“Must See” Timber Connections

“Must See” Timber Connections

Two joinery details that change how modern timber frames are made.

Whenever two pieces of timber meet in timber framing, they need to be connected. Carpenters call this connection ‘joinery,’ which involves cutting specific details into two pieces to keep them together. These joinery details are usually hidden from view once the timber frame is assembled. 

In this article, we will discuss two joinery details that have made a significant contribution to the visual and strength values of modern timber frames. These details are part of a ‘quiet revolution’ in timber framing, which has been made possible by technology.

Dovetails – the old dovetail connection has been around for centuries.  It’s a V-shaped tenon on the end of a timber that slots vertically into a matching pocket in another timber.  It’s often used in floor joists, connecting them to larger floor beams.  They can also be used for purlins, corbels and wherever a small timber intersects a larger one.

Tapered dovetail mortise in receiving beam
Improved tenon with double taper.

The new type of dovetail features a double taper that pulls timbers together as it settles into place.  The new shape provides more contact surface and ensures that the joined pieces stay tight as they adjust to indoor humidity levels.  Strength and beauty are given a helping hand, thanks to this smart dovetail design.

Housed Mortise – this is a joinery detail that “fortifies” the typical mortise and tenon connection.  Essentially, it’s a step or recess that borders the mortise on all sides, allowing the tenon and the whole connecting timber to be set into the receiving beam or column.  In the pre-modern period, a housing was a considerable amount of additional work for a carpenter to create and was therefore used sparingly.  Where a timber needed to resist larger rotational or lateral forces (think old mills and larger civic or church buildings) a housed mortise was an effective and worthwhile detail.

The Housed Mortise allows the incoming timber to be set fully into the receiving column.

With the advent of CNC timber cutting, the effort and time needed to create a housed mortise has been significantly reduced.  And while most timber frame projects don’t need the structural benefits of a housed joint, these connections have one additional trait: they’re aesthetically pleasing.  The gap that typically can be seen where two timbers meet, disappears, as it happens out of sight, thanks to the recessed housing.

If you’re thinking of a timber frame for your next project, be in touch!  You can reach us by phone: 204.377.5000 or by email: info@cstf.ca.

US – Canada Free Trade Turns 35

US – Canada Free Trade Turns 35

Free trade between the US and Canada will celebrate its 35th anniversary on New Year’s Day, 2024. 

In 1982 the US unemployment rate reached 10.8%, the highest level in the entire post-war period.  Over 12 million job-seeking Americans were idled. In Canada unemployment reached 13%. There was sharp disagreement about the best course of action to address the underlying economic stagnation. Unions and employment advocates called for higher tariffs and stronger trade barriers as the only effective way to protect jobs.

Predictions of massive job losses, a deterioration of worker rights and a loss of sovereignty were major concerns raised by those opposing free trade.

US President, Ronald Reagan argued that the best medicine for the unemployment crisis and an under-performing economy was not protectionist measures, but free trade. Many on both sides of the political divide called his ideas naïve and reductionist.  Canadian Prime Minister Brian Mulroney also faced push-back, with opponents saying a trade deal would simply make Canada the 51st US state.

The Reagans hosting the Mulroney’s at a White House state dinner in 1988.

Trade negotiations took five years and yielded the Canada-US Free Trade Agreement (CUSFTA) in 1987, which came into full effect on January 1st, 1989.  Mexico was not included in this initial agreement and lobbied hard to have the agreement expanded to include the whole continent.  Once again, labour leaders and politicians predicted economic disaster if a low-wage economy like Mexico would be added to the deal.  It would take until 1994 before the North American Free Trade Agreement (NAFTA) was signed into law and all three countries began to remove tariffs on each others’ goods and services.

Celebrating the 1994 NAFTA signing.  Salinas, Bush, and Mulroney.

As with so many things, the tally of wins and losses can be difficult to distill from the wide array of other changes happening in the global economy at the time. Technological change in the early 1990’s was dramatic, China was growing as an export powerhouse, the Cold War ended, and the European Union was also liberalizing trade.  In these years, the economies of all three countries saw dramatic growth and economists attribute the largest impacts to NAFTA.

  • US trade with its neighbours more than tripled following the deal.
  • It’s estimated that 14 million US jobs are directly tied to open trade with Mexico and Canada.
  • Consumer prices declined, especially for agricultural products and energy.

Cornerstone Timberframes has been exporting timber structures to the US for more than 21 years.  While free trade has felt positive it doesn’t show up as a factor for the builders and homeowners who choose us.  Our clients tell us their purchases are driven primarily by three considerations:

  • The attentive and friendly service that Cornerstone is famous for.
  • Feeling heard and understood by our design team, which results in beautiful, personalized designs.
  • The sweet realization that a US dollar is worth 35% more in Canada.

If you’re looking to build and want to realize the benefits of free trade, talk to a friendly Cornerstone Timberframes representative today!

Creating Your Backyard Oasis

Creating Your Backyard Oasis

with a pergola or Gazebo

One of the joys of summer is being outdoors, surrounded with pleasant views, unharried by the cares of the world.  If you are looking for outdoor happiness, a well-designed and properly sited timber frame structure, like a pergola, gazebo or outdoor bar can transform a pleasing backyard into an oasis of wellbeing and delight.

The Checklist:

To make the work of planning your get-away a little easier, here are the top 10 things you’ll want to know before you spend a dollar on designs or materials. Good design starts with a location, examines how a space will be used and then creates a shape and features for that space that help you maximize your comfort and enjoyment.

First, let’s narrow down the best spot for your oasis:

  1. Review your yard’s exposure to all the things that will have a bearing on your enjoyment. Think about the times of day when you’re most likely to use your gazebo or pergola – what’s happening at those times with sun, shade, neighbours, street noise and the like?  Do you have a wind-sheltered spot?
  2. Next, where are your favourite views? Move around your yard and note the views you like, as well as any that you’d rather not see. Plantings and privacy screens can often help with the latter, so don’t count out a location if it scores well in #1 but has a view to the neighbour’s tool shed – the solution can be beautiful.
  3. For your top locations, think about the path your family and guests will use to reach your gazebo or pergola.  Look for any issues that might affect ease of access.  Remember that distance matters: the closer it is to your home, especially your kitchen, the more you’ll use it and enjoy it.  Being close also reduces electrical runs, path materials and makes every transit between home and oasis easier.

How do you want to use your outdoor space?

  1. Consider how many people you’ll routinely have and the largest number at any one time.  A properly sized space will range between 1-1/2 and 2 times your “everyday” group size.  For larger gatherings, having a patio area as part of your oasis is an easy way to provide room for those additional guests.
  2. Is food preparation and outdoor dining on your menu?  Outdoor kitchens can be compact and simple, and they can also be large and lavish.  Think about the kinds of meals and cooking style you prefer and list the essential elements you’ll need to achieve a hassle-free food prep experience. 
  3. Other Outdoor Features to consider: Think fireplaces, water features, hot tubs, TVs, special lighting, pizza ovens, swings, hammocks and whatever completes your definition of relaxation and refreshment.  Some of these are large and need careful consideration in your design while others can play a part in creating privacy and hiding a less desirable view. 
  4. Do you hate being bugged?  No surprise: mosquitoes, wasps, and flies can make it a challenge to fully relax outside. Thankfully, window and screen materials for gazebos have seen big improvements in variety, functionality, and toughness.  Your gazebo designer can recommend a solution and make sure that window openings make best use of your preferred anti-bug defense.

The shape, style, and material used to make your backyard oasis will enhance your use and enjoyment:

  1. Shape alone, could easily be its own blog topic. Simply stated, square and rectangular pergolas and gazebos are the go-to solution if you’re after the most efficient and affordable space.  Hexagon and octagon shapes involve more material and joinery ($$) but have more wow factor, especially when you step inside a gazebo and look up at how the roof timbers converge.
    Single slope roofs, also known as shed roofs, are simpler to build and can provide a more contemporary feel.  Ask your designer to show you the different roof types or visit our “Look Book” to see the many ways you can configure the shape of your get-away.
  2. Sidewall height needs to allow for at least a 6’-8” (2m) clearance under the eave beam, with 7’ to 9’ heights being most common.  Roof slopes from shallow to steep are a personal choice.  You may want to match an existing building on your yard or let your oasis be its own thing.  Overhangs of 12”-24” are typical, but again, your preference rules.  If you matched the roof pitch of another building, matching the overhang also makes good sense.
  1. If you’re a person who loves wood, this one can be a difficult consideration, but here’s some help:  Cedar is the gold-standard material for handling weather.  It comes in a variety of species with “western red” and “northern white” being the most common.  Both are highly rot-resistant and can be allowed to go silver or helped along with a moisture repelling finish like Sansin’s Wood Sealer. Douglas fir and white pine need to keep dry feet and we recommend using a post stand-off to keep columns clear of puddles.  A good three-coat stain finish is essential.

For more contemporary designs glue-laminated posts and beams can do wonders, allowing longer spans and high-capacity connections, while keeping a sleek, minimalist look.  

Ask your designer to see examples of available wood types.


Pavilion – a roofed structure, free-standing or attached to a larger building.  Is typically open-sided but may also be enclosed by walls.
Gazebo – an open-sided, free-standing, roofed building usually located in a natural area like a garden or park.
Pergola – an open roof structure that provides shade and can also support climbing vines that provide additional shade and privacy.

Why Wood is Good

Why Wood is Good

9 Reasons to Design and Build with Mass Timber

1. Ease of Use

No other construction material is as versatile or easy to use as wood. It can be cut, shaped, and fastened with basic tools.  With experienced supervision, installation is quick and can be undertaken by a small crew with only basic carpentry knowledge. Repairs and modifications are easy and do not require heating or other special measures in cold weather.

2. Fire Resistance

Mass timber is inherently hard to ignite, and when exposed to flame it develops a char layer that resists further combustion.  Full scale fire testing shows that mass timber can meet and exceed required fire ratings, acting like non-combustible construction.  See firetests.cwc.ca for details.

3. Seismic Resilience

Timber can resist seismic forces that cause rigid masonry to crack   and crumble.  Wood fiber’s elasticity allows it to bend and twist without breaking.  Good connection design is critical.

The classic example of seismic performance is the Ying Pagoda in Shanxi, China, built in 1056.  It is 67m / 220’ tall and has withstood a dozen major earthquakes over the past millennium. In 1556 (its 500th anniversary) it survived the Jiajing Great Earthquake, the deadliest quake event in recorded history. While built of wood, its exceptional resistance can also be attributed to its design.  The Ying Pagoda uses a locking joinery that keeps radial beams in place between the inner core and columns at the outer wall.  When things shake and sway these critical connections are designed to move and not break – a flexible, brilliant solution.

4. Acoustic Properties

The International Building Code (IBC) sets out a 50dB sound reduction standard for walls and floors. Concrete, with its high density can achieve this with 15cm / 6” of section. Solid wood is 1/5 the density of concrete, an advantage in almost every aspect of construction, except for resisting sound transmission.  Low amplitude sound waves in the 50-100 Hz range are of special concern in floor assembly design with footfalls and furniture movement being the most noted complaint examples in older wood-framed buildings.

Unlike traditional wood frame construction, the draw of mass timber is being able to see the wood.  Exposed wood ceilings are especially desirable, and this requires sound insulation to be placed on top of the floor as opposed to it being added into a ceiling void. 

A 5-ply CLT floor of 175mm thickness (6 7/8”) by itself has an STC rating of 41. To increase this to a 60 dB rating a multi-layer assembly is required. The top strategies for improving floor sound deadening are:

  1. Decoupling – use of an acoustical mat that creates a low-density zone that inhibits lower Hz sound waves.
  2. Use of a sound absorbing layer – loose-fill limestone or mineral wool board can act as diffusion layer that breaks up and scatters sound waves.
  3. Increase mass – using light concrete toppings (gypcrete) of 25-50mm (1-2”) helps the assembly resist sound vibration.
  4. Flooring material – a variety of floor coverings can provide significant reductions in impact sound transmission.

An updated inventory of STC and ICC ratings with tested assemblies can be found at Woodworks, a US not-for-profit that conducts research on mass timber construction: http://bit.ly/mass-timber-assemblies 

Mass timber is an innovative space where new ideas are constantly improving outcomes.

5. Thermal Comfort

Mass timber’s thermal properties are perfectly suited to human use.  Mass timber components are slow to transfer heat and cold and help moderate the temperature of indoor spaces even when outdoor temperatures move into extremes.

CLT walls by design and construction are “thermally tight”.  In stick framed walls, a common failing is poor draft sealing – air leakage at seams, and at hundreds of nail, staple, and screw punctures, significantly reduces their performance. The CLT’s solid, multi-layer core makes it essentially wind impervious. CLT panels are machined to fit precisely, and simple sealing details ensures a higher fit and finish.

Tests at Oakridge National Laboratory’s Large Scale Climate Simulator showed that CLT walls outperformed stick frame wall assemblies, reducing peak heating and cooling demand by 30%-50% and improving thermal comfort by up to 46%.*

*“Impact of Mass Wood Walls on Building Energy Use, Peak Demand, and Thermal Comfort”, M Salonvaara, 2022.

6. Sustainability

Sunlight, soil, and water – that’s the basic recipe for producing wood.  Nature excels at making use of available resources, bringing things into balance, while building forest communities whose only “waste products” are oxygen, clean water, and a surplus of beauty.

The production of wood and mass timber stand in stark contrast to the energy intensive industrial processes for making concrete and steel.  One way to understand and compare these building materials is to examine their contribution to our world’s existential challenge of climate change.  Consider the graph below:

This graph compares wood, concrete, and steel, by looking at the CO2 emissions generated in the production of a single beam, designed to span a 7.3m (22’ 3”) distance while supporting a 14.4 kN/m unfactored load. All three materials are optimized to the span and load but achieve it with much different carbon emissions.

The wood beam is a glue-laminated timber made up of responsibly harvested trees.  The trees once grew and collected carbon from the atmosphere and now as a wood beam will hold the CO2 for as long as the building exists.  

While the decades pass, new trees are growing where the original trees were harvested.  With better informed forest practices, the circle of carbon collection and storage can be sustained indefinitely.  

7. Speed of Installation

Mass timber structures are fabricated entirely off-site, and deliveries are coordinated to match on-site schedules.  Mass timber components assemble quickly and will typically reduce installation schedules by 20-30% over alternative materials.  

8. Cost Savings

As mass timber becomes better understood and accepted by architects, engineers, and builders, it is also becoming more cost competitive.  In the last two years, studies are showing that an effectively designed mass-timber building is within +/-5% of steel and concrete.  With lighter foundation requirements and fast installation, the cost advantage of mass timber will continue to gain market share.

9. Human Health

In Canada and the US, like most of the developed world, the greatest part of our lives is spent indoors.  Study after study is showing that the spaces we inhabit play an important role in our physical and emotional wellbeing.  Spaces that are enriched by the presence of natural objects and materials are associated with lower levels of stress, feelings of wellbeing, and overall improvements in mental focus and mood.

Wood’s ability to buffer humidity by absorbing and releasing moisture makes for more comfortable homes and offices. Mass timber is chemically inert and uses polyurethane adhesives that do not release VOC’s or other irritants.  Studies of mass timber buildings find the use of wood supports better air quality, thermal comfort, visual and acoustic qualities than equivalent structures built with steel or concrete.