Like for Like: Restoring Wood Components in Heritage Buildings
Bill Kumlin, AAA, AIBC, SAA, Heritage Architect
The conservation of historic buildings represents the history and culture of our country, provides a sense of identity, and is an essential part of sustainable community development. As a heritage architect, there are a lot of aspects to consider when doing restorations and renovations. It isn’t the same as renovating a house built thirty, forty, or even fifty years ago; these are often protected and historically recognized properties. They were built with methods and materials that are no longer used, and many rules and regulations govern the work that can be done.
I have been interested in historical buildings ever since I was a kid. It might sound corny, but I grew up near Calgary, and I loved looking at old buildings in farmer’s yards and fields. My biggest fascination was: How did they build it? Who built them? Or, how did they get in the shape that they are in today?
We know that, without today’s technology, they built things differently. That means, when we go to renovate them, we sometimes need to take a different approach.
A few years ago, the University of Calgary launched a Built and Landscape Heritage graduate certificate program. It was intended for practitioners in architecture, landscape architecture, planning, engineering, and other related disciplines who want to acquire specialized knowledge and skills related to heritage conservation. Completing this program was a great way to explore these interests further, and it added an extra layer of service to our firm, Kumlin Sullivan Architecture Studio.
There are a number of principle issues that must be considered when it comes to the repair and replacement of wood building components in a heritage renovation scenario – removal and demolition, wood species, component profiles, glazing, and paint/finish history. The Tribune Building in Calgary is an excellent example of where these principles were used.
We replaced a window on the left-hand side with a door to match the one on the right. New frames were required for the new door, and all of the window and door frames were stripped and repainted.
Removal and Demolition – Ultimately, the goal is to reuse and refurbish as much as possible, but sometimes there is age damage or rot from moisture penetration that can’t be repaired. Those components need to be replaced. When we’re taking something out because of this, there has to be an increased level of care. You can’t throw things out as you go along, as you do with a typical demolition. You need to keep salvageable items in case you can reuse or reinstall them.
Or you need to keep representative pieces on hand and record them, as you will need them to help duplicate the details for replacement items.
Wood Species – When replacing items like doors and windows, it’s essential to consider the wood species. Most of the buildings I work on were built between the 1870s and the 1930s. Often, the type of wood that was used to build these structures isn’t commonly used anymore. The question you have to ask is: what was the spices originally used, and what should it be replaced with? To be historically consistent and honest, the goal should be to replace it with the same species – like for like – or, at a minimum, one that is period-appropriate, like oak or fir. Understanding how wood behaved in older construction like wood and masonry becomes important in the replacement of the components. It should be historically appropriate and technically sound.
Profiles – When working on door trims and mouldings, it usually comes down to the details. Often, mouldings were custom made for these older buildings. That is, they weren’t necessarily ‘off the shelf’ like today. And it’s likely that the company that made them is no longer in business. Luckily, we have modern tools to help replicate those shapes – contour gauges, routers, and jigs make it easier to create a suitable replacement. Contour gauges allow us to get an almost exact match of the frame or trim profile. Many times, there is a router blade that has been produced that exactly or nearly matches an historical profile. And these can be controlled by creating a jig to hold the piece of wood and guide the tool to make the new piece almost perfectly match the original detail.
This process allows us to carry on with the ‘like-for-like’ component replacement.
Glazing – Most of the buildings I work on were originally constructed with single glazed windows. Today, sealed double glazed units are the standard as a minimum. That means that the thickness of the building wall assembly, and the depth of the window unit with the added frame thickness for the double glazing, won’t necessarily match up perfectly. That can take away from the ‘like for like’ replacement that we’re trying to achieve. Because of this, there may be some concessions you have to make. No one wants single glazed windows anymore. The heritage architect must be consulted to determine the best approach to take in a situation where the actual frame detail must be altered slightly to suit today’s codes and methods.
Paint/Finish History – When renovating old buildings like these, there are often as many as six or seven coats of paint over the wood components. Very few were stripped back to the wood when repainted. If you are salvaging building components for reinstallation into the project, getting down to the original wood may require sanding off a layer of wood to get at what’s underneath.
The history of the paint colours is key to maintaining the historical integrity of the building.
Heritage architects try to delve deep into those layers and determine the paint history. This old paint was very hard and penetrated into the wood grain.
Less so in harder commonly used woods like oak, but it did happen. The woodworker may be called upon to retain pieces of the wood frames during demolition and assist in peeling back the historical layers of the paint. Like with the mouldings, many of the paint companies aren’t around anymore, so it can be difficult to find a match. That being said, going through the layers does give you options for period-appropriate colours.
Ultimately, the goal is to preserve these buildings to the best of our abilities while making sure they meet today’s architectural and living standards. Understanding the construction and detailing methods of the period is key to duplicating our historical architecture. These old structures house all the clues we need to restore them accurately, as long as you know where to look, and you treat them with respect.
Bill Kumlin is one of the founding partners of Kumlin Sullivan Architecture Studio in Calgary. He has been in the construction industry for over 40 years and as a registered architect for over 30 years. He has been in private practice since 1998, 17 years before joining Barry Sullivan to form the Kumlin Sullivan Architecture Studio.