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Looking to level up your traditional woodworking skills? Getting to grips with carpentry joints is a brilliant way to enhance your woodworking techniques and create secure, stable timber products. One of the most popular styles to add to your repertoire is the mortise and tenon joint.

Start from scratch and work your way up to a fully functioning mortise and tenon joint in this easy-to-understand guide.

What Is a Mortise and Tenon Joint?

The mortise and tenon joint is a staple of carpentry, especially relevant in the traditional oak beam frame industry. The joint itself is made up of two parts that slot together perfectly, joining two separate pieces of wood. These parts are:

  • The mortise: this is a rectangular area carved out of one of the pieces of timber.
  • The tenon: this is the corresponding projection that fits perfectly into the mortise.

A mortise and tenon joint is ideal for creating super strong, interlocking connections between your timber. It is perfect for load-bearing objects, including tables, chairs and Oak beams, and is also frequently seen in window and door frame construction.

Before You Get Started

We are going to take a look at some step-by-step instructions to put together your mortise and tenon joint but before diving into those, we have some tips which should make your joinery easier.

The first is always to work with sharp tools, so be careful and follow appropriate health and safety guidance. Precise cuts are crucial for creating snug joints, ensuring your individual pieces of timber do not wiggle around or sit unevenly. Along the same line of thought, do not rush your cuts. A little bit of patience goes a long way to create accurate mortise and tenon joints.

Wood and Shop has a great video on cutting a tenon that shows precise cuts in action.

Even with sharp tools and accuracy, it’s still a smart idea to do a dry fit before glueing (if you intend to glue your joints). This makes sure that your joint is just right before you finalise it.

Step-by-Step Guide to Creating a Mortise and Tenon Joint

Get cracking with your first mortise and tenon joint with these step-by-step guidelines:

  1. Begin by planning the length and width of your mortise and tenon, marking each accurately on your sawn timber using a pencil. A rectangular stencil can make this simpler or you can use a ruler to mark out your location.
  2. Always carve out the mortise before the tenon. It is simple to adjust the tenon to fit the mortise, but not the other way around.
  3. You can use a drill press, chisel and mallet, or a router to carve out your mortise. It should have a width of around ⅓ of the timber board’s overall width for a strong joint suitable for Oak beams.
  4. Carefully cut your tenon using a saw, following your marked lines and always choosing to cut too large rather than too small. After your initial saw, you can use sandpaper to make your tenon slightly smaller and ensure a tight fight. For tenons which need a little more downsizing, opt for carefully planing the timber.
  5. Wood glue can help create a super tight fit which fills little gaps for a sturdier joint. Use a clamp to hold your mortise and tenon in place while the glue dries, being vigilant to ensure it is perfectly aligned. Check the glue is appropriate for the right timber species such as Oak or Douglas Fir.

Learn More at EcoChoice

At EcoChoice, we are experts in all things timber, including sourcing your wood sustainably. To continue your carpentry with a good conscience, take a peek at our timber products sourced from sustainably managed forests.

All our suppliers are independently certified by organisations including the FSC and PEFC, so you can be certain that the timber you are using to practise your mortise and tenon joints supports conservation, biodiversity and the end of illegal deforestation. To learn more, get in touch with our team today.

Master the Mortise and tenon join

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Unsure which timer is best for your project?

Our timber experts have years of experience and will be able to match the perfect species to your project, as well as provide a quote for sustainable timber at highly competitive prices.

Frequently asked questions

Do you supply timber for domestic uses?

Yes, we supply timber for domestic applications as well as commercial and public constructions. From garden decking to shed cladding, we will be happy to supply smaller deliveries for home use.

Is your timber FSC-certified?

Yes, all timber we supply is FSC or PEFC certified and sourced from independently verified responsibly managed forests. If we can’t find your request in FSC/PEFC certified timber we’ll suggest an alternative that is certified or clearly note that the offer is minimum EUTR.

Where does EcoChoice deliver to?

EcoChoice delivers to construction sites, warehouses and homes across the UK, as long as there’s access and unloading for our trucks.

What are the best timber species for exterior use?

There are many different timber species suitable for exterior use and which is the best for your project depends on your requirements. In general, though, we recommend EkkiGreenheartOpepe and Oak for heavier civil/marine uses. For intermediary external use such as decking, where the timber needs to be both strong and durable but not on the same level as civil engineering (bridgespiling, etc) we usually supply CumaruIpe, Jatoba, and Balau. And for the lighter exterior use where the timber is non-structural such as cladding, we deliver CedarLarchThermowood and others.

Which timber is the most durable?

Durability Class 1 timbers are the most durable. This of course depends on the use (hazard) class they’ll be in service for. For direct ground and water contact such as sleepers, fenders, marine piling, etc, Ekki and Greenheart are known to be the most durable timbers available. For decking and cladding where there’s no direct ground contact (use class 3) there’s a much wider range of timbers such Larch, Cedar, Thermo modified Pine or Ash and others.

What’s the best timber for internal cladding?

Internal cladding, where your timber is not in ground and not exposed to the elements can be classed as either use-class 1 or 2 – in which case most timbers will meet this durability criteria. That is not to say they’ll be the best, since internal environments have lower humidity (moisture) levels than outside. So in these cases, it’s best to go for a kiln-dried timber cladding board as these are more stable and delivered already in lower MC (moisture content) than the usual fresh sawn timbers sent to external applications. A word of caution – as timber reacts to variations in moisture, it’s best to avoid cladding any areas inside your bathroom.

How can I make decking less slippery?

The first thing is to ensure your deck boards are kept clean from leaves and other debris which will, over time, cover the surface and make it more slippery. Grooved boards can be used to improve grip if installed and used perpendicular to traffic, so especially useful in narrow passages and footbridges. Lastly, you can add our Grip-Choice strips: these are a mix of epoxy with aggregates that add gripping ridges to your deck area. Gripchoice is an easy way to make decking less slippery and safer, especially over large areas or where there’s high traffic. We can pre-install Grip-Choice strips for your decking before delivery or ship the strips separately to add to your existing deck’s grooves as a retro-fit solution.

What wood machining services do you offer?

We can offer planing, sawing, drilling and profiling of rough-sawn wood to any profile you require: from handrails to large port fenders.

Can you supply pre-drilled timber?

Yes, we will be happy to provide pre-drilled timber which is tailored to your needs for quick installation, thus saving you valuable time on site.

What cladding profiles do you supply?

We provide a wide range of cladding profiles, including tongue and groove, featheredge and shiplap. You can check the standard profiles here – but we can also match or custom make profiles to suit your specific needs.

Does timber change colour?

Yes, timber is well-known for changing colour over time. Some species can darken quickly right after installation, and like most untreated wood will eventually weather to a beautiful silver-grey. Interior timber is less likely to change colour (depending on conditions), and timber can be stained, painted or treated with UV-resistant oils to reduce colour change.

Do I need to treat exterior timber?

Some timbers such as Oak and Ekki, can withstand the strains of exterior use without any treatment. However, to extend the lifespan and maintain the aesthetic of your wood, we do recommend treating your timber with stains and oils. Pre-treated timber, such as ThermoWood and OrganoWood, are low-maintenance options which are more durable, but can have their life service extended by applying a clean and stain maintenance schedule.

Do I need to treat interior timber?

Depends on what area the timber is being used. For floor joists and timber rafters, it is common to see timber treated, or least very well kiln-dried. Other uses such as flooring may benefit from varnishing while internal timber cladding for decorative purposes shouldn’t require any treatment other than if you want to change its colour with different types of stains or oils.

Where are you based?

We’re based in Cambridge, UK, and coordinate multiple sawmills all over the world to manufacture your order. We then organise delivery with a range of hauliers so that your orders gets to your site on time.

What are the usual decking sizes?

Timber decking is usually 21x140mm or similar. For heavier applications where there’s more load and traffic, we deliver 35 or 45mm thick boards (such as Hastings Pier). Narrower boards are also possible: 95-90mm is a standard width – but we can manufacture whatever size you require.

What are the usual cladding sizes?

Typical cladding section sizes are 18×95 and 18x145mm although we can always custom make a section to suit your project’s design requirements. That includes waney edge boards in Oak or Chestnut as well as extra wide 195mm boards.

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Having needed the supply of cladding, decking boards and other specified timbers through out the year Eco choice have been very helpful in sourcing the specified timbers and quantities required at a very competitive price.

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Having needed the supply of cladding, decking boards and other specified timbers through out the year Eco choice have been very helpful in sourcing the specified timbers and quantities required at a very competitive price.

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