Understanding Wood Joints | Ask This Old House

Understanding Wood Joints | Ask This Old House

In this video, Ask This Old House general contractor Tom Silva teaches host Kevin O’Connor about the different wood joints, including their strengths and weaknesses.

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Kevin O’Connor meets general contractor Tom Silva in the shop for a lesson on wood joints. With several power tools and jigs on the table, Tom explains how joinery works and some of the most popular methods. He teaches Kevin everything from mitered and lapped joints to dowels, biscuits, floating tenons, and pocket hole joinery, with examples of each type to show how they work.

Different Types of Wood Joints
Butt Joints
Miter Joints
Half-lap Joints
Dado and Rabbet Joints
Box Joint
Mechanical Fasteners
Floating Tenons
Biscuit Joints
Pocket Hole Joinery

Where to find it?
Tom explained how to identify different types of wood joinery and why they’re used in woodworking.
Half-lap joint—Formed by creating two rabbet cuts, which requires cutting half of the end of the board. DOMINO DF Q-Plus by Festool [https://www.festoolusa.com/]
Half-lap butt joint—Formed by creating one rabbet cut, as explained above, and then placing the other board into the opening created by the rabbet cut. Hoffman—PDS 32 [https://hoffmann-usa.com/]
Miter Joint—Formed by creating two, opposing, 45-degree angle cuts on the ends of the board and then bringing them together, creating a 90-degree angle. Cut created using a Zeta P2 made by Lamello [https://www.lamello.com/]
Floating tenon joint (aka biscuit joint)—Formed using a biscuit joiner, a specialty tool that drills mortises wide enough to accept biscuits or tenons that are pre-cut and connect two boards with mortises together. Cut created using biscuit joiner, Top 10 by Lamello [https://www.lamello.com/]
Box joint—Formed by creating a series of cuts on each end of the board that create a castle or finger-shaped look. Cut created using Kreg Jig® K5 [https://www.kregtool.com/home]

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About Ask This Old House TV:
From the makers of This Old House, America’s first and most trusted home improvement show, Ask This Old House answers the steady stream of home improvement questions asked by viewers across the United States. Covering topics from landscaping to electrical to HVAC and plumbing to painting and more. Ask This Old House features the experts from This Old House, including general contractor Tom Silva, plumbing and heating expert Richard Trethewey, landscape contractor Jenn Nawada, master carpenter Norm Abram, and host Kevin O’Connor. Ask This Old House helps you protect and preserve your greatest investment—your home.

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Understanding Wood Joints | Ask This Old House


  1. Veenay Mungal on April 13, 2022 at 5:50 pm

    Great video guys, I now have a better understanding of wood joints… 👍👌👍

  2. rayscdn07 on April 13, 2022 at 5:52 pm


  3. Karl Alan on April 13, 2022 at 5:52 pm

    The biggest difference between the floating tenon and biscuits is the grain direction. In floating tenon, since the grain is perpendicular to the joint, it is super hard to break. The biscuits could be just about any direction, but more often than not, it’s similar to the joint, so it helps more with alignment than strength.

  4. Kasbak Gaming on April 13, 2022 at 5:55 pm

    And if you want to know how to make the jigs and machines that make most of these joints easily, watch Matthias Wandel.

  5. John Arnold on April 13, 2022 at 5:56 pm

    Tommy, just so you know, if I hit the lottery I’m going to hire you to redo my house. However you want, you got a blank check. Your imagination will be the limit

  6. Mariusz Chrobak on April 13, 2022 at 5:56 pm

    I wish I had patience to use that awesome technics to do some nice furniture…

  7. Collin DeBello on April 13, 2022 at 6:00 pm

    I enjoy watching. I remember being knee high to my great uncle and him and I doing woodworking projects and watching this old house and remembering this old house. I enjoy I can continue on learning even after he has passed. Thank you

  8. Angella S. on April 13, 2022 at 6:01 pm

    Okay Tommy, now we need to know when to use which method! Great information as always! Thanks 🙏!

  9. Arthur Daley on April 13, 2022 at 6:01 pm

    End grain glue surface is just as good as side surface.

  10. robohippy on April 13, 2022 at 6:03 pm

    Tried the pocket screws and didn’t like them. One of the 2 pieces being joined would ‘climb’ as I would screw them together, and one would end up higher than the other. Funny to see the Festool set up being called a tenon. Guess that works, but then the more common biscuit would be a tenon also. Missing are dove tail and spline joints. Guess the biscuit could be a spline. Oops, new product, biscuit cutter that will slide and make a full length dado….. Splines to match or contrast…

  11. Dino B. on April 13, 2022 at 6:06 pm

    I am following all of the instructions from This Old House while building my house.

  12. 5th Journey Off-Grid Homestead on April 13, 2022 at 6:08 pm

    Always good info, have been watching for years

  13. Michael Katt on April 13, 2022 at 6:11 pm

    I wouldn’t go as far as saying a master class but good info none the less.

  14. Rick From the Cape on April 13, 2022 at 6:15 pm

    Love Tommy! A real craftsman.

  15. Karl Alan on April 13, 2022 at 6:15 pm

    That biscuits type slot with the hardware was cool. Never seen something like that before. Also didn’t know there was an automated dowel machine like that either. Always seen jigs you clamp to the project instead.

  16. Betty Maverick on April 13, 2022 at 6:18 pm

    For most purposes most of these joints are overkill and more work than needed. Super strong joints for weak structures. Just saying.

  17. Jeb Prendergast on April 13, 2022 at 6:19 pm

    Take two boards, nail ‘em together, boom!

  18. rbnhd1976 on April 13, 2022 at 6:21 pm

    Thanks toh

    let’s go brandon

  19. Manny Fresh on April 13, 2022 at 6:21 pm

    Why can you build cabinets all day without worrying about expansion???? Is it because of the use of ply?

    Thanks for the information. Learning a lot as a newbie woodworker.

  20. august on April 13, 2022 at 6:21 pm

    Did they mention dovetail and I missed it ?

  21. Asperger’s Corner on April 13, 2022 at 6:21 pm

    Is that Mike Ditka?

  22. a 6 on April 13, 2022 at 6:23 pm

    Floating tenon: aka oval dowel

  23. 日本 japan火の鳥 on April 13, 2022 at 6:25 pm


  24. Caleb Hensinger on April 13, 2022 at 6:29 pm

    I’d have have to imagine wood joints would be quite the carcinogen… 😉

  25. Timothy Schriefer on April 13, 2022 at 6:30 pm

    There was the guy not too long ago showing that end grain glue was actually stronger.

  26. 𝕱𝖑𝖊𝖊𝖎𝖓𝖌 𝕴𝖑𝖑𝖚𝖘𝖎𝖔𝖓𝖘 on April 13, 2022 at 6:31 pm

    Love the Tom Silva videos the other guys are great to 👍

  27. JimL on April 13, 2022 at 6:31 pm

    Weird you missed the most popular and historical joints – mortise and tenon, and dovetail.

  28. efox2001 on April 13, 2022 at 6:31 pm

    What is the name for the tool that drills two holes at once? I haven’t seen that one before.

  29. MasterHustler on April 13, 2022 at 6:32 pm

    Tommy is a pros pro. Thank you for the knowledge.

  30. Art VanDelay on April 13, 2022 at 6:33 pm

    Times like this, you miss Norm Abram. No offense fellas.

  31. Alonzo Johnson on April 13, 2022 at 6:34 pm

    Tom 🎸

  32. ming on April 13, 2022 at 6:42 pm

    Very good job !

  33. LeicaGermanShepherd on April 13, 2022 at 6:43 pm

    endgrain glueing is good, it has been proven.

  34. Tim Kendall on April 13, 2022 at 6:44 pm

    I’ve been watching This Old House going all the way back to Bob Vila, I always learn something new. Thank you👍

  35. N. Johnsoh on April 13, 2022 at 6:46 pm

    You know you will get called out on the biscuit joints:
    1) Stronger due to glue surface area? No.
    2) Perhaps a little if grain direction of the biscuits is perpendicular to the joint? A little.
    3) Good for alignment? Absolutely.

  36. Todd on April 13, 2022 at 6:47 pm

    Draw = drawer Idear = Idea …. Remove the R when it’s there and add an R where there isn’t one. Got it.

  37. Tyler Harlow on April 13, 2022 at 6:47 pm

    Tommy & Kevin, top tier duo

  38. Rt L on April 13, 2022 at 6:47 pm

    Indirectly-related question: in an old house, when you re-paint previously-painted door casings, do you caulk the edges where the two side jambs meet the head jamb?

  39. SciPunk215 on April 13, 2022 at 6:48 pm

    Very thorough.
    The only thing missing was the spline.

  40. Bruce Chan on April 13, 2022 at 6:48 pm

    I didn’t get the last part about pocket screws. Tom said that you cant use pocket screws if the width is greater than 6 inches. Moments later he also said that you can build cabinets that are 3 or 4 feets.

  41. Craig Yarmula Sr on April 13, 2022 at 6:49 pm

    Another great video.

  42. forseti52 on April 13, 2022 at 6:50 pm

    Dove tail joint?