Clay Tile Density Checker Question

I’m an IA/PA operating in the valley in Texas. We have plenty of hail storms here (especially around the Laredo area), as I’m sure you are already aware of, as well as plenty of clay roofs.

I’m looking for a handheld clay tile density checker. This past summer one of my claims was sent to an engineering firm to check/analyze the density of the clay tiles after a hail storm. When I asked what instrument he was using, he refused to tell me.

When he used the instrument, he was able to slide the tile in between two sensors and slide the instrument back and forth. When the instrument located a hairline fracture, it made a “ping” sound.

Do you have any idea what this instrument is? Would you know what the name of the manufacturer and where I could possibly purchase one? I’d prefer to settle the claims in the field without having to force the client to wait the additional days and/or weeks with damaged clay roofs.

My present and future clients would surely appreciate your insights!

chastainrichard at yahoo.com in case you don’t want to reveal your secrets (for some reason it’s a closely held insiders instrument :mrgreen:) or pm me.

Hi Richard,

I know that there are electronic methods for detecting leaks in membranes used to protect roofs. Basically they sense anomalies or interruptions in electrical conductivity. These interruptions are typically in the form of cracks or tears. I have not yet heard about any similar device being used to detect damage to clay tiles with results that provide any useful information. I would certainly question the validity of any claims made by anyone using a device for which they cannot provide proof of effectiveness validated by an unbiased testing and certification organization.

Fractures, and variations in density are very different things. Hail impact does not produce changes in density in clay tile to any degree that affects it’s ability to shed water, which is the most important criteria in evaluating clay roof tile.
Proper vitrification and solid continuity are key to the ability of tile to shed water. Levels of vitrification are not changed by impact from hail, however continuity can be interrupted by cracks.

According to the amount of impact energy carried by a hailstone, impact may create a crack that:

  1. propagates a short distance and does not continue through from the face to the back of the tile.
  2. propogates clear through the tile but is limited in length and width so that it does not allow through-tile leakage, but may trap and hold water that may, over time and in an environment subject to freezing weather, expand relatively rapidly (1-5 years) to finally allow moisture intrusion of the tile.
  3. splits the tile into two sections.

I question what useful information removing a tile from a roof and testing it for microscopic cracks provides.

  1. The drying process during manufacture of clay tiles creates micro-cracks of various sizes that may easily resemble micro-cracks created by the impact of hailstones carrying low impact energy and that carry a very similar chance of long term problems. Thus, micro-cracks from hailstone impact are not really a concern.
  2. Relatively low quality clay tiles can have visible shrinkage cracks and poor vitrification that may give the same results as hail induced cracks with limited propagation.
  3. If a tile is split, an electronic device is not necessary to determine the extent of the problem.

So, you’ve got someone taking one, or a few tiles off the roof to test them to show… what exactly? And what does showing the condition of a few specific tiles prove about the rest of the roof?

I’d say he refused to tell you because the information produced by his “instrument” meant nothing.

NRCA mentions density test numerous time in their manuals
wet during mfg & dry after firing

Barry,
I’m not aware of any such equipment. Since density is a measure of mass per unit of volume, I can’t imagine there is a handheld device that would determine density. Samples have to be taken into a lab and analyzed (i.e., by a petrographer). I also am not aware of a device for determining if tile has any cracks. Typically, it is determined by visual inspection. And I have also heard there are those who can tell by sounding the tile.
Thank you for contacting NRCA.
Joan P. Crowe
Director of Technical Services
National Roofing Contractors Association

i’d like to see the specs if tool/instrument exists

sound like the guys from the old days that drove around on sunny days & sprayed on a liquid waterproofing agent,
dihydrogen monoxide

NRCA mentions density test numerous time in their manuals
wet during mfg & dry after firing

Barry,
I’m not aware of any such equipment. Since density is a measure of mass per unit of volume, I can’t imagine there is a handheld device that would determine density. Samples have to be taken into a lab and analyzed (i.e., by a petrographer). I also am not aware of a device for determining if tile has any cracks. Typically, it is determined by visual inspection. And I have also heard there are those who can tell by sounding the tile.
Thank you for contacting NRCA.
Joan P. Crowe
Director of Technical Services
National Roofing Contractors Association

i’d like to see the specs if tool/instrument exists

sounds like the guys from McKee’s era that drove around on sunny days & sprayed on a liquid waterproofing agent,
dihydrogen monoxide

NRCA mentions density test numerous times in their manuals
wet during mfg & dry after firing

Barry,
I’m not aware of any such equipment. Since density is a measure of mass per unit of volume, I can’t imagine there is a handheld device that would determine density. Samples have to be taken into a lab and analyzed (i.e., by a petrographer). I also am not aware of a device for determining if tile has any cracks. Typically, it is determined by visual inspection. And I have also heard there are those who can tell by sounding the tile.
Thank you for contacting NRCA.
Joan P. Crowe
Director of Technical Services
National Roofing Contractors Association

Richard, if a defect is not visible would it not be advantageous to use Infrared.
One must also consider snake oil sales man exists everywhere and you should try to avoid liability by using a professional services to determine the quality of a product.
JMO

NOTE: Keep tile cuttings and the batch numbers in a container or form a system for your company. keep all materials cataloged. Each roof will have a verification catalog.
When/If a claim is pending you can then have any samples tested. Then that material has **provenance **and you can follow it back to its origin and date of manufacture.
You have a batch number to fall back on and job cataloged. All you need to do is photo the materials used on the roof and keep them in a file on your PC…

As for tensile, compaction and torsion testing, I recommend you leave ALL testing to labs.

Barry, could thermography be used to look for unseen defects in clay?

Likely a hand held or portable Ultrasonic Flaw Detection instrument. I am not familiar with any particular brand or specific device, but perhaps these sources may be of assistance:

http://www.olympus-ims.com/en/applications-and-solutions/introductory-ultrasonics/introduction-flaw-detection/

http://www.olympus-ims.com/en/applications/thickness-measurement-ceramics/

Very sold statement.
One that means a lot but say little is an engineering gorgon for brick veneer lateral cracks. (Heat expiation related lateral cracks)
I though engineers used scientific equipment and/or calculations of mass, weight and measure movement.
I have heard some great story tellers in my years doing masonry and concrete.
I butted heads with some real closed mined civil engineers.

Very helpful information on the manufacturing of clay tiles Kenton.
It seems that the manufacturing process would not create a conclusive deduction other than to say there are many.
Thanks buddy.

I’ve never seen a Clay Tile which has any integrity… period.

In Arizona (and other southern states) they’re installed for the architectural design of the roof, the modified bitumen or similar material beneath the tiles is what sheds water.

Dale, can a thermographer using IR and a 320 x240 or higher camera and a special lens for tight close-ups, i.e. on clay of concrete tiles for this example, and have a conclusive image to determine fractures or fishers allowing water intrusion?

Can a fracture be definable with the camera, right angle operator, and lens ?

I can see this image obtained only the software would have to be advance and the object at close range.

Ask Jim if it’s possible.

Regards.

It sounds like You are doubting my masterful waterproofing skills…You Sir are a scoffer…:roll:

If you can’t see it with your eyes, it doesn’t matter anyway.