Granite Countertops and Radiation

Recently the Connecticut Department of Environmental Protection (DEP) and the Department of Public Health (DPH) have received a number of calls with questions regarding the safety of granite countertops. Specifically, whether they emit radiation and radon gas, and how much is safe. In response to the increased level of questions, the Connecticut DEP has performed dose rate surveys on over 400 granite slabs, samples and demo countertops. Most have shown insignificant increases in dose rate over background.
"Background" refers to the amount of radiation that is naturally present in the environment and includes contributions from cosmic and terrestrial sources. The annual exposure for the average citizen of the USA , including background radiation, medical exposures, radon, industrial and commercial sources, is about 360 millirem. The background portion of that varies widely, depending on the type of rock or soil in the area, and the elevation above sea level. Variations of 40-50 millirem a year from area to area are common in Connecticut. The International Commission on Radiation Protection (ICRP)recommends a limit of 100 millirem a year for members of the public from industrial sources.

We found a few types of granite with slightly elevated dose rates above background. If a person leaned against the highest of these for two hours a day for a year, they would have an increase of about one quarter of the variation found above or about 10 to 13 millirem a year.
We have not surveyed for radon levels in homes with granite countertops. Studies by the Health Physics Society and Dr. Chyi at the University of Akron, indicate that a tightly sealed house with a granite countertop with a dose rate twice background would still be less than 1 tenth of the EPA guideline. However, there may be exceptions, which could push radon levels well over the 4 pCi/L guideline from the EPA. (Note: The calculations in this document make some assumptions about the meter being used, room size and countertop area that may not be the same in your case. For example, their meter, a non-energy compensated GM tube, over- responds by a factor of two. If you use an energy compensated GM tube or an Ion Chamber instrument, you would not start out by dividing your countertops net dose-rate by 2.)
Testing Your Home For Radon

The EPA recommends, and we concur, all homes should be tested for radon. Homes that test high should be surveyed to determine the source of radon, and then make decisions as appropriate. Consider using several radon test cartridges. Do not place one in the kitchen near a sink or stove where humidity could reduce its effectiveness. Try a room right next to the kitchen, the basement and a bedroom. Do them all at the same time. Choose a time of year when you can keep all the windows closed.

Choosing a Granite Worktop Company

Choosing a granite company depends a lot on the granite required, what the granite is to be used for plus the location, timescales involved and what other work is being carried out.

Complete new kitchen If you are purchasing granite kitchen worktops to go with new kitchen units you are getting through a large company it is possible that the kitchen supplier has their own granite worktop provider and they probably will not be very happy if you say you are getting the granite elsewhere, because they will want to make their mark up on the granite in addition to the kitchen units. They will possibly make it difficult for you to buy the granite yourself by refusing to return after fitting the units to reconnect services and connect the plumbing for the sink. However if you are making a large enough saving on the granite it may well be worthwhile to get a corgi registered installer to come and do the final connections rather than using the kitchen fitters again.

Replacement worktops only If you are only replacing worktops and plan to keep your existing kitchen units it is worth using a granite company with a very quick turn round time to minimise the time you will be without the full use of the kitchen. Traditional granite installers need 10-12 days to cut & polish the granite, however some cheaper companies send the granite to Europe to get the worktops made and then brought back into the UK, as using foreign labour is cheaper but this means a turn around time of up to 3 weeks. If you find the right company it is possible to get the granite cut, polished and installed in around 2-3 working days.

If you are having building work done where there is will be a carpenter on site, it might be that you can further reduce your costs by getting the carpenter make the templates for granite worktops for kitchens/bathrooms, vanity units, hearths & plinths and bars.

Also ask your builder if they have any experience of installing granite, as of he does and has the right equipment it could be a cheaper option to just use the granite company on a supply only basis. For this the builder/carpenter would need to create the templates with accurate measurements and also collect the granite. However one thing to bear in mind is that the granite is very heavy and also relatively fragile whilst in transit, so if the builder breaks a worktop while loading it or whilst installing it, it will be down to you rather than the granite company for a replacement at additional cost.

Make sure you are able to view the actual final granite, especially if you are trying to match it to the colour scheme of your new kitchen, because the samples you may have been sent can vary a lot from the batch of granite that you finally purchase.

Stone Maintenance Guide for Granite and Slate

Granite Tile

Composition: Quartz tile, Feldspar (varies)
Hardness : Hard
Absorption : Varies - Oil, Water
Limitations : Absorbs oils and other liquids, brittle
Sealer : Sub-surface repellents - oil repellent type recommended
Cleaner: Neutral pH detergent or pure soap
Finish: None Normally - Wax OK

Notes: Granite Tile is typical for kitchen counter use. Sealing is recommended for most stones. Granite Tile is the hardest of the polished stones commercially available and is used in high stress situations. Polished Granite Tile usually is more absorbent to liquids than many people suppose. Flamed Granite Tile surfaces are very absorbent due to the stress fractures in the stone caused by the flaming process and should be sealed if it is desired to maintain the original color and appearance of the stone over time.

Slate

Composition: Muscovite Chlorite (wide variation in composition)
Hardness : Soft - easily scratched
Absorption : Low - medium oil, water other liquids
Limitations : Absorbs oils/ liquids, cleft planes can spall
Sealer : Sub-surface repellents oil repellent type recommended
Cleaner: Neutral pH detergent or pure soap
Finish: Acrylic OK - wax OK

Notes: Cleft slate is very durable in most situations but quality varies. Slate is typically rustic in appearance but some milled or smooth products are available in some varieties. Wear is typically taken on the peaks or high spots of the textured surface. Acrylics are used when a highly reflective finish is desired. Excellent exterior paving stone. Higher absorbency varieties may not be suitable for exterior areas in freezing climates.

Slate characteristics vary with source. Domestic is typically black, green or mottled (Pennsylvania) and is relatively dense. Many imported slates are available today with wide ranging physical characteristics and overall suitability. Evaluate your stone for density, tensile strength, absorbency and abrasion resistance. Make sure your slate characteristics are compatible with the intended function.

Granite for Bathroom Counter Tops

Granite is commonly chosen for all types of projects within the home for many people across the United States and the world. It is used all the time when remodeling and can add that finishing touch to whatever part of the house that you want. One place that granite does well in the home is in the bathroom. You may wonder why granite may be chosen for the bathrooms, but there are actually a couple good reasons to have granite for bathroom counter tops. Many new homeowners like the look and feel of granite; it makes things look pure and elegant when the granite shows through in the bathroom counter tops. Additionally, granite for bathroom counter tops is a good idea because it will not take as much effort to clean as it would in another part of the house like the kitchen.How can granite be used for counter tops in the bathroom? Many people actually line the whole bathroom sink and counter top with granite, making it the material of choice for all the bathrooms inside the house. Also, aside from having granite for bathroom counter tops, granite is also sometimes chosen for the floors of the bathroom as well. One of those reasons is that the bathroom is typically not the place where many spills or drops take place, thus making the bathroom a perfect place for granite material as well as bathroom counter tops made of granite.

Cleaning when you have granite for bathroom counter tops can also be very easy. When the granite bathroom counter tops are installed a sealant will probably be placed over it. By using a finishing polish on the granite bathroom counter tops you are ensuring that it continually looks nice, clean, and beautiful. The major reason that granite is used for bathroom counter tops is that the material is easy to clean. But even if anything small does happen to your granite bathroom counter tops, you will certainly be able to clean them yourself very easily by using a piece of fine steel wool or even calling in a professional to make your granite bathroom counter tops look beautiful again.

Installation and Care of Cultured Marble Countertops

Installation :

If you're handy, as a homeowner you can install these tops yourself. When it comes to whirlpool decks, shower walls, wainscoting, or anything that might take additional cuts to fit pieces together properly, you may want a professional to install your cultured marble.

To install a normal vanity top, scribe to your wall. I always put masking tape on the top, and then use a marker to scribe. Use a belt sander with a large-grit sandpaper (like 40) to remove material from the backsplash or sides of the vanity top. Be sure to only sand the sides that will be up against a wall. Why? The sides that aren't going to be against a wall and will show are finished and polished. You don't want to have to try and polish them yourself, or have a professional come in and re-polish.

One the top is sized, the plumbing and fixtures may be added. Be sure not to tighten fittings too much. Less is more when it comes to cultured marble countertops, as they crack if too much pressure is applied.

Once all the fittings are mounted, you can use silicone to adhere the cultured marble countertop to the top of your cabinet, but you do not have to do this. Often your plumber will do this for you. I've lived in my home for over 8 years, and never actually siliconed the marble tops down, and they are just fine.

Also, you can put caulk between the top of your countertop and the wall to give it a finished look. If you've built a new home, you may want to wait a year or more before you do this. New homes move and shift a lot. The wood in your home will shrink and swell. If you add caulk right away, it may crack and pull away from the wall or top, and you'll have to dig it all out and replace in a year anyway, so why not wait until the house has settled a bit. Some homes never quit settling. You'll just have to play it by ear and use your common sense.

Care and Maintenance :

Wash the top with a non-abrasive cleaner and a damp cloth or sponge. Never use anything that will scratch the tops, and always make sure the top is wet while you are cleaning it. Cultured marble countertops are durable, but scratch easily. Do not use harsh cleansers, bleaches, peroxides, or other harsh chemicals on your top.

You can periodically apply paste wax, any wax product that is designed specifically for cultured marble tops (I've even used car wax), to maintain your tops luster. Apply it with a soft cloth or sponge, and buff out with a soft cloth.

Overview of Cultured Marble Countertops

Cultured marble countertops are beautiful. They look like real marble, but are a man-made resin that costs a lot less than real marble.

Some neat things to know about cultured marble (cultured onyx and cultured granite too):

They are a cast polymer product. The man-made resin is liquefied and the material poured into a mold to form your top/and or sink.It is a nonporous surface, so it resists stains and mildew.Usually come in a gloss finish (a gel is used in the manufacturing process for this), but these tops can be ordered with a flat finish to mimic solid surface materials like Corian, at a fraction of the cost.They can be ordered with sinks built (or formed) right in. These types of sinks care called integral (vs. drop-in sinks or self-rimming sinks).

If you have a belt-sander and are handy, you can install cultured marble countertops yourself.Are easy to keep clean (but be sure to never use an abrasive cleaner on them).Come in a wide assortment of colors and marbling (although the exact color and marble - or veining - pattern cannot be guaranteed because each top is individually made).
Come in several styles and patterns. The veining in cultured marble countertops is always varied, but your top doesn't have to even be veined. Tops can be a solid color, two-toned, onyx, or granite looking.

Get a cultured marble vanity top with a different colored integral bowl for a dramatic effect.Cultured marble countertops cost more than laminate tops, but if you get an integral bowl, they aren't much more than a laminate top with a drop-in sink.

These tops look great in the bathroom, but they are rarely used in a kitchen area. They will scratch, scuff, and chip easily under normal kitchen use. The bathroom usually doesn't get as much wear and tear as the kitchen, and using cultured marble countertops (or cultured marble in the shower, tub surround, or as a wainscoting) in the bath can really "dress-up" the bathroom.

There are several companies that manufacture good cultured marble countertops. You don't have to purchase your top through a large company to be sure you've got a good top. The equipment to manufacture these tops can be easily handled and afforded by smaller companies. Some small companies create the best tops.

These tops usually come with a 3 or 5 year limited warranty against defects.

Granitic Flatrocks

Exposed, gently sloping, granitic outcrops of the Piedmont physiographic region support distinctive communities characterized by lichens and sparse vascular plants. This community group ranges from eastern Alabama to Virginia and is probably best represented in Georgia, with another noteworthy cluster in north-central North Carolina. Granitic Flatrocks in Virginia range in elevation from about 70 to 100 m (230 to 320 ft) and occur on true granites and a range of related rocks such as granitic gneisses and granodiorites. Most examples are located on gentle slopes along streams, where the erosive power of water over time has worn rock surfaces smooth and created small, gravel-filled depressions.
Lichens (e.g. ., Xanthoparmelia conspersa, Cladonia caroliniana, and other Cladonia spp.) and the bryophyte (Grimmia laevigata) are dominant biota on granitic flatrocks, covering much of the exposed bedrock. However, vascular plants dominate locally in crevices, flats, and depressions where moisture and thin layers of detritus accumulate. Among the vascular plants, Small's stonecrop (Diamorpha smallii), Small's purslane (Portulaca smallii), and granite loving flat sedge (Cyperus granitophilus) are globally rare and endemic to these habitats. Other typical vascular plants include roundleaf fameflower (Talinum teretifolium), Appalachian sandwort (Minuartia glabra), rock spike-moss (Selaginella rupestris), buttonweed (Diodia teres), elliptical rushfoil (Croton willdenowii), broomsedge (Andropogon virginicus var. virginicus), little bluestem (Schizachyrium scoparium), fork-tip three-awn grass (Aristida dichotoma), purple three-awn grass (A. purpurascens), common hair sedge (Bulbostylis capillaris), open-flower panic grass (Dichanthelium laxiflorum), and orange-grass (Hypericum gentianoides). These small-patch communities often cover less than 0.4 ha (1 ac) and are considered globally rare. Major threats include invasive non-native weeds and quarrying.

Granite Countertops and Radiation

The information about granite and radioactivity in granite.

>Granite Overview
>Radioactivity and Granite
>Testing

Granite Overview :

In geological terms, granite is an igneous rock, meaning it was formed when magma (molten rock) cooled very slowly until it solidified in a process that can take many of thousands, or even millions of years. Since the rock forms so slowly, minerals have a long time to grow into the crystals that give granite its decorative appearance. Depending on the crystals that are formed, granite can come in a wide range of colors. This and other factors, make granite a popular building material in homes and buildings.

Radiation from Granite :

Any naturally formed rock material has the potential of containing varying amounts of naturally occurring radiation. Natural radioactive elements like uranium, radium, and thorium can be present in a wide number of minerals that appear as crystals in granite from around the world. So, it is not unusual for materials such as granite to have some amount of radioactivity (emissions of alpha or beta particles or gamma rays). Depending on the composition of the molten rock from which they formed, some pieces of granite can exhibit more radioactivity than others.
When present, certain radioactive elements in granite will decay into radon, a colorless, odorless, radioactive gas which may be released from the granite over time. You can see in the diagram below how the decay of Uranium-238 (a radioactive element) produces Radon-222 gas:

However, since granite is generally not very porous, less radon is likely to escape from it than from a more porous stone such as sandstone. It’s important to know that radon originating in the soil beneath homes is a more common problem and a far larger public health risk than radon from a granite countertop or other building materials. Also, any radon from granite in kitchens or bathrooms is likely to be somewhat diluted in the typical home since those rooms are among the most ventilated.

Testing :

Radiation coming from granite countertops results from natural radioactive material in the granite. Identifying the presence and concentration of radioactive elements in granite requires expensive and sophisticated portable instruments or laboratory equipment. These instruments and equipment require proper calibration, and interpretation of their readings requires a knowledgeable and trained user. At this time, there is no generally accepted home testing protocol for radiation in granite countertops.

U.S. Custom House, New Orleans, LA

The U.S. Custom House in New Orleans is one of the oldest and most important federal buildings in the southern United States and one of the major works of architecture commissioned by the federal government in the nineteenth century. This monumental granite building was begun in 1848 and built over a period of 33 years. The grand Marble Hall in the center of the building is one of the finest Greek Revival interiors in the United States.


Located a few blocks from the Mississippi River, the great waterway that enabled New Orleans to become an important port city, the U.S. Custom House was planned in the 1840s in response to increasing trade through the Mississippi Valley. The building was also designed to accommodate other Federal offices, most notably the main post office and federal courts.


The partially completed building was first occupied in 1856 when the U.S. Customs Service moved into the first floor. The post office followed in November 1860, and the building served as the city's main post office through the remainder of the nineteenth century. Although construction was suspended during the Civil War, the building was occupied briefly by Confederate forces and then by the Union Army after New Orleans was occupied in 1862. It was also used to house captured Confederate soldiers, reportedly up to 2,000 men at one time.

The impressive exterior of the U.S. Custom House retains its original design, which includes modified Greek and Egyptian Revival elements. The immense four-story building occupies the full trapezoidal downtown city block bounded by Canal, North Peters, Iberville, and Decatur Streets. Due to the shape of the lot, the corner of the building at Canal and North Peters Streets is rounded. The majority of the building is constructed of brick sheathed in gray granite from Quincy, Massachusetts; however, the entablature material is cast iron.