Hey, what about my Granite Countertops..... and mold?

Home Inspector with BONSAI Inspection Company

So with all the recent hype regarding granite countertops and radon gas emissions, I thought I'd combine granite countertops with one of my other 'hot topic' specialties: mold investigation.

On the scale of hygiene, the typical granite countertop falls somewhere below Stainless and Corian, well ahead of ordinary laminates, and relatively even with quartz (aka "engineered stone"). A special variation of engineered quartz called "Silestone" exists that is advertised as having built-in anti-microbial properties. This is due to the addition of a special chemical compound during its manufacture.

Unlike engineered stone however, granite benefits greatly from the addition of a sealer. Left unsealed, granite can absorb small amounts of liquid, which may lead to staining. Similarly, open pores in granite surfaces can also harbor small amounts of liquid. These situations may lead to bacterial growth

The great news about granite however, is its superior ability to be cleaned. In a study by the Hospitality Institute of Technology and Management, granite was beaten only by Stainless Steel in a standardized hygiene test. The study showed that washing a granite surface with ordinary yellow dish soap and water reduced E.Coli bacteria levels by 36,000 times. If the dish soap was followed up by a 10% solution of household vinegar, the reduction of E. Coli increased to 80,000,000 times! Because caustics like vinegar can damage some sealers, its best to just stick with the dish soap.

So here are a few tips to keep in mind:

  • Granite should be initially sealed and then reapplied following the manufacturers recommendations
  • Avoid cutting raw food directly on a granite surface - use a cutting board.
  • Wipe up any spills immediately and wash down when completed.
  • Avoid using bleach or other caustics as this can damage the sealer
  • Avoid placing hot objects directly on the surface as this may also damage the sealer.

Follow these quick tips and keep your surface dry and clean - and you can be sure mold won't be hiding in the depths!




Comments (9)

David Henke
Long & Foster Real Estate, Inc - Newtown Square, PA
Realtor, Homes Just West of Philadelphia PA

Good information... and something to balance the radon info as well.  May come in handy at my next inspection.  Thanks

Mar 16, 2009 02:01 PM
Kathy Knight
Intracoastal Realty Corp - Wilmington, NC

Yeah i agree - good info - granite is more maintenance than people think - good topic Mike...

Mar 16, 2009 02:04 PM
Marie Westerman
Blanchard and Calhoun Real Estate/ Wilson Parker Homes - Evans, GA
New Homes Sales Specialist Evans GA REALTOR

Thanks for the great information.

Mar 16, 2009 02:15 PM
Franklin & Brentwood, TN Homes Mike Nastri
Keller Williams Realty - Franklin, TN
It matters to us as much as it matters to you.

Interesting that granite cleans better than synthetic solid surfaces.  I would have guessed otherwise, especially since bleach can be used on Corian® and the like.

Mar 16, 2009 02:23 PM
Ralph Post
Suntree, FL
Melbourne Florida - Exp Realty LLC

Thanks,  Been thinking of what to replace a counter top with. Granite sure looks nice.

Mar 16, 2009 02:23 PM
Russ Ravary ~ Metro Detroit Realtor call (248) 310-6239
Real Estate One - Commerce, MI
Michigan homes for sale ~ yesmyrealtor@gmail.com

Mike you are a guru on granite.  Thanks for the information It is great.

Mar 16, 2009 02:25 PM
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

Thanks for the tips Mike.  I didn't know granite cleaned so well.

Mar 16, 2009 02:52 PM
Tad Petersen / Home Inspector, Mpls
Safeguard Home Inspections, Inc. - Watertown, MN

Thanks Mike, you just helped my cause when my wife wants to change countertops.

Mar 17, 2009 10:39 AM
Kate Hart
Hart & Associates Staging and Design - Radnor, PA

Thanks Mike, I have had some clients ask me about the Radon thing and this is good info too. I installed granite counters a year ago and I was just getting ready to reseal them. KH

Mar 29, 2009 04:14 AM