company logo
  Glacier Blue® Architectural Topics & News
     Monthly Educational Newsletter
September 2007
In This Issue
JJR Architects is Our Architectural Firm of the Month
Achitects & Contractors - We Want to Hear From You!
Educational Topic of the Month: Avoiding Freeze & Thaw Damage to Exterior Paving Applications
Need Samples?
Join Our Mailing List!
Circulation almost 10,000
View our Portfolio of Completed Projects - recently updated! Some new projects have just been added to our site, including an estate in Southern California and a branch of the First Republic Bank in Manhattan, NY. We will be adding more in coming weeks.

Take a look at some of our Finishes & Edge Treatments

Miss one of our back issues? You can read them by visiting our Archived Newsletters page.
Sandstone vs. Limestone
Want to know the difference between sandstone and limestone? You can read a report by Dr. William Kelly, Associate Director of the NY State Geological Survey by clicking here.
chathamDevonian Stone of New York, Inc. is a full-service stone mining and fabrication company that specializes in "high-end" cut-to-size Glacier Blue® Sandstone products. The stone has been chosen for many commercial, residential, and institutional projects across the country. Look for a full color story about Devonian Sandstone and the First Republic Bank in Manhattan, NY in the November issue of Stone World magazine.
Architectural Firm of the Month - JJR Architects
jjrJJR, LLC is a nationally recognized practice providing innovative planning and design services through an interdisciplinary approach that teams landscape architects, urban planners, civil engineers, environmental scientists, and LEED accredited professionals. Founded in 1961, JJR has over 110 full-time staff at offices in Ann Arbor, Michigan, Chicago, Illinois, and Madison, Wisconsin. The firm has received more than 200 planning and design awards. Recent award-winning projects include the Waterfront District Plan for Cleveland's eight-mile urban lakefront, botanical garden design for the University of Wisconsin-Madison, Lakeshore State Park in Milwaukee, and the East Detroit RiverWalk. The team at JJR strives to effect a positive change in people's lives, promote sustainability, and provide excellence in design and technical solutions. For more information visit
Architects and Contractors - We Want to Hear From You!
What subjects do you enjoy reading about? What do you look for in the building materials you use, and in the companies that manufacture them? These are just some of the things we want to know. After all, we created this newsletter for you and therefore want to give you the kind of information you want to read.

Each month we cover an "Architectural Topic of the Month", and we feature an architectural firm or design company as well. Is there a topic you would like to see covered in our newsletter? Would you like to see your firm or company featured in our newsletter? If so, please take a moment to let us know by sending an email to
Your thoughts and suggestions are appreciated!
Educational Topic of the Month: Avoiding Freeze & Thaw Damage to Exterior Paving Applications
paving stones

When stone is used on patios, walkways or terraces in climates where temperatures drop below freezing, frost damage can occur unless proper precautions are taken. When it comes to ensuring the longevity of exterior paved applications, two factors are of the utmost importance: construction and the removal of subsurface water. When these are done properly, it is the most effective way to protect a paved surface from frost damage.

One of the main secrets to avoiding frost damage is to make sure there is no water trapped underneath your paved surface. Although most things contract when temperatures go below freezing, water does not, so when water turns to ice, it expands. The trick is to make sure you don't have any moisture underneath your pavement, and you can do this by surface grading and subsurface drainage. If you have a walkway or a patio, it is extremely important to grade the surface so that the water will run off and away from it.

When pavement is being graded, we recommend using at least a 1.5-2% slope. For patios and walkways or any exterior paved surface with stone, a minimum of a 2% slope is necessary in order to make sure any water runs off of the top. Once the water runs off, it will either run into a drainage area, into a trough, a grass area or onto a driveway. As long as the water continues to move away from the paved surface, that is the key.

Depending on the soil conditions beneath the paved surface, you also want to consider having a good drainage system under the stones. Some types of soil hold more moisture than others, such as clay-type soils or topsoil. With these, the water in the soil will stay trapped and when it freezes, it will expand which will cause it to lift the pavement, the stones, and the edging. Then when everything thaws out, some of the dirt will begin to trickle down underneath the stone that's been lifted and the lifted stone will never go back into its original position. If this happens year after year, the first year it will get a little out of shape, the second year a little more out of shape, and so on, until five years down the road the stones will be lifted in all different directions, causing disastrous results and an unsightly, unusable paved surface that needs to be completely rebuilt. 

When a patio or walkway is constructed, we recommend placing layers of different materials underneath the paving stones as a form of drainage. A six-inch thick base of gravel, or ¾ inch crushed stone, should be put down first, on top of a graded subgrade with a minimum of a 3% pitch. On top of that put about four inches of stone blend, which is a mixture of ¾ inch stone plus stone dust, which helps to really stabilize the patio. Then on top of that put a one inch layer of stone dust and then lay the paving stones on top. Layering the materials in this manner will allow any surface water that does not run off to seep down between the joints, through the stone dust, through the stone blend, through the gravel and eventually be absorbed into the sandy soil beneath the drainage layers. If the soil is not a sandy type that will absorb the water that trickles down, drainage tiles or a drain pipe may have to be installed in the lowest layer that contains the gravel. If this is necessary, the sub base will have to be pitched to the gravel toward the drain. In either case, a drainage system must been constructed that will collect water and carry it away from the bottom of the paved area.

In cases where concrete is used beneath the stones on a patio or walkway, it is still necessary to put a drainage system in place. We recommend pouring at least a 4-6 inch layer of concrete and then using mortar to set the stones into the concrete. One of the most important aspects of this step is to backbutter the stones with a highly concentrated loose mortar mixture and also to ensure there are no voids in the mortar mixture between the stone and the concrete slab. After that, it is recommended to use a high quality joint material that will not allow any water to pass through the joints in the stone and collect between the concrete and the stone. If that happens, the same disastrous results would occur as described above. 

If a concrete base is going to be used beneath the stones, it is necessary to use a grout that will not allow water to get in because if the water goes into the grout and then freezes, the ice inside the grout will expand, the grout will contract and eventually crack. Once that begins to happen, a void in the grout is created in between the stones and that becomes a place where water can collect. If that water freezes, it will expand and more water will get in and expand even more. It becomes a destructive cycle that only gets worse with time and eventually destroys the paved surface.

There are companies who make grouts that are appropriate for exterior purposes, primarily cementitious setting materials rated for outdoor use. These are polymer modified cement based grouts, or epoxy grouts. They will last the test of time if the installation is done correctly. Some of these products are manufactured by Laticrete, Speed-e-Roc, GDC, Southcrete, Super-Tek and Fox Industries. For more detailed information about grouts, you can read about them in next month's newsletter.

Sealing your stone in an exterior application is probably a good idea, as it will stop some water from going down into the stone. But you will need to use a special kind of sealer as well, one that is made strictly for exterior use.


Educational Topic for Next Month:



Need Samples?
If you would like us to send you samples of our Glacier Blue® Devonian Sandstone, we will be happy to! You may send your request to with "Sample Request" in the subject line. Please provide us with your name, the name of your architectural firm or company, and your mailing address. Please allow up to one week for us to process your request.
We hope you enjoyed our informative monthly e-newsletter. For questions, comments or more information, please e-mail or call us today.
Robert Bellospirito, President
Devonian Stone of New York, Inc.

©Devonian Stone of New York, Inc. 2007. All Rights Reserved. Content may not be copied or reproduced in any way without the written consent of Devonian Stone of New York, Inc..