Let’s Talk Sand

Our Ecologic™ Mortar uses a sharp well graded proprietary blend, so it’s not just ANY Sand!

The dictionary definition of Sand: weathered particles of rocks, usually high in silica, smaller than gravels and larger than silts, typically between about 0.06 mm to 5 mm. The particles are hard and will not crumble. Sand is used as an aggregate in mortars, plasters and renders as well as a component in concretes. The properties of sand used in a mix have a major effect on its workability, final strength and durability.

The types of sand normally used in building are:

  1. Sharp sand: consists of predominantly sharp angular grains. Clean well graded sharp sand for mortar, render and plaster is selected as the best for the strength and durability it imparts to the finished work. Workability is improved by mixing with fat lime as the binder and allowing this to stand as coarse stuff (not possible with OPC as a binder on its own).
  2. Coarse sand: A sand which is composed of predominantly large and medium sized grains. The higher the proportion of large grains, then the coarser the sand. Coarse sand is used for external renders and mortars to improve durability. Very coarse sands usually require a lime binder, blending with other sands or the addition of a plasticizer to assist workability. Sharp coarse sand is the most durable but the least workable, although suitable for roughcast.
  3. Soft sand: A sand which is composed of predominantly small and rounded grains. It often has a set content, the proportion of which is variable. It feels soft in the hand when squeezed. The smallest rounded particles assist workability but can give rise to cracking and failure in the finished work.
  4. Well-graded sand: A sand with an approximately even particle size distribution. As the smaller particles may fit in between the larger particles, this even distribution reduces the proportion of voids to solids and thus is less demanding on the binder than poorly-graded sand.
  5. Blended sand: A blend of sands of different grain sizes and sharpness to achieve a good particle size distribution. This provides a balance between durability and workability. Used mostly in connection with plaster for backing coats and pointing mortar when the quality of available sand needs to be improved. Sand may be blended by sieving it to adjust the particle size proportions, or by using sands from different sources.

Taken from Ecole d’Avignon/Re’seau Art Nouveau

Click here to read more about the ‘right’ sand for your mortar project.

Sand

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The Stonemason’s Gospel According to Ian Cramb


dsc_0004Lime Explained by Andrew deGruchy (pg. 143)

Limestone, the material calcium carbonate, has never changed from its beginning up to and including now. There have always been two classifications, ‘pure’ and ‘impure.’ Today it is classified as pure (high calcium) and two levels of impure lime based on the magnesium content, Dolomitic and Magnesian.

What has changed over the course of time, especially in more recent years, is how the calcium carbonate stones have been prepared by firing them in the kiln to produce quicklime. There is a most simple way of burning limestone in a vertical kiln using wood for fuel and keeping the temperature between 1650F and 2000F and then cooking it slowly over a few days. This has been done for centuries.  The proof that this method of cooking the stone has extreme merit is evidenced by the very old buildings throughout the world which still stand that utilized this method of preparing lime. ‘Lime’ is what limestone is called when it is cooked and slaked to make a putty that is incorporated into making building mortars, plasters and paints. The technical chemistry was unknown to old lime burners and masons. They just knew what worked and kept using the time-honored methods of preparing the lime.

When burned limestone has water reintroduced to it, called slaking, it then blooms into a beautiful white putty-like material. The volume of putty produced is double that of what was once the condensed rock. This ‘lime putty’ will draw carbon dioxide out of the air for a very very long time and slowly convert back closely to a limestone again. Lime putty has its initial set over a six week period by exposure to air. However it will attract carbon dioxide almost to a point of being completely ‘carbon neutral’ over time in regard to the embodied energy first required to produce the lime.  Through lime’s interconnected pores it even knits minor fissures together by moving about some of the not fully burned ‘free lime’ which creates more surface area to draw in the carbon dioxide.

Early masons knew that some limestone deposits produced limes that set quicker and became harder sooner. So, unlike simple air-setting lime putty, hydraulic limes were used throughout the world and in the United States to build with when the impure raw material had reactive silica or certain clays naturally found in the stone. These impurities were cooked along with the calcium carbonate stone. The term ‘hydraulic’ means to set with water and under water. Portland cement is hydraulic lime. The reason it is overall strongly suggested not to be used for masonry building conservation is that the synthetically added materials used to make Portland cement become intensely hydraulic also make the whole lot detrimental by various degrees of incompatibility with original porous building components. Two of those detrimental characteristics are that Portland cement is brittle and does not accommodate movement and secondly it reacts with sulfates. But a great incompatibility and detriment to historic masonry buildings is the increased densification of mortar that consequently occurs with every increment of additional Portland cement added to make the mortar become very hard. Densification does not allow the building to remain ‘breathable’ through the mortar joints but instead allows water to become held back and sometimes trapped into absorptive inner bedding joints. This phenomenon forces the wetting and drying cycles of the building to occur through the porous historic units and this is what greatly contributes to accelerated deterioration of the irreplaceable bricks and stone used to originally build a building.

In Ian’s first book he used and suggested mortar mixes that I and every other mason has typically used. These mixes gauge-in some Portland cement into high-lime (Type S lime) containing mortars. The reason we all did this is because readily available Type S Hydrated Builder’s Lime and cement were what we had to work with prior to the commercial availability of natural hydraulic limes now sold in the US. If Type S lime was blended with sand alone we discovered it would not hold up to the freeze-thaw cycles in northern climates. Why this occurs when nothing has changed about the limestone itself puts the spotlight on the cooking procedures. Too hot and too fast of a burn can cause the limestone to become ‘dead-burned’ and loose its ‘reactive’ nature which allows it to closely convert back to a hard and durable limestone again. A durable mortar made from reactive lime which maintains vapor permeable pores and has a desired malleable nature to accommodate minor building movement is the best for vertical, above grade work. Pure air- setting limes that remain reactive because they are burned at a low temperature can be obtained in the US too. However, due to the six week set time the cost for building with these limes goes up exponentially. So in this book the mortar mixes are more clearly defined from Ian’s first book as being mixes that use a binder of hydraulic lime but not the hydraulic lime that is Portland cement. I hope this helps you in designing appropriate mortar mixes for certain corresponding applications. It is a labor of love and worth understanding in order to realize the greatest long-term service life which can be obtained for repairing a vintage building and its components. I hope my contribution of this knowledge into what makes one lime better than another brings about a higher degree of excellence in the historic building conservation work you endeavor to do.

Sincerely,

Andrew deGruchy

 

P. S. Ian passed away in 2013 and has left his legacy in print.  You can purchase this Ian Cramb  book from LimeWorks.us at the on-line store.

 

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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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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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“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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Case Study on Masonry Repair and Patching Material – Lithomex

Damaged stone and brick is a common problem for many historic structures around the world. Lithomex is a breathable in-kind repair material for most types of damaged stone and brick. The following is an example of a Lithomex repair on a historic 19th century stone house…

Lithomex Repair in Merion Station, PA:

This house, located in Merion Station Pennsylvania, near Philadelphia, was constructed in the 1920s during the Arts and Crafts style movement. This movement was a direct descendant of the British Arts and Crafts movement which was initiated by William Morris during the mid 1800s as a reaction to the Industrial Revolution and its lack of concern for human lives in the work place. This movement was meant to bring back pride to the true craftsmen once again with an emphasis on hand-made vs. mass production.

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Before applying Lithomex

This house was handcrafted using a variety of stone including Mica Schist, Serpentine, Red Sandstone, Brownstone, PA Bluestone, and some Limestone. It was originally pointed with a high Portland cement content mortar, either 5:1:2 or 1:3 formula of Cement, Lime and sand. Unfortunately this was a recipe for disaster.

During the following 80 years, the softer sandstones received the greatest damage due to the freeze/ thaw cycles of the cold Pennsylvania winters. This combined with later modifications including new windows which were installed improperly allowed water to be trapped behind and within the stone walls. Leaks developed within the house and the homeowners decided it was time to fix things the right way.

BEFORE PHOTOS

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Lithomex being applied

A team from Galli Masonry Restorations took on the challenge to bring this historic home back to its original glory. First they removed all the old pointing and filled in the voids with LimeWorks.us Natural Hydraulic Lime mortar. Then blended with Lithomex colors and textures to replicate the original look of the stone. The damaged serpentine, brownstone and bluestone was repaired and blended in to be virtually unnoticeable.  The color and composition of the final pointing work was chosen by the homeowner which was a mix of Ecologic® Mortar DGM non-pigmented, DGM Grey and black Slag-fleck.

 

 

 

Back Camera
Back Camera


 

Damaged stone

 

 

 

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Damaged wall at window

 

 

 

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Measuring damaged serpentine stone

 

 

 

 

 

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Lithomex on chimney

 

 

 

 

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Crafting Lithomex

 

 

 

 

AFTER PHOTOS

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Side of house after Lithomex application image 1

 

 

 

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After Lithomex application image 2

 

 

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After Lithomex application image 3

 

 

 

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After Lithomex application image 4

 

 

 

 

 

 

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After Lithomex application image 5

 

 

 

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After Lithomex application image 6

 

 

 

 

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After Lithomex application image 7

 

 

 

All Photos Copyright George Galli, Galli Masonry Restoration

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The Bill of Rights for Masonry Structures by Larry D. Jones

ruins1

Article 1
Respect all that is left of me, sacred as it is, my historic fabric.

 

 

 

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Article 2
Clean me not, unless it serves to halt my further deterioration.

 

 

 

Facade-w-Grand-Rose-Window

 

Article 3
But, if you must, clean me first, just water please, and the gentlest means possible.

 

 

 

 

The-Rotunda

 

 

Article 4
If am clean, but still look old, leave me be, graceful aging, it is called.

 

 

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Article 5
Whatever you do, please don’t boil me in acid or scour me with sand.

 

 

 

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Article 6
Know that a good state of repair is in itself, good preservation.

 

 

 

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Article 7
Know what is wrong with me, before you plan how to fix me.

 

 

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Article 8
Repair me only where I need it, and with materials just like me.

 

 

 

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Article 9
If I am leaking water, find out where and fix just that.

 

 

 

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Article 10
Please, no cure-all surface treatments to cover me up or clog my pores.

 

 

 

Photo Credits:

1 Bryan Papciak
2 Sean K Maxwell
3 Kate Milford
4 Steven A. Cholewiak
5 Rasekh Fatmi
6 Trey Ratcliff
7 Trey Ratcliff
8 Trey Ratcliff
9 Frank DiBona
10 Trey Ratcliff

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Repairing Broken and Damaged Stone and Brick using Lithomex – FAQ by Randy Ruth

by Randy Ruth

Randy-doing-Lithomex

Of course following the Lithomex technical data sheet is important to ensure a quality application, but what about the little things that can’t fit on one sheet of paper?  The small details that help make good finish “POP” into a quality indistinguishable patch. There are many things that are far to subtitle to translate onto paper from experience and feel of mortar and trowel. So practice, timing and tools are critical overview subjects to be discussed here.

Practicing patching old single salmon bricks not in a wall is a cheap and technically challenging exercise. The porosity of salmon bricks demonstrates the importance of controlling suction. If suction is not controlled, bond failure can occur while detailing outside corners. It’s these corners that give rise to the technical challenge. By coating multiple sides of a brick, it helps create focus on multiple surface planes. The initial reshaping step doesn’t have to be perfect. It just has to have about 1/8 inch extra material beyond the desired finish. Once Lithomex is well bonded to three sides of a brick, wait for the material to stiffen to thumbprint hard.

DSC_0126Re-troweling the surface will compact the patch to compensate for any slight shrinkage. While using trowels, squares, straight edges, miter rods and improvised tools to shave back and cut away undesired material to the finished profile will create the rough finish. When finishing a masonry unit in a wall, long metal straight edges are great to use as a profiling tool. With the edges exposed over to adjacent units or edges, they act as a guide to bring the finish to proper plane. Typically much of this profiling can be done in the first day of patching; however 12-24 hours later more intricate detailing and carving can be done. Tooth chisels can be used during this time frame to scratch in tooth marks or crandled finishes.

photo-e1328884464676

As more time is allowed to let the patch “firm up” stone masons chisels can be used in a traditional method to give more authentic characteristics. Sanders and rubbing block are also useful for honing the surface to a more polished or pristine finish.

Following these tips and practicing will build upon previous experiences for the craftsman or aspiring novice, facilitating a better rounded approach to brick, stone and terracotta patching.

Other Examples in Use:

 



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The Mysterious Newport Tower, Restored Using Natural Hydraulic Lime

newporttower18th
The Newport Tower is a peculiarly placed piece of stonework.  It currently resides in Touro Park surrounded by one of the ritziest resorts on the eastern seaboard.  Often called the “Old Mill”, it’s generally accepted to have once been a windmill built in the mid 17th Century. But some believe it was built much earlier either by visiting Vikings, Native Americans, traveling Chinese sailors, or even medieval Scottish Templars led by earl Henry Sinclair during a voyage to New England about a hundred years before Columbus.  Either way, this structure was built to last, being a minimum of 360 some years old. A mortar comparison showed the Newport Tower to be made of lime, sand and gravel.

A team from Contracting Specialists Incorporated recently performed some structural restoration by removing Portland Cement repairs and shoring up the stone with Natural Hydraulic Lime as well as placing a new cap on the top with NHL. These repairs ensure the structure will retain its historically appropriate ingredients while also keeping it structurally sound for generations to come.

Additional Resources
http://en.wikipedia.org/wiki/Newport_Tower_(Rhode_Island)
http://www.unmuseum.org/newporttower.htm
http://www.thenewporttower.com
http://www.neara.org/images/what/Newport__loose_threads.pdf
http://www.newporttower.org

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Green Construction in Today’s Built Environment – FAQ by Randy Ruth

by Randy Ruth

When people talk about “green” construction, I often wonder what the environmental benefit of the construction is. Is it new construction? If so what is the environmental impact? I would hope that a perfectly good existing building wasn’t torn down to make way for supposed progress.

It is my belief that the greenest building is the one that is already standing and most likely played a role in a community’s development. It could be an old department store, manufacturing warehouse or barn. Sometimes plans call for only the façade of a building to be saved which helps keep the architectural integrity of a community intact. This can be a positive compromise because the more useful modernized building can be built and yet some historic fabric is retained to tell the story and retain the flavor of what the building was in its local context.

In the end, as long as something is retained for adaptive reuse, whether it is for aesthetics or the entire structure, there is a measure of success in reducing a “green” construction project’s carbon footprint.

In most instances, a building that has been saved from the wrecking ball is old. What does old really mean? Well that’s pretty subjective but I would like to think of old in the context of US building history as being pre 1930, or roughly 80 years and older. When an old building is going to be adaptively reused one way or another then appropriate materials should be used to fix what is broken with compatible repair materials. Using in-kind repairs will further promote the legacy and overall usefulness of a building for years to come while lowering its impact on the environment.

Old buildings are usually very strong and often made of brick and stone that has proven to stand the test of time. However it’s the mortar that binds those materials together and meant to be sacrificial. Mortar should fail first not irreplaceable historic masonry units. The embodied energy to replace a masonry unit is much greater than the mortar. Therefore, it is imperative that a suitable replacement mortar be used to mend what is failing and the mortar be weaker and slightly more permeable than the surrounding masonry units.

In the case of masonry mortar, lime is typically the binder in these old buildings and should be regarded as key to the dynamic that has allowed the building to be in service so long. Often the original mortar is still in place, proving its superiority and therefore should be replaced in-kind. The use of modern day Portland cement based mortars, which are stronger and denser when placed over the top of lime based mortars, are less sympathetic to the historic masonry and can trap moisture causing further damage to the historic fabric. The historic masonry units and adjacent historic elements can best be kept in conservation with the use of the right lime mortar. The correct Natural Hydraulic Lime (NHL) mortars when used where they are appropriate can become a compatible repair materials that is sympathetic  to the working dynamics of an historic masonry building. Secondly, NHL mortars remain reversible without damage to the building unlike the alternative which is the too over-used hard, brittle and dense Portland cement based mortars which are known to cause irreversible damage in conjunction with historic masonry fabric.

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