DLT-Mass Timber

Dowel Laminated Timber (DLT)

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Mass timber uses state of the art technology to connect layers of wood products together using either glue, nails or wooden dowels.

The resulting large structural panels are exceptionally strong and versatile and collectively known as mass timber. 

They can be pre-fabricated off site and installed quickly and efficiently and it makes a great complement to light and heavy timber framing options. 

It’s a proven high performance material for structural systems with superior strength and stability.

At International Timberframes we design, manufacture and install a 100% Wood DLT product called Wood100 DLT

Architects, engineers and builders are realizing the potential of 100% wood Dowel Laminated Timber (DLT) as a healthy, sustainable and energy efficient building product.

Why Is Mass Timber Growing In Popularity?

  • Wood’s ability to sequester CO2

  • Lower carbon footprint than concrete or steel

  • Strength and dimensional stability

  • Superior earthquake resistance

  • Maintains load bearing capacity in fire

  • Quick and efficient installation

  • Health benefits of natural solid wood

  • Energy efficiency

wood100 interior

The first forms of modern mass timber appeared in Europe in the late 19th and early 20th centuries.  In the 1970’s in Switzerland mass timber as we know it today started to appear as NLT (nail laminated timber) and CLT (cross laminated timber) products.  With technological developments in design and production, mass timber grew and became established in Europe, arriving in and being accepted in North America around a decade ago.

As the benefits of mass timber have become truly understood its use continues to grow in North America.  

One of the greatest benefits of building with mass timber is wood’s ability to sequester CO2.  As trees grow they capture CO2 from the atmosphere and store it in the wood. When trees are harvested for building materials, the carbon is captured for the life of the structure. In addition to storing carbon, wood products are associated with low levels of carbon emissions during manufacturing, (especially compared to concrete and steel) thus reducing the overall carbon footprint of a building’s construction.

Combined with sustainable forest practices, mass timber could help to reduce the GHG impact of the construction sector.

By some estimates, the average carbon content of a tree is close to 50 percent of its total volume. Construction-grade lumber typically holds about 1 tonne of CO2 for each cubic metre of wood, while the average single-family home in Canada stores almost 30 tonnes of CO2 within the wood products used for its construction.

Because of their strength and dimensional stability, mass timber products are proving to be a practical alternative to traditional construction methods.  Lightweight and flexible, they have superior resistance to earthquakes for example.

Mass timber systems are structurally comparable to steel and concrete but lighter. Mass timber projects utilizing wood instead of steel or concrete can have smaller, less expensive foundations, and are suitable for all soil conditions.

Because of its structural properties and dimensional stability mass timber is well suited to floor slabs, wall panels and roof / ceiling panels. The walls and floor panels may be left exposed in the interior which provides additional aesthetic attributes. Different compositions of mass timber can be used with light framing to provide lateral stability, thus allowing for greater building heights, or mixed structures.

Mass timber can be installed quickly and efficiently.  Precise pre-fabrication off-site means an efficient construction process allowing structures to be built faster than ever. One of the biggest benefits of mass timber panels as compared to other types of construction is the ability to prefabricate the entire project. This saves precious time and money on-site because the installation process becomes more efficient.

Wood’s low thermal conductivity provides natural insulation that reduces heat transfer.

Mass timber is capable of maintaining load bearing capacity in the event of fire, as the  large wooden blocks char on the surface rather than burn completely, allowing for more time to evacuate and extinguish fires.

The aesthetics of beautiful exposed wood coupled with structural integrity is compelling for architects, builders and home-owners alike. Many studies have documented the health benefits from living, working, recuperating and learning in spaces surrounded by natural solid wood.  Lowered stress levels, better sleep and wellness levels and improved productivity are all reasons for ever increasing use of mass timber in schools, hospitals, offices and homes.

For all of these benefits to be realised we strongly believe that mass timber should genuinely be 100% wood.  When you start adding layers of glue then many benefits are diminished particularly in the areas of health and sustainability.

At International Timberframes we manufacture and install only 100% wood Dowel Laminated Timber (DLT) – a product we call Wood100®DLT.

fire resistance mass timber
breathability of mass timber

Mass Timber at International Timberframes - Wood100®DLT

We design, manufacture and install 100% Wood Dowel Laminated Timber (DLT)

We believe wood is the most natural and healthy material to build with.  We also understand that construction is a major contributor to waste.  We must take whole-hearted steps to conserve our planet by doing everything as sustainably as we possibly can.

At International Timberframes we DESIGN, manufacture and install only 100% wood Dowel Laminated Timber (DLT) – a product we call Wood100®DLT.  We were the first company in BC to manufacture and install DLT in a commercial application.  You can see the project, Radium Community Centre,  in our Featured Project Gallery.

We have 25 years experience in mass timber, having worked on development of DLT in Europe in the 1990’s.

What is DLT

To produce DLT, layers of wood are friction-fit together with hardwood dowels rather than glue or nails/screws. The dowels hold the boards together, the friction fit achieved by the differing moisture content of the softwood boards and the hardwood dowels.

The dowel layers are assembled into solid wood panels designed for walls, floor, ceilings and roof structures.  Depending on the application, multiple layers of wood can be used to create panels up to 360mm thick.  The resulting indestructible solid wooden blocks perform better than other construction methods at heat insulation, fire security, radiation shielding, earthquake safety and protection against condensation and mould growth.  

After designing and pre-planning for location of windows, electrical and plumbing where relevant, the solid wood panels are pre-fabricated here in our shop. When the site is ready they are delivered and assembled quickly and efficiently.

Types of DLT

We produce 2 types of DLT, cross laminated and stacked

Cross Lam – Cross Laminated DLT are large sized panels manufactured by cross laminating 3 to 7 layers of softwood lumber.  The panels are made by layering wood on top of each other on their wide edge at alternating angles and pegging them together with beech dowels.

Stacked – In Stacked DLT these panels are manufactured by stacking the wood layers on top of or next to each other on edge in the same direction as the previous and pegging them together with beech dowels

We are proud to be pioneering both stacked and cross laminated DLT across Canada.

Cross Laminated DLT

Dowel Laminated CLT

Cross Laminated DLT are large sized panels manufactured by cross laminating 3 to 7 layers of softwood lumber.  The panels are made by layering wood on top of each other on their wide edge at alternating angles and pegging them together with beech dowels.

Stacked DLT

dowel laminated timber stacked panel

In Stacked DLT these panels are manufactured by stacking the wood layers on top of or next to each other on edge in the same direction as the previous and pegging them together with beech dowels

Using Stacked and Cross Laminated DLT

Sometimes it is the different aesthetic of each product that drives the choice of which one to use.  However there are important differences between the two in terms of application and performance:

  • stacked DLT has higher structural values for ceilings and roofs
  • cross laminated DLT has higher structural values for shear walls and in seismic zones

Cross laminated DLT offers superior thermal insulation over stacked DLT, NLT and glulam. It has almost double the R-value of any other solid wood product. This means that you can build a highly insulated wall in a similar thickness (14”)  to that of a regular framed house to reach a U-value of 0.2    

Why Do We Make 100% Wood Dowel Laminated Timber (DLT)?

sustainable mass timber interior
sustainable house

Environmental Sustainability / Recyclability

Construction is a major contributor to waste and everyone in the industry needs to be more responsible in the products they are leaving for future generations to manage, live with and dispose of. Our 100% Wood DLT is completely clean, truly cradle-to-cradle product.  It contains no glues or other chemicals making it 100% uncontaminated and therefore 100% recyclable wood. It can be disassembled and re-used or composted at the end of its life. The energy consumption during manufacture of our DLT is roughly 3.5 times lower than in the manufacture of other mass timber products. This significantly lowers production emissions. Compared to concrete and steel, DLT is a natural choice for sustainable construction – there is significantly less energy used in the production of wood products than in steel or concrete.  We are proud to make a 100% wood, 100% re-usable, 100% recyclable product.

If you are interested in learning about the carbon benefits of your wood building you can use the Canadian Wood Council Carbon Calculator.  After inputting wood volumes, the tool estimates how much time it takes Canadian forests to grow that volume of wood along with the associated carbon benefits – both the amount of carbon stored and the amount of greenhouse gas emissions avoided. 

mass timber fire resistance
recyclable mass timber

Energy Efficiency

A solid DLT home has the world record for heat insulation in structural materials and therefore minimal operating costs.  Recent tests of 3 wall systems with the same R-value showed the supremacy of cross laminated DLT.  An average 100% wood DLT home needs ⅓ of the heating system compared to a traditional framed home with the same R-value.  Cross laminated DLT offers superior thermal insulation over stacked DLT, NLT and glulam. It has almost double the R-value of any other solid wood product. This means that you can build a highly insulated wall in a similar thickness (14”)  to that of a regular framed house to reach a U-value of 0.2

It’s like having air conditioning and heating systems with zero energy consumption – in the summer the home stays cool and in the winter it stays warm.

cross laminated DLT

Health

With no off-gassing from glues or contamination from chemicals, 100% Wood DLT offers a significantly healthier indoor environment, particularly for those with allergies and hyper-sensitivity. It has been scientifically proven that the heart beats more slowly and you sleep deeper and more soundly in solid wood rooms rather than artificial surroundings.  Much research has been done into the calming effect of wood in kindergartens and classrooms and patient recovery times in hospitals. 

fire resistance of solid wood
mass timber fire resistance

Fire Resistance

Mass timber has exceptional fire resistance compared to concrete and the natural properties of DLT allow for much longer and safer evacuation.  Many studies have been undertaken into the char rate of mass timber and DLT.  After 90 minutes of burning at 1000 degrees a 340mm solid wood wall or roof panel is still structurally sound and the side away from the fire is untouched. Remarkably the temperature of the solid wood panel is only 2 degrees higher.  This is crucial for fire-fighters and rescuers as they can walk on and touch solid wood floor and roof panels without harm.  At such temperatures concrete breaks and exposes the rebar and the surface reaches almost 1000 degrees.  It’s impossible for fire and rescue crews to walk on, touch or even get close to that.

Wood is a much more predictable material than concrete or steel and the char rate can be calculated. Concrete however could collapse at any time without warning.  We can work with you to calculate the char rate of your solid wood projects.

In glued mass timbers the glue layers act as fire accelerators and in the event of fire these products emit toxic fumes.

breathability of mass timber
sustainable mass timber

Breathability

Different layers of different materials with different characteristics can create issues in moisture management.  In terms of building physics, cross laminated DLT walls consist of just one thick block of layered wood: a wood-only mono-material.  There are therefore no changes in the vapour permeability within the wall and no moisture can condense as on vapour-barrier foils or insulation materials that are often used in conventional construction methods. 100% wood DLT regulates the indoor climate much better because moisture can be transferred freely between the entire wall system.   In our DLT the moisture flow is not blocked by layers of glue which can reduce the breathability of the construction by up to 80%. Such reduced breathability can cause condensation and poor air quality in the build. 

mass timber wall pre fabricated

Ease of Use

DLT is safer and easier to mill, lathe, route and generally use in CNC machines because it does not use nails or screws. The absence of nails or screws in DLT means that other trades can safely and easily use saws, drills etc at later stages of the build for electrical or other service conduits.

Wood Fibre Insulation

  • A healthy living climate

  • Sustainable and environmentally friendly

  • Thermal insulation

  • Heat protection

  • Noise control

  • Fire resistance

  • Vapour permeability

  • Airtightness

Wood fiber insulation is a safe, natural, and high performing alternative to many synthetic insulation options currently on the market.

At International Timberframes we offer Pavatex T&G wood fibre boards. The thermal insulation and storage properties, and the easy handling format of the boards, mean that the material is ideal for use in a wide range of constructions.