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Joinery & Connectors

Working With Wood

Timber Joinery

Many historic structures in North America were built at a time when metal fasteners were not readily available. Instead, wood members were joined by shaping the adjoining wood members to interlock with one another. Timber joinery is a traditional post and beam wood construction technique used to connect wood members without the use of metal fasteners.

Timber joinery requires that the ends of timbers are carved out so that they fit together like puzzle pieces. The variations and configurations of wood-to-wood joints is quite large and complex. Some common wood-to-wood timber joints include mortise and tenon, dovetail, tying joint, scarf joint, bevelled shoulder joint, and lap joint. There are many variations and combinations of these and other types of timber joinery. Refer to Figure 5.18, below, for some examples of timber joinery.

For load transfer, timber joinery relies upon the interlocking of adjoining wood members. The mated joints are restrained by inserting wooden pegs into holes bored through the interlocked members. A hole about an inch in diameter is drilled right through the joint, and a wooden peg is pounded in to hold the joint together.

Metal fasteners require only minimal removal of wood fibre in the area of the fasteners and therefore, the capacity of the system is often governed by the moderate sized wood members to carry horizontal and vertical loads. Timber joinery, on the contrary, requires the removal of a significant volume of wood fibre where joints occur. For this reason, the capacity of traditional timber joinery construction is usually governed by the connections and not by the capacity of the members themselves. To accommodate for the removal of wood fibre at the connection locations, member sizes of wood construction systems that employ timber joinery, such as post and beam construction, are often larger than wood construction systems that make use of metal fasteners.

Wood engineering design standards in Canada do not provide specific load transfer information for timber joinery due to their sensitivity to workmanship and material quality. As a result, engineering design must be conservative, often resulting in larger member sizes.

The amount of skill and time required for measuring, fitting, cutting, and trial assembly is far greater for timber joinery than for other types of wood construction. Therefore, it is not the most economical means of connecting the members of wood buildings. Timber joinery is not used where economy is the overriding design criteria. Instead, it is used to provide a unique structural appearance which portrays the natural beauty of wood without distraction. Timber joinery offers a unique visual appearance exhibiting a high degree of craftmanship.

For further information, refer to the following resources:

Timber Framers Guild

Wood Foundations

Codes & Standards

Permanent Wood Foundations

A permanent wood foundation (PWF) is an engineered construction system that uses load-bearing exterior light-frame wood walls in a below-grade application. A PWF consists of a stud wall and footing substructure, constructed of approved preservative-treated plywood and lumber, which supports an above-grade superstructure. Besides providing vertical and lateral structural support, the PWF system provides resistance to heat and moisture flow. The first PWF examples were built as early as 1950 and many are still being used today.

A PWF is a strong, durable and proven engineered system that has a number of unique advantages:

energy savings resulting from high insulation levels, achievable through the application of stud cavity insulation and exterior rigid insulation (up to 20% of heat transfer can occur through the foundation);
dry, comfortable living space provided by a superior drainage system (which does not require weeping tile);
increased living space since drywall can be attached directly to foundation wall studs;
resistance to cracking from freeze/thaw cycles;
adaptable to most building designs, including crawl spaces, additions and walk-out basements;
one trade required for more efficient construction scheduling;
buildable during winter with minimal protection around footings to protect them from freezing;
rapid construction, whether framed on site or pre-fabricated off-site;
materials are readily available and can be efficiently shipped to rural or remote building sites; and
long life, based on field and engineering experience.

PWFs are suitable for all types of light-frame construction covered under Part 9 ‘Housing and Small Buildings’ of the National Building Code of Canada (NBC), that is, PWF can be used for buildings up to three-storeys in height above the foundation and having a building area not exceeding 600 m². PWFs can be used as foundation systems for single-family detached houses, townhouses, low-rise apartments, and institutional and commercial buildings. PWFs can also be designed for projects such as crawlspaces, room additions and knee-wall foundations for garages and manufactured homes.

There are three different types of PWFs: concrete slab or wood sleeper floor basement, suspended wood floor basement and an unexcavated or partially excavated crawl space. Lumber studs used in PWF are typically 38 x 140 mm (2 x 6 in) or 38 x 184 mm (2 x 8 in), No. 2 grade or better.

Improved moisture control methods around and beneath the PWF result in comfortable and dry below-grade living space. The PWF is placed on a granular drainage layer which extends 300 mm (12 in) beyond the footings. An exterior moisture barrier, applied to the outside of the walls, provides protection against moisture ingress. Caulked joints between all exterior plywood wall panels and at the bottom of exterior walls is intended to control air leakage through the PWF, but also eliminates water penetration pathways. The result is a dry basement that can be easily insulated and finished for maximum comfort and energy conservation.

All lumber and plywood used in a PWF, except for specific components or conditions, must be treated using a water-borne wood preservative and identified as such by a certification mark stating conformance with CSA O322. Corrosion-resistant nails, framing anchors and straps that are used to fasten PWF-treated material must be hot-dipped galvanized or stainless steel. Exterior moisture and vapour barriers must be at least 0.15 mm (6 mil) in thickness. Dimpled drainage board is often specified as an exterior moisture barrier.

For further information, refer to the following references:

Permanent Wood Foundations (Canadian Wood Council)

Permanent Wood Foundations 2023 – Durable, Comfortable, Adaptable, Energy efficient, Economical (Wood Preservation Canada and Canadian Wood Council)

Wood Design Manual (Canadian Wood Council)

Wood Preservation Canada

CSA S406 Specification of permanent wood foundations for housing and small buildings

CSA O322 Procedure for certification of pressure-treated wood materials for use in permanent wood foundations

CSA O86 Engineering design in wood

National Building Code of Canada

Sustainability

The Basics

Environmental Issues

Safe Handling

Using common sense and standard safety equipment (personal protection and wood-working machinery) applies when working with any building products. Gloves, dust masks and goggles are appropriate for use with all woodworking. Here are a few key points specific to treated wood:

Pressure-treated wood is not a pesticide, and it is not a hazardous product. In most municipalities, you may dispose of treated wood by ordinary garbage collection. However, you should check with your local regulations.
Never burn treated wood because toxic chemicals may be produced as part of the smoke and ashes.
If preservatives or sawdust accumulate on clothes, launder before reuse. Wash your work clothes separately from other household clothing.
Treated wood used for patios, decks and walkways should be free of surface preservative residues.
Treated wood should not be used for compost heaps where free organic acids produced early in the composting process can remove the fixed chemicals. It is, however, safe to use for growing vegetables in raised soil beds. If, after reading this, you are still concerned, place a layer of plastic sheet between the soil and the treated wood wall.
Treated wood should not be cleaned with harsh reducing agents since these can also remove the fixed chemicals.

Environmental Concerns

All wood preservatives used in the U.S. and Canada are registered and regularly re-examined for safety by the U.S. Environmental Protection Agency and Health Canada’s Pest Management and Regulatory Agency, respectively.

Wood preservation is not an exact science, due to the biological – and therefore variable and unpredictable – nature of both wood and the organisms that destroy it. Wood scientists are trying to understand more about how wood decays to ensure that durability is achieved through smart design and construction choices where possible, so that as a society we can be selective in our use of preservatives.

Comparing treated wood to alternative products

A series of life cycle assessments has been completed comparing preservative treated wood to alternative products. In most cases, the treated wood products had lower environmental impacts.

Click for consumer safety information on handling treated wood (Canada).

Mid-Rise Buildings

The Basics

Mid-Rise FAQs

What do the experts have to say about wood-frame mid-rise construction?

Graham Finch, Building Science Research Engineer

Michael Green, Principal, Michael Green Architecture

Mid-rise Wood Construction – a detailed look at a changing landscape (Part 1)

Mid-rise Wood Construction – a detailed look at a changing landscape (Part 2)

Seven-storey wood-frame earthquake test

BC Housing is supporting wood-frame construction for seniors’ rental housing

Is mid-rise and tall wood building construction a new phenomenon:

Wood-frame and heavy timber construction (up to ten storeys) was the norm in the early 1900’s, and many of these buildings still exist and are in use in many Canadian cities.

Check them out here: http://www.flickr.com/photos/bobkh/337920532/.

Over the past 10 years, there is a revival in the use of wood for both mid-rise (up to six-storeys) and tall buildings. In British Columbia alone, as of December 2013, there were over 250 five- and six-storey wood product based mid-rise buildings either in the design or construction phase.

Why have code change proposals?

This 2015 building code change is not about favoring wood over other building materials; it’s about acknowledging, via the highly thorough code process, that science-based innovation in wood products and building systems can and will lead to more choices for builders and occupants.

Are these buildings safe?

Regardless of the building material in question, nothing gets built unless it meets code. Mid-rise wood-frame buildings reflect a new standard of engineering in that structural, fire and seismic concerns have all been addressed by the expert committees of the Canadian Commission on Building and Fire Codes. As an example, when it comes to concerns from firefighters, there is increased sprinkler protection for concealed spaces and balconies, greater water supply for fire protection, restrictions on types of building claddings used and increased consideration for access by firefighters . In the end, when occupied, these buildings fully meet the same requirements of the Building Code as any other type of construction from the perspective of health, safety and accessibility.

What are some of the new safety provisions being proposed?

Fire safety:

Increased level of sprinkler / water protection:

More concealed spaces sprinklered

Balconies must be sprinklered

Greater water supply for fire protection

Non-combustible or limited combustible exterior wall cladding on 5^th and 6^th storey

25% of perimeter must face one street (within 15m of street) for firefighter access

Seismic and wind provisions:

Similar to BC Building Code

Guidance (Appendix) on impact of increased rain and wind loads for 5- and 6-storey

Acoustics:

Requirements for Apparent Sound Transmission Class (ASTC)

Supported by science from FPInnovations, NRC and many others.

Doesn’t wood burn?

No building material is impervious to the effects of fire. The proposed code changes go above and beyond the minimum requirements outlined in the NBCC. Health, safety, accessibility, fire and structural protection of buildings remain the core objectives of the NBCC and wood industry at large.

What about construction site safety?

The Canadian Wood Council has developed construction site fire safety guides which outline best practices and safety precautions to take during the construction phase of a building.

Are mid-rise wood-frame buildings cost effective?

For the most part, yes. Mid-rise wood-frame buildings are often a less expensive construction option for builders. This is good news for main-street Canada where land is so expensive. The recommended changes to the National Building Code of Canada (NBCC) would give the opportunity to erect safe, code compliant buildings that would otherwise not be possible. The net benefit of reduced construction costs is increased affordability for home buyers. In terms of new economic opportunity, the ability to move forward “now” creates new construction jobs in cities and supports employment in forestry communities. This also offers increased export opportunities for current and innovative wood products, where adoption in Canada provides the example for other countries.

Mid-Rise Wood Construction in Ontario: Navigating 2024 Ontario Building Code Updates

Course Overview

In late 2014, following years of research and development in advanced wood products and systems, amendments to the 2012 edition of the Ontario Building Code (OBC) came into effect permitting mid-rise wood construction for residential and office buildings up to 6 storeys. This marked a significant shift, expanding the use of light-wood frame construction beyond the previous 4-storey height limit, and opening new opportunities for cost-effective and versatile building solutions. To improve affordability and harmonize with the National Building Code, the 2012 OBC was further amended in mid 2023 to permit limited combustible cladding and combustible exits to be featured in mid-rise wood construction. These amendments, with some minor editorial changes, were also carried forward to the 2024 edition of the OBC, which came into effect on January 1, 2025. This presentation will provide an overview of the technical and regulatory changes to the OBC with respect to the design and construction of mid-rise wood buildings and explore the role of this building archetype in achieving our housing targets with affordable, high-quality, and sustainable construction.

Learning Objectives

Understand the intent, scope, and application of technical and regulatory changes as well as key 2024 OBC provisions for mid-rise wood construction in Ontario.
Explore the advantages of 5- and 6-storey wood buildings on the housing supply efforts in Ontario through market potential, project highlights, and the role of modern methods of construction.
Know how to access free design and best practice resources for mid-rise wood construction and how to access free WoodWorks project support.

Course Video

https://vimeo.com/1198518622

Speakers Bio

Hailey Quiquero
Senior Manager
WoodWorks ON / Canadian Wood Council

Hailey Quiquero is currently the Senior Manager at WoodWorks ON for the Canadian Wood Council. Prior to their current role, Hailey worked as a Product and Design Manager and Computational Design Specialist at R-Hauz, as well as in various roles at Entuitive and Carleton University. Hailey holds a Master’s Degree in Structural and Fire Engineering and a Bachelor’s Degree in Architectural Conservation and Sustainability Engineering from Carleton University. Throughout their career, Hailey has been involved in research, teaching, and structural design within the engineering field.

Vusal Ibrahimli
Technical Specialist, Codes and Standards – Fire
Canadian Wood Council

Vusal Ibrahimli, M.A.Sc., E.I.T. is a Technical Specialist, Codes and Standards – Fire at the Canadian Wood Council. He supports fire-related code and standards initiatives and provides technical expertise for wood construction, including contributing to education and conference programming related to fire performance and code compliance.

Durability

The Basics

Durability by nature

For outdoor applications of wood, we have a strong tradition here in North America of using our naturally durable species: Western red cedar, Eastern white cedar, yellow cypress and redwood. These are familiar choices for decks, fences, siding and roofing. These species are resistant to decay in their natural state, due to high levels of organic chemicals called extractives. Extractives are chemicals that are deposited in the heartwood of certain tree species as they convert sapwood to heartwood. In addition to providing the wood with decay resistance, extractives also often give the heartwood colour and odour.

Only the heartwood has these protective deposits. The sapwood of all North American softwoods is susceptible to decay and must be protected by other means when decay resistance is required. Sapwood is the newer part of the tree, closer to the bark. It needs no decay protection in the live tree because wound responses keep out any invading organisms. The heartwood is the inner, older part of the tree and is no longer alive.

Heartwood is often visibly distinguishable from sapwood by colour (heartwood is generally darker), but not in all species. However, even if you’re sure you have heartwood of a durable species, you may not have the level of resistance you think. Decay resistance is often highly variable, and may be lower in plantation-grown trees. There is currently no way to reliably estimate the durability of a piece of naturally durable heartwood.

More Information

Click Here for a table showing natural durability rankings of common softwood species.