Prudent home inspectors in Austin, Texas always seek to present all view points when inquiring a new topic that arises such as radon gas in granite counter tops.  Since I do not test for radon, I will not offer my opinion to the validity of this article, but will let the reader be the judge. What about radon in granite countertops? Answer.. Does the EPA believe there is a danger of radon gas or associated radiation being emitted from granite countertops? Granite is a naturally occurring igneous rock, meaning that it was formed by the cooling of molten rock.  It is quarried and processed to produce commercial products such as countertops. It is possible for any granite sample to contain varying concentrations of uranium that can produce radon gas, a source of alpha and beta particles and gamma rays. Some granite used for countertops may contribute variably to indoor radon levels.  At this time, however, EPA does not believe sufficient data exist to conclude that the types of granite commonly used in countertops are significantly increasing indoor radon levels. Some granite may emit gamma radiation above typical background levels.  While radiation levels are not typically high, measurement of specific samples may reveal higher than expected levels on a case-by-case basis.

While natural rocks such as granite may emit radon gas, the levels of radon attributable to such sources are not typically high. EPA believes the principal source of radon in homes is soil gas that is drawn indoors through a natural suction process. To reduce radon risk you should first test the air in your home to determine the radon level. There are many home radon test kits available at the retail level and on-line, starting at about $25.

ASHI HOME INSPECTOR - AUSTIN TEXAS

Austin Home Inspectors don’t encounter radon much because we seldom have basements with trapped air that would cause high levels or radon to sit without air drafts from moving them along.  Recently an article was written by Kate Murphy on “What is Lurking in Your Countertops?  This article is worth reading if you have granite counter tops to know what questions to ask & where to go to for more information.  As  an Austin Home inspector, I do not personally inspect for radon, but if you are concerned if radon is present in your house, then call the EPA.

July 24, 2008 What’s Lurking in Your Countertop? By KATE MURPHY

SHORTLY before Lynn Sugarman of Teaneck, N.J., bought her summer home in Lake George, N.Y., two years ago, a routine inspection revealed it had elevated levels of radon, a radioactive gas that can cause lung cancer. So she called a radon measurement and mitigation technician to find the source. “He went from room to room,” said Dr. Sugarman, a pediatrician. But he stopped in his tracks in the kitchen, which had richly grained cream, brown and burgundy granite countertops. His Geiger counter indicated that the granite was emitting radiation at levels 10 times higher than those he had measured elsewhere in the house. “My first thought was, my pregnant daughter was coming for the weekend,” Dr. Sugarman said. When the technician told her to keep her daughter several feet from the countertops just to be safe, she said, “I had them ripped out that very day,” and sent to the state Department of Health for analysis. The granite, it turned out, contained high levels of uranium, which is not only radioactive but releases radon gas as it decays. “The health risk to me and my family was probably small,” Dr. Sugarman said, “but I felt it was an unnecessary risk.”

As an Austin ASHI Home Inspector, I am a huge fan of radiant barrier in the attic under the roof decking. The big reason, my utility bills are below $175 per month in the hot summers of Austin. Home inspectors are in hot attics every day. The sweat that pours down my face from the time I enter the attic is from poor ventilated attic space & no radiant barrier. Radiant barriers are great because they reduce the amount of heat transfer from roof surface into the attic. Therefore a/c ducts do not get excessively hot so the a/c has to work less to cool the house. The following article will help you to understand why your attic should have radiant barriers.

Radiant barriers are materials that are installed in buildings to reduce summer heat gain and winter heat loss, and hence to reduce building heating and cooling energy usage. The potential benefit of attic radiant barriers is primarily in reducing air-conditioning cooling loads in warm or hot climates. Radiant barriers usually consist of a thin sheet or coating of a highly reflective material, usually aluminum, applied to one or both sides of a number of substrate materials. These substrates include kraft paper, plastic films, cardboard, plywood sheathing, and air infiltration barrier material. Some products are fiber reinforced to increase the durability and ease of handling. Radiant barriers can be used in residential, commercial, and industrial buildings. However, this fact sheet was developed only for applications of radiant barriers in ventilated attics of residential buildings.

How are radiant barriers installed in a residential attic?

Radiant barriers may be installed in attics in several configurations. The simplest is to lay the radiant barrier directly on top of existing attic insulation, with the reflective side up. This is often called the attic floor application. Another way to install a radiant barrier is to attach it near the roof. The roof application has several variations. One variation is to attach the radiant barrier to the bottom surfaces of the attic truss chords or rafter framing. Another is to drape the radiant barrier over the tops of the rafters before the roof deck is applied. Still another variation is to attach the radiant barrier directly to the underside of the roof deck.

How do radiant barriers work?
Radiant barriers work by reducing heat transfer by thermal radiation across the air space between the roof deck and the attic floor, where conventional insulation is usually placed. All materials give off, or emit, energy by thermal radiation as a result of their temperature. The amount of energy emitted depends on the surface temperature and a property called the “emissivity” (also called the “emittance”). The emissivity is a number between zero (0) and one (1). The higher the emissivity, the greater the emitted radiation. A closely related material property is the “reflectivity” (also called the “reflectance”). This is a measure of how much radiant heat is reflected by a material. The reflectivity is also a number between 0 and 1 (sometimes, it is given as a percentage, and then it is between 0 and 100%). For a material that is opaque (that is, it does not allow radiation to pass directly through it), when the emissivity and reflectivity are added together, the sum is one (1). Hence, a material with a high reflectivity has a low emissivity, and vice versa.

Radiant barrier materials must have high reflectivity (usually 0.9, or 90%, or more) and low emissivity (usually 0.1 or less), and must face an open air space to perform properly. On a sunny summer day, solar energy is absorbed by the roof, heating the roof sheathing and causing the underside of the sheathing and the roof framing to radiate heat downward toward the attic floor. When a radiant barrier is placed on the attic floor, much of the heat radiated from the hot roof is reflected back toward the roof. This makes the top surface of the insulation cooler than it would have been without a radiant barrier and thus reduces the amount of heat that moves through the insulation into the rooms below the ceiling. Under the same conditions, a roof mounted radiant barrier works by reducing the amount of radiation incident on the insulation. Since the amount of radiation striking the top of the insulation is less than it would have been without a radiant barrier, the insulation surface temperature is lower and the heat flow through the insulation is reduced. Radiant barriers can also reduce indoor heat losses through the ceiling in the winter. Radiant barriers reduce the amount of energy radiated from the top surface of the insulation, but can also reduce beneficial heat gains due to solar heating of the roof. The net benefits of radiant barriers for reducing winter heat losses are still being studied.

Recent technology has brought choices when shopping for windows. Argon gas or krypton gas fill between the panes gives a higher R value, reduced heat & lower utility bills. Doing home inspections has allowed me to see all the styles of windows & how they perform relative to the traditional style of window. You have to judge for yourself. Before you do, read this article to give more insight into this technology.

Window Technologies: Argon or Krypton Gas Fills

An improvement that can be made to the thermal performance of insulating glazing units is to reduce the conductance of the air space between the layers. Originally, the space was filled with air or flushed with dry nitrogen just prior to sealing. In a sealed glass insulating unit, air currents between the two panes of glazing carry heat to the top of the unit and settle into cold pools at the bottom. Filling the space with a less conductive, more viscous, or slow-moving gas minimizes the convection currents within the space, conduction through the gas is reduced, and the overall transfer of heat between the inside and outside is reduced.

Manufacturers have introduced the use of argon and krypton gas fills, with measurable improvement in thermal performance. Argon is inexpensive, nontoxic, nonreactive, clear, and odorless. The optimal spacing for an argon-filled unit is the same as for air, about 1/2 inch (11-13 mm). Krypton has better thermal performance, but is more expensive to produce. Krypton is particularly useful when the space between glazings must be thinner than normally desired, for example, 1/4 inch (6 mm). The optimum gap width for krypton is 3/8″ (9mm). A mixture of krypton and argon gases is also used as a compromise between thermal performance and cost.

When performing my home inspection I always flood the shower to determine if the pan leaks or even if it has a pan. You the consumer do not want to move into a house & discover later that your shower leaks. Trust me, I speak house. I am an ASHI certified inspector & I do not want you to buy someone else’s problems. Let me find the problems first.

Should you install slate tile in the shower? Before you say yes, you need to consider the qualities of slate. It is a natural product thus making it porous. In other words, it will leak through to the other side. That does not mean that you should not use a porous natural stone, but if you do, then a good weather barrier must be installed along with a water proofing drain pan & plastic resin water proofing on the wood members. A 30# weather barrier then should be installed prior to installing the hardi backer cementous board prior to slate tile. After the slate tile is installed, coat the surface with a stone sealing liquid compound. Now enjoy that slate shower. Read the article below for more information. (Keep in mind the article below does not explain what I did about installing the weather barrier, plastic resin & shower pan). I have tested many shower pans & seen showers installed installed as I described. Guess what, they don’t leak! I am giving this article just so you read the other sides viewpoint.

Slate in the Shower
My client wants to install slate tile in her shower to match the tile on her bathroom floor. I know that slate is porous and harder to keep clean than ceramic tile, but is there a good sealer that can be used with the slate so that maintenance will be manageable? Contributing editor Michael Byrne, a tile-setter and consultant in Los Olivos, Calif., and moderator of JLC Online’s tile forum, responds: The quality and density of slate can vary quite a bit. Honed slate tiles dense enough to be exposed to water don’t absorb sealers readily, whereas some softer slates with cleft finishes will actually start disintegrating in water. And while not all penetrating sealers perform well with slate, top-coating sealers can lead to disaster when they yellow and begin to chip off.

Generally speaking, I think that most tiles made from porous stones like slate and limestone are a bad choice in a shower stall. Regardless of the type of sealer used or how often it’s applied, keeping slate or limestone in a sanitary condition is almost impossible, as is removing the “dirty clothes” smell that these stones tend to accumulate. Porcelain-tile look-alikes might appear to be the first and best alternative, but they have their problems too. Some of these tiles have a coarse texture meant to make them slip-resistant; unfortunately, it also allows dirt, grime, grease, soap, and oils to lodge permanently on the tiles’ surface. For best results, choose a smooth-surface stone tile with absorption properties similar to those of vitreous or impervious tiles — and avoid any stones that require topical applications to achieve these desired properties.