moldy. Besides sealing grouts in wet areas, the key to mold-free grout is maintenance. Bathrooms should be kept dry by using exhaust fans, and grout joints should be cleaned regularly We do not recommend the commercially available grouts enhanced with additives. We have found the following sealing methods to be generally well-tolerated by chemically sensitive individuals:
• AFM Safecoat Grout Sealer: A clear, moisture-resistant sealer for porous tile grout to help prevent staining
• AFM Safecoat Safe Seal: An odorless, zero-VOC, water-based, low-gloss sealer for highly porous surfaces, it can be diluted in a 50:50 ratio with water and then mixed into the dry grout to form an integral grout sealer
While stone is generally a healthful and beautiful choice for flooring and decorative accents, it raises the same concerns about proper installation as ceramic tile does. The specifications we have outlined for ceramic tile also apply to stone.
We have tested several stone products for radiation and radon content and found a range of readings from very low to high levels. Although uranium content in construction materials is not usually considered to be a serious concern, Johns experience, as shared in Case Study 9.2, leads us to conclude that stone can contribute significantly to ambient radon levels in a home. We recommend that stone, especially granite, be screened for radon prior to installation, even though the Granite Institute has issued a scientific report concluding that granite countertops do not emit radioactivity into the home. Tests are easily performed as described in Division 13.
Refer to our discussion of the thickset method in the section on tile installation above and to the section on stone countertops in Division 6.
Tire following finishes are free of petroleum — based solvents and can be used for most stone flooring, shelving, and countertops:
• AFM Safecoat MexeSeal: A durable sealer providing water and oil repellency, applied over AFM Safecoat Paver Seal.003, an undersealer for porous materials
• Lithofin: Stone sealers
• Livos Meldos Hard Oil and Livos Bilo Floor Wax: A penetrating oil sealer and a clear, mar-resistant finish wax respectively; can be odorous when first applied and should be carefully tested prior to use by a chemically sensitive individual
• Naturel Cleaner and Sealer: Water — soluble flakes that clean, protect, and finish stone surfaces
Flooring Installation Over Concrete
Flooring materials such as wood, carpeting, and resilient flooring are often laid over a concrete slab. If the concrete slab has a high moisture content resulting from inadequate curing time or from a high water table, then the perfect conditions exist for mold growth: an environment that is dark, moist, still, and nutritious. Flooring manufacturers publish recommended maximum vapor-emissions levels for installations of their products over concrete slab. When these levels are exceeded, the warranty is void. Unfortunately, slabs are rarely measured for vapor emissions.
Where finished flooring, especially wood flooring, is laid over concrete slab with radiant heat tubing in it, we have encountered an additional problem. A slab that appears to be fully cured will have unacceptably high vapor emissions when the heat is first turned on. Often the heat is turned on only after floor finishes have been applied and the construction is completed.
We consider these to be important quality control issues and suggest the following specifications: [16] [17]
