Tips for Using Natural Stone
As with most masonry materials, it's very important for mason contractors, masons and architects to understand the qualities, hardness, porosity and other characteristics of the natural stone materials being used in each project. It's also important to follow some simple tips when using this natural product.
"The best thing that mason contractors can do is know the type of stone they're working with," said Tom McNall, president of Great Northern Stone in Huron Park, Ontario. "Too many times - and I'm not trying to pick any fights here - they'll treat brick the same as they treat granite, the same as they treat limestone, because it's essentially a material cut into a block and they're putting it up on the same wall.
"Now granite won't scratch as easily as a marble or limestone; brick won't react with acids as, for instance, marble will," he continued. "The best thing that we can advise is to get to know the product that's coming in and get to know the limitations."
There are also some general tips that mason contractors and their crews should keep in mind when working with natural stone.
"I think one of the biggest things is to make sure you have an adequate foundation to support the stone," said André Hagadorn, Adirondack Natural Stone, Whitehall, N.Y. "Typically, full-size stone veneer is three to five inches thick, so you'll have to have a special foundation or ledge when you're starting a natural stone project."
If a project gets behind schedule, sometimes mason contractors will try to speed things up by having quarries ship cut stone as soon as it's completed. Rick Schneider of Buechel Stone Corp. in Fond du Lac, Wis., said this is not necessarily the best option to pursue.
"It's important to understand that a stone quarry cuts by yield, not by how it's going to get put up on the structure," he said. "So, as a stone quarry, we want to complete all of the cut stone prior to shipping any of it. We want to make sure the whole thing is complete and then ship it out that way, versus sills first, windows and so on."
He also recommended that mason contractors be mindful of the cleaning techniques used once the project is completed.
"You always want to clean the stone with soap and water first, not using any kind of pressure sprayers - at a very low volume, it might be OK, but that's where the discrepancies comes in," Schneider said. "You can't have that nozzle turned on high, because you can dig into the stone and actually peel off some of the stone with that high pressure. That's why we don't recommend a power sprayer, because you can get carried away with how strong they use it on it.
He also stated that acidic cleaners should be avoided because "acid can eat into the stone and take away some of the color."
A high-quality sealer can go a long way to protect some building stones, while also enhancing that natural color.
"On an absorbent stone, it might be good to use a sealer that goes into the stone and doesn't allow moisture to absorb into it," McNall said. "However, a lot of stones have very little absorption, so putting a sealer on them could actually cause problems."
McNall said that mason contractors can apply a very simple test to check a stone's ability to absorb water. "All you have to do it put a little water on the stone for ten minutes and if it doesn't go dark on the surface, then it's not going to absorb much water."
He also advised that mason contractors shouldn't make assumptions about hardness and porosity just because the material is a certain type of stone. "The stones that are commercially sold as granites, can be anywhere from six - I've seen some go all the way to five on MOHs scale of hardness - all the way to nine, so they can vary considerably."
No matter what the characteristics, when treated properly, natural stone's beauty will last a lifetime and beyond.
"Natural stone has really come a long way and is getting quite popular again," Hagadorn said. "It's really hard to beat a natural product that will last a long time."
About the Author
Masonry, the official publication of the Mason Contractors Association of America, covers every aspect of the mason contractor profession - equipment and techniques, building codes and standards, business planning, promoting your business, legal issues and more. Read or subscribe to Masonry magazine at www.masonrymagazine.com.