Signs of stress: (Especially Important along Load-Bearing Walls)

     >Buckling

     >Bowing

     >Curved mortar lines

     >Cracks encompassing more than four masonry joints or bricks

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Causes of stress:

     >Water Leaks from plumbing lines

     >Moisture entering through mortar or roof

     >DIY Brick Repair with Improper Mortars

     >Water-Sealants & paints that prevent bricks from breathing

     >Aged & deteriorating bricks

 

There is an astounding array of information online which suggests that DIY home enthusiasts can facilitate their own brick and stone repairs. Although most caution that professional help should be obtained when four or more bricks or stones are affected, few, (if any), forewarn about the potentially disastrous results that can occur when mismatching brick and mortar porosities, coating brick with impermeable water sealants, or painting brick with non-porous paints: 

 

Modern Mortar Mismatches

The earliest American brick homes were constructed in the 1600s by German immigrants who practiced the art of mixing clay with grass or shells and curing it in kilns.  During the following century similar brick- making establishments expanded to other regions of our country. In 1788 Kentucky opened its first brick-making endeavor that served much of the South, including Texas.

 

In those long-ago days, brick-making consisted of packing wet mud clay into molds and curing them in a kiln. The result was a highly porous brick that, like its European counterparts, breathed and swelled, (permitting moisture to both enter and exit according to weather conditions). Mortars of the day were composed of earthen clay, plant matter and sand. This mixture also moved according to meteorological conditions.

 

In 1888, when the Industrial Era produced machinery that could tightly compact clay into brick molds, a denser brick consisting of only 10% moisture, (known as extruded brick), was created. At approximately the same point in time, John Smeaton discovered that heating "water-lime" during the curing process greatly enhanced mortar strength, birthing an industry known as concrete. These two events marked the beginning of our country's desire to create stronger, denser bricks and mortar. 

 

Modern brick is extremely dense and couples well with non-porous cements and mortars. Dense brick does not expand and contract, and neither does modern mortar and cement. [It is important to note that stones also have different porosities that necessitate examination].

 

When non-porous mortars are coupled with bricks that need to expand and contract

 it is the brick that will succumb to pressures within the fixed cavity!

 

Modern mortars used with bricks kilned as recently as forty years ago, can produce disastrous results. Our professionals know how to determine the porosity of your brick, in order to match it with mortar that will expand and contract at corresponding rates. Here are the factors we consider:

 

1) The Coefficient of Expansion:

How much does a brick (or stone) move as a result of temperature change?

2) Compressive Strength:

The ability of mortar to withstand a compressive load.

3) Ductility:

The ability of brick to deform under pressure without failing. 

4) Porosity:

The amount of moisture that will enter a brick, causing it to expand

5) ) Bond Strength:

The ability of mortar to adhere to the surrounding brick (or stone).

6) Modulus of Elasticity:

The ability of mortar to accomodate minor brick movement, including expanding and contracting, without cracking or crushing the brick or stone.

7) Tensile Strength:

Mortar's capacity to witstand tensile pulling against it.

 

In much the same way that mismatched mortars inhibit brick's natural tendency

to expand and contract, so too, do water sealants and non-porous paints. 

 

It is important to understand that there is a marked difference between water sealants and water repellants. Although repellants permit the natural admission of meteorological moisture into bricks and stone, both sealants and repellants block moisture within from exiting. Gaseous moisture tends to pool within the brick or stone, causing massive deterioration.

 

Technical Preservation Services, a division of the Department of the Interior, suggests that neither water repellants, sealers, NOR consolidants, (binders designed to strengthen the facade of bricks), be used on most porous bricks. The incident of internal pooling is far too great a risk and can result in the coating failing at the surface and pulling pieces of the brick's facade with it as it sloughs off. Their extensive treatise on the subject lists instances where it IS and IS NOT appropriate to apply either paint or water repellants to brick. 

 

At Plano Brick & Stone Repair we keep appraised of the varying situations that warrant intervention. You can count on us to fully assess your brick and stone needs before we begin work on your project. 

 

Plano Brick & Stone Repair is a subsidiary of Omega Masonry committed to Omega customers in Plano, Frisco, and Carrollton, helping us respond more quickly to your needs.