Restoring the Historic French Quarter with Breathable Lime Mortar

Founded in 1718, the French Quarter or Vieux Carré is the oldest neighborhood of New Orleans. Much of the quarter’s historic buildings were constructed before New Orleans even became part of the United States. Built extensively with lime mortars before the invention of portland cement, the iconic french quarter is a standing testament to the success of breathable masonry construction. These historic structures are now protected from demolition and any restoration or renovation efforts must be approved and performed with appropriate historic methods and materials to match the original historic architecture. During a recent visit, the LimeWorks.us team presented to the Vieux Carré Commission responsible for approving all restoration efforts to share with them a better understanding of breathable natural hydraulic lime mortars for appropriate masonry restoration. During their visit, the team documented deteriorating buildings and further damage that has been caused due to poor repair materials including harmful portland cement.

The team also spent a day with some of the leading area stonemasons, plasterers, and interior designers at Masonry Products in a workshop, teaching them appropriate methods and techniques for mixing and applying breathable Ecologic™ Mortar for repointing and plaster applications along with Lithomex for breathable stone and brick repair work. The team demonstrated mixing procedures, application and curing methods as well as breathable silicate paints and stains.

To learn more about appropriate historic masonry restoration or to start working with breathable lime mortars in New Orleans, visit Masonry Products at 401 N Alexander Street, the newest distribution hub for LimeWorks.us Ecologic™ Mortar and Natural Hydraulic Lime.

Photos here

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How To Stay Cool While Working with Lime in Extreme Heat

With temperatures across the U.S. exceeding well beyond the 90° F during the day and relentless scorching sun I have been asked the same question a lot in the past few weeks. Can or should I use lime products above the suggested 85° mark?

Using Lime in extreme conditions can require extreme or excessive measure to ensure a job well done. There is saying that if the worker is happy then the work is happy. If you are in the shade and are well hydrated then this comfort is passed on to the work and potential problems can be reduced. The most common and critical issue would be that excessive drying out of the wall is occurring. Repointing, laying masonry units, and stucco work all require adequate suction control to achieve a good bond. Dampening porous masonry prior to application and occasionally dampening the work will help allow the lime mortar to cure at a slower rate preventing a “flash set” or no set from a occurring. A flash set occurs when water is pulled out of the mortar quickly and in the case of cement mixes the set happens too quickly which is prone to a compromising the intended results. When the water is pulled out of the mortar too quickly from a lime mortar usually the mortar turns to dust and is rendered useless. The work will have to be re-done in its entirety.

Even when a flash set does not occur controlling how the mortar cures is very important in hot weather. A good tip is to cover the recently completed wall sections with damp burlap. Damp burlap works well because it is relatively light, will provide shade, hold water to increase localized humidity and breathe. All these virtues help provide a good environment for mortar to cure the way it should, slow, steady, cool, and damp. Burlap is also used as an indicator tool. When it becomes dry then you know the wall is getting dry behind it or soon will be. Misting the burlap when dry keeps the wall from receiving a direct stream of water and over saturation.

Burlap can be found at agricultural supply centers and has a wide range of uses other than keeping masonry damp.

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Discussion on Masonry Preservation and Sustainable uses for Lime

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Join us June 27th in Lancaster PA at the Central Pennsylvania Preservation Society. Lab Tech Randy Ruth will be presenting on the importance of appropriate masonry restoration with lime and the harm caused to countless historic structures across the country by Portland Cement. Randy will be presenting on 3 main topics and doing demonstrations. The event is free to the public and light refreshments will be served.

Review the presentation topics below and follow this link to register.

Historic Mortars: The Chemistry that Binds our Built Environment will review the use and development of masonry mortars spanning over nearly 5,000 years, as well as the basic chemistry of mortar manufacture and application and the role it plays in masonry buildings today and prior to 1870.

Masonry Preservation: Technical Applications of Common Masonry Problems will dive deeper into the application of different types of mortars to solve common masonry issues. Benefits of lime mortars will be discussed – including suitable Portland cement applications. Silicate consolidants, stains, and paints will be touched on regarding painting new buildings and preserving older structures.

Preservation & Sustainability will bring together the history and preservation of masonry and mortars to show how the preservation of masonry structures via adaptive reuse is key tot the sustainability of a community. Concepts such as urban planning and architectural significance will be touched on, as well as traditional building methods for low-rise new construction and how it affects a local economy.

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How do Natural Hydraulic Lime Mortars Compare to Common Type-O Mortars Containing Portland Cement? by Randy Ruth

by Randy Ruth

For well over 30 years it has been common practice to prescribe the use of a Type-O masonry mortar for use on the conservation of masonry buildings. The most common formula of a Type-O mortar is 1:2:9, a blend of 1 part white Portland cement, 2 parts Type-S hydrated lime (most often dolomitic lime) and 9 parts sand by volume. In recent years there has been an increasing amount of research on similar mix designs and how they compare to Natural Hydraulic Lime (NHL) based mortars used in Europe to repoint historic masonry buildings. Just recently, a professor and two graduates of Columbia University published a research study on the same topic here in the United States. The results of this study can be found in the Association for Preservation Trades International bulletin Vol. XLIII. Their innovative approach to allow a real comparison between different mortar types used in conservation reveals some interesting results.
Petrographic thin section images courtesy of William Revie of The Construction Materials Consulting Group; Striling, Scotland

Petrographic thin section images courtesy of William Revie of The Construction Materials Consulting Group; Striling, Scotland

The innovative approach the research team had developed with their curing protocol of various binder types, established a relatively level field of comparison for various mortars in regards to the way each mortar uniquely cures. With this testing detail established, the 11 commonly used repointing mortars were tested at various stages on their splitting tensile strength, compressive strength, water absorption and water-vapor transmission.

The tests reveal that for a splitting tensile strength the NHL/sand mortars are most comparable to traditional pure lime/sand mortars made of High calcium lime and dolomitic lime, while Type-O mortars were more than twice the splitting strength of NHL mortars. Although anecdotal, the cases where historic pure lime mortar has been used to repoint soft brickwork and has eroded causing a need for repointing, Type-O mortars could be consequently be too rigid for use a repointing mortar.

Compressive strength data shows that although NHL mortars have higher values than that of high-calcium lime mortars (with the exception of NHL 2 being less in strength than dolomitic lime) when compared to Type-O mortars their values are nearly half.

When mortars were measured for their water absorption, initially all NHL mortars significantly out-performed other mix designs. The most comparable mix was that of the Type-O mortars that ended up with similar characteristics to NHL mortars and still outperformed both pure lime mortars.

Water-vapor transmission results indicate that all NHL mortars process water vapor at much higher rates than dolomitic and both Type-O mortars, with values comparable to High-calcium lime mortars.

Although the results from the laboratory study are not entirely representative of values that are obtained in field work, they do represent what specifiers and conservation masons are attempting to achieve in real world situations. By eliminating variables, that can give anecdotal results and margins of error, the data suggests that NHL\’s are indeed appropriate when specifying a historic repointing mortar or a new construction mortar used for masonry mortar, plaster or stucco applications.

In conjunction with this study and the new ASTM C1713Standard Specification for Mortars for the Repair of Historic Masonry, Natural Hydraulic Lime clearly proves its self as an alternative to mortar mix designs that have been used widely in the United States for many decades and have shown, for one reason or another premature failure.

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Phone: 245-536-6706

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Yes, We Can Save The Frank Furness 19th Street Baptist Church

by Sean Maxwell 2012

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This beautiful church was designed by Frank Furness and is located at the corner of 19th and Titan in South Philadelphia.  It almost went the way of many Furness structures; due to neglect and time the church leadership is under pressure to begin repairs or plan for it to be demolished due to unsafe conditions sited by the License and Inspections Department of the city. Under the leadership of Reverend Vincent J. Smith and in partnership with the Greater Philadelphia Preservation Alliance and some volunteers, stabilization efforts have finally begun.

As the morning sun crept over the skyline on the last Saturday of April, Randy Ruth, mason and the laboratory technician from  LimeWorks.us volunteered to lead a workshop with a team of a few other volunteers to complete some small but crucial repairs on the north facing wall of the 19th Street Baptist Church.

The church has been in need of serious repairs for a number of years as observed and documented in a 2000 University of Pennsylvania report, Thesis by Molly Anne Sheehan, which show that the conditions of the church and the exterior Serpentine Stonework have continued to deteriorate steadily.

Under Randy’s supervision the team of volunteers used a lime mortar donated by LimeWorks.us for doing some in-kind repairs to stabilize the failing back-up walls behind the Serpentine stone. This lime and sand mortar reflects what would have been used originally when the church was constructed in the late 1800s. Ecologic® Mortar contains NO harmful Portland Cement and allows the building to breathe and process water as it did originally.  At some point in time, a hard and brittle Portland Cement stucco was placed over a significant part of the building, trapping moisture and leading to further deterioration of the soft, sedimentary serpentine stone and contributing to mold issues that the church basement still has to deal with today.

This was the first step in saving the most colorful building ever designed by Furness… A true master plan is needed for the next step in partnership with strong fundraising efforts to truly bring this sacred place back to its original glory.

Other stories about the 19th Street Baptist Church…

HiddenCityPhila.org

Plan Philly

Gallery photos  ©SeanKmaxweLL.com

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Phone: 215-536-6706

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Tadelakt Plaster Finish is FINISHED at the Bucks County Designer House

The walls are complete in the powder room at the Bucks County Designer House in Doylestown, PA. Here is a photo to tickle your fancy…

This Tadelakt Plaster application was done using all natural no VOC Takcoat™ as the base and a custom Ecologic™ Mortar for the second and third application.

Visit the Bucks County Designer House May 5 – June 3 in Doylestown PA.

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Tadelakt Plaster Application At the Bucks County Designer House & Garden

LimeWorks.us was commissioned to complete a Tadelakt plaster application at the Bucks County Designer House in Doylestown PA. Tadelakt is a very traditional plastering technique which originated in Morocco.  It’s especially applicable for bathrooms due to its resistance to water. Using a natural hydraulic lime based plaster, Randy Ruth spent a few days completing the plaster application.  His approach included a three coat application using TAKCOAT™ as the base and a custom blended scratch and finish coat consisting of “color: #008000;”  in a base of Ecologic® Mortar and Natural Hydraulic Lime.

Take a few minutes to look through these progress photos.

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All Photos © Sean K Maxwell

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Understanding Mineral Paints and Stains for Masonry Applications

Ecologic™ Silicate mineral paints are mineral paints made using potassium silicate, also known as waterglass. They are combined with inorganic, alkaline-resistant pigments and these paints have zero VOC offgassing.

Silicate Mineral paints were patented in Germany during the late 19th century. Examples can now be found around the world in masonry conservation and alterations as well as new construction. This long track record has proven these paints and stains are durable, long lasting and low maintenance applications for all types of masonry.

Mineral paints and stains chemically bond to all forms of masonry substrates such as brick, stone, mortar, stucco and cement. Unlike latex paints, they are non film-forming, creating a permanent bond that works in harmony with the masonry. Ecologic™ Potassium Silicate Paint is a thick bodied paint.

Ecologic™ Colorwash Stain however is a translucent potassium silicate stain that allows the masonry texture to come through the finish. Both can be brushed, rolled or sprayed on. For artistic expressions or when feathering colors with Ecologic™ Colorwash Stain a sponge may be appropriate for a unique finish.  For long lasting, breathable applications Ecologic™ Potassium Silicate Paint is an exceptional choice, while Ecologic™ Colorwash Stain may be more appropriate for changing previous masonry repairs where there are mismatched colors.

Both are available in 10 standard colors and can be custom ordered.

For more information about mineral paints and stains as featured in This Old House Magazine, or to learn about our line of  lime paints please visit our website or call 215.536.6706.

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Phone: 215-536-6706

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What Sand Should I Use With Natural Hydraulic Lime For Repointing My Building? FAQ Friday with Randy Ruth

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Quick and short of it…. Make sure the sand meets ASTM C-144. But you might ask yourself, what the heck does that mean? ASTM C-144 is a standard specification for aggregate for masonry mortar, brought to you by the American Society for Testing Materials (ASTM). To start off many people will use the term aggregate rather than sand. This is because aggregate is a broader term which can refer to recycled materials that can be use in lieu of sand if so desired. The specification has a lot of good guidelines to follow when choosing sand, such as cleanliness, shape, composition and grain size distribution.

Good, clean sand is important. Depending on where you, get sand you may run into some complications. If you’re purchasing your sand from a distributor, pre-bagged sands are very clean as they are typically washed and dried. However, bulk sand may have some impurities, it is unlikely but should be noted for other potential issues discussed in a moment. If you are getting sand from a nearby creek or stream for historical purposes, be careful. You should check with your local laws to see if it is even legal as there could be environmental implications. That being said, be sure that the sand is free of silt and organic matter.The shape or sharpness of sand will help make a mix denser and create overall a more durable mortar. Angular aggregates fill in void spaces better then rounded sands. A good visual for this is to try and imagine a case of bottled water with round bottles, now imagine the same bottles but square. The square bottles will be tight against each other, while the round bottles only touch at four contact points, leaving voids.

Composition of aggregate will determine long term effects of the mortar. There are aggregates out there that can cause delayed expansion and failure of mortar. One to look out for is crushed dolomite limestone. There are others but for most restoration work that is the most common. Your local supplier should know if they carry this type and will most likely not recommend it for any masonry mortar.

Grain size distribution is the most important factor, when choosing an aggregate. The ideal sand should have a wide range to sizes in its composition. Workability and durability are greatly affected with good distribution. If you can gain access to a sieve analysis, look for a bell curve when the numbers are plotted on a graph. This shows that there are a few large pieces, an increasing amount of medium sizes and a small amount of fines or powder. Excess fines in a sand result in poor workability and is often corrected by an excess amount of water, resulting in poor durability.

Good sand that is clean and dry will have a theoretical void ratio of 33%. In other words, given a certain volume of sand there will be an ideal space of air of between the grain of 33% and 66% sand. fortunately there is a simple test anyone can do to see what the void ratio of sand is.

First get two clear containers one being at least twice the size of the other, fill the small container with water and pour it into the large container and make a mark. Then fill the small container again and pour it into the large container, being sure to have left the first measure of water in the container. Mark the level of the second measure and space 4 lines evenly between the two creating a total of six marks on the large container. Empty the large container and fill the small container with water. Pour the small container of water into the large container, reaching the bottom of the six lines. Now fill the dry small container with dry sand pour it into the large container. After everything settles you will be able to see how much water was displaced. Starting with the top line representing 0%, each line moving down the large container will represent 20%. The resulting percentage will be the void ratio and represent the minimum amount of lime by volume you should use to make a good mortar.

Poor sand can have ratios above 50% and will increase the amount of lime required thus resulting in added expense for you project. So when in doubt conduct a small test on the available sands choose the one that has a ratio closest to 33% to save on the amount of lime required and sleep easier knowing that you have decent sand.

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“Soft Reds and Hard Tans” Exploring Historic Masonry Architecture in the French Quarter

by Randy Ruth

New Orleans. It’s quite the town especially during the weeks leading up to Mardi Gras, known as Carnival. Technically beginning on January 6th and concluding on the day before Ash Wednesday (aka Fat Tuesday), the long celebration is concentrated on the final few weeks, giving rise to more frequent parades and events.  Granted I had never been there before but what I expected was much different from my experience. As a Philadelphia native, I had assumed that it’s nothing but one insane party similar to events that might occur during the Mummers parade on New Year’s Day in Philly, and be only on Fat Tuesday. What I had experienced was by far richer in both culture and architectural significance. I don’t mean this to down play the heritage of historically significant Philadelphia. It’s just that New Orleans has a charm that I believe to be facilitated by it organic architectural style, originating in function over form.

Spending most of my time in the oldest neighborhood in New Orleans also known as the French Quarter or as some may traditionally refer to it as Vieux Carré, I felt a certain type of warmth from the people and its buildings. The symbiotic relationship felt I found to be rooted in the architecture bound mostly by French, Spanish and African influence. This dynamic create a true Creole culture. Perhaps this is why nobody can exactly pinpoint the exact year that Carnival festivities began, a very real unique place and people whose origins can be traced to their roots but only studied in regard to its complex organic creation. The trend can be translated to local architecture in the French quarter however it is a bit easier to study.

A New Orleans local showed me around the French Quarter explaining all the influences of Spanish, French, African and local climate on many of the buildings architecture. Probably the most iconic would be the balconies and galleries extending over the sidewalks. Just to be clear balconies are cantilevered into the building with no supporting posts extending halfway over the sidewalk, while galleries typically extend to the edge of the street. Unbeknownst to me I found that the reason for this is threefold.

First, has to deal with the influence of the Spanish and French architects designing buildings since New Orleans beginnings. However, more often than not these buildings needed to be protected from the weather. Wind driven rain during hot summers created the need to have large open windows to permit air flow but something needs to prevent the buildings from getting wet on the inside, hence the need for balconies to act as an eve to prevent rain from entering the interior. The same principle also protects the inferior masonry walls. New Orleans suffers from poor clay local clay for making bricks. The result being bricks called “soft reds & hard tans” that in most cases must be protected with a stucco or render of lime.

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What is currently known as the Napoleon house was first occupied by the mayor of New Orleans from 1812 to 1815. Although Napoleon never came he was offered this residence during his exile in 1822.

 

 

 

 

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Detailing of deteriorated “Soft red” brick rendered with lime stucco as a Trompe L’oei to imitate limestone blocks on the Napoleon House.

 

 

 

Another defining characteristic of architecture in the French Quarter is the entresol, also known as mezzanine. Entresol’s were needed for storage in commercial buildings due to the high local water table.  Looking at the exterior of a building one can clearly notice the well defined tall window front that help hide the storage floor between the 1st and 2nd floors.

 

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This store front exemplifies the use of an entresol commonly found in the French Quarter.

 

 

 

Due to New Orleans high water table, rising damp is a big issue for many of the building. Because the majority of the historic Buildings located in the Vieux Carré district were built before the advent of Portland cement, lime was used and accommodated moisture very well.  However, today pure lime technology is used to restore the local historic properties, which results in fewer lost or damaged cultural resources.

The time I spent in New Orleans was certainly too limited. There was far too much to see in the few days I was there. Its impact left me forever moved by its places and people. For anyone who has not been there. GO! The treasure hidden in the city is everywhere, waiting for people to experience it and take a piece of it home. Perhaps the next time I visit I will see you there.

 

 

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