Edgewater Stonemasons President Craig Beattie recently began writing a series of articles for the Frontenac Heritage Foundation’s periodical entitled “From the Banker”. The following is the first in a two part series on stone bonding of the Kingston area:

From the Banker

The term ʻbankerʼ refers to a bench or table traditionally used by stonemasons for cutting stone; the purpose of this and future articles is to share the lessons that I have learned working as a stonemason on conservation projects across Canada. It is my hope to give interested parties greater insight into the noticeable and not so noticeable qualities of the brick and stone masonry that defines Kingstonʼs built heritage, and to promote the best practices for conserving this irreplaceable resource.

To readers of this publication, stone ʻbondingʼ may or may not be a familiar concept. It is a term that is used quite simply, to describe the arrangement of stone within a wall. It can tell us interesting things about the structural qualities of our historic buildings, and it goes to the heart of their visual appearance. Bonding is comprised of two separate but overlapping categories: face bonding, which is concerned with the visible arrangement or pattern of stone in a wall for aesthetic purposes, and bed (or structural) bonding, which is the strategic placement of large stones throughout a wall to increase its structural integrity. In this, the first of a two part series, we will examine how the appearance of a stone building is shaped by its face bonding, and look at some of the more prevalent styles in the Kingston region.

A physical characteristic of a masonry wall that helps to define its appearance, face bonding tells us much about the time period and the people involved in its construction. The variety of patterns are often synonymous with different architectural styles, and are a tool at the architectʼs disposal for conveying messages about the buildingʼs intended purpose. Historically, it also had much to do with practical considerations in terms of the sort of stone available, and the ownerʼs budget. In cases where it was left up to the builders to decide, their regional backgrounds whether English, Scottish or Irish would often times inform the decision. Although varying greatly in their overall appearance, there is one common element among all well-executed bonding styles, and that is the control of vertical joints within a wall to create stability. It was long ago determined that long vertical stretches between stones (stack joints) created a weak point in any wall, and that this could be avoided by overlapping the stones to tie each one into the next.

The following list of bonding styles is by no means exhaustive, but is intended to showcase some of the more prevalent styles in the Kingston area.

Random Rubble: This is a bond that is often referred to as the most beautiful style, as it makes use of a complete assortment of stone shapes and sizes. It can be seen all over Kingston, and exposed interior limestone walls are almost exclusively random rubble. A mason building in this style would essentially place stones in the wall as they come to hand, creating a random look that highlights the natural elements of the material. Donʼt let the name fool you though; although the appearance may be random, the style still conforms to the basic rules of stonework. Vertical joints are interrupted as often as possible, stones are placed with their greatest depth into the wall, and sedimentary stones are laid along their natural bedding plane. The modern appreciation for random rubble

represents a cultural shift, and would likely have been amusing to early masons; it was the most economical style since it utilized whatever material was available and required the least amount of labour and skill on the masonʼs part. At a time when mass production of material was in its early stages, there was a high value on creating uniformity, which required time and money, and was a reflection on the masonʼs mastery over the material. Today, we view the irregularity of stone as an admirable quality, while producers of manufactured stone spend fortunes (and fail) trying to replicate the unique natural qualities of the material.

Coursed Rubble: Seen in many of this areaʼs Ontario Cottages, coursed rubble refers to a continuous run of stone at the same height across the length of a wall. This creates a ʻcourseʼ of stone with a full uninterrupted horizontal joint, and each vertical joint in the stonework is broken by adjacent stones on the next course. This style would require that builders sort through their supply and use only stone that met the height requirements, which in this area was often 5-6”, commonly available in local quarries. Although the weathered grey patina of our heritage limestone buildings does not display any obvious tool marks, much of the coursed rubble in this region was originally finished with a ʻpunched faceʼ which refers to a technique of flattening a stone using a ʻpunchʼ, a long pointed masonʼs chisel. Many Ontario Cottages feature a coursed rubble bond at the front of the building, and random rubble stonework along the sides and back. This reflects the added importance placed on the front entrance of the house, the most visible section to visitors or passers-by.

Snecked Rubble: Seen in many of this areaʼs formal buildings such as churches and estates, this is a high-skill form of stonework that requires a significant amount of labour. The principle tenet of this style is that small stones called snecks are used to separate stones of different heights. Snecks are used in conjunction with levellers (the majority of the face stone) and jumpers, which are large squared stones placed in a balanced manner throughout the wall. The overall effect is visually pleasing, and creates probably the most structurally sound bond because of the way horizontal and vertical joints are broken. It is also referred to as Scotch-bond, and can be found all over Scotland; it has been suggested that this styleʼs origins may be traced to the defensive fortifications there, where builders were looking for innovative ways to resist the English and their effectiveness at dismantling castle walls. Unfortunately it is one of the most misused styles, as many of its rules and intricacies are not widely known by todayʼs masons. Snecked rubble can range in appearance from highly ordered to rustic depending on the type of stone used.

Ashlar: This style of work is known for its clean lines, and highly structured order. Each stone is finished to a very narrow set of tolerances, with an emphasis on squareness and uniform surfaces. The stone can be finished smooth or with decorative finish, and is typically arranged in a coursed pattern. It is the most labour-intensive bond as well as the most homogenous, and would have required a strong skill set to transform the natural blocks of stone into a finished product.

Next time…

The lasting durability of our built heritage can be attributed to three interconnected qualities: Design, workmanship and materials. Structural bonding is a hidden aspect of a solid stone wall that encompasses all three, and is essential to itʼs longevity. In part two of our series on bonding, we will examine the anatomy of such a wall, and identify the key places that stone is used to maximize structural integrity.

Founded in 1972, the Frontenac Heritage Foundation (FHF) is a non-profit organization created to promote the preservation of buildings that contribute to the heritage of Kingston, Ontario, the County of Frontenac and the Islands, and Loyalist Township. For more information visit: www.heritagekingston.com

This dry stone retaining wall was constructed in reclaimed Kingston Limestone. In its previous incarnation, the stone had been part of a wall on the shores of Lake Ontario that had been slated for demolition. The material has a unique weathering that can be attributed to the constant exposure to the elements coming in off the lake, which we preserved as much as possible throughout our work on the wall.

The three foot high wall is interrupted by Limestone steps that provide access to the upper terrace. At the end of the wall is a four foot high battered gatepost that is mirrored with a matching gatepost on the opposite side of the driveway. 

In the place of traditional coping stones, the wall was capped with turf that extends out over the top of the wall, and serves to integrate the new wall with the terrace above. Combined with the weathered stone, this gives the wall the appearance of having existed here for many years.

Edgewater Stonemasons is a Kingston-based firm specializing in natural stonework. We are a member of Dry Stone Walling Across Canada (formerly the Dry Stone Wall Association of Canada) and work with clients to design and build dry stone projects in a variety of forms and materials. 

Managing the effects of water on historic masonry buildings: Suggestions for preventative maintenance

It is well established that the majority of masonry-related issues in a heritage building can be traced back, at least in part, to water infiltration, and its long term effects on the building fabric. Excessive moisture can break down the lime component of some lime mortars, ‘washing out’ the joints and depending on where water is entering the building, this may happen from the inside out. In addition, frost damage caused by water allowed to accumulate in the core of a masonry wall can be seen in bulging stone walls around the city; as water freezes and expands, it can physically push stones apart. This creates a void in which larger pools of water can accumulate, freeze, expand, etc. Left unchecked, this process called ‘thermal jacking’ can eventually cause structural failure of the wall.  

These issues, which are often costly to address, can be avoided or at least minimized through preventative maintenance efforts designed to manage the movement of water. 

To this end, we have compiled the following list, that while not exhaustive, identifies some of the typical ‘trouble spots’ that are associated with water ingress, and offers ways to minimize this occurrence.

Roofing: This is really the first line of defense against water infiltration, not just to the interior of the building, but also into its solid masonry walls. Examine, or have a roofing contractor examine the condition of the roof, looking for curled or deteriorated shingles, or shingles that are missing altogether. 

Chimney: This is one of the most common areas requiring repair or rebuild. Sometimes this is natural weathering based on the high level of exposure that a chimney faces, but often the lack of a proper cap designed to shed water away from the chimney causes accelerated decay, and allows water to enter the structure from above. Examining the brick or stone below a chimney in the upper regions of a gabled end for example, will often reveal past repairs, a sure sign that water has entered the wall through the chimney in the past.  

Flashing: Missing or incorrectly installed flashing not only allows water to gain entry, but can even act as a trough, collecting water and directing it into the building. Ensure that metal flashing is installed and functioning properly in areas where the flow of water is interrupted. These include at the base of chimneys, in valleys and around the top of dormers. 

Eavestroughs and Downspouts: These items work in conjunction with one another, and offer one of the most effective ways of managing rainwater and snowmelt. The majority of the water that hits the roof is collected and directed a safe distance away from the building. In the absence of gutters, this large volume of water can run down the fascia, along the underside of the soffet and be deposited against the masonry surface. It may also pool at ground level, and saturate the foundation walls, potentially causing a moisture problem in the basement. 

Windows and doors: The junction between window and door frames and surrounding masonry should be sealed using caulking to prevent water ingress. This is an area which if not kept in good repair can allow significant amounts of wind driven rain to enter the wall. Stone window sils should be checked for cracks, and wooden sils should be examined for rot. The condition of mortar joints and caulking around the sil should be assessed as well. Sections of masonry underneath windows and doors frequently require rebuilding, evidence that prolonged infiltration of water has had a detrimental effect.

*A note on caulking: This is a material that can cause irreversible damage to brick and stone, and should be used selectively. Although it creates an effective barrier against water penetration, this same feature can prevent a solid masonry wall from drying out, (an essential function) by trapping water inside. When moisture vapor is not able to evaporate through the mortar joints of a masonry wall, it is forced to travel instead through the masonry units themselves which is an inefficient process and has a twofold effect: The brick or stone becomes much more susceptible to frost damage and more moisture is retained within the wall. This can result in accelerated mortar deterioration, and the breakdown of the masonry unit itself. If there is room, we will typically fill the vertical space between the stone and window frame with mortar, and then because the wood frame and mortar have differential rates of thermal expansion, seal this juncture with a thin bead of caulk. 

 Mortar joints: Empty or cracked mortar joints are an easy entry point for wind driven rain, or for moisture that accumulates on window sils, and other extruding features. Deteriorated mortar joints should be carefully removed so as not to damage the brick or stone, and the mortar replaced with a lime-based mix suitable for heritage buildings. One of the most common mistakes that homeowners and inexperienced masons make (although well-intentioned) is to undertake these repairs using a cement that does not possess the same qualities of a lime-based mortar, primarily the ability to transfer water vapour described above, and a relatively lower compressive strength which allows slight movements to occur within the building without causing damage to the masonry units. The process of repointing, as well as an overview of lime mortars will be featured in an upcoming article. 

Grading: This is another crucial item that is relatively easily addressed, but often overlooked. In this context, grading refers to the contour of the ground around the perimeter of the building. The high point should be against the foundation walls, and fall gradually away from the building, creating a natural form of drainage. When we inspect basement foundations that have historically had moisture issues, we often find low spots around the building that collect and hold water, slowly releasing it against the foundation walls. Although gardens and planters are popular features around the base of buildings, their shape and soil content are not conducive to moving water away, which is something that should be considered when planning gardens. 

It is our hope that this article will help draw attention to some of the not so noticeable but extremely important features of a heritage building. The list was compiled based on experience working on a variety of heritage buildings, on projects ranging from residential to commercial and public. Although no two historic buildings are exactly alike in terms of design and environmental exposure, water is a consistent threat, and managing the items on this list will help to minimize its detrimental effects. 

For an inspection checklist tailored to heritage buildings, please visit: http://www.gov.mb.ca/chc/hrb/pdf/maintenace_for_heritage_bldgs.pdf

Defining approaches to architectural conservation

Currently the term ‘restoration masonry’ has become synonymous with work in general on historic masonry buildings. From common interventions such as repointing, to stone or brick replacements, to crack repairs and rebuilding, restoration has become a buzzword used to encapsulate all heritage masonry work.

The restoration approach is actually part of the larger field of architectural conservation, which has traditionally had different meanings, but is today defined by four distinct philosophical approaches. Each of these approaches has its own unique characteristics, goals and set of priorities. Although they differ in many ways, they do share common elements: They are all preceded by careful research and inspections, and once implemented, they follow a careful set of processes from start to finish.  Most importantly, each of the following four approaches seeks in its own way  to express the historical character of the building in question.

Preservation:

The main function of the preservation approach according to the U.S. Department of the Interior, is the retention of all historic fabric through maintenance and repair. This approach is focused on maintaining a historic property in its existing state. This is done through identifying causes of decay such as chemical or water sources and removing those threats. 

Restoration:

The restoration approach seeks to return a structure to its original concept. Restoration techniques are often applied once it can be established that the form of a building at one point in time outweighs in importance its configuration at other periods of time. This philosophy relies on archaeological evidence and documentation before making any changes to the structure. As well, any replacements to the fabric of the building must be distinguishable from, while integrating with the original elements. Historical additions are for the most part preserved, unless the removal of such additions reveals a feature of great historical interest. Restoration allows for some modern building materials, provided that they are structural in nature and that all visible aspects of the house remain traditional.

Rehabilitation:

Rehabilitations focus on adaptations to historical properties based on different considerations, such as economic factors and historical value. The adaptation is undertaken to give the building a new functionality, while at the same time respecting the overall historical character of the site. This is done through preserving existing architectural features, and simplifying additions to maintain harmony with the original structure. Finding a use for the building that is similar to its original function is ideal, as it often requires fewer changes to the building, however ensuring a usefulness for the building is often a primary concern.

Reconstruction:

This approach is employed when parts of a structure are lost over time, or when disasters such as fire necessitates the recreation of the structure. Reconstruction is always based on solid evidence and documentation, and conjecture is not permitted in determining structure or features of the building. Research evidence and physical evidence are the two primary sources of information for conservators employing this approach. Moving an existing building can be considered reconstruction, but it is only considered when there is a significant benefit to public interest, as there are often environmental variables that differ from place to place and can subject the building to unanticipated threats. 

*A note on renovations:

Renovation is less a philosophy and more a process that focuses on updating a building, modernizing character elements or bringing it up to current standards. Renovations are not necessarily constrained by respect for historical characteristics, and in a renovation the function of the new work takes precedence over the existing structure. Renovations are undertaken mainly in new buildings, where improved functionality is needed, and it makes more sense for the owner to add or alter the existing structure than to find a new building. 

Edgewater Stonemasons recently participated in the 2012 Kingston Gardening Festival. Our display/demonstration included a traditional mortared Limestone garden wall, a live stonecarving demonstration, as well as an assortment of stonemasons’ tools. Sculptor Phil Smith from Smith and Barber was on hand, and his oak-leaf carving was auctioned for charity at the end of the show

New website up and running

As winter fades and we get set to embark on our third season in operation, we are happy to introduce our new and much improved website. The site is now more user-friendly, with frequent updates, an improved photo gallery and profiles of ongoing projects. A key feature will be resources for homeowners that will aim to help inform in a non-technical manner. Articles in the works include a guide to repointing, an overview of the most common restoration techniques, and preventative maintenance tips. Please enjoy the site and check back often! (www.edgewaterstonemasons.ca)