This post was originally published on RETROactive on October 31, 2012. However, since we live in Alberta, this topic is almost ALWAYS relevant – what to do about frosty windows!
With winter coming, some owners of historic places might be witnessing the formation of frost on their single pane wood windows and storms, most notably on the second storey. The reasons for this will vary and subsequently so will the solutions. Generally speaking, a little frost now and again should not harm the window frame but a more persistent formation will saturate the surrounding material and, in the long run, potentially cause significant damage. Should this be the case, ignoring the situation is far from the recommended solution.
Frosty window. Note the closed storm window vent cover. During the winter it should be open.
So what is one to do? The first step, as with any intervention on a historic place, is to develop an understanding of the problem. What is causing frost to form on the window? The answer: warm moist air comes in contact with the cold glass and condenses, which then freezes on the surface. So how does one mitigate this? Should you let the house freeze so that the interior temperature matches the outside, or should you turn the house into an oven to eliminate any and all moisture in the air? Obviously, neither scenario is plausible.
So what is one to do – replace the windows? Speaking from a heritage conservation perspective, replacing authentic historic windows would be the equivalent to someone shaving their head bald because they found a grey hair. Historic windows have, in my experience, proven themselves to be longer lasting than any modern window and can continue to serve their function with proper care and maintenance, while modern windows wear out and routinely need to be replaced.
As air moisture is the general cause of frosted windows, controlling it would appear to be the most appropriate approach. However, there is more than one way to control moisture during the winter. One can control moisture levels with a dehumidifier, or by preventing it from reaching the cold glass with weather stripping techniques. As well, one could better manage the presence of moisture with exhaust fans and insulation. Any combination of these efforts will help to reduce the frost on windows but it should also be noted that there are pre-existing systems that should be taken advantage of in regards to this problem.
Storm windows traditionally have three holes at their bases with a flap cover. During the winter, these should be open to let moisture and condensation escape. When bugs arrive with spring, close the flap. Double hung windows generally have locks where the sashes meet – use them to tighten the window and reduce air leakage. Should you decide to proceed with a form of weather stripping, concentrate on the interior side of the window and allow the storm window to breathe. This will create a micro-climate (similar to the ventilation in one’s roof), which should help prevent frost and therefore better sustain and protect the window.
Hopefully, the preceding information will be useful for those who might be dealing with frosty windows. There are many articles on the Internet, which tackle this issue and propose similar, different and additional solutions ranging from “free to expensive”. As a Heritage Conservation Adviser, my advice, and that of the Standards and Guidelines for the Conservation of Historic Places in Canada, is to start with the minimal approach. With any luck, that is all that will be needed.
Written by: Carlo Laforge, Heritage Conservation Adviser.
Alireza Farrokhi at the Head-Smashed-In Buffalo Jump during the 25th anniversary celebration in July 2012.
Alireza Farrokhi, Head of Conservation and Construction Services in the Historic Resources Management Branch, describes his work this way: “My unit is the operational arm of our branch. Other program areas protect historic resources and promote heritage conservation by designation, research, and advisory services to municipalities and private property owners; they tell how heritage conservation should be done. We are the group that does it.” Like other program areas, Conservation and Construction Services follows Standards and Guidelines for the Conservation of Historic Places in Canadaclosely.
Stewards of Provincially Owned Historic Resources
Conservation and Construction Services is responsible for “the heritage conservation, maintenance, and environmental management at all designated Provincial Historic Resources that are owned by the province.” That includes more than 50 restored historic structures, 14 operating historic sites, and 70 “mothballed” (vacant but stabilized) historic structures located at five sites not currently in use. The unit also collaborates with other government ministries—such as Alberta Environment and Sustainable Resources Development; Alberta Tourism, Parks and Recreation; and Alberta Infrastructure (the property manager for all government-owned buildings)—if heritage conservation work is required as part of a larger project.
The seven-member unit (which includes three Heritage Conservation Technologists, a Restoration Foreman, and two Restoration Craftsmen) is currently working on numerous projects throughout the province. Staff members once covered specific geographic areas, but are now more likely to be assigned projects based on their expertise. Members of the unit make up the crew for smaller projects. Larger ones are contracted out, with unit staff overseeing the project planning and management.
Restoring and Conserving
The unit’s ongoing workload ranges from conducting multiyear, multistructure restoration projects to addressing specific conservation problems, including some “that come out of the blue.” One staff member works full time at the Ukrainian Cultural Heritage Village, east of Edmonton, restoring buildings one by one. Another has been restoring the log structures at the Perrenoud Homestead near Cochrane. Members of the unit have also worked recently at the Rutherford House in Edmonton, the Stephansson House near Markerville, and Victoria Settlement near Smokey Lake.
Hewko House restoration at Ukrainian Cultural Heritage Village: before (2008) and, after (2009)St. Charles Mission re-roofing at Historic Dunvegan
Heritage and Environmental Conservation
Alireza’s current projects involve restoring “environmentally challenged” industrial sites. He and a colleague are currently working at three that were critical to Alberta’s history: Turner Valley Gas Works, Alberta’s first natural gas plant and a key player in the creation of the province’s oil and gas industry; Greenhill Mine Complex, a historic coal-mining operation in the Crowsnest Pass; and the Bitumount Site north of Fort McMurray, the birthplace of oil sands extraction technology.
Scale model of the sulphur plant at Turner Valley Gas Plant (top) and the genuine article (bottom)
“Back then, their focus was solely on energy extraction. They were not really concerned about the environment,” he says. “But now these are areas that we need to clean up with heritage conservation considerations, so we can’t just dig out the dirt and take it away.” Older structures and equipment must be rescued and stabilized; working in sections, contaminated soil and water must be removed, contained, and treated; nearby waterways must be monitored to verify that groundwater and surface run-off is now clean.
Other historic sites under the unit’s care often require environmental remediation as well, especially removal of asbestos and lead paint.
Regular Maintenance: Conservation at its Best
Conservation and Construction Services is also responsible for regular maintenance (as part of the heritage conservation process) at the sites under its care. To help with that, the unit is developing a maintenance manual for each historic structure. The manual will compile, for easy reference, all records of previous work conducted, related reports, cyclical maintenance requirements, and specific concerns to monitor “so we’re not caught off-guard.”
Alireza loves the challenge and creativity of heritage conservation work. “If a job is not challenging, it’s not interesting,” he says.
Modern buildings tend to develop predictable problems that have known solutions, he explains. But with heritage buildings, “the problems that we deal with don’t necessarily have known solutions. You have to come up with innovative ways of dealing with problems. I love that! It opens up the discussion. There are no right or wrong answers.” For every project, “you always consider the construction technology, what kinds of materials are used, why this is happening, and how you can resolve the issue without impacting the heritage fabric and values.”
An example is recent work at the Rutherford House, an interpreted site on the University of Alberta campus. The sun porch is used as part of the restaurant. Air leaked in through its windows, making the space hard to heat, and water condensation was rotting the wooden window frames and sashes. It was decided to add unobtrusive storm windows where none had existed before. That involved “coming up with different details, experimenting, discussing with our contractor what’s possible and what’s not, and monitoring the work along the way, experimenting to see if it works.” Now the heating and condensation problems are solved and the staff is “very happy,” Alireza says. And, “it would be very hard for you to pick out where the storm window is because it blends into the historic window as if it’s not there.”
From Iran to Canada
Alireza started his career as a civil engineer in his home country of Iran, doing project management for the construction of large-scale industrial and high-rise buildings. His eyes were opened to heritage conservation work when the firm that employed him was building the subway system in historic areas of Tehran. The discussions about the heritage fabric encountered there were like “poetry,” he recalls.
Alireza earned a master’s degree in heritage conservation in Tehran, then he cofounded a private company specializing in heritage conservation—a risky business venture in a country where almost all conservation work is done by the government. The company grew into one of the largest of its kind in Iran.
His company helped with stabilization of heritage structures of the 2500-year-old Bam Citadel, which was damaged in a devastating earthquake in 2003 in which some 43,000 people lost their lives. While doing that work, Alireza questioned why, at the same time that thousands of displaced people lacked basic necessities, conservation professionals were routinely advocating the use of the most advanced and expensive documentation techniques instead of less costly ones (laser scanning rather than study of years of existing aerial photographs.
That led him to the University of Calgary’s doctoral program in Environmental Design, to explore how and why professionals in heritage conservation (and potentially in other fields as well) choose which documentation technology to use. Alireza joined the Historic Resources Management Branch as a Restoration Officer in October 2011, and has been in his current position since July 2013, while also completing his dissertation.
After working on ancient monuments and sites in Iran, doesn’t Alberta’s heritage seem rather modest by comparison? Not at all, Alireza insists! “It comes down to a question of values—what you value. Heritage is heritage, regardless of how old a particular structure is. It brings people together, it creates a sense of community, and those are the important factors.
“And the conservation approaches are similar all across the board. For sure, some techniques are different, but the overall approaches are the same, so whatever you do in one part of the world could be adapted for anywhere else.”
New Uses for Old Places is a RETROactive series in which we are looking at examples from around Alberta of historic places that have found interesting new uses for spaces that were originally designed for other purposes. This week we will be looking at two examples of adaptive reuse projects that have involved the construction of additions to the historic fabric.
As previously discussed in this series, the Standards and Guidelines for the Conservation of Historic Places in Canada offer guidelines for rehabilitating and adaptively reusing historic places. The “S&Gs” include specific provisions for how decisions can be made that will allow for the modification of buildings over time. A tenant may require additional square footage to continue operations or to start a new business in a historic place. When these situations arise and building additions are required, the Standards & Guidelines provide guidance on how to proceed.
Standard
Conserve the heritage value and character-defining elements when creating any new additions to an historic place or any related new construction. Make the new work physically and visually compatible with, subordinate to and distinguishable from the historic place.
Standard
Create any new additions or related new construction so that the essential form and integrity of an historic place will not be impaired if the new work is removed in the future.
Guideline
Design an addition that is compatible in terms of materials and massing with the exterior form of the historic building and its setting.
Guideline
Design a new addition in a manner that draws a clear distinction between what is historic and what is new.
Guideline
Select the location for a new addition that ensures that the heritage value of the place is maintained.
Our first example, the Wetaskiwin Court House, was constructed as a three-storey, red brick building between 1907 and 1909 and served as a legal institution of regional importance for over 70 years. The court house was designated a Provincial Historic Resource in 1977 and the last court sitting was held in 1983.
A major rehabilitation project was undertaken in 2006 to convert the building to accommodate the offices and Council Chambers of the City of Wetaskiwin. As part of the rehabilitation, two new additions were added to either wing of the building. The project involved integration of older materials with new technologies, such as the tie in of the original cast iron radiators with the new geothermal heating and cooling system.
This slideshow requires JavaScript.
Our second example, the Strathcona Public Library in the Strathcona neighbourhood of Edmonton, is a two-storey brick structure that was constructed in 1913 and remains the oldest surviving public library in Edmonton. The Strathcona Public Library was designated a Municipal Historic Resource in 2004 and a Provincial Historic Resource in 2008.
Over the years the use had not changed but the needs of the institution grew and additional space and services became a requirement. A major rehabilitation project was undertaken to construct an addition at the rear of the building (the left portion as shown on the image to the right). The rehabilitated library was re-opened in 2007.
Click on the following link to access a copy of a presentation on this project given by Tom Ward, Manager of Heritage Conservation Advisory Services, at the 2013 Municipal Heritage Forum: Strathcona Library PowerPoint – 2013 Forum.
These projects exemplify that heritage need not be frozen in place. There are means by which to respect and care for the original fabric while allowing for the transformation of uses over time.
Written by: Rebecca Goodenough, Municipal Heritage Services Officer.
In this edition of New Uses for Old Places we are going to look at two Provincial Historic Resources on Calgary’s historic Stephen Avenue that are currently undergoing rehabilitation. The Bank of Nova Scotia and the Bank of Montreal Building are both slated to reopen with new uses this year.
In the early days of Alberta, banks were designed as statements of wealth, progress and confidence in a growing province. The buildings included lofty banker’s halls, adorned with fancy ornamentation — the ‘suits’ could look down on the tellers from the mezzanine above. The design was intended to impress investors and was conducive to the hushed conversation of financial matters.
But, what do you do with grand halls when the money managers move to a modern building? Historic banks can be difficult spaces to re-purpose due to challenges with acoustics, heating and the unconventional layout of the main floor. Nevertheless, for two former banks on Calgary’s Stephen Avenue, the commitment of the property owners and the selection of suitable tenants has resulted in the revitalisation of two very significant buildings on one of Calgary’s most active streets.
The Bank of Montreal building was constructed on Stephen Avenue in 1930-32 as a three-storey, steel-frame building clad in Tyndall limestone. The building replaced an earlier (1889) version of the building in an effort to modernize its image. The bank operated in this location until 1988. The most recent tenant, A&B Sound, left the building over a decade ago and it has since sat empty. Renovations are now under way to re-purpose the building to accommodate a restaurant/pub on the main floor, with 25,000 square feet of office space on the upper floors. The building was designated a Provincial Historic Resource in 2003.
This slideshow requires JavaScript.
Just across the street sits, the Bank of Nova Scotia. It was constructed in 1930 as a one-storey steel frame, brick and sandstone structure and operated as a bank until 1976. Since that time the building has been home to a range of restaurants and clubs and is now being renovated to contain a public house. The renovation will involve re-plastering of the walls and restoration of the marble flooring in the entranceway. The building was designated a Provincial Historic Resource in 1981.
This is the first installment of a new series of blog posts on RETROactive entitledNew Uses for Old Places. We will be highlighting examples from around Alberta of historic resources that have found interesting, new uses for spaces that were originally designed for different purposes. To start us off we are going to talk about the ubiquitous warehouse conversion.
This slideshow requires JavaScript.
One of the best ways to ensure a long and prosperous future for a historic place is to make sure that it is in use. Making certain that people are frequenting a site ensures that a historic resource stays relevant and in the forefront of public consciousness. This can be a challenge given that the purposes for which many of our historic places were originally designed for are now defunct. The conversion of a building to allow for a new use is known as adaptive reuse and it is a process that can require some creative thinking.
The values-based approach to heritage conservation recognizes the importance of activating our historic places and recognizes that alterations may be required to ensure the long-term sustainability of a site. The Standards and Guidelines for the Conservation of Historic Places in Canadaconsideradaptive reuse to be a rehabilitation conservation treatment. Rehabilitation is understood to be “the sensitive adaptation of an historic place or individual component for a continuing or compatible contemporary use, while protecting its heritage value” (Standards & Guidelines, page 16).
A popular form of adaptive reuse/rehabilitation is that of the warehouse conversion. More common in larger cities that once were home to warehousing and manufacturing sectors, warehouse districts are now often surrounded by non-industrial, higher density development and attract investors who see the potential in the character that the former industrial spaces have to offer. Warehouses make good candidates for adaptive reuse because they have large, relatively open floor plates, generous ceiling heights and numerous large windows. These features allow for the flexibility to subdivide the interior space for a variety of purposes without compromising the unique elements that make warehouses so charming (think freight elevators, bank vaults, exposed beams, etc.).
Edmonton and Calgary were home to the majority of manufacturing and shipping in Alberta. As such the majority of extant warehouse structures are located in these two cities, though there are others scattered in other communities across the province. A number of these structures have received historical designation at the municipal and/or provincial level and have been rehabilitated to accommodate a variety of new uses.
Written by: Rebecca Goodenough, Municipal Heritage Services Officer.
Click on the following links to find the listing on the Alberta Register of Historic Places for warehouse buildings featured in the slideshow:
In an earlier post, I talked about the importance of proper planning before undertaking work on a designated historic resource. Throughout my career, I have discussed, planned and observed many different types of projects involving modern and historic buildings. I have worked on simple maintenance projects, such as roof replacements or re-painting, and more elaborate ones, such as restorations and additions.
Providing advice to heritage building owners is the most enjoyable part of my work as a conservation adviser. Nevertheless, the size and scope of some projects are quite large. Buildings are made of a variety of materials, like stone, brick and wood. Skilled tradespeople, such as masons, carpenters and electricians know how to care for each material (or building system). Historic building conservation usually draws on the expertise of an exceptionally wide variety of skilled tradespeople. Making a plan to address problems with any major component requires a group of skills that only architects possess. This is why architects can be so helpful.
A project’s size or complexity should not discourage you. I recommend hiring an architect to help identify, prioritise, and cost the required conservation work on any large project. The architect’s report, often called a “conservation plan,” is invaluable. The plan will explain the problem, propose possible solutions and is a useful reference should the work need to be phased out over time.
Hiring an architect is just like hiring any other professional: just as some contractors are not familiar with the principles of heritage conservation (described in The Standards and Guidelines for the Conservation of Historic Places in Canada), some architects are not skilled in this area either. Fortunately, my fellow Heritage Conservation Advisers and I can help you plan a heritage conservation project (call us), which can include advice on how to hire the right architect.
Although hiring architects cost money, the benefits make it worthwhile. Architects know how to analyse a building for problems, they can propose creative solutions and help you select and supervise the right tradespeople. This is why architectural and engineering services have their own grant category within the Alberta Historical Resources Foundation’s Historic Resource Conservation program.
Not all projects or interventions require the services of an architect, but having the planning and scope of work established by contractors alone on large projects can lead to a bad outcome. Having a uniform and properly outlined conservation plan developed by an architect (or engineer, depending on the problem) makes it easier for conservation advisers to approve projects and for contractors to provide accurate cost estimates.
Don’t feel overwhelmed by large conservation projects. It’s true what Steve Smith said at the end of every episode of his Red Green Show.
Written by: Carlo Laforge, Heritage Conservation Adviser.
Misunderstandings about alterations to designated historic resources
Now and again, I receive a call or a question from someone who appears to be under the impression that their Provincial or Municipal Historic Resource cannot be “altered” and that it must be “preserved” as is. That is not entirely true. Under Alberta’s Historical Resources Act, “no person shall destroy, disturb, alter, restore or repair any historic resource…without the written approval from the minister (Section 20-9)” if the site is a Provincial Historic Resource. For Municipal Historic Resources, the written approval must come from “the council or a person appointed by the council for the purpose (Section 26-6).” To obtain a written approval, the proposed alteration must be evaluated under the Standards and Guidelines for the Conservation of Historic Place in Canada.
The Standards and Guidelines is a pan-Canadian document that is used as a tool to evaluate and sometimes enforce certain principles in the conservation of our historic resources. There are four major components to the document: the conservation decision-making process, the conservation treatments, the standards, and the guidelines – with each component going into more and more detail. The most critical of these is the “conservation decision-making process”. This process involves three stages that I like to refer to as the acronym U.P.I. (pronounced whoopee!) or Understanding, Planning, and Intervening.
The designation of a historic resource implies that we are trying to conserve it for future generations as part of our shared heritage. Understanding why a designation was put in place is the first step in determining what can and can’t be touched. This is summarised in a Statement of Significance (SoS). Each designated historic resource has one. If you do not know what the SoS for your designated building contains, you can search for it on the Alberta Register of Historic Places.
Planning is the most important part of any project and for historic resources it is critical in order to avoid mistakes and the potential damage or loss of heritage fabric – usually listed as character-defining elements within a SoS. As a Heritage Conservation Adviser, it is part of my job to help you understand and plan (and subsequently recommend approvals for Provincial Historic Resources) for projects that will affect your historic resource before any intervening occurs. When someone indicates to me that they will be going straight to an intervention (i.e. actual physical alteration to a historic resource) without any understanding or planning having taken place, I will tend to react like the guy in this video clip.
Ok, well maybe on the inside. Suffice it to say, that intervening without understanding or planning is not recommended. Although I did find the guy in the video’s treatment of the new homeowner’s lack of respect for their heritage building interesting – would you agree?!
Written by: Carlo Laforge, Heritage Conservation Adviser.
At the 2012 Municipal Heritage Forum Ann Ramsden, Director of Heritage at the Musée Héritage Museum, provided a presentation on the conservation work completed at the Little White School. Specifically, she spoke about ensuring barrier free access. Thank you, Ann, for sharing this case study.
Little White School, St. Albert
The Little White School is a two-room schoolhouse in the City of St. Albert. It was constructed by the St. Albert Roman Catholic School District #3 in 1946 and used as a school until 1987. It was designated as a Municipal Historic Resource in 2009 because it is valued for what it can tell us about Roman Catholic public education in St. Albert. The school is now owned by the City of St. Albert and managed by the Arts and Heritage Foundation.
When the museum acquired the building, it needed some conservation work. The stucco, doors and windows needed to be rehabilitated. The shingles were replaced and a ventilation system was incorporated into the roof to prevent condensation. Water was also leaking into the basement through the foundation. The biggest challenge, however, was ensuring barrier free access to the building.
Rear view of the Little White School, St. Albert
The Standards and Guidelines for the Conservation of Historic Places in Canada not only provides advice on how to rehabilitate building elements like stucco, windows or a roof, it also provides advice on planning additions (or other alterations) needed to accommodate changing uses of a historic place. Historic places certainly do not lose their integrity by adding a means of barrier free access. Additions that are compatible with the historic place, yet visually distinguishable from and subordinate to it are welcome, especially if they help ensure the continued use of the place.
Classroom, Little White School, St. Albert
The Little White School gained an addition that contains a wheel-chair accessible entrance and elevator. This is now the main entrance and provides room for students who visit the school to store their coats and boots. The classrooms received a preservation treatment; one of the classrooms is now being interpreted as a 1940s era classroom. The Musée Héritage Museum invites primary school classes to the school to learn more about St. Albert’s history. Students can come and spend a day at the historic school and learn how students from the 1930s thru to the 1950s experienced school. (The Musée Héritage staff has developed several lesson plans around various themes in St. Albert history.)
How do you determine whether or not a proposed change (what we call an intervention) is appropriate for a historic place? Would a fresh coat of paint preserve the heritage value of an old house? Does painting the brick affect its heritage value as a Municipal Historic Resource? How do I choose the colour of paint?
Answers to these questions and more are found in the Standards and Guidelines for the Conservation of Historic Places in Canada (or the S&Gs for short). Introduced in 2003 and revised extensively in 2010, the S&Gs are the definitive framework for heritage conservation in Canada, having been widely adopted by municipal, provincial, and federal authorities as a tool for determining how to conserve and manage change to historic places.
The S&Gs provide a foundation of conservation principles organized around fourteen standards, a standardized vocabulary of conservation terms, a straightforward decision-making process, and practical conservation guidelines for a wide range of resource types. Used in conjunction with Statements of Significance, the S&Gs also play a role in determining if work is eligible for conservation grants from the Alberta Historical Resources Foundation.
The presentation below, from the 2012 Municipal Heritage Forum, offers an overview of the S&Gs as a tool for municipalities to manage the historic places identified through surveys and inventories and subsequently protected as Municipal Historic Resources.
Old St. Stephen’s College, designated a Provincial Historic Resource in 1983, and office of the Historic Places Stewardship Section (the authors of RETROactive), is getting a new roof. The work is compliant with the principles and recommendations outlined in the Standards and Guidelines for the Conservation of Historic Places in Canada. Below is a brief description of the conservation work that will be completed throughout April and May 2012.
The roof over the west wing and its multiple hip-roofed dormers are cited in the Statement of Significance as character-defining. The design for the cedar roof replacement may seem straight-forward at first, but when planning this work it was important to consider not only the look, but how the roof would perform. The introduction of new underlay products and flashings were examined in order to better help keep the water out and extend the service life of the roof.
For any historic place, the Standards and Guidelines for the Conservation of Historic Places in Canada must be consulted for all proposed interventions. In this case, a cedar shingle finish for roof surfaces, ridge caps and dormer side walls was verified as appropriate with reference to general Standards 1 to 9 and Standards 10 to 12 for rehabilitation treatments (see pages 22 and 23 in your Standards and Guidelines document). Standard 8, in particular, confirms the replacement “in kind of any extensively deteriorated or missing parts of character-defining elements, where there are surviving prototypes.”
In addition to the replacement of the shingles, the opportunity to introduce new weatherproofing materials was presented. Particular areas at risk with this roof were identified, which included the six dormers penetrating each side of the peaked roof, along with multiple valley and ridge flashings. Also complicating the design is the presence of deep gutters with internal drains just behind the brick and cast-stone parapets. A new continuous ice dam membrane underlay was proposed that would be installed from the parapet through the gutter, to the top of the dormers, lapping the membrane up the dormer sidewalls, and to the underside of window sills. This has been likened to installing a weatherproof girdle under the shingles, covering most of the roof surface, to help protect the vulnerable complicated intersections from leaks.
The proposed introduction of new underlay material to this roof was confirmed in the Guidelines for Roofs (page 142), where it is recommended to “improve the detailing of roof elements, following recognized conservation methods, to correct faulty details.” Such improvements, however, should be physically and visually compatible with the authentic roof detailing.
So, all the boxes are checked with regard to the west wing’s roof replacement and the protection of its heritage values. The Standards and Guidelines for the Conservation of Historic Places in Canada provides a defendable verification that planned work for historic places retains recognized heritage values.
Written by: Tom Ward, Manager of Heritage Conservation Advisory Services
RETROactive 