This week we began preparing stone for an upcoming project on Lakeshore Boulevard in Kingston. We are based at Rideauview Contracts' facility in Erinsville, where large slabs of Limestone are being transformed into hand-finished pieces that will make up the snecked ashlar stonework on this custom new home. First the huge slabs of stone are brought into the shop by forklift where they are loaded onto a conveyor and split into small, rough blocks using a hydraulic guillotine. From here, the stones are stacked on pallets and brought to our work area, where they are individually finished by hand to specific shapes and sizes. The stone is then repackaged, and will be transported to the job-site when work begins this spring.
Edgewater is currently working in collaboration with Taggart Construction to dismantle and rebuild a Limestone wall as part of the George St. reconstruction project. The natural stone retaining wall, which sits adjacent to the Sword of Valour monument, will require substantial stone replacement. New Limestone is squared and built to courses with Lime-based mortar.
Prior to construction on a new Lakeshore Blvd home in Kingston, we were asked to restore an existing Limestone seawall. The stonework dates back approximately 30 years and was built on the bedrock shelf along the shoreline. Sections of the wall have collapsed, but for the most part it has withstood the elements in this high exposure location. Our scope of work includes rebuilding collapsed sections, tying the wall into a new Limestone staircase, and repointing all stonework.
When the wall is restored, it will complement the contemporary design of the new home and maintain a physical link to the past for its owners.
Our stone pillar project is well underway at the Highlander development in the East end of Kingston. Weather conditions have been challenging, but the project is moving along. We are using Owen Sound Ledgerock, and each pillar will be finished with a pre-cast concrete cap. More pictures to follow.
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.
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
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